How to test auxiliary batteries for amperage?

[bighatnohorse]

I need a way to test a pair of six volt Trojan 105's wired in series and setting in my shop.
Has anyone a method of amp testing batteries that are on the bench?
I can't think of anything 12 volt that will pull a lot of current that is readily available to use as a test load.
??

[MEXICOWANDERER]

Matt is right.

Full load testing means achieving 50% of CCA for 15-seconds while monitoring voltage. A capacity test will tell you if the battery is damaged. But it takes a lot longer and I deal with an OP's inquiry if it is valid. You wanted to know about carbon pile load testing.

Handheld CHEESE GRATER load testers are great for lawn and garden tractor size batteries. Try to test and regular RV battery and it would be tantamount to giving an Olympic weightlifter a 25-pound barbell and seeing if he could lift it.

Foolish me. If I was selling batteries like those, I would reveal to potential buyers exactly what happened and that the batteries were tested and proven good. But that's me.

Slap a STRONG 12-volt muffin fan onto the Harbor Freight 500-amp variable load tester and it turns mediocre into decent.

[Matt_Colie]

BigHat,

Don't work so hard.
You don't even want to do the test at started load, so don't.
Get a good volt meter, an ammeter (even cheap will work), either a refractometer (what I use) or a hydrometer and a pair of headlight bulbs. Charge the bank to full density (12.60). Measure the bank voltage. Connect the ammeter and the headlights to the banks and look at the clock and the ammeter. After a time, I like to use one hour, disconnect things. Let the bank settles (15 minutes is good) and measure the both the bank voltage and the electrolyte density.

You now know the state of charge from two benchmarks and how many Ampere-Hours were drawn from the bank. The amount of discharge should be close the distance between 12.60V and 12.00V that is the 50% discharge mark. You can make a quick guess, or you can do a short search on the web for the tables that list this data. If the density readings don't agree with the voltage, there is something wrong that could matter.

I used to carry the pair of old sealed beams and cables in a box as I did this test for boat owners more than a dozen times a year. I could still do it, I have the box but the business that requires discretionary income is dead in my area. Killed by the recession that has not nearly ended here(I don't care what they say), but I will be ready if and when it does ever end.

Matt

[bighatnohorse]

MEXICOWANDERER wrote:
If you need new batteries, what's the plan for logistics?

The batteries are in a box. I use a roller cart. And I have a small garden tractor with a front end bucket.
So it's a matter of shuffling them place to place. Lift with the tractor.
I will sell them if they are any good.

[MEXICOWANDERER]

If you need new batteries, what's the plan for logistics?

[John___Angela]

Raften wrote:
Get a load tester.

Yep. Are they even thirty bucks?

Something like this will work fine.

[bighatnohorse]

I dread having to lug these monsters anywhere.
The doctor says not to lift or carry anything heavier than a roll of paper towels.

Regardless, if I get the batteries close to the now grounded truck camper then I can substitute them for the camper batteries (via jumper cables).
If the bats are still good then they should lift the camper a few times no problem.

Thanks for keeping me mentally engaged with this project.
The camper is bagged and tarped at the moment so it might be a few days but I'll report back when this is done.

[doughere]

I have an amp meter on my system, to test capacity I use my inverter and a small crock pot to load battery. Current X time = Amp Hours. Not perfect, but good enough for me.

Doug

[MEXICOWANDERER]

Usually the Interstate battery Distributors have an 800-amp Auto Meter adjustable carbon pile load tester. The distributor. The guy with the trucks.

Harbor Fright sells 500 amp adjustable carbon pile testers.

NiChrome wire was killer expensive back in the early eighties. I shudder to think what 10-gauge costs now. Then it has to be spiraled ultra slowly on a lathe jig. I used 4x8 sheets of linen bakelite for load bank platforms. Yuk.

[Raften]

Get a load tester.

[2oldman]

Hydrometer.

[GordonThree]

guess its a matter of moving 200lbs of batteries or a 40lb tester 🙂 either way works

[naturist]

GordonThree wrote:
Hygrometer isn't going to read out damage to the plates.

Go to Advance / Autozone and rent their battery load tester. It's just a box with a big resistor and a meter, should be cheap / free with a deposit.

Or better yet, take the batteries to one of those places and ask them to test them. They will put them on a tester and run the test for you for free. Of course, they do this because they want to sell you a new battery, but not being able to do so because the problem is really elsewhere, but they are friendly and helpful none the less.

[GordonThree]

Hygrometer isn't going to read out damage to the plates.

Go to Advance / Autozone and rent their battery load tester. It's just a box with a big resistor and a meter, should be cheap / free with a deposit.

[2oldman]

Capt. Obvious might be on to something there.