# 2 12v batteries charging at different rates?



## 10sne1 (Jul 31, 2017)

Trolling motor battery set up. Two 12v batteries wired together to make 24v for a trolling motor. On an onboard dual charger, the batteries charge at a different rate. One battery takes almost no time to charge. Where the second battery can take hours to charge? Is this normal? thanks


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## DaleH (Aug 1, 2017)

Boy, while I don't use those setups ... are they the same type/brand/rating battery? If were close in specs and you switched their relative position ... does the quicker-to-charge battery still charge faster?


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## 10sne1 (Aug 11, 2017)

I need to replace my on board charger. I can get a 5 amp or 10 amp charger. I realize one will take longer to charge batteries, using A 5 vs a 10. I seem to remember slower charge of the deep cycle batteries is better? I always have 8/10 hours to charge my trolling batteries so time should not be an issue. The 5 amp is $100 cheaper, but do not wish to buy on price alone. Your thoughts, get a 5 or a 10? Thanks


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## eshaw (Aug 13, 2017)

10sne1 said:


> I need to replace my on board charger. I can get a 5 amp or 10 amp charger. I realize one will take longer to charge batteries, using A 5 vs a 10. I seem to remember slower charge of the deep cycle batteries is better? I always have 8/10 hours to charge my trolling batteries so time should not be an issue. The 5 amp is $100 cheaper, but do not wish to buy on price alone. Your thoughts, get a 5 or a 10? Thanks



I just bought an onboard charger for my boats trolling batteries about a month ago. I went with a 10amp unit myself. I believe you can get them clear up to 20 amps. As far as the charge goes that one battery sounds like it may be about spent, they should not charge that way. Everything I've ever read recommends that the batteries be approximately the same age.


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## KMixson (Aug 14, 2017)

Check for loose wires/connections on the battery that is slow to charge. You may have high resistance in your wires/connections causing it to trickle charge that battery.


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## mbweimar (Aug 16, 2017)

My 2 bank Marinco charger is designed to charge a starting battery, and a deep cycle battery simultaneously. The starting takes a higher amperage charge, while the deep cycle takes a lower amperage charger. The connections are marked on the charger so that you don't damage one or both of the batteries. Silly...I know, but I didn't know this until after the second set of batteries I put in my boat.


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## gnappi (Oct 28, 2017)

I've been alternating the connection to my two cells with a Schumacher trickle charger / maintainer on my all electric tinny because one is a "spare tank" AGM deep cycle @ 25Ah, the other an AGM deep cycle @ 95Ah. 

I'm wanting to streamline my maintenance tasks and found the Battery Tender 022-0165-DL-WH. Has anyone used this one? Also are there other options before I commit to this one? 

TIA Gary


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