Help Diagnose possible battery Issue

[CheesyMong]

Hi Guys

Just after some advice.

I was working on the CARPC today and had the following running

CARPC
LCD
Aircon
Radio
Driver's Door open

After about 10mins the car through an error code"run+mode+change+system+check", quick google and it sounds like the battery, so I put a multi-meter on the battery and it read 6.5v...fair enough there is the problem.

Powered down every thing and left the car for about 30mins, checked the battery again and it was back to 12.5v and not going down so it doesnt look like there is anything draining it.

Turned on the engine and at idle it starts at 14.x volts and as the CARPC boot and then aircon and the radio it slowloy drains to about 13.5.

The battery has been drained flat once before about 2 months ago...

SO the questions are.

1. Is 6 mins normal for the stuff I had running?
2. Is 13.5v at idle OK or does that seem low?
3. Anyone know how to test the draw on the battery or should I take it to a battery place for them to diagnose? It I do test it what am I looking for?
4. Will a battery like the Optima D35 YT solve the problem and allow when to run at equipment listed for more than 6mins with the engine off?

Cheers

Joel

[Ric]

It does sound like your battery is stuffed, probably from that time you ran it flat.
The first thing you must do is measure how much current is actually being drained by your devices.
You need to disconnect one of the battery leads (it doesn't matter which), and put a current meter between the battery and lead.
Try measuring them one at a time at first, because most meters can only measure up to 10 amps, and you might be drawing more than that.
Even at 10 amps, a standard battery should be able to run for several hours.

Note, disconnecting the battery for more than 10-30 seconds will reset your ECU, but that's not a problem, Subaru often do it deliberately to clear problems.

[CheesyMong]

Can multimeter's measure the current is is that another device?

Cheers

Joel

[teK--]

Multimeters can measure current but unless you have a high end one it probably won't handle more than about 10A, unless you have the clamp-on type sensors.

[CheesyMong]

Update

I have replaced the battery with a Optima 75/25 Identical to the D35 just with the option for front posts as well.

Had the original battery tested and it was outputting 330CCA a good sign apparently it was stuffed

We will see how it goes.

Cheers

Joel