Battery Load Testing

[franklinmanklin]

I have always taken my batteries to my local mechanic who uses a Snap-On tester. What do you guys use for checking deep cycle batteries for maintenance issues for lighting besides waiting for them to bulge and die? Brand and model is what I am looking for here.

 

[K8MHZ]

I have always taken my batteries to my local mechanic who uses a Snap-On tester. What do you guys use for checking deep cycle batteries for maintenance issues for lighting besides waiting for them to bulge and die? Brand and model is what I am looking for here.

I use batteries for various reasons. UPS, radio field ops, portable lighting, and the usual engine start stuff. Van, car, Harley, lawn tractor.

I use a smart charger to charge them. Internal (not load related) faults are displayed as a fault #.

For flooded SLA's used to start vehicles, I have a load tester (AKA toaster). It is not for use on smaller batteries.

To finish off my elaborate collection, I have a voltmeter and a clock. Any battery in question gets 3 proper charge / discharge cycles followed by a load test (again JUST on car batteries) with the toaster, or a voltage drop watch over 48 hours. Most times a bad battery will show a high self discharge rate.

Are you testing your own with the intent of making them last as long as possible, or are you doing one-shot tests for customers?

If you are testing for customers, they probably want some fancy info, like 'remaining AH' to compare with the initial AH in an attempt to predict a failure date. There are testers that display that info, but it's not of much practical use. Any concernable decrease in AH will induce a symptom detectable with just simple equipment.

 

[kwired]

I can't tell you what you should use for testing, but I can tell you a deep cycle battery and a typical automotive battery are not the same, and likely need different testing methods to get a true idea of what you have.

An automotive battery it intended to be able to supply a high amount of current for a relatively short duration, where a deep cycle battery will have a lower optimal design current but can deliver that current for a long duration.

An automotive load tester may give you indication of a bad cell but probably will not help you decide just how much life may be available in that battery.

 

[K8MHZ]

I can't tell you what you should use for testing, but I can tell you a deep cycle battery and a typical automotive battery are not the same, and likely need different testing methods to get a true idea of what you have.

An automotive battery it intended to be able to supply a high amount of current for a relatively short duration, where a deep cycle battery will have a lower optimal design current but can deliver that current for a long duration.

An automotive load tester may give you indication of a bad cell but probably will not help you decide just how much life may be available in that battery.

You are correct about battery types.

All a load tester will tell you is the voltage drop after a short time under a full load. Failure could be a bad cell, or it could be correctable like not being properly charged, or being low on electrolyte. Low electrolyte does not indicate a defective battery. It evaporates just like water and remember, the caps are vented. My batteries last for years. No way is there going to be no evaporation over that time, especially in an engine compartment in the summer.

When in doubt, add distilled water, not electrolyte. If the water did evaporate, the remaining electrolyte will be too 'strong' and need diluting.

 

[K8MHZ]

If you do need electrolyte, here is the procedure.

1) Top off with distilled water

2) Charge fully

3) Test specific gravity and adjust accordingly.

 

[gadfly56]

You can look here or here. I have no personal experience with either, but one of our techs has used the ACT meter and likes it.

 

[zog]

I have always taken my batteries to my local mechanic who uses a Snap-On tester. What do you guys use for checking deep cycle batteries for maintenance issues for lighting besides waiting for them to bulge and die? Brand and model is what I am looking for here.

IEEE Std 450 covers acceptable battery testing methods, the traditional method is a load test. What is becoming more common is an impedence test. I have done both for 20 years. Z testing is the way to go.

Equipment used.
http://www.megger.com/us/products/ProductDetailsBySubGroup.php?PSGC=I107&BS=I

 

[Electric-Light]

If there are a ton of units with same battery age, do a run time test on a few. If the runtime isn't 70% of better, then I would say useful life is over.

Ah capacity is hard to determine without draining them. Even costly computer UPS units rely on discharging battery until near cut off voltage is reached and calculating expected(at 100% rated capacity @ given load) and measured duration.