# Testing Deep Cycle Batteries?



## rmay635703 (Oct 23, 2008)

SinkTip said:


> I'm looking for a reliable, non-destructive, fast way to test mobility (medical) scooter batteries. They are a U1 style, 12v 34 a/hr. I'm doing mobile repair work on them in home. I have an automotive style battery tester that uses a heating element to create a load. I'm not sure it's the best way though.
> I figured I'd ask the experts.
> 
> Grant


There are electronic units that send a "signal" into the battery to provide its current state & capacity, they aren't cheap and are not as accurate as a load tester.

The best load tester is the one that is variable, you can set it to an appropriate value for your paticular battery size. When you use too large of a amp draw your battery will suffer more peukert issues and show a smaller ahr capacity than it really has.

Unless you draw the battery flat however I see no problems with using any load tester to check if a battery is good or bad. The higher the amp draw the faster your battery draws down is all.

Good Luck


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## czwbattery (Oct 13, 2009)

Hi, Mobile batteries are much different with the power Batteries, 

For Scooter batteries are power batteries, the Mobile batteries belong to Energy batteries.

Power batteries should be with the power cells.
Testing the batteries, should make cells, all of DATA' same , Capacities, IR, DR, Voltage,Rate of discharge , Models, etc.

Different battereis muanfucturers have the different technology skill and methods. 
So DO NOT PUT THE DIFFERENT BATTERIES OR CELLS FROM THE DIFFERENT MANUFACTURERS INTO A PACK.

Most of E-BIKE lithium batteries USE Cylindrical cells: 18650, 26650, 38120, 32900, 32600, 42120, etc.

LIKE 26650, 3.7v ( OR Li-Fe batteries 3.2V), pack into 12V, 10A or 20A, 


Singgle Squre cells: 3.2V , 10A, are most particular.
Also, 3.2V, 50A, 3.2V 100A, 3.2V, 400A, 3.2V 180A, etc.


Like 3.2V, 10A, they put 3pcs, 9.6V, 10A. or others.

The batteries are dangerous. So pay attention to the safety.


Good luck.


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## SinkTip (Jul 21, 2008)

rmay - Is there a particular model/brand of adjustable load tester you could recommend? Would you put a smaller amp load on a smaller a/hr battery or just try to simulate the load the device is likely to experience? 

Using the automotive tester I own, If one of these 12v 33a/hr batteries is bad, how fast would it drop voltage? How long would it be expected maintain voltage if it's good?

I wonder what the amp draw of my tester would be.


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## SinkTip (Jul 21, 2008)

czwbattery - I think you might have misread my post. I'm talking about Group U1 -12 volt 33 amp/hour Sealed Lead Acid batteries used in four wheel mobility scooters (the kind that elderly people use at the mall).
I am not talking about building a pack for a car, I am trying to find out the best way of testing them for people who use the scooters.

Thanks for your comments - they were very interesting anyway.

Grant


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## Amberwolf (May 29, 2009)

"czwbattery" is probably just a spammer from one of the Chinese battery (or other) manufacturers. We get a fair amount of spammers here (actually, I see them at most forums) who post either things that don't really make any sense for the threads they're in, or else things that *sort of* make sense for the thread, being slightly related to the subject at hand. Sometimes they just copy/paste (not quote) part of one of the previous posts in the thread, or from some random place on the web. 

Usually they have a link in their signature to their business, too, or whatever it is they're spamming for, but this one only has that link in the first post they made, here:
http://www.diyelectriccar.com/forums/showpost.php?p=145111&postcount=16
but not in the next post they made when they replied to themselves, nor here. Probably so they wouldn't look like a spammer. 

If they're not a spammer maybe they'll reply here to clarify why they replied to your thread with something that doesn't apply. 



Anyway, I'd say rmay's advice is good. I test the U1s and other SLAs I've got here by running them on my CrazyBike2, and watching what they output under load, but that's not practical for your application. 

I have asked a friend that does powerchair repair what he uses; I'll post here with his reply when I get it.
________
Laguna Bay Condos Pattaya


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## piotrsko (Dec 9, 2007)

My$.02 
pick a level that is approximate to 80% of the capacity of the battery AH's and use a load tester to draw a large current down to that level. monitor voltage, current, time used, and battery temp.

Now here's the hard part: deciding from the data what is a good battery. 

Ideally you would test a brand new one and use that discharge time as a reference. That is worsening quality batteries would develop less current for a shorter time. You can also calculate an Ideal battery capacity from some of the wiKi's here, But I don't do math all that well.

Most of the tried and true old style systems can only give you indications of condition.

Your mileage can and will vary considerably.


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## Amberwolf (May 29, 2009)

What my friend said was this:



> An automotive-type load tester will work provided the battery under test is fully charged. Ideally the load will be 3x the AH rating and for the tester I use it's reasonably close (105 or so amp load for testing 31 AH batteries). Apply a load for 10 seconds and note the voltage- my rule of thumb is 11+ is fine but be wary of anything under 10 3/4 volts.
> 
> BTW it seems that for equal load test results AGM batteries seem to generate more customer complaints about poor performance than gel ones, not sure why that is considering most AGM batteries have slightly higher AH ratings than equivalent U1s.


________
Barbi


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