# Deep Cycle Batteries



## SMC67

I like to know $$ vs Life on Deep Cycle Batteries. I will only be using them for DC output devices such as lights, small water pumps. As I improve my system; my goal is to have some type of emergency power with an ac converter to run an item as large as window unit Air conditioner for an example. I may dabble a bit in some small solar panels for recharging and storing electricity.

What little I know is, the big hang up on solar power is the ability to store electricity efficiently.

so, at some point doesn't the dollar value match the practicably of choosing a " Good " Deep cycle Battery?? Are you getting a premium product for a premium price or would a lesser product be as " Good ".

Example, I hardly see any different in a lot of batteries, but I have noticed a jump in quality in small batteries when you buy the Top Line premium. But, Having said that I don't believe is is worth the extra price vs say any other the other lesser brands. Unless you buy some cheap0 dollar store brand and they are extreme opposite of top line premium quality.

thnx


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## Tirediron

Deep cycle battries can handle deeper discharge than Automotive batteries, Golf cart batteries are the next step. then the designed for solar big bank batteries
Some old electric fork lifts have decades old batteries in them
Lobotomi has a lot of battery knowledge he may pick this one up
Solar power requires a shift in use habits , learn to use the suns cycles to your advantage etc:beercheer:


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## nj_m715

Golf cart batteries are considered to be the best bang for the buck unless you can get your hands on some good used batteries. GC batts due require you to keep an eye on the water level, but they make "self watering" caps that reduce water loss. AGM batteries are good and don't off-gas when charged, so some people like to use them over GC batts inside living space like a camper or small cabin.

I have AGM's in my slide in camper, but they're getting old. I'll probably replace them with a pair of golf cart batteries. It'll be cheaper and will boost my ah as well.


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## tommu56

SMC67 said:


> I like to know $$ vs Life on Deep Cycle Batteries. I will only be using them for DC output devices such as lights, small water pumps. As I improve my system; my goal is to have some type of emergency power with an ac converter to run an item as large as window unit Air conditioner for an example. I may dabble a bit in some small solar panels for recharging and storing electricity.
> 
> What little I know is, the big hang up on solar power is the ability to store electricity efficiently.
> 
> so, at some point doesn't the dollar value match the practicably of choosing a " Good " Deep cycle Battery?? Are you getting a premium product for a premium price or would a lesser product be as " Good ".
> 
> Example, I hardly see any different in a lot of batteries, but I have noticed a jump in quality in small batteries when you buy the Top Line premium. But, Having said that I don't believe is is worth the extra price vs say any other the other lesser brands. Unless you buy some cheap0 dollar store brand and they are extreme opposite of top line premium quality.
> 
> thnx


Running an ac will be out of the question unless you are ready to spend major bucks (10's of thousands)
I have an off grid cabin with 600 watts of panels good inverter and 1460 ah of battery (8 L16"s) charge controller and it was over $6000 in materials only. I can run a well pump designed for off grid OR microwave OR toaster (read intermittent) loads only one of these at a time.

Ill Run some really rough numbers for the AC unit to show you what it would take 
120v amps 15 convert it to 12volts 120/12 = 10 take 15 amps and multiply it by 10 15x 10 = 150 amps so if you run it for 1 hour it will take 
150 amp hours a pair of Trojan T-105 (6volt golf cart battery)	225 AH

So you could run it for an a little more than an hour on one battery

So you need 20 pairs to run one day now 225 ah x 20 = 4500 ah

Each one is about $115.00 now remember its 20 pairs 40 battery's 
115x40=$4600.00 you don't have solar panels, charge controller, or inverter (which will have to be 2X the running current of AC unit)

Sorry for the long reply.

tom


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## Dixie

good used batteries. GC batts due require you to keep an eye on the water level, but they make "self watering" caps that reduce water loss.


I bought six Trojan T-105's for my GC and it was well over $600. I didn't want to get used batteries and have trouble with them in a few months. Just remember they use distilled water not tap or bottled water so buy a few extra for the pantry.


