How long does you battery last with car un-used

tuscan_thunder · Post by **tuscan_thunder** » Wed Feb 14, 2007 10:49 am

As title. Seems a very topical topic at the moment.

Mine lasts about 8 days max with no running.

It's dead as a dodo just now after 14 days of inactivity.

Battery's about a 2 months old.

The_Rossatron · Post by **The_Rossatron** » Wed Feb 14, 2007 11:08 am

My old battery which was probably half knackered, lost a lot of charge after two weeks of inactivity then a few weeks days after it would only click in the solenoid. It died peacefully overnight.

David Bryce · Post by **David Bryce** » Wed Feb 14, 2007 11:09 am

after hearing most people complaining about theirs, I was surprised when mine started no probs after it sat for a month while I was in Thailand

renmure · Post by **renmure** » Wed Feb 14, 2007 11:15 am

Elise / Exige have been inactive since October/November

but are hooked up to accumate chagers in the garage so always tip top and ready to go.

dezzy · Post by **dezzy** » Wed Feb 14, 2007 2:00 pm

Longest I think I've left mine is about 7 days and no probs at all.

RDH · Post by **RDH** » Wed Feb 14, 2007 2:03 pm

3 weeks -no probs!

Though Dan did tell me it wasn't the original battery - it a new Bosch one - So i don't know about the original battery!

mckeann · Post by **mckeann** » Wed Feb 14, 2007 2:07 pm

mines has sat out for 1 month when i went to NZ and it started fine.

didnt last so well when i had a wiring fault last week though

tuscan_thunder · Post by **tuscan_thunder** » Wed Feb 14, 2007 2:12 pm

hmm...think i must have an earth leak somewhere....this will (not) be fun trying to find it.

Where should I look first? (The alternator leads were checked/renewed a few weeks ago and, when it's running, I'm getting high 13v (13.

to 14v so it should be charging ok

robin · Post by **robin** » Wed Feb 14, 2007 2:35 pm

*WARNING* car batteries are dangerous - do not short circuit them (hence we work on -ve terminal mostly as accidental terminal-tool-chassis contact does not result in a short circuit) - do not overload your multi-meter - do not attempt to start the car while meter attached!!!

--

The alarm system can be quite greedy. You can measure your standby current easily enough :-

loosen -ve terminal on bat, but don't disconnect
disarm alarm & quickly remove the -ve terminal.

Using a standard multi-meter set to 10A, connect black lead to the bat -ve terminal and red lead to the bat -ve cables (keep them all connected together) - one end of a jump lead is a handy clamp for that function - now use other end of jump lead to reconnect to battery.

Alarm will squawk a bit and everything should be back to normal. Leave ignition off. Once car has settled down, remove the jump lead from the battery so now all current flowing through the multi-meter. Read off current. If it's less than 2A (should be!) then reconnect jump lead, flip multi-meter onto next lower A scale (probably 2A) and measure again. Keep going until you are on the lowest scale that can display the current used. Let's say you end up with 200mA (0.2A) - your average elise battery is around 40-80Ah new capacity (depends on exactly which one you have and how new it is). If you had 0.2A and a 40Ah battery you can run for 40/0.2 = 200 hours before killing the battery. In practice you will get more than this, but best to play it safe.

If the current you measure is more than about 0.2A I think you're in trouble anyway.

If the current you measure is 0.2A or less, but your battery is going from fully charged to flat in less than one week then your battery needs help - either new electrolyte or replacement.

Cheers,
Robin

Victor Meldrew · Post by **Victor Meldrew** » Thu Feb 15, 2007 11:28 pm

My battery goes flat after about a week, thats alarm on or off. If I know it is going to be sitting idle for a while, I have an isolator hiding somewhere that I can turn everything off.

Dont do this unless its locked away though.

Post by **campbell** » Thu Feb 15, 2007 11:40 pm

Bottom line, I think a couple of weeks on full alarm setting is the most you can hope for in winter. I actually don't arm it when in the garage, and just leave it for immob to come on...rightly or wrongly, I assume that uses less "juice".

However I also have a battery trickle charger which I've used diligently of late, 'cept as Robin diagnosed the other night one of the battery cells has lost the plot so that didn't help me

I plan to install a neat wee plug socket somewhere in the front exterior (maybe inside a wheelarch liner with a wee dustcap) to enable easy hookup and disconnection from trickle charger for future, as I can easily go 4 weeks without using the car but want to be able to jump in and go without raking about under the bonnet all the time. Did I say "easily"?. Well, it hurts actually, but that's family life for you!

Campbell