Warm ground wire at batteries, no start Gen.

[Usmcsousa]

Hi everybody,
yesterday evening I tried starting up my generac 6kw generator and it wouldn't fire up.
my 95gulfstream class a was running and both chassis and house battey switches were on. Each time I attempted to turn the genset on, my headlights and house lights would dim significantly.
I made sure the AC and fridge were off to reduce the load on the genset and checked all breakers and fuses.
I decided to check voltage on my two group 27 house batteries and it read at 12.86 volts. But I noticed the black ground cable connecting the coach to my battery bank was warm/borderline hot. My red cable was cold to touch.
since it was dark and late, I disconnected my battery bank and shut the coach down for the night.
anyone have any ideas or suggestions for me to go from here?
the two issues may not be related but I figured I'd ask folks smarter than me what my next steps should be.
thanks all.

[Usmcsousa]

Thanks everybody for your help, inspected all my electric today, basically every connection, besides where the connectors connect to my battery bank,were corroded or loose and discolored, going to make an inventory list. Take some pictures and redo most of my system.
add one more thing to my "check annually" list .

[Tom_M1]

When my generator wouldn't start it turned out to be a bad ground connection at the chassis frame. I scraped the area around the connection down to bare metal and cleaned up the cable ends.

[Gjac]

I had this problem with my generator not starting a while back. I cleaned and tighten the connections I could read 12.5 v back to the starter but still no start. I backed my tow car up and jumper ed to the starter. It stared right up. Perplexed, I started to trace the wire from the genset to the battery pulling on the wire as I worked my way to the house batteries what I found was that as I wiggled and pulled on the cable it came out of the terminal. The inside was corroded(green) about 2 inches inside the cable while the terminal that was attached the battery was clean and tight. After stripping the plastic back and re crimping, soldering and applying heat shrink all was well again. I learned that just because you have proper voltage that does not mean that you have enough amps getting through to do the job.

[wa8yxm]

One of two conditions exists:
Suspect 1: Bad (dirty) connection battery to cable or 1b: cable to chassis, My guess is the battery end as the first one you check, for one thing, easier to get to.

Suspect 2: Bad cable. I have actually seen this (Twice) with my own eyes, on my own rig.. Only it was not the ground.. but that's a long story.

[RJsfishin]

You said the lites were noticeably diming. This means a noticeable drop in voltage, but maybe not at the battery
Why not check the voltage under starting load, first on the cables, (at genset or battery) then on the battery posts themselves. If there is a difference, you have cable/connection problems.

[sum1]

You say red is cold and ground is hot. If it's hot near the end or ends, loose connection(s). If it's hot in the middle, it's too skinny. Maybe it was replaced with a too-skinny wire.

[marcsbigfoot20b]

Carefully feel the starter temp. Maybe the motor is hydro-locked.

[Artum_Snowbird]

Yes indeed... normally your generator will take the starter current with no problem, but when you try to start it with a loose connection, the resistance of the loose connection is huge compared to the normal resistance of the motor windings trying to turn.

The battery drives to the maximum to satisfy the resistance and the wires, which normally take what they are designed to do, suddenly have a lot more to overcome. Now, instead of just turning the motor, the circuit pours into the loose connection and heats it up. This instantly drops the voltage way down, and it's not enough to turn the motor anymore.

You already know which one got hot, so replace that one for sure. Once a cable is overheated it looses it's ability to conduct efficiently.

Good luck.

[Usmcsousa]

Thanks for the quick replies, I'll inspect my cables at first light in the morning, might as well replace the cables either way, seems cheap enough and it can't hurt any..
do you guys suppose the generator not starting is related to this issue? I've had a few hard starts before but never unable to get her going.

[Artum_Snowbird]

A laser beam temperature sensor will give you the instantaneous heat and will show you the problem area quickly.

The temperature will register hottest where it is loose, and then as the heat dissipates down the wires you will see the lower numbers.

The cable itself may have a weak spot in the conductors and it just might not be the connection point. Unlikely... but you said they were tight.


I got mine for $20 from Costco just before Christmas.

[CA_Traveler]

OnaQuest wrote:
If the battery ground cable was getting warm (hot) you can bet it has a bad connection at that point. Check the cable terminal ends where it enters the insulation. If you see any green oxidation, replace the cable.

X2 I had a bad connection between the cable end and the battery connector into which it was inserted.

[OnaQuest]

If the battery ground cable was getting warm (hot) you can bet it has a bad connection at that point. Check the cable terminal ends where it enters the insulation. If you see any green oxidation, replace the cable.

[64thunderbolt]

check where the ground connects to the gen & or chassis.

[Usmcsousa]

Tom_M wrote:
Sounds like a bad ground connection. Disconnect your cables and clean the connections.

the batteries are both 2months old. And I cleaned the cables before they were installed, no rust/corrosion that I noticed last night on either cables or batteries. And my wing nuts were both tight.