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## SMC67

tommu56 said:


> Running an ac will be out of the question unless you are ready to spend major bucks (10's of thousands)
> I have an off grid cabin with 600 watts of panels good inverter and 1460 ah of battery (8 L16"s) charge controller and it was over $6000 in materials only. I can run a well pump designed for off grid OR microwave OR toaster (read intermittent) loads only one of these at a time.
> 
> Ill Run some really rough numbers for the AC unit to show you what it would take
> 120v amps 15 convert it to 12volts 120/12 = 10 take 15 amps and multiply it by 10 15x 10 = 150 amps so if you run it for 1 hour it will take
> 150 amp hours a pair of Trojan T-105 (6volt golf cart battery)	225 AH
> 
> So you could run it for an a little more than an hour on one battery
> 
> So you need 20 pairs to run one day now 225 ah x 20 = 4500 ah
> 
> Each one is about $115.00 now remember its 20 pairs 40 battery's
> 115x40=$4600.00 you don't have solar panels, charge controller, or inverter (which will have to be 2X the running current of AC unit)
> 
> Sorry for the long reply.
> 
> tom


yeah, ok maybe I was reaching when I said an Ac unit. But maybe by the time I get everything installed, maybe they come up with a somthing will store electricity :surrender:


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## nj_m715

A/C doesn't have to cost several thousand. You can get to work in a corvette or a pinto. I have a/c in my camper with a HF 1kw inverter. It can run my small microwave. Of course it doesn't do it all day, only a few minutes. I don't expect it to last forever but it is cheap enough to replace should the time come. I have about $500-$600 in my set up, but it is a small scale camper sized system. 

You don't need (or want to carry) 6 GC batteries if you're wired to your alt. 

To make a long answer short, the life of any battery depends on the care you give it. Keep it charged and watered, don't run it down too far and it will last years.


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## gypsysue

We use energy-efficient ceiling fans in our off-grid, solar-power cabin. Cools us off with little power draw on the system.


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## Walker

*"Cycle-life" in lead-acid cells*

Here's some info on battery life that we published on our website (GeoPathfinder) that compares sealed gel batteries with sealed AGM (absorbed glass mat), but the life times for AGMs are about the same as "flooded" cells. The added cost of gels starts to look pretty good when you see all of that added life!

Cycling Ability vs. Depth of Discharge	(for Deka batteries) 
Typical Life Cycles: 
Capacity withdrawn:	Gel Batteries	AGM Batteries	
100% 450 cycles	150 cycles	
80% 600 200	
50% 1000 370	
25% 2100 925	
10% 5700 3100


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## dahur

Has anyone experimented with a desulfator? I realize if you have warped, or eroding plate damage, nothing will fix that, but I'm thinking about getting one for my tractor's 12v. The one I'm looking at charges, and desulfates, (about $100). The guys on the Golf Cart forums are into batteries, and the ones's that have one say their desulfator has been successful in extending the life of their batteries.


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## Tex

Getting used batteries is becoming more tough, because they can be sold for scrap for up to $.30/lb. People aren't giving them away as easily as they used to. I still get them occasionally, but usually they aren't salvagable. Even so, used is the way to go if you have sources.


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## nj_m715

dahur said:


> Has anyone experimented with a desulfator?.


Don't waste the money. You guys know me, I'm all about home made, cheap options. I built built one of these yrs ago and "saved" a few batteries. It limits the amps not the volts, so it can "force" a charge into an old battery that may not otherwise take a charge. Don't make one unless you understand some electrical theory. You can hurt yourself or overcharge the battery.

3 Dollar Battery Charger


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## sailaway

dahur said:


> Has anyone experimented with a desulfator? I realize if you have warped, or eroding plate damage, nothing will fix that, but I'm thinking about getting one for my tractor's 12v. The one I'm looking at charges, and desulfates, (about $100). The guys on the Golf Cart forums are into batteries, and the ones's that have one say their desulfator has been successful in extending the life of their batteries.


