Car Battery Load Test With Multimeter | EASY DIY

6 * 1.7v = 10.2v, there's your minimum. 6 * 2.35 = 14.1v to 6 * 2.40 = 14.4v while running/charging. That's your numbers. Source - 34 years working in the battery industry.

My voltage is displayed on my dash on my bike. When I first power up, before cranking, the V sometimes shows it's as low as 6-7v but rapidly rising until it slowly creeps up to 12.2 where I crank it. If I try to start it too soon it dies momentarily and the bike does a factory reset. Usually the 2nd crank it starts up fine.

This is not really a situation to do a load test; if you see a 0.6V drop from full in a few minutes with the car off, then there is either a problem with significant drain on the battery, or the battery is rapidly self-discharging. What you should have done is first disconnect the negative lead and check amperage flowing out of the battery with car off. It should be very low, I've never measured it but I'd expect less than 200mA. And if it is high, like 1A, then I would expect there is a problem. But more likely, you would see a reasonable number, and all you should do then is leave the battery disconnected and see if it is self -draining. That is common in older lead-acid batteries, as the plates will sulfate and drop that sulfate to the bottom, where it builds up and eventually shorts a cell. If the battery is good, it will barely drop in voltage. Even with a little load on it, you should see it drop to 13.2V, which is the steady state for a full battery (2.2V per cell), before it finally drops and stays at 12V. But if a cell is bad, it will continue to drop, possibly down to 10V (5 times 2V) if one cell is bad, and even lower if the problem is across cells. Also, not sure I would call what you did a "Load Test", but labels may differ across the Atlantic. Here in the USA, a Load Test is putting a measured heavy load on the battery and looking at the current it supplies as well as the voltage the battery can hold up.

Nice overview. You didn't put the other promised link in the description.

That cranking sounded really slow rpm to me without even looking at the meter.😅

Spent 40 years fix German dumpsters , always problems with power drains, spilt drinks,water ingress?? A living nightmare. I’m retired and drive a Tesla mod3 ,never been sooooo happy 😉