Battery Grounds

[misphit]

Okay, for someone who's been wrenching on DSM's for 6 years, I probably shouldn't even have to ask this but here goes...

I recently picked up a Galant GSX. I've got a no-start situation and it's really annoying me. During the process of eliminating possibilities, I noticed that the battery grounds are not routed how I would consider 'normal'.

Normal is: one ground going directly from the negative post on the battery to the frame and a completely separate ground going from the negative post to the starter bolt on the bellhousing......... On the Galant, I see one ground going from the negative post to the frame - from there, it connects (from the frame) to the wire which is grounded onto the starter. No separate ground from the batt to the starter.

Is this normal? The starter is cranking slowly and I'm wondering if this could be contributing to the cause?

Thanks.

 

[luv2rallye]

You should ALWAYS have a separate cable from battery neg to starter mount bolt. Your starter draws 60-100 amps and the slightest resistance (such as in a connection) can drop enough voltage to keep starter from operating properly or slow. 0.1 ohm in a connection will drop 6-10 volts at 60-100 amps. Starters need 9.6V minimum while cranking.

 

[misphit]

Hm. Interesting.
After I posted my question, I was able to located a schematic for the motor of this Galant and it depicts the ground going from the batt to the frame then from the frame to the bellhousing. Weird.

I think that I would prefer to have it set up as you advised, Rallye. As long as it's not going to hurt anything, that is.

 

[dsmfa9nutter]

More grounds can only help.

 

[7"exhaust_tip]

You should ALWAYS have a separate cable from battery neg to starter mount bolt.

A year later, yes I know...

Anyways, I am curious how this works when the battery is relocated in the hatch. I've only seen a few people running a separate ground back to the engine bay just to connect to the starter.

I relocated my battery to the hatch a few years ago and just recently the starter has been having more and more trouble. As if it weren't getting enough voltage. Since the starter was swapped and tested and the same with the battery, I know its a ground problem which brought me to this.

I believe I still have the starter ground that goes to the bellhousing.

I don't understand how people get away without having that ground going back to the starter on their battery relocation.

Does anyone with a battery relocation that doesn't have it notice any weaker starting?

I'm going to recheck my other grounds to make sure they all have a good connection, but I honestly think this is my problem.

 

[turbo tim1]

Hm. Interesting.
After I posted my question, I was able to located a schematic for the motor of this Galant and it depicts the ground going from the batt to the frame then from the frame to the bellhousing. Weird.

I think that I would prefer to have it set up as you advised, Rallye. As long as it's not going to hurt anything, that is.

that grounding sounds fine to me as long as the ground from battery to chassis is directly connected in the same spot to the ground going to the starter

 

[luv2rallye]

You should ALWAYS have a separate cable from battery neg to starter mount bolt. Your starter draws 60-100 amps and the slightest resistance (such as in a connection) can drop enough voltage to keep starter from operating properly or slow. 0.1 ohm in a connection will drop 6-10 volts at 60-100 amps. Starters need 9.6V minimum while cranking.

Well I was talking about a battery in engine bay. For one in the rear it's ok to connect battery neg to frame and at engine have a heavy cable from frame to starter mounting bolt. Just make sure the connections are good (clean, large surface area, tight, and protected from moisture). Remember every time you go through a connection of any kind, (frame, terminal, housing, one new cable to another new cable, even the battery post) there is always some small resistance there (or larger if not a good connection). For normal current draws that's ok, but for the large current draw that a starter has it can drop significant voltage there (voltage drop = current x resistance).

 

[luv2rallye]

that grounding sounds fine to me as long as the ground from battery to chassis is directly connected in the same spot to the ground going to the starter

Ya that works but it's better to have a separate cable going from battery to starter as that uses one less connection the current will go through. Also during cranking the large starter current will then not cause a voltage drop across that chassis connection raising the ground voltage (from the battery to the frame or battery to starter).

 

[3kgt2nv]

on every car ive relocated the battery i run a 0 gauge to a distrabution block under hood then 4 gauge to the different parts, engine, starter, frame.