The whole car battery thing?

[Darren S]

Chaps - I'm wondering if someone can explain the whole volts, amps, draw on the battery, etc to me.

I'm stumped when it comes to electrics other than changing a bulb or a fuse. I've got an issue on the Evo where if its not used for a few days, the car will simply not spin over. A new battery hasn't fixed the issue - and when tested, it doesn't appear to be loosing much in the way of voltage - approx 0.2v per day when not used.

When running - the terminals are reporting a healthy 14.6v, so I'm assuming that the alternator part of the equation is fine and doing its job? When the car fails to spin over, the voltage is usually over 12v on either battery (new and old) - but has dipped below that before now.

Therefore, am I correct in saying that it's actual amperage that isn't on tap when I go to start the engine? My limited understanding is that a starter motor needs a hefty clout of amps to spin the engine into life - and not so much in the way of voltage? If so, can amps get drained away much in the same way that voltage can?

I'm seriously thinking of getting an auto-electrician in at the minute (any recommendations, anyone?!) as I simply cannot rely on the Evo to start at the minute. It did a 60mile trip on Wednesday (mainly motorway miles) and when I tried to start it this morning - it didn't have enough amps to spin the starter motor - though the fan and radio came on. That's pretty piss-poor in anyone's book to go from running fine to virtually dead in less than 72 hours.

Any suggestions, thoughts, ideas, etc would be welcome. Aside from the annoyance factor, even I know that simply recharging the batteries is ultimately going to screw them up.

Cheers guys,
D.

 

[SnapMonkey]

Something could be draining the battery.

Usual suspects include Alarm, radio, lights etc.

 

[Dink]

unless you lose a cell completely you will almost all ways get 12v but only a proper drop test will show it's Capacity (Ah)

the lead plates inside can get ruined and thats how you will lose the ability to start the car but still show 12v

 

[scotty2hotty81]

You need to check the amp draw by putting a multi meter in line on the negative terminal, just check nothing is on when you lock the car, ie sit in it and listen to anything still running, make sure boot/glovebox lights are Going off. I'd imagine you should have a Ma draw of around 0.03-0.04

 

[Darren S]

Cheers guys.

Dink - that makes sense from what you're saying.

Scotty - when you say checking the negative terminal - I take it that, the positive should still be connected and not just the negative on its own? (sorry if this sounds stupid! )

I do have one of the below - if there are any more tests I could to help identify the issue?

http://www.gunson.co.uk/item.aspx?cat=663&item=1855

Prime suspects for me are Tracker and the after-market headlights. Would headlights with ballast units draw anything with the ignition switched off? Even slight amounts?

Thanks again,
D.

 

[scotty2hotty81]

That multi meter should do it, with positive terminal connected-disconnect neg terminal one lead from meter to terminalon battery other lead to earth lead (so its in line) make sure meter is on amps, don't switch on ignition/operated central locking as you will fry your meter, the test is in "rest" state ie as it is over night,

Tracker is perm live to charge the battery attached to it, it won't be this.
lights are switched on when you switch them on, I doubt they will cause drain.

 

[The Fatty]

it could also be that the battery only has waht known as a 'floating charge', which will show 12v+ when not being used, but when the battery is put under load the voltage dropped dramatically. This is normally casued by damaged plates inside the battery. Is is a sealed battery? If not, check its got distiled water in it...

 

[Darren S]

it could also be that the battery only has waht known as a 'floating charge', which will show 12v+ when not being used, but when the battery is put under load the voltage dropped dramatically. This is normally casued by damaged plates inside the battery. Is is a sealed battery? If not, check its got distiled water in it...

That's an idea, but I've also bought a new battery and that behaves the same. The Evo batteries and notoriously 'small' (for want of a better term) in regards to their amperage. The current one is only rated to 330amps, whereas its easy to get a Bosch one for the Clio that's rated at 520amps. Seems silly from a design level that such a car would be given a woefully small battery.

Just got it on charge on the drive now. I'll be doing some of the tests mentioned on here in a few hours. Hopefully something will make sense!

D.

 

[Gaz_]

Have a nose through here

http://www.cliosport.net/forum/show...the-car-not-being-used&highlight=flat+battery

 

[Darren S]

FLOL - I give up. More in fear that I'm going to feck something up royally, rather than actually find out anything useful.

I can't even get the tester setup right. It keeps stating on the display "Connect the test leads" when I've got both those and the rotary switch to how it says in the manual. Speaking of which - if you're not an electrician, then the manual makes as much sense as a book on conversational German being read by a Japanese Buddhist monk.

I'll have to get someone to look at it as electrics simply do not make sense to me. Either what I'm really looking for or how to go about it. I got a couple of sparks off the battery terminals earlier at which point, I thought enough was enough.

Thanks again for the suggestions though guys.

Cheers,
D.

 

[scotty2hotty81]

At least you had a go, the worst you could do is blow the meter, should be a piece of pi$$ for an electrician .