I've had a hell of a time with my battery staying charged in the back.

I've got the battery grounded to the chassis. A good thick cable ran to the starter from the battery. And my alternater is ran to the starter. My head is grounded the chasis.

It was reading 14V but on my way to work it dropped to 12V with the fan off and radio off. It's not going to last very long like this I think.

 

Are you having signs of charging problems. The stock volt gauge isn't that accurate.

 

I thought that also,
yeah, the voltage is actually dropping..
I hooked my computer up to it and it shows 12-12.1 V
And its getting harder to crank.(New battery also, new altenater has about 700 miles on it)

I drove for about 30 minutes like this. I think it maybe charging, just not much.

Even with a strong battery it's not going to run very long with out an altenater I believe.

 

What gauge wire did you run from the battery to the starter? You said the head is grounded to the chassis, what gauge is that wire? The main ground for the engine is the thick, heavy gauge wire that went straight from the (-) post of the battery to the alternator bracket (not the wire on the back of the head, I think that's for the computer,) did you keep that wire and run that to the chassis?

Also are you sure there's a good connection at the starter, where the alternator wire meets the wire running to the battery?

 

I used welding lead. It's about a 2 gauge I'd guess. Battery cable and ground is 2 gauge. The ground isn't on the alternater bracket, it's mounted on the head right below it the bracket.

I sort of think it's bad connection. I hate to put on the altenater bracket bolt, because it's stripped. I'm going to have to fix that sometime soon though.

What is a good ohm reading on the cables. I don't know any thing about that. I take it that ohm is the resistance in the cables.

 

I dont know what you are using as a battery box, but I have heard of the stainless steel retainer plates grounding the battery accitidentally; kinda like leving the battery on a cement floor. No complaints from the composite boxes...

 

If the wire from the head to the chassis is the 2 gauge wire also, that should be fine, I'd just make sure then that you have a good connection to the cars frame and not on the firewall or anything (maybe that's adding more resistance to the line?) You want the circuit to have the least amount of resistance possible. For the ohm reading (yes it measures resitance,) I'm guessing you want something lower than 1 ohm. The lower the better...

 

I have the composite box (moroso) and the largest AC Delco that would fit. I also ran my positive and negative all the way to the front of the car and another negative to the trunk area. I have a ground strap behind each head and additional straps from the engine to the front sub-frame. On start up my charging voltage goes to about 13.7 and then drops as the battery gets full again.
So I guess no problems to report here.

 

guess what, it's the altenator AGAIN.

You'd think after buying couple it would rule that out. 2 rebuilts, and this is the 2nd new one.

She's back charging close to 14 again. Question, is it always suppose to charge at 14? That maybe what's waring them out.

 

Depending on how you wired your starter relay (I use a Ford style mounted on the fender) you could have the alternator wire on the wrong terminal. The starter side of the relay is only powered during cranking. I run the alternator wire to the battery side of the disconnect in back so the car kills when the disconnect is pushed. It is also a good idea to run a negative cable from the battery to the engine block.

Just my .02
Miles

 

Another good feature of increasing the gauge of the wire is the added insulation you get from it. We used really cheap 1.5 gauge wire for your ignition kill switch in my racing go cart. Even when the switch wasnt in kill, we were still being grounded to the frame throughout the whloe length of the wire. When we actually got it running (with very little spark) it arced right through the insulation.