Battery Relocation cold starts issue

[cp[mike]]

Your current setup is fine. (pun intended)
Up your 100 amp fuse to a 200 which is the max recommended for 2 AWG. If it still doesn't work then you should consider running a dedicated line.
This is the simplest, cheapest, fastest and safest way imo.

i would agree. otherwise it sounds like you have everything hooked up correctly, just too small of a fuse.

[Raf99]

ok, thanks.

So stupid Q. How do you read the amperage draw on a battery/line while starting the car? (not that i have the tools, but just curious)

[sonikaccord]

You need an ammeter. The best one to use for our app is the kind with the claw/clamp and you just hook it around the wire you want to take the current from.

[cb7 calling]

Your starter does not pull more than 100 amps at 12v. Over the length of the 14 ft wire the voltage drops a bit. So while the starter is pulling 90 amps your fuse sees 150. The drop is greater when the copper is cold. If that 100 amp fuse was right by the starter it would never blow. Just like the factory set up. There is a calculator you could use at rockford fosgate website to find the exact size fuse you need over whatever length wire you are using.

[Raf99]

Just a followup for anyone who may read this.
So I traveled 2 hours today to talk to a legend in car stereo installs. He has owned his own car stereo installation business for decades and is well known in the area. I went to him today and we had a good chat. As cp[mike] noted I should be running a dual output off the post. He noted that with a 2AWG wire from the starter to the battery in a 15 foot run, taking the cold into consideration (and an older starter) I would see up to 120AMP pull on the battery. Which makes sense as an 100amp fuse would blow after a few cold starts, not blow in summer/hot starts and the colder it got and longer the car sat = the quicker it would blow. So he noted the best setup would be:

- dual output batter post. 1 output to starter (2AWG) and the other output to amp/dist.block (2AWG or 4AWG)
- one/two feet off the battery/starter line put a 120+AWG breaker (I got a 180Amp breaker)
- recommended an Odyssey battery (www.odysseybattery.com)

And so we have this:


This setup was with no amps or distribution blocks connected but simply the battery (in trunk), 2AWG wire, in-line fuse, and starter.
Hope this thread helps

[cb7 calling]

That's all accurate to me. Imagine the voltage drop all your other accessories are seeing when the car is off. When its on there shouldn't be an issue because the alt is not relocated and runs everything directly. I guess another thing to consider is charging strain for your alt to the battery because of the run to the back. In cold weather if you have a system you should get a dash mount volt meter so it does not drop too low.

[Raf99]

Well, found this yesterday

[Raf99]

So to recap:
- Battery in trunk
- 2 post split off batter. 1 2AWG wire going to distribution block for amps with in-line fuses for each amp. 1 2AWG wire going to engine bay/starter with circuit breaker in the trunk. This wire going to the engine bay connects to the starter.
- Two other wires connected to the starter for power too. 2AWG alternator with in-line fuse and 4AWG wire to fuse box

Original issue: Kept blowing in-line fuse in trunk for starter wire. Determined with the length of wire + size + cold starts/CCS = not large enough fuse. Took a lot of brains to determine which size fuse should be needed

Resolution: Replaced in-line starter fuse in trunk with proper circuit breaker


PROBLEM FREE FOR MORE THAN A YEAR............ until yesterday.

- Noticed battery was not charging. Suspected it was the alternator.
- Finally determined the in-line fuse I put in the engine bay on the alternator wire (between the alternator and starter) was burnt / melted


I'm thinking the same original issue of the in-line fuse in the trunk applies to the alternator fuse problem I have now. But I'm a little confused with some things....

- Why is the OEM alternator 90amps, but the fuse in the fusebox is 80amps for the ALT?
- With the extra AWG and length going from the battery to the ALT is the 80amp fuse I was using not enough in the long run? (same as original problem)
- Do I need a higher output alternator?
- Is there something I'm not thinking of?


Battery voltage car off: 14.7
Battery voltage car on (measured at trunk. all accessories on): 14.1
Battery voltage car on (measured at alternator. all accessories on): 14.1


So I know the alternator, wiring, etc. is good. But I cannot think as to why I burnt this fuse up. This setup was running for over a year.
Any thoughts on those experienced with this would be appreciated. This site is the only place to ask such technical questions unless I go visit the guy 2 hours away again

[lucifer1]

I know this has been a while

Melted fuses are from either too much current or loose connections. I would use a bolt down amg fuse or eliminate fuse with fusible link at alternator instead.

[Raf99]

I know this has been a while

Melted fuses are from either too much current or loose connections. I would use a bolt down amg fuse or eliminate fuse with fusible link at alternator instead.

Never had a problem since the fix.