# Troubleshooting Deep Cycle Batteries



## phideaux (Nov 7, 2015)

I'm about to pull my hair out , trying to find the status of my batteries in my Bad Boy MTV. This set also is used to power my PS inverter.

It has 8 batteries 6v, 242 AH .
I have an auto watering system , so I keep a good water level.
I keep the charger on them anytime I'm not using the vehicle.

A few months ago , I noticed it was losing power, getting weak, until finally it just was dead.

Found out the the extension cord that plugs into the onboard charger was bad, and therefore the batteries weren't being charged, and were drained totally,.

So I got new cord , checked water levels, and ran charger 24 hrs, until it auto shuts off when fully charged.

Now , my question , for battery Gurus here,

I know 3 ways to check batteries, 
1. Voltage, with a digital voltmeter.
2. Charge of each cell, via specific gravity, using a Hydrometer.
3. Battery amp test, using a load tester, ( not so good on deep cycle 242 AH batteries.)

*If anyone has any other methods of proving/testing deep cycle batteries , I would appreciate the help.*

I want to find/prove which batteries, of the 8, are truly not holding charge , before buying 8 new ones.

I'll keep the good ones and core trade the bad ones.

The MTV only runs 15 minutes before losing power, after full overnite charge.

:brickwall::help:

Jim


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## Tirediron (Jul 12, 2010)

I would load test each battery individually, the weak ones should drop off pretty quickly, before you replace them I would try "over charging" the weak ones, with an old school charger, for about 10 hours , un less you have a battery conditioner, then use that, although just a plain old charger, without auto shut off is all that I ever use.


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## phideaux (Nov 7, 2015)

I've been told , to never use a fast charger on deep cycle batteries.
Don't know about that myself, but they say it will ruin a deep cycle.

I have a Genius 12V conditioner charger, that I can run on them 2 at a time.

My old hydrometer is not so good anymore , so I got a new one ordeed , to try and get a good read on every cell.

Hope I get a better reading.



Jim


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## RedBeard (May 8, 2017)

Sounds like a sulfate problem. Battery genie make a really nice desulfate charger.


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## RedBeard (May 8, 2017)

Little info for you.
https://www.batterystuff.com/kb/articles/charging-articles/make-the-bad-sulfation-go-away.html


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## RedBeard (May 8, 2017)

phideaux said:


> I've been told , to never use a fast charger on deep cycle batteries.
> Don't know about that myself, but they say it will ruin a deep cycle.
> 
> I have a Genius 12V conditioner charger, that I can run on them 2 at a time.
> ...


Just saw this post. Sounds like you might already have one.


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## phideaux (Nov 7, 2015)

Well I don't have a load tester . 
At least one for deep cycle 242 AH batteries.

I'v got a new Hydrometer coming.

I do have a 11 stage Genius 








and one of these








Jim


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## obg12 (Apr 9, 2016)

Caribou said:


> You're pretty sure that you have one or more dead batteries. Test your batteries. The load test will tell you which batteries and the hydrometer will tell you which cells, your choice.
> 
> Overcharging the weak ones will cause the surface of the plates to clean themselves revealing new lead to better conduct electricity. The old dead material falls to the bottom of the battery. When the dead material builds up to the bottom of the plates it shorts out your batteries and you can hear the waning tones of the Fat Lady's song. Your better built batteries will have a deeper void at the bottom to allow for more treatments.
> 
> If your battery tests dead, and you are considering using it for a core deposit, you have nothing to lose by over charging.


I talked to a guy that works at Johnson Controls battery recycling plant not far from here a few years ago,he said they vibrate battery's on a rack while charging I think they do that to settle the waste lead to the bottom


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## hiwall (Jun 15, 2012)

Find the bad batteries and try giving the epsom salt treatment to put fresh life in them. Maybe get another year or two out of them.


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## Flight1630 (Jan 4, 2017)

On my big truck I have 4 when I have a bad battery i know it because it cranks really slow in the morning. If you don't change out the bad battery it can and will kill the rest. Also do the load test a day or so after you charge them. If you don't the load test will say all batteries are good even when you have a bad one.


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## Tirediron (Jul 12, 2010)

if it is possible to operate the mtv with the batteries exposed, have some one drive it on an even slope at the same power setting while measuring each individual battery the weak one(s) should show up then, a simple load tester is cheap https://www.amazon.ca/Schumacher-BT-100-Battery-Load-Tester/dp/B000AMBOI0 and well worth owning.


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## RedBeard (May 8, 2017)

phideaux said:


> Well I don't have a load tester .
> At least one for deep cycle 242 AH batteries.
> 
> I'v got a new Hydrometer coming.
> ...


That's it! Set that puppy to 12 volt repair mode and let it desulfate the battery. Do you know how to put it in repair mode? Not being a punk just asking because they can be tricky. Here is a manual for it.


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## phideaux (Nov 7, 2015)

Tirediron said:


> a simple load tester is cheap https://www.amazon.ca/Schumacher-BT-100-Battery-Load-Tester/dp/B000AMBOI0 and well worth owning.


I just ordered that one from Amazon, 
Wish I had ordered it with the Hydrometer ,

I ordred it last night from Amazon....maybe they will combine them tomorrow.

