wis bang Posted July 22, 2020 Posted July 22, 2020 I have two M31 batteries in parallel with starter cable size wires connecting the large posts and it is just connected to my trolling motor via one set of the threaded terminals. Is it possible to connect a two bank charger with out disconnecting the large connections between the two batteries? I added a 20 amp hour battery for my 'hotel' needs so I'm already thinking of a separate 2 amp charger for it and don't want to complicate adding a maintaining charger to the two motor batteries. Quote
papajoe222 Posted July 23, 2020 Posted July 23, 2020 Only if the charger specifies that it charges them individually. Most do, but my old two bank didn't and I would have to disconnect the jumper when charging. If you don't have the manual on your charger, you can contact the company, or search the model online to find out. 1 Quote
Super User slonezp Posted July 23, 2020 Super User Posted July 23, 2020 I guess you could use a charger with alligator clips but why? If you have an onboard charge or are planning on getting an onboard charger, wouldn't you want it done right? Quote
Super User Jig Man Posted July 23, 2020 Super User Posted July 23, 2020 Just to be safe, you could install disconnect switches on one battery so you could just open them while charging. Quote
wis bang Posted July 23, 2020 Author Posted July 23, 2020 9 hours ago, Skunked again said: Yes, you should be able to. I was reading that a maintainer will work on both batteries when they are parallel when hooked to just one and I'm starting out wit a pair of new batteries. I'm trying insure increased life. I have a 'shop' charger that I used after every trip at 10 amps with the batteries separated and only got 3 years from a set of WalMart 29 series so a maintainer appears to be in order 1 Quote
Skunked again Posted July 23, 2020 Posted July 23, 2020 As long as the maintainer is big enough (amperage wise)for both of them. I ruined a 31 series deep cycle, by putting to small of a charger on it. Several people I fish with, run Walmart batteries, 3-5 years is the norm, either with an on-board charger, or a shop charger. Same results. I've heard great things about the Trojan T-1275. The problem for me is, they're about $200 a piece. The amp hours, lifespan/charge cycles, etc is greater though. They're also taller than a standard deep cycle. I'm already over budget on this build, not sure I really want to go more in the red! BTW, I wouldn't get caught up in whose name is on the battery. There are only a couple of battery manufacturers in the U.S. . Quote
wis bang Posted July 23, 2020 Author Posted July 23, 2020 I sent acid trucks to a few battery plants many years ago, had delivery guys buying batteries at East Penn's plant but no longer. Used to see 5 or 6 different companies, a few are gone too...have to consider the amperage needed. and consider the 'get what you pay for' calculator..... Quote
Super User Tennessee Boy Posted July 23, 2020 Super User Posted July 23, 2020 I had two TM batteries wired in parallel on my first boat. I charged them as one battery with a six amp charger for years with no problems. I'm sure it was slow but they were always charged when I got up the next day. I've heard some people say it's not good to charge batteries to slow. I've heard others say they stay cooler and last longer when charged slowly. I don't know the answer but I got seven years out of the first set of batteries and had the second set five years when I sold the boat. Quote
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