My trunk mounted battery shamozzle

[jp5Touring]

So with all the talk of bad grounds and battery cables and such as of late I thought I would give my 3 months of ownership 73 2002 a really good electrical going over.

Well I found a couple of concerning things and would like input on the best way to correct my wiring. I plan to replace all my large battery cables. They look pretty old and the coating appears to be shrinking exposing bare positive cables.

 

First behind my rear strut bar kill switch is a major concern i think. Notice bare positive cable next to my strut bar.

 

 

I will replace with new with correct red cable.

Also my ground set up is kinda weak I think ?  yes, no ?

 

 

Can some one confirm what these are ? Regulator ? and ?

 

 

One of my other big concerns is the 50 amp fuse mounted at the front of engine bay.

The main power wire comes off the starter selonoid to power the 50 amp block. My battery long cable goes positive to the selonoid.

I then have 4 power wires that I think go to alternator power, the small round relay picture above  and I'm not positive on the other two. Guessing Ignition key and not sure on the fourth wire.

 

 

 

While I'm pretty sure about most wiring but it can make my brain hurt.

 

ShouId I run a small fuse  box with four individual fuses ?  Not one 50 amp fuse.

I'm open to ideas on the best way to make this correct.  

Thanks 

 

 

Edited August 20, 2019 by jp5Touring

[SydneyTii]

For the exposed cable or others poorly insulated near the lug, get some shrink wrap the same as is on the shock tower lug and that should take care of that, make sure the lug is tight and not to short, looks like the PO just trimmed the cable to much. As for red for live that’s up to you, I’d just put good quality (one that doesn’t just peel off) red tape in a band around wires that are hot wires, near their termination points.  Many places in the world don’t use just red as an indicator of a “live” cable, just so long as you make it relevant to where you live.

Most of the battery relocations just use the e30 terminal block, there has been good conversation on the merits of whether to fuse.

Just make sure you cannot easily “ground” any hot wires.

Ground to the shock tower looks ok.

Good luck.

Edited August 20, 2019 by SydneyTii

[M3M3]

if you are going to replace battery cables anyway, ditch the battery in the trunk and put a smaller AGM battery under the rear seat.

[jp5Touring]

15 minutes ago, mlytle said:

if you are going to replace battery cables anyway, ditch the battery in the trunk and put a smaller AGM battery under the rear seat.

 

I just purchased a new AGM battery couple weeks back. Also the PO had speakers mounted under back seat. So theirs that.

I can take a good look at the battery cables tomorrow and shrink wrap them. I considered doing the under seat mount but just want to drive it till winter. I got a lot going on medically right now so just small projects for now.

Biggest concern is the janky distribution block needs to be replaced with something else and should I add fuses to the 4 smaller power wires ?  Is that 50 amp fuse correct for a battery ? That sounds huuuuge to me, no ?

 

[xr4tic]

A rough wiring diagram of your power wires might help.

 

The ground spot will be OK, as long as there is sufficient metal to metal contact.  You would have to either remove metal from both sides of the bolt hole on the brace and the shock tower, or you could take the nut off, expose the metal on the back side, and put the nut back on.  You would then have to coat it with paint or undercoating to prevent it from rusting.

 

I wouldn't run the alternator through the fuse, ideally it should go right to the battery.  The bolt holding the fuse holder looks reeeeeal close to the power wire too.

[Healey3000]

Hi,

 

I would also suggest that you redo the positive terminal.  Perhaps it's the lighting but it looks like the positive cable is pretty corroded where it is exposed.  If you have slack in the cable, cut off and crimp on a new lug.  What gauge is that wire?

 

As has been suggested, connect the alternator to the solenoid such that there is a direct path to the battery.  Nothing wrong with having three wires gathering on the solenoid.

 

Do you still have the stock fuse box? If so, you don't really need that 50 amp fuse, unless it's just a convenient distribution point.

[jp5Touring]

Okay so clean up and  shrink wrap the battery cable ends. 

Run alternator power wire off the battery solenoid.    What gauge would be suitable ?

 

I plan on replacing the 50 amp fuse bar,  and yes I do have the stock fuse box.

 

Anyone know what the small round relay is for ?

 

Thanks for the input

[dlacey]

Horn relay

[Healey3000]

Hi,

 

The factory used 4 mm2 wire from the alternator to the hot junction and a 6 mm2 from there to the battery.  Assuming you have a stock alternator, a 4 mm2 from the alternator to the solenoid should suffice.  Red would be good .

[Conserv]

8 hours ago, jp5Touring said:

 

...Anyone know what the small round relay is for ?...

 

 

It’s the horn relay.  The large rectangular housing is the regulator for the alternator.

 

Regards,

 

Steve

 

Oops: dlacey responded previously!

 

 

Edited August 21, 2019 by Conserv

[Simeon]

You don’t need to fuse the 4 sub-circuits since BMW couldn’t be bothered but if you are reorganising/ remodelling you might as well. 

 

This is what I did in this area. 

 

 

 

 

 

[Stevenc22]

Buy some fresh battery cables from autozone. They are premade in 1/2/3 ft sections and use it to redo your setup.

 

Your setup is rough right now.  Try and move the cut off switch such that it is not right on top of the strut bar. Maybe a cut a piece of wood to lift it up and center it amongst the strut bar.

 

In my engine bay, i have a positive and negative stud for everything to connect to.

 

[TobyB]

Fusing the alternator is OK if everything else in the car is also on the fused side.

But that way, the fuse only protects things FROM the battery, not the alternator.

Depends on what you want.  You have to figure out load paths.

 

50a is about right for a stock 2002, tho- I set Jenn's up that way.

I would NOT use that screw- type fuse block.

 

The correct automotive way is to use at least 2 fusible links- one for the loads, one

for the alternator.

 

I would not switch the positive lug of the battery unless you were required to do so

by some sanctioning body.  Switching ground is about 600 times easier- and probably safer, too.

 

Your positive lead's had its jacketting shrink.  Makes me wonder how it's aging...

 

t

[jp5Touring]

Just a little project creep,  No grommet going in the back of car so pulled back seat to drill out and correct.

 

 

My positive cable connection .I have enough length to cut off and repair.

 

PO used welding cable looks to be 4 gauge if I read it right

 

 

Edited August 21, 2019 by jp5Touring

[Mike Self]

I'm sure you have one, but make sure the ground from the engine block to a convenient place on the body (since you have a trunk-mounted battery) is at least the same size as the battery to body ground.  The starter motor draws more current than all the other accessories on the car combined (unless you have a 1000 watt amp), so that's important.  Otherwise the starter current draw will return to the battery via the accelerator linkage--not a good way.  

 

mike