At the moment if I leave the ignition on and lights for 15mins then it's killing a 100ah battery-it's been tested with a computerised battery tester that reports no problem with battery.
Iinterestingly it's drawing 30amps on a clamp meter.

Other than the expected don't leave lights or ignition on-suggestions please

you need to see what its taking with nothing on then ignition and then just lights(if poss)

i think 30 amps is quite alot for just lights, try it also on each notch of ign.

Why do you need to leave the ignition on with the lights for 15 mins? 30 Amps sounds about right with the headlamps and ignition on position 2 (both heater motors will probably be going aswell).

reason I'm asking is with just the radio on 20mins will kill the battery, now the battery has been tested and past with computerised load tester-passed.

What I'm trying to gather is if there is an underlying cause or if generally you either start and go or don't have the ignition on even the first click as it's a **** poor design.

While not advocating having the ignition on and engine off, you have to agree 15 mins is pretty crap.

hello fanatic,

a 100ah battery will only deliver 100ah when its fully charged.

30 amps does seem a bit high for the items you mention being switched on, except perhaps you have got uprated h/l bulbs for example, and other items drawing power which have escaped your notice.

so its a marginal situation.

even a good battery cannot be fully recharged if it has suffered some recent abuse such as multiple deep discharges, which it seems has happened, such as extreme temperatures, which is very possible, or a loss of fluid due to boiling.

then again, a malfunctioning charging system, or a courtesy light permanantly on, or an alarm system glitch will all contribute to the problem.

these abuses are cumulatively detremental and if it was a cheap battery at the getgo then the situation may be unrecoverable.

so what can be done?

if you read the following essay, it explains the whole problem, what goes wrong, what the pitfalls are and how to effect a recovery by applying a properly planned recharging program.

If you are lucky you may be ok, but its gorra be worth 10 minutes study to find out?

Only the Rich can afford Cheap Batteries

good luck