Testing Batteries

[JWhitcomb]

Over the years I have become convinced that the best sure way to test a battery is with a hydrometer. I really don't trust just a voltage reading as they will read good but in fact have no capacity. Any one know how good the testers put a load on while reading work? Are they any good for deep cycle batteries.

 

[C Schomer]

I like the load tester that Hensley Battery sells. It has a resister made out of 1/4" stock and a 1000 amp meter. Hydrometers are fine to show the condition of the electrolyte and the plates(to a degree) but a good load test is the real 'acid test'! I don't know about testing deep cycle batts - if they don't work good anymore(that's enough testing for me), I just replace them. I guess a hydrometer would probably be a good indicator for them - they don't have to produce cranking amps. Craig

 

[LarryB]

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=6317



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Tests both 6 and 12 volt batteries and charging system outputs. Accurate color coded voltmeter with scale from 1 to 16 volts. Heavy duty battery clips.

Battery capacity: 6V, 12V

Amp setting: 50 amp load

Shipping weight: 2. 9 lbs.

ITEM 6317-2VGA



$27. 99

 

[C Schomer]

With due respect and not to be a smarta$$, a 50A load tester wouldn't be worth the powder it would take to blow it up! Turning on all the lights and accesories will be a bigger load than that. The idea of a load test is to put a max load on the battery and see if it holds for 15 seconds or so and watch for bubbling or hissing(bad signs) cells. That will tell how it will do in real life. I've only seen a load test fail to detect a bad battery once. This crazy battery would only fail at certain temps and the load tester wouldn't reproduce it. Craig

 

[LarryB]

Whheeeellll, I never!



Hey, your right, I never gave it much thought. You gotta admit though, it does have heavy duty battery clips



Larry

 

[JWhitcomb]

I agree that if deep cycle batteries don't work anymore that is a good test but I would like to be able to test before I take off for a trip or plan to spend a day running the trolling motor on my boat. I can just turn everything on before the trip and see how long the battery lasts but most of the time I don't have the time previous to the use to do that. That said, it seems the way to go if needed and short of just buying a new one that is what I plan to do when time permits.

 

[WCrovo]

I have a Snap On tester, you need to load and spec grav test to know how good your battery is. The books say 15 sec. 's but that will bite you in the bum(Utah word). Sometimes you need to go over the 15 sec's to get the truth. Take your batteries to a good shop and they can charge and ck them for not a lot of $'s. Good luck.

 

[C Schomer]

I've had a couple long talks with battery authorities lately, trying to figure out all the battery differences(auto vs. RV). A starting batt isn't good for deep cycle and a deep cycle batt isn't good for starting and they won't hold up good if used the wrong way. I've read that they use different alloys in the plates to give the batt different charactoristics. That's why I'm thinking, it may not be a good idea to put a HARD load test on a RV battery. I doubt if it would hurt very much. Usually a weak cell will show up fast with a good load test. A wimpy load tester won't show what you really need to know. A hard load test puts way more load on than just a starter so you can see if the amps hang in there and watch the cells(if you can take the caps off). They may all bubble, but weak cells will bubble a lot more and may even hiss. WEAR SAFETY GLASSES and don't get your face too close - I've had cells explode from broken connector bars causing arcing. Acid goes everywhere! If you really need to know, I would go ahead and do the load test - better than being left high and dry! Craig