Note that some cars come with smart alternators that are ECM controlled. When the ECM detects a drop in electrical load, it will lower the voltage to around 12.9V to help save fuel / increase fuel economy. I noticed this in a Mazda 2. (but your case seems different though)
Ted_v2 wrote:From my browsing on the some forums i see the most mistakes made is due to electrical upgrades or lack off.
i have a few questions.
1/ Do you need to fuse your alternator +VE wire to the battery?
2/ Does it make sense running more than one length of wire from the front battery?
3/ Where should the rear battery take its power from?
4/ At what point does a alternator upgrade make sense.
5/ Should amps share the same grounding point? eg. Splitting a 0g ground wire into 2 4g via a distro block.
6/ How short should the grounds on a amp be?
1) Not 100% necessary IMO, but I could be wrong. If upgrading alt output to batt +ve, leave factory wiring in place and just add additional wiring.
2) Depends on current draw. Look up AWG charts to find wire gauge / length / current capacity. The MOST important wires to upgrade here are the alternator casing (actual ground) to vehicle chassis and to batt negative.. don't forget that.
3) Anywhere you want.. Front battery is usually neatest and easiest to wire it to.
4) I'd say any system over 1500 - 2000Wrms.. or powerful systems that are played at high volumes for long periods.
5) Ground all rear amps / rear batt / processors etc to the same point on chassis. Various grounding points can create ground loops. (look it up)
6) Basically, shorter the better. Or use good quality conductors if running longer distances.. but keep it short.
