Battery issues?

[LeveeLiving504]

Generator will not start. Checked Voltage on both batteries and it’s saying 14v when they are connected together. Pulled the batteries off and getting around 13v on each battery. Put batteries on charger separately and topped off. Both showing 13v. Hooked back up together on generator and still only getting 13v. Please help


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[Scoobyshep]

Generator will not start. Checked Voltage on both batteries and it’s saying 14v when they are connected together. Pulled the batteries off and getting around 13v on each battery. Put batteries on charger separately and topped off. Both showing 13v. Hooked back up together on generator and still only getting 13v. Please help


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How are you hooking them up? How are you testing the batteries?

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[doghead]

What generator?

 

[LeveeLiving504]

803a. Everything was working fine. Forgot to start for a few weeks and found this. I’ve tested in series and alone and getting around 13v.


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[nextalcupfan]

I get 12V on the left side battery on my 803a. (The side with the exhaust manifold and fuel cutoff solenoid)
I believe the stock battery cables have a diode in them.

I would check for 24V at the main starter connection.

 

[kloppk]

...
I believe the stock battery cables have a diode in them.

There are no diodes in the stock battery cables.

 

[glcaines]

I would pull the batteries and take them to someone with a battery tester.

 

[Ray70]

Correct... Just because your DMM shows 13V ( really it's probably 12.5 or so ) doesn't mean your battery is any good. You need to load test the batteries.
You may have 1 battery with only a surface charge and no amperage behind it.
Other than that if you are correctly hooked in Series there's no way you can have a complete connection but only 13V across both batteries, if the batteries are good. Are you sure 1 battery isn't backwards, putting them in parallel?

 

[Scoobyshep]

Correct... Just because your DMM shows 13V ( really it's probably 12.5 or so ) doesn't mean your battery is any good. You need to load test the batteries.
You may have 1 battery with only a surface charge and no amperage behind it.
Other than that if you are correctly hooked in Series there's no way you can have a complete connection but only 13V across both batteries, if the batteries are good. Are you sure 1 battery isn't backwards, putting them in parallel?

Putting one backwards would not make it parallel, From an electrical theroy standpoint it would yeald 0 volts (12+ plus 12- =0) in practice usually a fire.

 

[Ray70]

Agreed that reversing a battery would not create a complete parallel circuit, but would it really cause a fire or even a short? Wouldn't there simply be no current flow because there is no connection between the negative of either battery and the machine? Only the 2 positives are connected to the machine.
Or am I visualizing it wrong? In reality with stock cables you probably couldn't reverse a battery anyway because the terminals and cables are different diameters and the error would be noticed immediately.
So I think he should still load test both batteries. You can get a 100A tester at Harbor Freight for like $20

 

[Scoobyshep]

Agreed that reversing a battery would not create a complete parallel circuit, but would it really cause a fire or even a short? Wouldn't there simply be no current flow because there is no connection between the negative of either battery and the machine? Only the 2 positives are connected to the machine.
Or am I visualizing it wrong? In reality with stock cables you probably couldn't reverse a battery anyway because the terminals and cables are different diameters and the error would be noticed immediately.
So I think he should still load test both batteries. You can get a 100A tester at Harbor Freight for like $20
View attachment 823444

If you went across both batteries, possible fire. I wouldnt want to try it .

Defiantly use a good old battery toaster.

 

[frank8003]

Put two new + tested batteries in it properly connected and write back.

 

[Dieselmeister]

803a. Everything was working fine. Forgot to start for a few weeks and found this. I’ve tested in series and alone and getting around 13v.

Even a dead battery can show 13 volts with no load on it. Put your meter across one battery, and have someone turn the switch to prime or start. Then put your meter across the other battery, and turn the switch to prime or start again. Your bad battery will show a significant drop in voltage. Even just turning on the panel lights will drop a dead battery voltage close to 0.

 

[LeveeLiving504]

Thanks for all the help from everyone. Went and bought 2 new AGM Batteries from Sams, $139 each. Installed one and tried it and it was my older red top that was the culprit. Took out the other Red Top and running on both Duracell AGM’s. Starts up fine.


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