Uncle Joe showed me his desulferator this summer and a couple of batteries he had hooked it up to, it works. I bought one at Northern Tool for $75.00, but haven't had an opportunity to use it yet. Sail


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## UncleJoe

sailaway said:


> Uncle Joe showed me his desulferator this summer and a couple of batteries he had hooked it up to, it works. I bought one at Northern Tool for $75.00, but haven't had an opportunity to use it yet. Sail


Yes I do. I have a 5w solar charger/desulfator that DW got me for Christmas last year. I didn't set it up until March when I put an 9 year old interstate battery on it.
Yes it does work, however, it took until late Aug for the "maintenance charge" indicator to come on; meaning the battery was ready for use. It's in a 1982 GMC dump truck right now and it works well for the time being but I'm interested in seeing how it will hold up during extended periods of cold weather.


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## dahur

UncleJoe said:


> Yes I do. I have a 5w solar charger/desulfator that DW got me for Christmas last year. I didn't set it up until March when I put an 9 year old interstate battery on it.
> Yes it does work, however, it took until late Aug for the "maintenance charge" indicator to come on; meaning the battery was ready for use. It's in a 1982 GMC dump truck right now and it works well for the time being but I'm interested in seeing how it will hold up during extended periods of cold weather.


That's close to what the Golf Cart guys say. It doesn't work overnight, but it takes time for the square wave pulses to knock the sulfide crystals off the plates, and back into electrolyte. When that happens the battery can take and hold a charge better. It's still nice to hear of success. This is the one I'm thinking about:
Amazon.com: 12-V Xtreme Charge Battery Charger - XtremeCharge is designed to be a MAINTENANCE charger for any type of 12-V lead-acid battery. By imposing only the appropriate amount charge rate, the battery is maintained safely at its proper operatin

If I fully charge my tractor battery, let it set overnight. When I test it in the morning, it's at 12.55v which is about 85% charge. When I test the cells with my hydrometer, it's showing in the green, but not too far in. Since it's only a year old, I want to see if this will make a difference in holding more of a charge.


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## johnc

*running an ac unit off grid*

I have 3 80 watt solar panels on a rotating pole to follow the sun. I have a 650amp hour battery storage. I run a small window ac unit in the summer only when it can get maximum sun at peek hours 11am to about 3pm with half discharge of my battery bank . I have about 7000 invested plus my wife watches tv threw the solar energy . Plus got a good chunk of money back on my taxes. Lowered my electric bill about 25.00 in the summer long term I be leave it will pay for it self John


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## johnc

SMC67 said:


> I like to know $$ vs Life on Deep Cycle Batteries. I will only be using them for DC output devices such as lights, small water pumps. As I improve my system; my goal is to have some type of emergency power with an ac converter to run an item as large as window unit Air conditioner for an example. I may dabble a bit in some small solar panels for recharging and storing electricity.
> 
> What little I know is, the big hang up on solar power is the ability to store electricity efficiently.
> 
> so, at some point doesn't the dollar value match the practicably of choosing a " Good " Deep cycle Battery?? Are you getting a premium product for a premium price or would a lesser product be as " Good ".
> 
> Example, I hardly see any different in a lot of batteries, but I have noticed a jump in quality in small batteries when you buy the Top Line premium. But, Having said that I don't believe is is worth the extra price vs say any other the other lesser brands. Unless you buy some cheap0 dollar store brand and they are extreme opposite of top line premium quality.
> 
> thnx


I would use a gel filled batteries last longer and be able to withstand a greater discharge. And will charge back with no problems the coast for one is a bit more but you will get your money worth. John


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## piglett

johnc said:


> I would use a gel filled batteries last longer and be able to withstand a greater discharge. And will charge back with no problems the coast for one is a bit more but you will get your money worth. John


if any of you guys are near Newark Delaware I can give you the address to a place that has 6 month old glass mat batteries. they come from the city busses in Philly , 
the Gov. pays for most of the cost on the busses & they have always changes them out every 6 months even after they switched to glass mat bat.

I got 4 of them for my 96' Freightliner with a 12.7L Detroit
the price $35 each:2thumb:

piglett


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## johnc

what type of amp hour rating does those batt. have if they are less then 100amp hours I would not mess with them. Why I run some power at night the lower the amp hour rating the less time it has to run. John


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## nj_m715

Optima batteries are in the $185 ball park, so it's a very good deal. They hold up very well and can survive a deep discharge that would kill an acid battery. If you want more amp hours, wire more of them together.


