Is my battery dying?

[RedRummy]

My FD has got one of those tiny batteries in it, its some Japanese make, no idea of the power it produces.
Anyway, when my car is running, and I have my lights on, when I press the brake pedal the lights dim a little bit and I can hear the engine note change slightly.

Using anything electrical in the car has the same effect -putting heater on etc - the headlights will dim a bit.

Is my battery dying - what battery should I replace it with - mine is very small cos the intercooler piping is taking up most of the engine bay  :rolleyes:

[trotter]

From the symptoms it sounds like it ain\'t producing enough juice to run everything. Have you added anything else electrical recently? ICE, etc??

The engine note change is normal as the alternator requires more revs to charge the battery when its heavily loaded - aircon is one of the worst for this ive noticed, but if its doing it when driving then i\'d say you\'re battery is indeed rubber ducked!!

Stick a voltmeter across the terminals and see what comes up.

[RedRummy]

Stick a voltmeter across the terminals and see what comes up.

Last time I checked it was OK, producing enough juice.

It has been run flat a few times, and it only takes a few mins with the lights on and not running to drain it

Maybe I should bite the bullet and get one of those Odessey batteries.

[rx jamie]

sounds like your altenator if anything, get it checked out. a car will run perfectly well without a battery under normal conditions. its only really required for starting the car.
i run without a battery for drag racing.

but it sounds pretty normal to me.

[pdtaylor18]

put a voltmeter across the battery and see if you are getting over 12v.  Think the alternator pumps out near 14v but thats only a rough guide for any system.

[RedRummy]

will check tomorrow - got a few niggly bits to sort out...

Anyone else find that "nipping out to sort out a few bits on the car" ends up taking all weekend, and acheiving very little.. LOL

[Initial-D]

Could be a bad earth I\'d have thought.
The battery is being charged by the alternator when the car is running/

[RedRummy]

I get 12.4v across the battery when its switched off... so seems powerful enough...

Just a bit odd that the system seems to dim when I use something, like the electric windows (the lights will dim a bit)

[philiwily]

Mine does this aswell but never got round to investigating. Noticed it about a month ago when i put the brakes on with my headlights on they dimmed a bit. Gives a shout if you suss it lol.
Phil

[pdtaylor18]

Yoy also need to see what the alternator is kicking out, it may well be ok during daytime driving when you are not using the lights and its only just about topping the battery up, however using the lights, rear window etc using huges amount of power and can quickly drain a battery unless given max from the alternator. Put the volt meter across the battery when its running to get a good figure.
Bad earths need to be tracked down and it might well be just bad earths in both your cases.  With rotary engines coming out a few times in the cars life its hardly surprising there are a few problems.  Try slaving in some earths from battery to chassis, engine to chassis and then try the same at the headlights, see if it makes a difference somewhere, it might just pin point where the bad earth is.  Once tracked down you really need to get some good bare metal between the contacts before you bolt it down.  ideally protect the earth point by a dab of paint, or even vaseline to help stop moisture getting in.