Volvo V70XC parasitic drain and occasional no-start issues

[abscate]

You just look at The voltage to ground across the battery, and the voltage at the fuse box to a good ground on the engine. No need for long cables.

If you are worried about the ground cable, remove it and measure resistance on it directly. You can use a temperature gun to see if it gets warmer due to resistive loss

[2001downunderxc70]

You just look at The voltage to ground across the battery, and the voltage at the fuse box to a good ground on the engine. No need for long cables.

If you are worried about the ground cable, remove it and measure resistance on it directly. You can use a temperature gun to see if it gets warmer due to resistive loss

Can you explain this to me like i'm five? (sorry! I'm learning as I go here). So I check the resistance (ohms) from the negative to the ground point on the car - at the battery terminal and also at the positive by the fusebox to the ground?

Should I be worried about the ground cable?

Edit: does it matter if the internal lights are on when i'm measuring this at the battery terminals?

[abscate]

I'll make the measurement and snap some pix

It does,t matter if the small lights on as long as they are on for both measurements.

Captions to follow. Ambient temp 1.0 C

[dj_v70]

If I understand you correctly, the car runs fine now. Just to be clear, you can’t troubleshoot this (except visual) until the issue reoccurs.

If your measurement regarding less than 1v in front of car is correct (hopefully, you had a good clean connection with voltmeter), you are almost there. Problem is either in pos cable from battery to that point or battery to chassis ground. Considering that you note that playing with negative cable temporarily fixes it, I’d start there.

[2001downunderxc70]

I'll make the measurement and snap some pix

It does,t matter if the small lights on as long as they are on for both measurements.

Captions to follow. Ambient temp 1.0 C

Legend, thank you so much! It's an ambient temp here of 29 C and after midnight, so i'll give this a shot first thing in the morning when the kids are awake.

12.69V under the hood

12.69V testing points

12.58V at the battery

resistance touching the probes together

Resistance at the same points under the hood = 0?


Tried this earth point for the negative in the rear batter compartment - see below - (connecting multimeter from negative to this point) but also reading zero. Tried with both multimeters as well... Where am I going wrong here?

[2001downunderxc70]

If I understand you correctly, the car runs fine now. Just to be clear, you can’t troubleshoot this (except visual) until the issue reoccurs.

If your measurement regarding less than 1v in front of car is correct (hopefully, you had a good clean connection with voltmeter), you are almost there. Problem is either in pos cable from battery to that point or battery to chassis ground. Considering that you note that playing with negative cable temporarily fixes it, I’d start there.

That's the one. Car starts and runs fine now, but still with the 0.3A parasitic draw. The measurement of 1-2V at the front of the car was 100% correct, as i've been taking consistent measurements almost daily from the same points over the past month. Removing and re-attaching the negative cable brings everything back to normal.

Indebted to everyone for the help so far! Will report back in the morning when the kids are awake.

[dj_v70]

You really have 2 symptoms and they should be troubleshooted separately. They could be related, but there is a fair chance that they are not.

One is your parasitic draw issue. That one didn’t make your car break down in traffic. I ignored this symptom in my post above as it is the least of your issues. My expectation is that there is no immediate impact from this given new battery ... unless the car sits for days without use. While it is important to get all symptoms up front, it can get confusing trying to troubleshoot both in a single thread, I’d start a new one for this.