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## piglett

johnc said:


> what type of amp hour rating does those batt. have if they are less then 100amp hours I would not mess with them. Why I run some power at night the lower the amp hour rating the less time it has to run. John


 these are BIG batterys about 50% bigger than the Optima batteries that i have seen. i still have one here at the house to start my old oliver bulldozer.

this is what it it says on the label on the side
"Power-Tech absorbed glass mat technology E.P.M. products Baltimore,Md."

hope that helps
piglett


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## johnc

optima batteries are not that great out of the 6 batteries 3 optima at 55amp hour 3 universal batt. at 110amp hour hevy discharge and charge 2 plus years 2 optima are bad the universal batt. cost about 225. you why the dif. John


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## nj_m715

I don't know what you said, but I like optima (or any glass mat) over lead acid batteries. I ran them down to very low voltages and they recovered. Most acid batts would have been dead. Once they get into single digits, they just don't hold a charge. 
I have overheated an optima winching my jeep out of a mud hole. I melted the lead out from around the side post bolt. I never knew there was a standard 3/8" nut inside of a side post mount. That battery was still in the jeep 8 yrs later when I sold it. IMO they cost more, but they are worth it. The only time I would use something else is when I have a low voltage cut out, like most inverters use. All my vehicles have glass mats.


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## johnc

For a vehicle they are outstanding and they do last a lot longer then a acid filled batt, not the best one on the market for use within a solar system I use a a higher amp glass mat bttery also John


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## nj_m715

I'd agree with that. I run optimas in the cars and I have a couple golf cart batteries waiting to be hooked to a few panels. I just can't get it done now. Golf cart batteries are the best bang for the buck, unless you can get your hands on a good used forklift battery


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## pdxr13

*Deka Gel cycle life*

If you look at the spec sheets for DEKA gel deep cycle batteries, you will see that one of their charts has a note for a certain model "cycles x2" meaning that to fit this one battery on the chart and not make junk of the rest, the scale of life-cycles had to be manipulated. That model is an 8ggc2, which was designed to run in electric cars (vibration resistant, rapid and deep discharge, high-current charging, good power to size/weight, not more expensive than other AGM or gel, made in USA).

They aren't cheap, and are 6v, so 48v requires 8 batteries, 7 heavy copper interbattery jumpers, and about 600# with racking. With care, and no deeper than 50% depth of discharge (2100W/Hrs to 50%), these could be still 80% good at 10 years. Yeah, 2 grand + shipping is a lot, but they are no-maintenance gels.

I saw an ad this morning for Group27 deep cycle flooded batteries at $69.99 each. A set of 8 of these with core charge would be $600. They would last 3 years, used carefully (never, ever, discharged below 50%, topped up with solar/generator daily), with watering/wiping/venting and a good charger. This would be 2 strings of 4 (12v), paralleled to make 48v. They might buy the time needed to save $100 a month toward some gel's.

Why 48v battery bank? Higher voltages reduce losses from heating wire. 48v is right on the cusp of transitioning "low voltage" to "high voltage" because of the ability of a 45v source to just-barely make enough current across your chest cavity to stop your heart if everything is just perfectly wrong. 48v does not come close to needing special wire, breakers, assembly techniques, just a slight bit more caution about checking to see if the wires are powered before working on them.

Inverters over about 2500W are not found in 12v input. It's too much current between the battery and inverter at full rated load, and people like to use what they think they paid for. 24v battery voltage inverters go up to about 3500W, and 48v battery system inverters are often 4KW "continuous" (and really capable of it), with very short times to about double that. The reason to get a 4KW inverter is not to use it, but so that starting loads like a refrigerator or pump motor or microwave oven can start properly.

