Adding a new earth bolt

[PeterMac1 Lurker Find all posts View Profile Close PeterMac1]

Hi guys,

I'm a long time follower, first time poster, so G'day and thanks for all the info so far!

I've just purchased a 150 series and I'm in the process of adding a second battery. The install is going well so far, and I've been reading through the dual battery posts for a few tips and tricks, which has been useful.

The dual battery kit I purchased came with a long power cable to join the main battery to the isolator and then on to the second battery, and a short black earth cable which I plan to earth via the vehicle body. Initially I thought I would piggy back the earth cable off an existing earth bolt (I spotted the horn next to the air filter which looked suitable) but now I'm wondering if I could/should utilise one of the spare threaded inserts in the engine bay to provide an earth to the dual battery on its own.

Can anyone advise as to:

A) is it OK to piggyback off an existing earth point,
B) can you utilise one of the empty threaded points mounted in the engine bay to add an additional earth point, and
C) if the answer to B is yes, will any correct size bolt do or does it need to be a specific earth bolt (I notice the ones currently in place are marked with an 'E').

Thanks.

Peter.

[Hogey66 Senior Member Find all posts View Profile Close Hogey66]

Hi guys,

I'm a long time follower, first time poster, so G'day and thanks for all the info so far!


Can anyone advise as to:

A) is it OK to piggyback off an existing earth point,
B) can you utilise one of the empty threaded points mounted in the engine bay to add an additional earth point, and
C) if the answer to B is yes, will any correct size bolt do or does it need to be a specific earth bolt (I notice the ones currently in place are marked with an 'E').

Thanks.

Peter.

Welcome.
Earth will be fine to either a new or existing point. Most important is to make sure you get a good earth connection so once you have connected it check with a multimeter for continuity from your new lead to the other battery negative pole before you connect your new battery. If using a spare threaded hole be aware there is probably paint in it that may compromise the connection thus the need to check with a meter.

[PeterMac1 Lurker Find all posts View Profile Close PeterMac1]

Welcome.
Earth will be fine to either a new or existing point. Most important is to make sure you get a good earth connection so once you have connected it check with a multimeter for continuity from your new lead to the other battery negative pole before you connect your new battery. If using a spare threaded hole be aware there is probably paint in it that may compromise the connection thus the need to check with a meter.

Hogey66, thanks for that. I did note the paint in the threads, and was planning on inserting and extracting it a few times to clear some of the paint away before I tested it.

With respect to the continuity test, what ohm value would be regarded as an acceptable level of resistance?

Cheers.

[mjrandom Out of control poster! Find all posts View Profile Close mjrandom]

Just remember whatever current draw you are taking from the battery has to return via the earth connection. Don't screw a 25mm2 cable to an M6 bolt. Find something sizeable. To check continuity place your multimeter on the ohms setting and go negative to negative though this will be at no load and can be unrepresentative of the connection at load. So run your auxiliary items and do the same check. Ideally 0 ohms.

[ozwapet2 Advanced Member Find all posts View Profile Close ozwapet2]

Personally I would be using the same point/bolt that the existing battery is earthed to, so you virtually have a continuous negative cable run between the two batteries. This would need to be with sizeable cable at least as thick as the positive interconnecting cable.

3 B&S cable would be ideal but 6 B&S probably Ok.

[Fred63 Advanced Member Find all posts View Profile Close Fred63]

i agree with the post above.
The bolt you are talking about with existing earth wires is only a 6mm bolt and the wires connected to it would be 4mm sq at best.
run it back to the main battery or where the main cable is connected to earth.