Which battery is duff?

[stu9000]

Hi
I have 4 x 110 lead acid leisure batteries. They seem ok but when I put a load , say 2 to 4 amps, they visibly drop from nearly 13v to 12.3 and counting.

I guess one or more is dead. I took the chief suspect off the line but it is not dropping when isolated.

Two are two year old hankooks. The older two are about 5 years old. System maintained with mppt and two 100w panels .

Im on board now. Does anyone have any trouble shooting tips?

Thanks

 

[davidej]

I think checking the voltage while putting a large current draw, is the only way of checking unless you have one one of the electronic gismos which our local supplier uses

 

[Stemar]

Does the voltage stay down when you cut the load? I'd expect some drop under load, though not that much for a small load, but it should recover when you take it off. If it drops and recovers, I'd start by cleaning terminals and connections.

 

[stu9000]

Voltage come back up again after cut load. Terminals and connectors are clean.

Thanks.

If I draw 4 amps would u expect it to drop from.12.71 to 12.30 within 5 mins. I'm.surw that isn't normal..?

 

[NickRobinson]

Separate them and test.
I pulled my two house batts to take home to capacity test and one was warm...
On the onboard volt/ammeter all was fine, the solar (in my case) masking the 10v hot batt

 

[Norman_E]

As indicated above any battery that gets warm on a light load is in trouble. Another issue is that if you have batteries in parallel with each other a dead or dying one will pull down the rest. Costly though it is the OP probably needs to replace all four batteries.

 

[Neeves]

Isolate each battery in turn and try them individually and/or take out each h battery in turn and try the remaining 3.

Same test, or same load each time.

Your problem in doing this might be cable length to do it.

As above - disconnect solar.

Jonathan

 

[ChromeDome]

Charge them fully.
Disconnect/isolate all
Use a load tester (can be this type) to read the drop / stamina of each.

Not too expensive, dead simple to use.

 

[stu9000]

Thanks. Will check if any are hot. I agree solar likely to be masking the problem. If that doesn't work will buy a load tester.

 

[Pye_End]

Are they sealed? One advantage of open is that you can test the cells.

 

[stu9000]

No battery getting hot under.load

 

[NickRobinson]

Thanks. Will check if any are hot. I agree solar likely to be masking the problem. If that doesn't work will buy a load tester.

A load tester may not be the best way for house batteries. I just use a car headlight bulb, measure on amps, gives c.4A
run the freshly charged batt down to c.12v then hours x amps is pretty realistic. (Free too!)

 

[RAI]

If they are normal lead acid, get a hydrometer. It may be easier, take the tops off and see if any cells are dry.
Dry usually means dead.

 

[stu9000]

Lead acid. One had the magic green eye dissappear on me a month back. I topped it up and the green eye returned. But maybe its knackered..

I am using the heating as a load. 2 amps once its up and running. Its gone from 12.9 to 12.69 in half an hour with all four connected. Not got time now to try each one separately. Car headlight bulb a nice idea.

 

[Daydream believer]

Charge them fully.
Disconnect/isolate all
Use a load tester (can be this type) to read the drop / stamina of each.

Not too expensive, dead simple to use.

I have an identical issue with my 2 batteries. Dropped from 13 V to 12.4 within 4 minutes of using the fresh water pump. I saw the picture of the load tester above so looked on you tube. The design of that style looked a bit hit & miss so I investigated further & found that there much better digital ones with far more accurate readings.

Then I saw a review of one where the customer pointed out that there was no option to register amps as a storage item. Only cold cranking amps. These are a short term issue more in keeping with vehicle starting etc & he wanted to know how to measure long term storage.

So not wishing to buy the wrong gadget I rang the battery manufacturer Tech manager & he told me NOT to buy one, as it would be a WASTE OF MONEY. It does NOT give accurate details of long term storage.

The upshot is that I have returned them to the supplier for a longer term load test. If they pass then I will possibly have to pay courier charges but if they fail miserably they said that even if out of warranty they will still consider replacing as not very old. Has to be better than spending cash on something that will not actually do the job

Thinking about it, I suppose the obvious alternative would be to hook up something of known current draw & watch voltage over 24 hours.

 

[Boater Sam]

The green eye is a joke, it means nothing. Its only on one cell anyway.
It is likely that your battery charging regime is suspect and that the batteries are sulfated.

Charge them all fully, like 24 hours @ 20A, separate them all, let them rest for an hour with no load then measure the voltage of each one. If any or all are below 12.6V then I would replace.

 

[KeelsonGraham]

A good ol fashioned hydrometer (£9) will quickly tell you which cells are duff.

 

[Rappey]

Use a load tester (can be this type)

I think there are far better and more gentle methods nowadays ,namely electronic testers which can test a flat battery (very helpfull ) and measure the internal resistance etc for as little as £25 on ebay .

 

[William_H]

OP has found a volt drop with a load when all batteries are connected. he simpluy needs to charge the batteries in parallel then disconnect3 batteries leeaving only one in service. Apply the load and check volt drop after say 10 mins. Note the results and disconnect that battery and connect another then compare the results. The results of all 4 batteries compared will I think soon indicate if one is dud. ol'will

 

[Babylon]

OP has found a volt drop with a load when all batteries are connected. he simpluy needs to charge the batteries in parallel then disconnect3 batteries leeaving only one in service. Apply the load and check volt drop after say 10 mins. Note the results and disconnect that battery and connect another then compare the results. The results of all 4 batteries compared will I think soon indicate if one is dud. ol'will

Absolutely correct. It is called 'trouble-shooting' or 'process of elimination' and is the very first thing to do in any such situation.