If a person used a 4KW inverter on the above-mentioned 600# $2000 (or 600# $600) pile of batteries at full power, say running a waterheater element (crazy, but for testing) at 120v (4000W), the battery would be at 50% discharged in 20 minutes. Don't do this, as it probably exceeds recommended max. discharge rate of the batteries. Plug into the wall socket on the grid and 2KW/hr is about $0.25 added to your electric bill (no problem, unlimited!), but it would bring a $2000 battery to its' knees quickly. This was the wrong test for a battery. This is a test for a fuel-powered engine-generator set rated at an honest 4-6KW/5hp, where for a half-gallon of fuel ($2) the generator can put out a lot of power for a half-hour, to run power tools, clothes washer, charge batteries, pump water, run air conditioning, etc.

Inverters exist in my world to allow a generator to not run while still having light loads or very-brief medium-heavy loads using grid-standard or 120v/60Hz power-conserving appliances. Solar panels do the same job of allowing a generator to not run while charging the top 15% of battery capacity. Batteries charge fast while deeply discharged, and "accept" less and less current as they approach their fully-charged state. A battery bank at 50% is a perfect candidate for high-current charging with a genset that can deliver a lot of current, but as the battery gets charged to about 85-90%, it won't accept current quickly. Generators don't "like" to be run lightly loaded, and will carbon the valves, leading to increased maintenance and lower overall efficiency. It might take 90 minutes to charge from 50% to 85% on a genset, and 3 hours more to charge to 95%, all while burning expensive gasoline/propane/Diesel and counting up run-hours on the rotating equipment. This is a job for mid-day sun! A modest solar array of a few hundred STC Watts can continue charging the battery bank to near-100%, while running the light mid-day always-on loads like refrigeration.

Flooded (like the $600 bank of Group27 batteries) batteries "sulfate" when left uncharged, or partly-charged. This reduces their capacity permanently, with small-hope offered by "pulsing desulfators". Charged batteries also resist freezing in cold weather much better than discharged batteries. Eventually, batteries neglected become so useless that you buy a new set of batteries or begin using tea light candles by the hundred for heat/light. Gel/agm batteries show little of this effect as part of paying 5x as much initially.

It's a "system". Costs can be reduced and flexibility increased by having several ways to charge and discharge battery banks, based on conditions and opportunity. Sun worshippers pay dearly for an all solar PV system in the Pacific NW, with recommended battery bank size of 10 days of average AND peak consumption, with zero (0) useful Amps output by an array during common November-February conditions that can last weeks. Adding wind, micro-hydro, and/or internal combustion lets the battery size get more reasonable at around 3 days, and the PV cost drops to a good used car rather than a new MBZ 600-series. But....no, go ahead an get all PV if you have the cash and huge unshaded space for the array.

Cheers.


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## extexanwannabe

Might any of you recommend a website or a book that could detail using inverters, deep cycle marine batteries, and solar chargers? It is a very detailed subject, and I'd like to learn more about equipment, cost, efficiency, etc. thanks!


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## YouNeedBatteries

For the most part deep cycle rechargeable batteries are all pretty similar, no matter what brand. There are some brands that are more reliable, but they are significantly more expensive and their price is not proportionate to their reliability.

GEL cell batteries are more reliable, can stand larger ranges of temperature, and you can take them on an airplane (not that it matters in this case). They are also much more expensive and most people actually don’t need them. Also, I would very careful when purchasing a GEL cell battery. Many retailers (you’d be surprised how many) sell AGM batteries as GEL cell and most customers won’t ever know the difference. It isn’t a GEL cell battery unless it actually says GEL on the battery itself. I only sell AGM batteries. They work just fine for their applications. 

As for the golf cart batteries, nj_m715 is right when he said that they are the best bang for your buck. However, I would shop around. Most golf cart batteries are nothing but common 12V 35Ah (anywhere between 30Ah to 40Ah actually) batteries. The places that sell golf cart batteries sell them for much more when you can just as easily get the same battery somewhere else for cheaper. Cross reference it with part number Group U1. This is a very good and popular battery, but for more power, I would go for the 12V 55Ah (Group 22NF), 12V 75Ah (Group 24), 12V 90Ah (Group 27), and the 12V 110Ah (Group 30H). If you search for the batteries using these part numbers, you’re more likely to get a better deal.


