Wired Amp and 2 days later, Battery light comes on...

[choke artist]

Ok, so I'm perplexed...

I've got an '83 720 with the Z24 carbureted. Two days ago I wired a 600w amp and a 10in sub to an existing head unit. Last night I put the flooring back in and made the wiring nice and neat and now this evening I get in the truck and after I hit the road, the battery light comes on. It's fairly bright but diminishes as I accelerate. After hauling down the road, I got it to turn off. When I got home, I added a bit of water and checked to be sure all the connections look good.

Took it for a drive again and it seemed to be idling a bit high. The battery light was on again and when I shut it off it dieseled for a few seconds...which it's never done before...what the heck is going on???

[banzai510(hainz)]

How about buying a Vhinese volt meter for about 15$ and putting it across the batter to find out what your voltage is.

 

Could be coincidence that the stereo was hooked up and just have a alternator going out.

 

Put on Volts and put it across the batter when running. then put on the lights and ck the voltage again and see what it reads.

 

if in dought you can always remove the power wire to the stereo and see if that is loading it down.(or proplem goes away)

 

cl for loose connections at alternator

[datsunaholic]

It's idling high and dieseling because the choke is staying closed.

 

The choke is staying closed because the alternator has gone bad (the choke doesn't work when the alternator light is on, even dimly).

 

I'm assuming that's a 600W PEAK amp. 600W @ 12V is 50A. While I doubt you're running the thing at full blast all the time, you only have a 60A alternator stock, which means you've overloaded it since you're pulling over 10A just with the engine running. With the headlights, wipers, and heater going you're probably pulling 40A without the stereo system. That leaves you with 20A IF you have a good alternator. That means you can have a PEAK max of a 240W amp.

 

You're gonna need to upgrade the alternator if you want to run a big amp.

[choke artist]

Ok, I think the alternator was already going out because no alternator light shows when I turn the ignition to "on." This morning the light was on again. On the way to work, I stopped and disconnected the power cord going from the battery to the amp and within fifteen seconds the light goes off and stays off.

 

If I need to replace my alternator anyway...which it looks like I might (I'll find out in the next day or two) do I need a brand new one, or an actual "upgraded alternator?" And is there any problems/drawbacks with having a bigger alternator?

[datsunaholic]

The only drawback to a bigger alternator is the (relatively minor) mods needed to install it, and if it's physically bigger there's not a whole heck of a lot of room in a 720 for it. There's a thread somewhere on how to use a Saturn alternator; I think it was for a 620 but the steps are pretty much the same.

[Npdavies.]

The only drawback to a bigger alternator is the (relatively minor) mods needed to install it, and if it's physically bigger there's not a whole heck of a lot of room in a 720 for it. There's a thread somewhere on how to use a Saturn alternator; I think it was for a 620 but the steps are pretty much the same.

Here's the thread for the Saturn Alt.

http://community.ratsun.net/topic/18218-how-to-install-a-saturn-alt/

[choke artist]

Problem solved! Replaced my alternator and wow!...what a difference! I hadn't realized it was idling higher than it should've before since the truck was new to me. I just kept thinking,"the gas mileage should be better on a well kept 4 banger like this."

 

The truck is one sweet ride now. My question now is, what are my options for getting sound back in the lil banana?

 

1. Do I reconnect the amp and keep the sound in the mid/low range?

 

2. Do I buy/install a capacitor...will this help?

 

3. Get a smaller amp?

[datsunaholic]

I don't know how well the capacitors work, but what they will do is even things out by charging up when things aren't loud, then discharging when the load is high. This keeps the big bass notes from pegging the charging system every time. The alternator will still be working pretty hard if you run the thing near max all the time, though, as the capacitor will have to constantly charge between big loads. Me, I'd run a smaller amp but then again I don't need to FEEL my music. I will admit though that I've found that having an amp makes the sound better becuase it doesn't overload the head unit, but you have to size the amp appropriate for your electrical system.

[blackwolf]

a capacitor does help but datsunaholic is right about it having to charge constantly i have a 84 720 king cab with 1100 watts pushing 2 10's as long as im not using any running lights its fine but once i turn my lights on i get a real dim battery light with a 60 amp alt. i suggest upgrading to the saturn alt. im going to as soon as i have extra money