Generator Battery Going Dead

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mkgrady

Senior Member
Location
Massachusetts
I installed this Briggs & Stratton 10KW generator 3 years ago at a residence. I have been doing the yearly maintenance ever since.

There is a problem with the battery going low. There is an LED panel inside the house that flashes when the battery gets low or has any other problems. The manual says if the batter goes low to charge it (???). I tried that and it went low again after a couple of weeks (as I expected). I also verified the battery is in good condition.

I downloaded the unit schematic diagram and unit wiring diagram that show the components but they don't present them in a way I can follow. There is a 25W 1/2 ohm resistor in the circuit but I can't tell what it does. It shows a battery charge rectifier and I suspected it was the problem

I contacted the factory and asked if it this sounded like a failed trickle charger rectifier. He said yes but I felt like he was just yessing me because he didn't know. I bought it, charged the battery with a real charger, changed the rectifier and after 18 days the battery is low again.

Any ideas? Thanks, Mike
 
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zbang

Senior Member
Location
Roughly 5346 miles from Earls Court
How often is the generator being run and what are the storage conditions for the battery? A couple of winters with a low charge on it can kill a cheap battery. Or the internal charger could be a piece of junk and it ruined the battery. Or, the charge monitor could be junk.

How did you test the battery? A volt meter won't do, you need a -real- battery load tester. Yry the battery on moderate load for 30 seconds. If it doesn't pass, replace it. Can you measure the charge current? Also, unless the charger is a smart one, it can kill a battery by overcharging. Consider adding something like a "Battey Tender" smart charger.
 
Sierrasparky

Sierrasparky

Senior Member
Location
USA
Occupation
Electrician ,contractor
They make these battery chargers with a recon setting. I think that is what keeps my batts going so long.
 
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danickstr

Senior Member
perhaps you can add the circuit that Generac provides for their generators, which monitors and charges the battery through a wall wart and a PC board.

It also is the same circuit that is how the system knows to kick on, if my memory serves me, but don't quote me on that :smile:
 
tom baker

tom baker

First Chief Moderator & NEC Expert
Staff member
Location
Bremerton, Washington
Occupation
Master Electrician
You didn't mention if you checked the battery electrolyte.
An poorly designed charger can overcharge and ruin the battery. If the battery sits for a long time with low charge it may not be ablet to accept a charge.
Most auto part stores now have good, low cost, microprocessor based battery chargers, I saw one yesterday in NAPA, the Battery Tender mentioned may be a good one. Look for a multistate charger.
I would typically replace a battery on a generator every three years, 4 years max.
 
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gardiner

Senior Member
Location
Canada
With batteries you do have to pay attention to the conditions they are under even when not in use. Is there a possibity it froze at some point in the past? Has it been removed from the generator at some point and stored on a cement floor for any length of time? Both of these seem to cause the battery to fail to hold its charge afterwards.
There is one other thing I ran accross years ago, the charger unit supplied with the generator was the same unit used on a smaller gen. The smaller gen operated on a 6 volts battery and the larger used 12volts. There was this little switch on the regulator, which had been toggled into the 6 volt setting instead of 12.
 
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mkgrady

Senior Member
Location
Massachusetts
mivey said:
What is the net battery load?
Click to expand...

I don't know, but it is a good sized battery, 33 amp hours. It just has to start the gen once per week and it starts easily.

zbang said:
How often is the generator being run and what are the storage conditions for the battery? A couple of winters with a low charge on it can kill a cheap battery. Or the internal charger could be a piece of junk and it ruined the battery. Or, the charge monitor could be junk.

How did you test the battery? A volt meter won't do, you need a -real- battery load tester. Yry the battery on moderate load for 30 seconds. If it doesn't pass, replace it. Can you measure the charge current? Also, unless the charger is a smart one, it can kill a battery by overcharging. Consider adding something like a "Battey Tender" smart charger.
Click to expand...

The battery was strong until the trickle charger quit. I spoke with the battery factory (SBS)about testing the battery. They said to fully charge disconnected from gen. It should read about 13.7 volts and loose about .2 volts per day. That is exactly how it tested so I assumed the battery is good. The cells are sealed so I can't test the electrolyte.

I just installed a smart charger, a Battery Minder Plus, #12117 to replace the built in trickle charger. First I charged the battery for several hours at 2 amps. In three weeks I will know if it does the trick. I'm betting it will.

tom baker said:
You didn't mention if you checked the battery electrolyte.
An poorly designed charger can overcharge and ruin the battery. If the battery sits for a long time with low charge it may not be ablet to accept a charge.
Most auto part stores now have good, low cost, microprocessor based battery chargers, I saw one yesterday in NAPA, the Battery Tender mentioned may be a good one. Look for a multistate charger.
I would typically replace a battery on a generator every three years, 4 years max.
Click to expand...

The Battery Minder Plus comes highly recommended by many motorcycle friends. Some have had their batteries for 10 years.

powerslave said:
These units have a 3 year warranty. If it's still inside that window, do yourself a favor and call an authorized B&S service dealer to take a look at it.
Click to expand...

If my fix doesn't work I will do that unless I get another idea. The 3 years was up in May.

Thanks for all the responses
 
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