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## Meerkat

extexanwannabe said:


> Might any of you recommend a website or a book that could detail using inverters, deep cycle marine batteries, and solar chargers? It is a very detailed subject, and I'd like to learn more about equipment, cost, efficiency, etc. thanks!


 I already made the mistake of buying marien batteries according to ' solarrvpanels.com '. On the site it gives info about wiring batteries and what batteries to use.I think somebody here gave me the site address to help me learn more,too bad I did'nt read it through before i went and bought 2 marien batteries and a small converter.People here tried to help me but i was as green as a new blade of grass.
So now I could cry in frustration of myself.
Listen and learn to these people,theres no cheap shortcuts.


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## LincTex

Meerkat said:


> I went and bought 2 marine batteries and a small inverter.


Do they say "Deep cycle" or "trolling"?

........ or do they say "marine starting"?


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## Meerkat

LincTex said:


> Do they say "Deep cycle" or "trolling"?
> 
> ........ or do they say "marine starting"?


 They are in the building outside so soon as I can check on them I'll let ou know.Thanks Tex.


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## pdxr13

*books*

"Living on 12 Volts with Ample Power", 
"Wiring 12 Volts for Ample Power"
Use interlibrary loan to borrow the paper books.
Buy a .pdf from their site on CD http://www.amplepower.com/products/cd/index.html

Really useful ideas from boat-electrical people in Ballard (Seattle) Washington, even if you don't buy their fancy equipment.


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## Tex

The only drawback of wiring for 12V is that you have to use much bigger wiring. Lower volts requires higher amperage to get the same power. I like the simplicity, but a house of any size will be mega expensive to wire.


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## Tirediron

Tex said:


> The only drawback of wiring for 12V is that you have to use much bigger wiring. Lower volts requires higher amperage to get the same power. I like the simplicity, but a house of any size will be mega expensive to wire.


You might want to research the wire size a bit, the final load is in watts, volts x amps, so the load on the wires should be about the same unless the 12v device is a lot less efficient, which should be the opposite. the main reason direct current isnt used main stream is because it is hard to transmit long distances.
There may be some wire size difference but it shouldn't be huge. of course DC stranded wire will be more money because of sales volume.


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## Tweto

Tirediron said:


> You might want to research the wire size a bit, the final load is in watts, volts x amps, so the load on the wires should be about the same unless the 12v device is a lot less efficient, which should be the opposite. the main reason direct current isnt used main stream is because it is hard to transmit long distances.
> There may be some wire size difference but it shouldn't be huge. of course DC stranded wire will be more money because of sales volume.


Tirediron;

I know what stranded wire is, but what is DC stranded wire?? BTW I agree with everything else you said.


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## LincTex

Tirediron said:


> You might want to research the wire size a bit, the final load is in watts, volts x amps, so the load on the wires should be about the same unless the 12v device is a lot less efficient.


Not true at all. 
I can send 1 amp down a 22 gauge wire at 1000 volts (I do it all the time in aircraft) 
and that VERY thin wire will handle 1000 watts with ease. (V x A = W)

You can not take the same size wire (22 gauge) and expect it to handle a 1000 watt load at 12 volts (83.3 amps) without a lot of smoke.

This is ALWAYS true: Wire SIZE determine how many AMPS it can handle, period.

Wire size has nothing to do with voltage (but type of insulation does).

A 1000 watt space heater on 120 volts draws only 8.3 amps - - a VERY easy load to handle on standard 14 or 12 gauge household wiring. You cannot run a 1000 watt device on 12 volts unless you have wire big enough to handle more than 83 amps.


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## trkarl

Tirediron said:


> You might want to research the wire size a bit, the *final load is in watts*, volts x amps, so the load on the wires should be about the same unless the 12v device is a lot less efficient, which should be the opposite. the main reason direct current isnt used main stream is because it is hard to transmit long distances.
> There may be some wire size difference but it shouldn't be huge. of course DC stranded wire will be more money because of sales volume.


