trolling motor battery issues, 1997 Pantera II
We are the proud new owners of a Bass Cat boat. First boat bought for me and my son. I grew up with my Dad's small aluminum boat and little DuckTwin engine, so this is a big leap for us. Learning a lot.
The trolling motor has been running out of juice part-way through a day on the water. Took the batteries that were in the boat when bought to get tested and the first one tested was charged but low on capacity so we replaced them. Same thing started happening after a day or two with the new batteries. Finally started monitoring the battery charges (the battery indicator up front for the trolling motor lights up but doesn't show any voltages, for some reason, maybe related to this problem).
On the water yesterday I took a reading after the trolling motor grew weak. The forward most of the two trolling batteries was down around 4 something, I think. Maybe the sun glare made me get that wrong. Yikes. The other was 12.22 or so. I took the reading again when we pulled in after running back to the ramp. Both were stronger, the one was up to 9 (maybe the 4 I read earlier was a 9?) and the other was up to 12.5 or so.
Got home and charged them overnight (ProMariner ProSport Plus 3-bank charger). The weak battery now reads 11.47 and the other 13.07. (I did take readings on the batteries when new and they both read 12 something from the store, and I took some readings after running and charging and noticed a difference which has now gotten worse.)
It seems as if trolling motor is only getting power from the one battery.
Pulled the batteries out with the wires attached, hoping to see if they are wired properly and learned that there are essentially two sets of identical wires running from each and these go down around the gas tank and disappear from sight. A thick black wire comes off of each battery, a thin black wire comes off of each, and thick red wire comes off of the rear-most battery, a thick white wire comes off of the front-most battery, a thin red wire comes off of each. (and the charger wires come off of each.) From what I have read so far on the boards, Bass Cat runs both sets of wires up to the front and then the trolling motor plug has the jump done in the plug itself.)
So, I am not sure what to do next.
- Is the one battery now permanently injured after the deep discharging? Or is there maybe also a problem with one bank of the charger? How to diagnose?
- There are circuit breakers on wires coming off of the positive terminals. The thick wires have 50amp breakers. I can't tell what size the thin red wires have on them.? We replaced one with a 20amp breaker that the marine shop decided on, not sure how. Is that the right size? (I noticed a lot of rust around one and it broke when trying to remove and clean. I see something similar on the crank battery. Should I replace that also? What size is that breaker?)
- What are the thin red and black wires for? I assume the thick ones are for the trolling motor. Are the thin ones for the battery gauge?
- I thought only the cranking battery recharged when the (200 hp Mercury EFI) is running. But, it seemed as if maybe the trolling batteries were recharging from the running also. Is that likely?
- How to diagnose further what might be causing the trolling motor to draw down only the one battery?
Thanks in advance for any and all help.