Let's Discuss Battery Load Testers

I have a basic multimeter and can diagnose simple battery voltage/alternator issues with it. However, this only gives a partial picture of the health of the battery.

Whenever I've gone to Autozone or any other parts store with a battery to be tested, it's always failed. I'm not sure if all the batteries have actually been bad, or if it's been an amazing coincidence that the batteries always fail in the exact spot where I'm most likely to buy a new one.

With our own (small) fleet and a bunch of friends that I help out with their own vehicles, I'd like to be able to load test a battery. Is this a reasonable thing, or does a true load tester cost $400 and I'm better off just buying a new battery if there's any question. In true GRM fashion, I'm looking for some bang for the buck, if that's possible.

Here are some contenders I've found on Amazon:

http://www.amazon.com/Schumacher-BT-100-Battery-Load-Tester/dp/B000AMBOI0/ref=sr_1_1?s=automotive&ie=UTF8&qid=1456630561&sr=1-1&keywords=battery+load+tester&refinements=p_72%3A1248861011

http://www.amazon.com/OTC-3182-130-Amp-Digital-Battery/dp/B000F5HU6W/ref=sr_1_5?s=automotive&rps=1&ie=UTF8&qid=1456630814&sr=1-5&keywords=battery+load+tester&refinements=p_72%3A1248861011%2Cp_85%3A2470955011

http://www.amazon.com/Actron-CP7612-Battery-Load-Tester/dp/B0009XQUJI/ref=sr_1_16?s=automotive&ie=UTF8&qid=1456630455&sr=1-16&keywords=battery+load+tester

http://www.amazon.com/BA5-100-1200-Cranking-Electronic-Battery/dp/B0017R5EQK/ref=pd_sbs_263_4?ie=UTF8&dpID=41sWUMO4w6L&dpSrc=sims&preST=AC_UL160_SR160%2C160&refRID=04CV6K7R1M1EXATAT4FD

http://www.amazon.com/3181-Heavy-Duty-Battery-Load-Tester/dp/B000O3U2UQ/ref=pd_sbs_263_3?ie=UTF8&dpID=51D9ukzvHyL&dpSrc=sims&preST=AC_UL160_SR152%2C160&refRID=04CV6K7R1M1EXATAT4FD

http://www.amazon.com/BA7-100-1200-Electronic-Battery-System/dp/B0015PI7A4/ref=sr_1_2?s=automotive&ie=UTF8&qid=1456631437&sr=1-2&keywords=solar+battery+load+tester

Any feedback would be appreciated!

Great question! I have the first type you list that is the old style analog toaster. It seems to work fine and has helped me identify batteries that were on their last legs. I've often wondered, though, if the extra expense for the digital ones was worth it.

I have one like this. I can't remember for sure, but I believe it cost me $70 or less. I wouldn't spend any more than that for something I rarely use.

If you go with a load tester I'd recommend a 500 amp carbon pile over the cheap fixed load "toaster" tester, you can do better than the toaster with an analog volt meter on the battery while cranking the car over.

If your meter has min/max, just hook it to the battery and record the minimum voltage hit during cranking. You could argue where the line between pass/fail should be, but bottom line if the minimum voltage is ok during your cranking period, the battery is good enough, in that car, at the present time.

But i wouldnt be surprised if any meter with a min/max function is more expensive than an HF carbon pile load tester.

The thing i actually use the carbon pile load tester for is testing alternator output.

Also, if you want the parts store to pass your batteries, make sure they're under warranty with that store and they will start passing.

I can't belive I'm typing this but the all electronic unit for HF does seem to work just as good if not better then my snap-on toaster type.

tester

I have the HF one. It works. Smokes a bit, but that's what happens when you leave the toast in too long. Voltage while cranking would be a useful test as well, and I used to do that until I decided to get the HF unit.

I'm not a huge fan of pass/fail battery testers. The ideal way to tell the health of a battery is to load test it when it is brand new and use this value as a baseline. Then you periodically test the battery and compare the results to your baseline.

It seems all the testers you listed would let you do this if you were so inclined.

Mind you, the only time I've tested batteries in this way is when someone else paid me to do it.

I'm not a huge fan of pass/fail battery testers

Well, whether it's an electronic tester or a human looking at gauges, either way pass/fail is just a line in the sand. Even if you do math based on the reserve capacity and decide to pull X amps for X minutes, there's not a spec sheet on the side of the battery that says what the voltage should be at the end. The minimum cranking voltage test at least has a somewhat distinct cutoff point at 9.X volts because even if the engine is spinning 200-250rpm, the ECU will be flaky or off below 9.0 volts and the engine may not start. I usually see 'healthy' batteries dropping to 10.5 during cranking.

The way i explain it to my students is that in a shop environment there is no guarantee you're going to see the same car again in 3 or even 6 months which means it's very possible that there will be a change of season and a battery that seems 'ok' right now will end up becoming a problem before the vehicle comes in for the next service or repair. It feels a little icky to recommend a battery replacement when a tester says it's operating at ~75%, but part of the idea is that you're supposed to be ahead of the curve and forewarn the customer of a future issue so that they feel like they're being taken care of. Another thing is that for a typical non-car person, a dead battery typically costs way more in total than a preemptive battery replacement because they usually won't find out until 30 minutes before they are supposed to be at work and may have to miss several hours of work (at 10, 20, 30, 40 dollars an hour?) and possibly pay out of pocket for a tow truck and/or a rental or make their significant other miss some time at work running a family around with one vehicle etc. So it is usually cheaper for a customer to replace a battery that isn't dead than one that already is.

Vigo wrote: But i wouldnt be surprised if any meter with a min/max function is more expensive than an HF carbon pile load tester.

That's why I suggested a analog multimeter, you can eyeball min/max good enough with a needle, not so much with flashing numbers.

Thanks for all the feedback - I'm planning to go with the HF tester.