Watts is the amount of work to be done. Lower the voltage you must raise the amperage. Wire size is determined by the max amount of amperage to be put through it. More than that and the wire burns up because of the resistance to the amps flowing through it.

That is why your house breakers are rated in amps. Pull too many amps and the breaker trips preventing a fire from the wire burning up. Check out a wire gauge ampacity chart. It will tell you the gauge or size of wire you need to safely run a given amount of amps through it.

LincTex nailed it.


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## Tex

Tirediron said:


> You might want to research the wire size a bit, the final load is in watts, volts x amps, so the load on the wires should be about the same unless the 12v device is a lot less efficient, which should be the opposite. the main reason direct current isnt used main stream is because it is hard to transmit long distances.
> There may be some wire size difference but it shouldn't be huge. of course DC stranded wire will be more money because of sales volume.


My "Ugly's" electrical reference and the NEC say otherwise.

The reason AC is used on power lines is because AC voltage is easily stepped up and down using transformers. Also, AC power is the natural result of a rotating generator. The voltage is stepped up on the transmission lines because the higher voltage will require less current and that results in less "line loss". The voltage is stepped down at the end user for safety.


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## nj_m715

Tex said:


> My "Ugly's" electrical reference and the NEC say otherwise.
> 
> higher voltage will require less current and that results in less "line loss"


So, you're saying that your book says it's easier to transmit over long distances?


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## Tirediron

I post corrected, thanks for the good explanations, 
Stranded wire is a cable made up of multiple smaller wires, it is somewhat more efficient for dc loads than solid single strand usually used for A/C


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## dragon5126

nj_m715 said:


> Don't waste the money. You guys know me, I'm all about home made, cheap options. I built built one of these yrs ago and "saved" a few batteries. It limits the amps not the volts, so it can "force" a charge into an old battery that may not otherwise take a charge. Don't make one unless you understand some electrical theory. You can hurt yourself or overcharge the battery.
> 
> 3 Dollar Battery Charger


Modern desulfators have nothing to do with amperage, they charge by using a frequency modulated voltage that causes a continous charge/discharge rate that causes the sulfates to fall off the plates/grids so lead is deposited on clean lead rather than on sulate/ sulfer coated lead.


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## nj_m715

The 120v dc charger should clean up the plates too. It pulses high voltage to break up and dissolve the sulfur. As the battery "takes" the charge the voltage lowers and the amps increase. If you want to buy one, than buy one. I'm just saying you can do the same thing for a couple bucks.


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## Tex

nj_m715 said:


> So, you're saying that your book says it's easier to transmit over long distances?


What Tirediron, Linctex, and myself are saying is that wiring is rated for current and not power. If you wire a house for 12VDC, it will require 10 times the current capacity of a house wired for 120V to handle the same power. It was kind of a tangent to the original intent of the thread.

AC is easier to transmit because it is easier to step it up and down with transformers. The original power lines were DC until they realized that line loss was killing them and DC cannot be as easily increased to high voltages. Transmissions lines have resistance. P=I^2*R. The higher current causes more power to be wasted in the form of heat. The current is lowered on transmission lines by boosting the voltage. This lowers the required current for the power demanded by the grid. P=E*I

To get back on track, dragon5126 is right about newer desulfating battery chargers. Wet cell batteries use an equalize charge (higher voltage) for a recharge after a deep discharge, but restoring a bad battery will require a charger that dragon5126 is describing. And even then, it may not work. It depends on the condition and type of failure in the battery.

edit: nj_m715 - I think you and dragon5126 are talking about the same chargers, just using different terms.

My specialty isn't really batteries. I fix Uninterruptible Power Supplies. They convert AC into DC to charge batteries and then convert that DC back into AC to feed the critical load. A typical DC bus in this equipment is floated at 540VDC. I just take care of batteries because they are connected to my equipment. I have several friends who specialize in batteries and rectifiers(chargers) if I need help with problem cells. Sometimes, we will put a cell charger on an individual 2V wet cell. (desulfating charger used to boost the sagging voltage of an individual cell) Half the time the cell ends up being replaced.