Jim


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## phideaux (Nov 7, 2015)

RedBeard said:


> That's it! Set that puppy to 12 volt repair mode and let it desulfate the battery. Do you know how to put it in repair mode? Not being a punk just asking because they can be tricky. Here is a manual for it.


Yep, Thanks,.... I have had that Genius for quite some time, It has saved some batteries for me, ..but its ONLY 12 VOLT, so I have to series up 2 of the 6V batteries. for it, I will charge and float up to 10 or 12 , 6V batteries in parallel for 12v output. Great unit.

I have eight 6v 232AH batteries for my solar pack,(12V output for inverters)
I have 4 Trojan 12 v 150 AH batteries in my 48 V golf cart
I have eight 242 AH batteries in my 48V MTV.
I have 2 , 1000 CCA batteries in my diesel truck...
One 12 v in my car.

So I really needed to have that Genius and that load tester.

Guess I'll just wait till I get my stuff in.

Is it possible for those to check V good and take full charge , but discharge so quickly ?

Jim


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## RedBeard (May 8, 2017)

phideaux said:


> Yep, Thanks,.... I have had that Genius for quite some time, It has saved some batteries for me, ..but its ONLY 12 VOLT, so I have to series up 2 of the 6V batteries. for it, I will charge and float up to 10 or 12 , 6V batteries in parallel for 12v output. Great unit.
> 
> I have eight 6v 232AH batteries for my solar pack,(12V output for inverters)
> I have 4 Trojan 12 v 150 AH batteries in my 48 V golf cart
> ...


Yes that's what they do when the plates are sulfated (that spelling might be wrong). Also the genuis won't charge a battery with a dead cell. So if its charging you can rule that out.


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## phideaux (Nov 7, 2015)

Looks like I'm gonna have to wait till I get that Hydrometer and Load tester , so I can seperate these boys, and check em one at a time.

Charging them 2 at a time (2 , 6s) still cant tell if ones good and ones weak.

Gotta be sure its all abttery problems before investing $1400-$1600 .

Hope I can salvage a few to use for backups to my Solar pack.


Jim


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## Viking (Mar 16, 2009)

When I installed a solar system on our motorhome I started out with two existing 6 volt deepcycle batteries and added two more new 6 volt batteries, I installed them so that any problem with the older batteries wouldn't bring down the new ones, the older batteries finally got weak and I used liquid Battery Equaliser from BatteryStuff and it gave me another years use until I was able to replace all four batteries. I have used the Equalize feature on the Xantrex inverter/charger, but there are some warnings on using the feature and one is that the higher voltage of an equalize charge could damage battery plates or insulators between +&- plates, the Equalize charge voltage is around 16 and is timed for just a short time period. The best approach to getting the best service out of deep cycle batteries is to work off of the top half of a full charge, always use distilled water to top off cells and have a good charging system that automatically goes through Bulk, Absorb and Float cycle, I have that on my solar backup power system, the inverter/charger is constantly monitoring the batteries and keeps them topped off when necessary.


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## LincTex (Apr 1, 2011)

Might want to look into getting a Battery Acid Refractometer, they are about $40-$50


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## LincTex (Apr 1, 2011)

Definitely get a good desulphator first, though


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## phideaux (Nov 7, 2015)

Got my new Hydrometer , and my new load tester last night.

Here are the results of ...
SG on each battery 
and
Voltage before load applied , and voltage after 10 seconds of 100 amp load.

View attachment 19660


To me , it looks lie I only have one GOOD battery.
#3. The only battery that stayed above 6v under load.

#2 and #7 appear to be bad.
# 1 ,#4,#5,#6, #8 seem weak.

Anyone have any input?

Jim


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## RedBeard (May 8, 2017)

Well that could have been better...


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## Tirediron (Jul 12, 2010)

Does the load tester have a built in analog voltmeter ? if so it should show the drop off under load, a swift deep drop show a really weak cell,


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## phideaux (Nov 7, 2015)

It does have an analog built in Voltmeter , but only shows Good, weak , and bad, just an idication, 

So I hooked my digital voltmeter to the battery , then the load tester, and watched my digital meter before and during loading the battery with 100 amp load .

I also am not happy with all the variations from one to the other, 

and the low SG electrolyte readings, don't make me happy either.

Looks like I'm going to be buying 8 new batteries, 

Although #3 is probably the only good battery, and #2 and #7 are no good.

I may be abe to rehab 2 or 3 more.

Jim


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## LincTex (Apr 1, 2011)

Don't forget to try the desulphator. I have brought back bad batteries with one.


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## RedBeard (May 8, 2017)

Yea what linctex and caribou said. Try the desulphate mode first. I seen it work numerous times.


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## Tirediron (Jul 12, 2010)

A bit of an over simplification but batteries only fail for 2 basic reasons loss of plate transfer efficiency (sulphation, or degradation) and plate shorting from debris in the base shorting them.


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## RedBeard (May 8, 2017)

Tirediron said:


> A bit of an over simplification but batteries only fail for 2 basic reasons loss of plate transfer efficiency (sulphation, or degradation) and plate shorting from debris in the base shorting them.


Does the acid degrade?


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