How long should battery stay good when car is not driven?

[Circlotron]

This is VERY specifically a VN-VP (perhaps V8) question.
Got a new battery about 15 months ago and has been good with it. Went away for a few days holiday with the family in the missus' car and so Rory-the-white-VP had the luxury of sitting in the garage for 11 days and nights. Got home this afternoon and went to swap car positions and it only cranked a turn-and-a-half and that was it. Battery was very flat. Bunged it on a charger and pumped it up again and all seems okay. I'm pretty surprised that it went flat that quick. I know there is a residual current drain to the computer and the alarm security box thingo, and 100% sure the boot light doesn't stay on - I went and checked it in the dark just now, so what could it be? Are these cars known for running down the battery when not going?

 

[Jxfwsf]

Got a vn calais and it's been known to sit for 2-3 weeks unused and it's battery is 3-4 years old and it's never given me a problem starting (went flat after about 2 months sitting once but that's about it)

get out the dmm and see how much idle current draw there is (if it's more than 150-250 mA look further)

 

[SweetWagon]

Had an Optima Yellow in the VS, sat for ~8 months in the car and still had juice to crank a couple times. mind you it was disconnected the whole time, Just depends how good your battery is and if there is any slow current draw on it as mentioned.

 

[Circlotron]

Today I discovered that the EFI relay is staying on all the time, even with everything switched off. Someone has stuffed around immensely with the wiring on this car because the relay should only come on when the ignition switch is on. Half-assed LPG conversion I'm afraid. Might have to put another relay driven off the ign sw and use it to switch the coil of the EFI relay. Oh dear.

 

[Ozzyjim]

Glad you found the prob...
Also, I have a VS that has drained the battery easily - found out today that the reason is I was not locking the car keeping a higher drain on the battery - lock it, drain goes away.. I also have a non sealed battery in the VS, but I have a sealed battery in the shed I use just to test H/U's and other parts... The Sealed unit was purchased in nov last year and well and truely holds its charge better than a non-sealed IMO... I have only given the sealed battery a quick top up charge once ~20min on a 1600ma float charger..

 

[Jxfwsf]

ahh, messing with the efi/inj relay so that the ecu doesn't light up the cel when gas is selected throwing the inj voltage fault code.

now the fix.... i'd fix their f up and cut the injector power at the correct point (so the injectors aren't powered but the ecu still thinks they are), they've cut the wire to early in the circuit, unfortunately i don't have the correct position for you.

 

[Circlotron]

Okay...
One thing I did notice is that with key off there is no battery feed to the EFI relay contacts. Should go battery -> fuse -> relay contacts according to the diagram.

Pull the relay out with the engine running and it stops straight away, gas or petrol, so it is doing something, though I can't imagine what if it is turned on all the time. May as well pull the relay out and put a wire link in it's place for all the good it is.