Battery testing

[MH Hawker]

Its sort of been one of those mornings. I went out to have my oil changed and get a tire balanced. During the oil change they tested my battery and it showed it at 390 cranking amps on a 600 amp battery. I didn't have it changed mainly because they sell interstates so I went by advance and had it tested and it showed 450 amps so I went home and broke out my brand new cheese grater style tester and that's showing a full 600 amps.

It sure make me believe a lot of places have rigged testers. I know the old style testers don't have the fancy read out`s or that sort of stuff but the measurement of amps under load hasn't changed.

Or am I way off.

 

[Bondo]

Re: Battery testing

Its sort of been one of those mornings. I went out to have my oil changed and get a tire balanced. During the oil change they tested my battery and it showed it at 390 cranking amps on a 600 amp battery. I didn't have it changed mainly because they sell interstates so I went by advance and had it tested and it showed 450 amps so I went home and broke out my brand new cheese grater style tester and that's showing a full 600 amps.

It sure make me believe a lot of places have rigged testers. I know the old style testers don't have the fancy read out`s or that sort of stuff but the measurement of amps under load hasn't changed.

Or am I way off.

Nope,... I'd run it, til it won't start yer car,....

 

[UncleWillie]

Re: Battery testing

All three measurements are valid but none of them mean very much.

Cranking amperes (CA), also sometimes referred to as marine cranking amperes (MCA), is the amount of current a battery can provide at 32 ?F (0 ?C). The rating is defined as the number of amperes a lead-acid battery at that temperature can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12 volt battery).

Hooking up a meter and measuring 390 or 450 or 600 amps only tells me that the three meters test at three different currents.
If your load meter pulls 600 amps, and your battery was truly a 600 CA battery, the voltage would still be a little above to 7.2 volts after 30 seconds at room temperature.

You can't just hook up the meter and read the current for 5 seconds.
You need to measure the time it takes for the voltage to drop to 7.2v.
Test equipment is only as good as the person operating it.
Understand what you are trying to measure or the result will be meaningless.

 

[sweet addiction]

Re: Battery testing

I am not trying to get off topic here, but marine cranking and cold cranking are two very different things. Very rarely does a boat owner need to even concern themselves with a batteries cold cranking amps rating. Just trying to make things clear. :joyous:

Marine-Cranking Amps (MCA)-- A rating that is used to define the number of amps that a lead-acid marine battery at 32?F (0?C) can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12-volt lead-acid battery). This artificially high rating should not be confused with CCA.

Cold-Cranking Amps (CCA)--A rating that is used to define the battery's ability to start an engine under low-temperature conditions. BCI defines it as "the number of amps a lead-acid battery at 0?F (-17.8?C) can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12-volt lead-acid battery).