>>
>> Back during my engineering training it was explained to us that testing a battery voltage
>> without a load is pointless. With the engine running you are not testing the battery
>> voltage. Now with engine off and headlamps on . . . .
>
At least it gives a reasonable level of confidence that the alternator is at least charging the battery, agreed an engine off test would test the battery itself better.
>> Second - and have posted this before but no-one believes me . . . .
>>
>>
>> The "everything off" current can be very high, my experience was a Passat which once
>> ran its battery down overnight and when the AA man could not identify the cause
>> he called base and was told the specified everything off current was 1.8A.
>>
1.8A is bonkers, that would drain a fully charged battery flat within 2-3 days, the AA must've moved the decimal point two places. 1990s Vauxhalls' spec. was 30mA quiescent , which is about what SWMBO's 2001 Zafira draws (alarm and remote locking sensor). OK more modern cars have more gubbins permanently live, but battery capacity isn't increasing, so they must be working to similar quiescent current limits.
Last edited by: spamcan61 on Thu 3 Mar 11 at 09:32
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