Old school battery testing

[Sandancers]

Having had dealings with lead acid batteries before I am of the opinion that the old school methods of testing them are the best.

IE, charge it up, see what the resting voltage is, leave it alone and see how quickly it self discharges, measure the acid with a hydrometer, if possible. If it is a starter motor battery then a test with a good old fashioned battery drop tester.

Yet the preferred way from a garage these days to test a battery seems to be to put it on a small electronic tester unit which can't possibly suck big lumps of amps out of it.

Is there some form of super trickery in these little boxes that can replicate the drop test ?

 

[Reallyretired]

No idea but I have one of those little electronic boxes and it's pretty reliable at telling when a battery is duff or otherwise, though its really only for starter battery.

 

[TheBig1]

Yes the internal resistance in the modern type is very precise and the microcontroller takes dozens of measurements over an hour or two. It not only measures the battery internal resistance, but will tell you capacity pretty spot on and predicted life expectancy. The more you spend is not always the best answer though. If you will be coupling up a big inverter, you need to know the battery can produce instant energy for that load still. An old fashioned load tester and a decent meter will still tell you that. I have never subscribed to the old idea of a large bulb over several hours. Too many unknown variables in that

 

[Lenny HB]

Yes the internal resistance in the modern type is very precise and the microcontroller takes dozens of measurements over an hour or two. It not only measures the battery internal resistance, but will tell you capacity pretty spot on and predicted life expectancy. The more you spend is not always the best answer though. If you will be coupling up a big inverter, you need to know the battery can produce instant energy for that load still. An old fashioned load tester and a decent meter will still tell you that. I have never subscribed to the old idea of a large bulb over several hours. Too many unknown variables in that

I have to differ when I had two leisure batteries fail a starter battery tester passed then as OK one at 79% the other at 80%.
In use as a leisure battery one would give 10ah the other 11ah.

 

[TheBig1]

I have to differ when I had two leisure batteries fail a starter battery tester passed then as OK one at 79% the other at 80%.
In use as a leisure battery one would give 10ah the other 11ah.

Did you give the load tester more than one 10 second cycle and measure drop between tests? A 10ah capable battery would be flat with mine within a couple of tests. All it is is a very big wire wound resistor and a pair of chunky leads. A good battery will heat it up instantly.

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[Sandancers]

I have to differ when I had two leisure batteries fail a starter battery tester passed then as OK one at 79% the other at 80%.
In use as a leisure battery one would give 10ah the other 11ah.

When you say starter battery tester do you mean the small electronics box jobbie or an old school drop tester ?

 

[Odd-no-more]

When I was working I had a chiller box in the van, if I had a job that was going to take all day I unplugged it. One day I forgot and the battery was flat. The AA came and tested the battery with a little box he told me it should be replaced and he could do it now. I declined and got the van jump started. I had the van for a few years after that and no problem with the battery. I have mistrusted those little boxes since then.

 

[Lenny HB]

If was an electronic one because acorrding them they tested OK refused to replace them under warranty.

 

[Sandancers]

If was an electronic one because acorrding them they tested OK refused to replace them under warranty.

This is what I am experiencing. The little box says the battery will charge up fine, but I know that it just won't supply the power. Usually the battery is fully charged and the MH starts first turn, so fine. But when replacing the fuel filter the engine needed to turn over a bit before firing to prime the filter and the battery just died.

I am going to have a conversation with Halfords technical dept. about what they classify as a "test" on a starter battery.

 

[Spriddler]

No faffing about with Hi or Low tech drop or discharge tests for me. If I've had a battery that's gone flat a couple of times I check the drain on it when the ignition is switched off, then check the alternator output at that battery's terminals and if all seems O.K. I fit a new battery. Seems to have done the trick for the past 40 years.

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