Alternator Terminals

[JIN]

Hi guys.

My next project is doing BIG 3 upgrade to stabilize the electrocity since my electrocity is a bit unstable for now..

All the cables, fuses, etc are on way for delivery but I just want to clarify the terminals on alternator.

I am pretty sure the terminal with round rubber cap on it is positive, but I can't see the negative one.

Could anybody tell me the exact place of positive and negative terminals on alternator?

I couldn't find which one is positive or negative from manual as pic below.

BTW, our alternator is rated at 100AMP, right??

According to my research, the fuse(for alternator to battery) should be rated same amp(100AMP) with alternator.

Is this correct?

Thanks for your comments in advance.

[DJKOR]

The 'negative terminal' of your alternator happens to be the metal casing of the alternator itself. As the body of the car is one big grounding point, it makes sense for the alternator to use this as its ground.

[JIN]

The 'negative terminal' of your alternator happens to be the metal casing of the alternator itself. As the body of the car is one big grounding point, it makes sense for the alternator to use this as its ground.

Thanks DJKOR.

I thought so coz I couldn't find the terminal.

I've done big3 upgrade today and the result is really impressive.

I was going to do it with 0AWG but my parcel (which contains power cables + battery terminals etc..) has been lost somewhere. :(

Anyway I used 4AWG because I am not going to upgrade my sound system anymore and it only hits upto 800WRMS in total.

1. 4AWG cable from alternator to battery positive terminal through 100amp fuse.

2. Battery Negative terminal from Chassis (2points)

3. 2 points on Engine block to Chassis

Before the upgrade, I was having serious voltage drop if my sound system was on.

From 13.8 to 11.xx very quickly..

However, after the upgrade, it doesn't even go below 13.5V after 30 mins with sound system on.

I think there's something wrong with my 2 channel amp becasue this was happening right after I installed the amp which is second hand one.

Just wondering, what's your voltage like when the engine is running?

Mine is about 14V or just a bit above and starts to drop slowly till about 13.7V if nothing is on except engine.

Cheers.

[DJKOR]

That's good to hear that your upgrade has helped out. Always a good system upgrade to do, especially when it is so simple to do.

Just wondering, what's your voltage like when the engine is running?

Mine is about 14V or just a bit above and starts to drop slowly till about 13.7V if nothing is on except engine.

Most charging systems on cars will run at around 13.8v when the engine is running idle in the conditions you have stated. It is completely fine if it goes slightly above 14v initially. When I get back, I'll test to see what voltage drop I get while my system is running.

[David the Viking]

Most alternator regulators will be around 14.4v max. Anything below 13.8v the battery will not be charging properly.