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Old 10-02-2018, 10:50 AM   #1
Jersey Devil
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Two 6volt And one 12 volt series?

I presently have one 12 volt battery in my 2018 3731 Montana.Its a Exide Stowaway 80 amp 20 hrs that it came with.
I have purchased two Trojan T-105 6volt batteries to run in series for 12 volt.Would it benefit me to series the one 12 with the two 6’s because I have no other use for the 12 volt so figure if I can use then I will.
The Exide is 80 amp and 2trojans alone 225 amps together.if I connect in series will the 80 be added to the 225?
 
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Old 10-02-2018, 11:02 AM   #2
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You should always have matching battery's because of the capacity when charging. If the 12 volt ends up fully charged and the (2) 6 volt in series is not at its full charge then the 12 volt will end up boiling until the other battery's end up to full charge. Of course this is coming from many years owning a golf cart.
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Old 10-02-2018, 11:12 AM   #3
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Donate your 12 volt battery - don't mix it with the 6 volt one.
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Old 10-02-2018, 11:54 AM   #4
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I agree you should not mix batteries. But DO NOT series the 12 v battery with the two 6 v batteries. That would give you 24 volts. You can series the two 6 v batteries and then PARALLEL the 12 v battery with them and maintain the 12 volts. But not a good idea. IMHO of course.
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Old 10-02-2018, 12:08 PM   #5
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Yes just had a friend just tell me different amps a no no to run in series.
Thanks for the heads up.
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Old 10-02-2018, 12:20 PM   #6
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Quote:
Originally Posted by Jersey Devil View Post
I presently have one 12 volt battery in my 2018 3731 Montana.Its a Exide Stowaway 80 amp 20 hrs that it came with.
I have purchased two Trojan T-105 6volt batteries to run in series for 12 volt.Would it benefit me to series the one 12 with the two 6’s because I have no other use for the 12 volt so figure if I can use then I will.
The Exide is 80 amp and 2trojans alone 225 amps together.if I connect in series will the 80 be added to the 225?
I have used 6 volt golf cart batteries on my boat for many years. Make sure that you only put 2 of the 6 volts batts in series to make up 12 volts. If you want to use the extra 12 volt battery you have, just wire it in "parallel" with the 2 other batteries you have wired in series. I have used this scenario in my rig now since it came with a 12 battery and I use two of the 6 volts from the boat with no ill effects from charging. Email me at 1jhmoore@charter.net and I will send a wiring diagram.
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Old 10-02-2018, 06:43 PM   #7
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I have used 6 volt golf cart batteries on my boat for many years. Make sure that you only put 2 of the 6 volts batts in series to make up 12 volts. If you want to use the extra 12 volt battery you have, just wire it in "parallel" with the 2 other batteries you have wired in series. I have used this scenario in my rig now since it came with a 12 battery and I use two of the 6 volts from the boat with no ill effects from charging. Email me at 1jhmoore@charter.net and I will send a wiring diagram.
What is the advantage wiring the 12volt parallel?
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Old 10-02-2018, 06:55 PM   #8
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What is the advantage wiring the 12volt parallel?
In parallel volts are constant and amps are additive. In series volts are additive and amps are limited to the lowest amp rated battery.

Using round numbers, two 12 volt 100 amp batteries in parallel gives 200 amps capability at 12 volts. Two 12 volt 100 amp batteries in series gives 100 amps at 24 volts.
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Old 10-02-2018, 07:32 PM   #9
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In parallel volts are constant and amps are additive. In series volts are additive and amps are limited to the lowest amp rated battery.

Using round numbers, two 12 volt 100 amp batteries in parallel gives 200 amps capability at 12 volts. Two 12 volt 100 amp batteries in series gives 100 amps at 24 volts.
I understand the result of series and parallel.
What I don’t quite understand is two 6volt in series is 12 volts and amps only what one 6 volt offers.
Is there any advantage adding a 12volt battery with 80 amp at 20 hr in parallel to the two 6volt in series that equal 225 amps at 20 hrs?
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Old 10-02-2018, 07:55 PM   #10
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I understand the result of series and parallel.
What I don’t quite understand is two 6volt in series is 12 volts and amps only what one 6 volt offers.
Is there any advantage adding a 12volt battery with 80 amp at 20 hr in parallel to the two 6volt in series that equal 225 amps at 20 hrs?
You would wind up with a 305 amp bank with that configuration. Mixing 6v and 12v batteries in the same bank is not recommended.
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Old 10-02-2018, 08:18 PM   #11
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I agree with Zack. Even with the dissimilar batteries the amps should still be additive.
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Old 10-02-2018, 09:52 PM   #12
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What is the advantage wiring the 12volt parallel?
The purpose is to add additional storage power. Some rigs come from the factory with two 12 volt batteries wired together in parallel for additional storage power.
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Old 10-02-2018, 11:32 PM   #13
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I have 2 6's and a 12 in my unit. I installed a marine battery rotary switch. It has an off, one set of batteries, both sets, or the 2nd set. So I can use it to totally disconnect my batteries. Also, I just run with the 6 v batteries since they have more amphours. It for some reason I get low, I can switch to the 12 v battery.
I just did this because I had a new 12v when I started, but heard that 2 6s are better so I bought them and didn't have anything else to do with the 12v battery.
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Old 10-09-2018, 07:29 AM   #14
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I an not a battery expert, but 3 years ago a purchased my current Montana with 2 new 12 volt batteries. I removed the 2 -6 volt interstate batteries from my trade in. I then installed the 6 volt batteries next to the 12 volt ones and wired them up with thick cables. It has been like this for 3 years plugged in 24/7 when not in use in my pole barn. I check the water level every month or so and have not had any issue what so ever. These batteries are not even in an enclosed box, they are just sitting in a plywood box a built to hold them tightly so they will not move around.

We boon dock for weeks at a time and use the genny maybe 1-2 hrs a day to keep them charged up.
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Old 10-09-2018, 07:54 AM   #15
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Originally Posted by beeje View Post
I an not a battery expert, but 3 years ago a purchased my current Montana with 2 new 12 volt batteries. I removed the 2 -6 volt interstate batteries from my trade in. I then installed the 6 volt batteries next to the 12 volt ones and wired them up with thick cables. It has been like this for 3 years plugged in 24/7 when not in use in my pole barn. I check the water level every month or so and have not had any issue what so ever. These batteries are not even in an enclosed box, they are just sitting in a plywood box a built to hold them tightly so they will not move around.

We boon dock for weeks at a time and use the genny maybe 1-2 hrs a day to keep them charged up.

That is exactly the way I have mine
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