Thread: Low battery - 6.5 - 8.5V

Originally Posted by drivesafe

Hi Dan have measured the voltage on your auxiliary battery?

If your cranking battery is still in your Disco, and loosing voltage like that, I suggest you check out your alternator.

If the alternator has cooked a diode, while it will still work while the motor is running, it can flatten a cranking battery in a similar way to how yours is discharging, while the motor is off.

Yeah just checked and the aux measured 11.9v and managed to start the car via a jumper lead.

I hope its not the alternator the battery isnt at all swollen like it was last time though so you might be on the money. I will have to look up those threads about installing an isolator on the alternator.

Ive set the SC80 in storage mode and will see what the cranking battery measures in the morning. Then I might go for a drive and get it tested to confirm if its the alternator.

Cheers

Dan

No one likes buying batteries, of all the ones you can buy Century in my experience has to be the worst by far. However, usually just the blue and yellow ones. I have never really had a bad time with the black ones. Delco, super charge, exide thats what you want.

So the battery has worked fine all weekend, which is a good sign. I last drove the car yesterday around 4pm and the SC80 is only flashing red 3 times before going green, which means the batteries down to 60-70% (i think), so there is definitely a drain.

Can i just take the earth lead off the alternator to isolate it or do i need to unplug it as well? Can i do that in the petrol without pulling apart the fan and belts?

Cheers

Dan

There's no earth lead to an alternator. It earths through the engine. There is a 12V cable to the alternator, a big thick red one connected to the battery, and the control cables. I think the V6 is the same alternator as the V8 so a three pin plug off the back. You can disconnect the red alternator cable at the battery, and at the alternator, and I think if you then unplug the three pin control cable at the back of the alternator you will isolate it from the battery enough that it won't cause any issues. Of course, it won't charge either, but it won't be doing that if it's stuffed anyway. You could then charge the battery using a battery charger, and see if it loses voltage while sitting there. Other's with more experience may correct me on this.

In the V8, the alternator is quite easily accessible from underneath by removing a small plastic panel underneath the engine, drivers side.

If you paid by Visa that is proof enough, either off your statement or app.
If you bought online or from from a Battery shop they keep records too of your purchase via the battery codes etc.
I sent one back by post from Brisbane to Sydney once and had a new one sent up overnight.
Good luck.

Originally Posted by Disco-tastic

Hi all,

This morning the D3 wouldn't start - it at first gave a low voltage warning then would just switch off when you turned the ignition on. I plugged in the IID Tool and it showed an at rest voltage of 8.5V and when you had the ignition on a voltage of 6.5V

The battery is just under two years old (I can't find the bloody receipt! ) and shows no signs of damage. The car was last driven last Sunday, so it has sat still for less than 5 whole days. I have a Traxide SC80 installed, and when I last checked it on Sunday it was flashing to show it was over 85% charged.

I have never seen it drop this low, and I was of the understanding that the SC80 isolated the batteries when voltage dropped below a certain level, giving me some security against this happening. I have seen people isolating the SC80 when storing the car for a while - Can someone please explain why?

Also, can someone recommend a good battery charger - I have thought about getting one for a while now as Finn's battery will need to be topped up every now and then. I have anderson plugs at the back of the D3 which is my preferred charging method.

Cheers

Dan

Originally Posted by Grahame Roberts

If you paid by Visa that is proof enough, either off your statement or app.
If you bought online or from from a Battery shop they keep records too of your purchase via the battery codes etc.
I sent one back by post from Brisbane to Sydney once and had a new one sent up overnight.
Good luck.

Thanks Grahame.

I cant even find the transaction history. Not sure why, as I know roughly when it was and i know the store.

At this stage it looks like the alternator anyways. Car is ok for a day sitting but wont last longer than that. Over the weekend i will isolate the alternator and measure voltage drop. With the alternator connected i measured a 0.3V drop (12.47 to 12.17) over an 18hr period.

Sooooo I snapped the retaining clip off the alternator 3pin plug. I didn't know what the red clip was for (I'd never seen one before) and accidentally snapped it, leaving the tongue inside the clip. On trying to depress the clip I snapped the end off it so now it has no mechanical retaining mechanism.

Does anyone know of another way to fix the clip on? I had a quick look to see if a zip tie would work, but I can't see any suitable holes on the alternator side.

I can get a new plug from the US for $40 but I'm not that keen to as I don't have any tools to remove and reinsert the wires...

Well, I left the alternator disconnected for 15hrs to see if the battery still dropped and the battery went from 12.68 to 11.9V in that time, so I'm guessing it's not the alternator. the second battery was isolated through the SC80 and was at 12.6V, so it doesn'e appear to be anything to do with the SC80.

My next step is to totally disconnect the battery overnight and measure the voltage drop.

If the battery comes up good from that, does anyone have any ideas what could be drawing the current?

Cheers,

Dan

PS. thanks for the suggestions regarding the alternator. I ended up getting a zip tie in there.