Ok, one last thing. If we were to do this mod, should we invest in a 100 amp circuit breaker or fuse since the stock line is fused to protect the amp and battery? I know it seems as if we are all going in circles, just want a few more opinions, thats all. Thanks.

 

I am looking to do this mod my self but just one thing that I thought of knowing a little about electrics.
If you install an extra cable form the alternator to the battery you have in effect 2, cables running in parallel to each other. So if you have a 100amp fuse or circuit breaker on each, the current that is now possible before any fuses blow is 198amps 99amps in each cable.



:Thinkingo

 

^^^ Yes, the most POSSIBLE is 198. You could accomplish the same thing by using a 200 amp fuse (I will use this in my example for simplicity). A fuse does not resist or induce current. Adding a bigger fuse to the line means the potential for more current is there, but it will still only run at what it was running before.

The idea of a fuse is to have a safety device set up 20% higher than the amperage you are running. If there is a short, the fuse will blow because the amperage is now higher than what the fuse can take.

It would not be a good idea to just throw a bigger fuse in. It will not create more power (just the potential to handle more power).

 

Thanks for the clarification. Just curious as to what you would suggest to keep everything protected. I know the original fuse is 100 amp. Thats why I figured just installing a 100 amp breaker on the NEW line would also protect it as did the original fuse. JohnCoupeUK makes a lot of sense saying that the protection would jump to 198 amps instead of the optimum 100 amp protection. So.....how should we fuse this extra line and/or refuse the orginal cable from the Alt to the Bat? Would putting two 50amp fuses (one in the original fuse box, and one on the new cable) result in the 100 amp protection that we need?

 

yup, well, 98 amps. a 50 amp fuse blows at 50. so at 99, one fuse will blow, and then almost instantly the other one will blow. think of the two cables as one cable, and then just add up the rating of whatever fuses you have.

 

Not Quite as simple apparently due to difference in resistance.

Just been speaking to Harry6582 (older brother) who is a major tuner of Mitsubishi GTO’s and also Electrical bias technician. He recons is to stick with 100 amp fuse on new wire and disconnect old wire at the battery (probably need to do it in fuse box as wire probably shared).

I have a diagram but cannot post any one tell me how.

 

yeah, that is true actually. especially with two differently sized wires. i didnt even think about that. the bigger wire will have less resistance, thus allowing more current to flow through. you'll pop 50 amp fuses quick on the bigger wire, then all the power will go through the smaller one and pop that.

better to just do as he said and get rid of the old wire.

to post a diagram, go to www.photobucket.com.

sign up there and upload your image. then just copy and paste the line underneath the thumbnail image that has [IMG] in front of it.

 

Can’t claim full credit for this it is just a modded pic of Shadohh’s

It shows the wire we need to disconnect and how it uses the old wire
(at connection E31-1) still connecting to the battery charger power sensing unit.

 

Ok, just for clarification, so we ALL do this correctly:

1. Both the original and the new cable will be connected to the alternator, allowing the alternator to do its power/charging sensing.
2. The NEW cable goes directly to the battery with a 100 amp fuse/circuit breaker.
3. The ORIGINALLY fused cable going to the battery from the fuse box (the charging cable from the alternator) needs to be DISCONNEDTED and taped/secured.

This sounds right. Let me know if there is something I am missing.

JohnCoupeUK, is there any way to make your revised pic a little bigger? Its hard to read.

 

I’ve just realised there is a real simple solution.

Fit the new wire complete with 100A fuse/mcb and then all you have to do is remove the original 100A fuse labelled (fusible link “A” dark blue) on the drawing .

This will disconnect the original wire from the bat but still leave it connected to the sensing wire.