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## Tex

If you ever get a chance to salvage some oval shaped wet cells made by AT&T, get them. They were designed to last over 75 years. Many of the cells I take care of are over 30 years old and still going strong. They have an oval base and are a little over 2 feet tall.


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## pdxr13

​


pdxr13 said:


> "Living on 12 Volts with Ample Power",
> "Wiring 12 Volts for Ample Power"
> Use interlibrary loan to borrow the paper books.
> Buy a .pdf from their site on CD http://www.amplepower.com/products/cd/index.html
> 
> Really useful ideas from boat-electrical people in Ballard (Seattle) Washington, even if you don't buy their fancy equipment.


The topic is actually "Low Voltage DC", "Charging and Battery Management", "Wiring for Anticipated Loads" and "Economics of Making Your Own Power", not necessarily just 12v. Totally agree that 24v and 48v battery banks make good sense when running an inverter over about 1500W, with 48v nearly REQUIRED to use a big inverter that can real-world put out a steady 4KW+. 0000 copper cable is some big money when doing 50'+ runs, not to mention the PITA of routing and the weight in a vehicle.

I've developed my own "rules of thumb" for where to use 12v, 24v, 48v in alt-energy application.

12v: Where cheap/light, with short runs, and not a lot of power is needed. Truck camper is ideal for all-12v. Small travel trailer (<18' without A/C or generator built-in) will also run fine on 12v. Think "small, power-efficient, high-quality" for the system. No electric heating elements, ever. No hairdrier, no toaster, no little plug-in space heaters! Propane as much as possible. A pair of 6v golf car batteries, <300W PV, MPPT controller will support a 4 cubic foot refer with tiny ice cube freezer as long as it's a rocker-pump type, as well as run heater ignition/blower, laptop computers, cellphones, LED lights, receive-comm, etc. A tiny inverter-generator, like gasoline Honda/Yamaha 1000 W model, will do backup charging (during dark weather or soot blocking sun) and tool-running duty.

24v: Here's where we start running 2500W pure sine inverters to use kitchen luxuries like blender, microwave, and Kitchen Aid mixer. Try to keep DC wire runs short/neat and fat, just like 12v, but in a bigger vehicle (12000 pound gross motorhome, 35' sailboat, etc.) or a smaller structure. Many options for batteries, from a pair of 12V group27's for a couple hundred bucks (100A @ 24v = 1200W/H to 50% DoD) to a quad of 6v 65# golf cart batteries (200A @ 24v = 2400W/H to 50% DoD) to a set of Twelve 2v batteries that weigh 120# each for an off-grid cabin. Lots of options!

48v Bigger vehicle or medium structure. 48v is the nominal battery voltage, not necessarily the voltage put out by the PV, wind generator, or internal combustion genset. The advantage of 48v is that most of the system is going to be using 120v/240v from the inverter(s). 6KW inverters are safe and reasonable when correctly installed close to a battery bank designed for the load. Pumps for deep wells are sometimes 240v, which several larger inverters do put out. Costs are higher, generally, than for 12v or 24v systems, but copper costs can be a savings, and lower-currents in the system make for better fire safety. No free lunch.

42v systems are found in several vehicles, including the GM Silverado Hybrid. Will this become a higher-than-24v standard for the future?

Older RV's with A/C seem to want to run their generators all the time to provide grid-like power availability. This was great when gasoline was 100 gallons for $23.00 and you made $700/week, but not so great when it's 17x that price and you make $500/wk. What if you could run the genset for a couple hours every couple of days and use an inverter with batteries in between for light loads? Much fuel would be saved, and it would be quiet! The generator would need the oil/filter changed every 100 hours still, but that would not be once a week, but every 6 months. Much better.

When "dry camping" (not in a park with water/power/sewer hookups), I've found that the limit to how long we could stay was how much water we had, not how much fuel we had. But, using less fuel means we can use that space/weight to bring more water and stay longer. This is true hiking, car camping, trailer, or monster motorhome camping; water is life. On a sailboat with a watermaking machine, power + time equals fresh water to supplement tankage. Power can be genset, propulsion engine, wind, solar, or batteries.

Cheers.


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