-
Generator battery dying
I have a 13 kW Wrico generator with a Kubota V1505 engine. It was installed fifteen or twenty years ago. Some of the original Liberty generator wiring was retained, but much was replaced or bypassed. It runs great and is a good fit for the coach. Recently, after a few months of not running the generator, I found the Group 24 start battery completely dead. Without much thought as to why it died, I replaced it. A few weeks later I was surprised to find the new battery was completely dead. Reading zero volts. I replaced it and started troubleshooting.
Here’s what I’ve found, and I feel like I’m missing something. If I connect just the positive cable to the battery, I have +12v between the negative cable and the battery’s negative terminal. Using an ammeter, I see there is a minuscule current flowing. I’m guessing that the oil pressure or coolant temperature senders might be drawing current even when it’s not running. I’m not sure about that. I don’t know what else could draw power when it’s not running. If I disconnect the thick red cable that runs between the alternator and the starter post (that also connects to the +12v on the battery), the current and voltage between the black cable and the negative terminal of the battery go away. Before I had measured the current draw, I pulled the alternator thinking there might be an internal short. I didn’t think I should be seeing any potential between the engine ground and the battery. I think the alternator tested okay, showing a functional diode between the positive post and the case. I couldn’t find much reference for bench testing it, so I’m not sure I did it right, or did enough.
I don’t see any shorted wires anywhere, and I expect a short would produce a lot more current than I’m seeing. I ordered a new alternator, thinking it wouldn’t kill me to have a spare. My current plan is to monitor voltages for a few days to see if it starts dropping again, and then maybe install a trickle charger. The second battery definitely died more quickly than the first though. Am I missing something obvious here in my logic?
1984 96" with 8V92TA
(remodeled Liberty Coach)
Greenwood, MO -
2 Replies
-
My generator battery is charged off the house batteries through an isolator.
-
You know, I did find two cables that were bringing a house circuit into the generator bay, but they had been taped off. I’m pretty sure that they go to my battery isolator, too. When I upgraded my Vanner isolator and equalizers with Victron equipment last year, I had a cable that I suspected went to the generator, but I don’t think I ever chased it down. That would make sense.
Since reinstalling the old alternator and the new battery two days ago, the battery is holding charge. There is still a trickle of current running, but it looks to be a fraction of a milliamp. The only other things I did were to replace the terminal ends on the battery cables and to wire brush the terminals and terminal blocks I could reach on the generator. It occurred to me that the only thing that would be able to kill a battery in a matter of days was probably a bad glow plug switch. I’ll check those out for any corrosion that could cause an intermittent fault.
I have new rubber isolation mounts and slide roller bearings on the way, so I’ll have to pull the generator all the way out soon. I’ll give everything a closer inspection then. Either way, I’ll probably tie the generator battery back to that battery isolator.
Log in to reply.