Battery dead, main fuse power supply wire earthed?

[hammoj28]

Looking for some help, went out this morning and the car wouldn't start, went to charge battery and it's damaged.

I've recently moved the battery to the boot so I double checked the connections in the engine bay, found that the main power cable was earthed somewhere, ended up being the power supply cable to the fuse box is getting an earth somewhere?

I have recently fitted an OBC, wondering whether I should take it out and see if it make a difference?

Car is an E30 318iS with an M50 conversion

Any ideas?

[bigbird76]

Im not an expert on electrical but you will get a reading that power is on the neutral using a multimeter.

Others will comment but i think you need to connect a mulitimeter and check which curcuit is drawing amps from the battery.

If you look on youtube you will find guides on how to do this

Here is one



Goodluck

Leigh

[Brianmoooore]

If any 'live' wire in the OBC loom was earthed, the OBC loom would be a molten, fused mess or would be, if all the relevant supplies are protected by fuses.
Similarly, if the red supply cable to the fusebox (which also goes on to the ignition switch), an isn't fused) was earthed, I'd expect it to be showing signs of severe overheating.
What is your evidence for saying the wire is earthed?

[hammoj28]

If any 'live' wire in the OBC loom was earthed, the OBC loom would be a molten, fused mess or would be, if all the relevant supplies are protected by fuses.
Similarly, if the red supply cable to the fusebox (which also goes on to the ignition switch), an isn't fused) was earthed, I'd expect it to be showing signs of severe overheating.
What is your evidence for saying the wire is earthed?

Only evidence I have is that I've done a continuity check between the power supply wire to the fuse box and one of the bolts which holds the struts to the turret? Am I missing something?

[hammoj28]

Im not an expert on electrical but you will get a reading that power is on the neutral using a multimeter.

Others will comment but i think you need to connect a mulitimeter and check which curcuit is drawing amps from the battery.

If you look on youtube you will find guides on how to do this

Here is one



Goodluck

Leigh

Thanks for the link, handy to know. Shall give it a go.

[Brianmoooore]

Only evidence I have is that I've done a continuity check between the power supply wire to the fuse box and one of the bolts which holds the struts to the turret? Am I missing something?

With what did you do this check?

[hammoj28]

A multi meter set to the continuity function....the one where if you touch the two points it beeps. I touched one end onto one of the nuts on the suspension strut top and one end onto the power supply cable coming from the fuse box. It beeped?

Am I being a wally or is there a problem? I assumed that meant that there was an earth somewhere in the fuse box?

[Brianmoooore]

In my experience, meters tend to beep on the continuity function at resistances below about 60 ohms, which is far from a short circuit on a 12 volt system.
Did you notice the actual reading on the meter?
Which way around did you connect the meter probes? (Try it both ways.)
Was the fusebox feed disconnected from the other leads to the battery positive terminal when you took the reading?

[DanThe]

You defo had it on the positive terminal and not on the nut that holds the plastic clamp to the body?

[hammoj28]

In my experience, meters tend to beep on the continuity function at resistances below about 60 ohms, which is far from a short circuit on a 12 volt system.
Did you notice the actual reading on the meter?
Which way around did you connect the meter probes? (Try it both ways.)
Was the fusebox feed disconnected from the other leads to the battery positive terminal when you took the reading?

Hmm, I shall try this again tomorrow and check the reading. Didn't notice what it was when I checked. Can't remember which way round i connected it either so shall try both ways.

You defo had it on the positive terminal and not on the nut that holds the plastic clamp to the body?

Not connecting it to the positive terminal, just the between the wire coming from the fuse box (which should go onto the positive terminal) and the earth nut. No power involved. My battery is so damaged it won't even charge.....its a new bosch battery.

[bigbird76]

My multimeter does the same thing as you are saying, And as Brianmoooore stated multimeters pick up the slightest thing, Connect the multimeter up like the video says and start pulling fuses.

Leigh

[hammoj28]

Not getting a beep now for some reason, tried it with opposite sides of the meter, however, I am getting a reading of 0.91 continuity.

Leigh, I will try that to see if I can locate it, thanks.