Pairing a deep cycle with a heavy duty starting battery

[gatorb8]

Originally Posted by twinboat

That's not what the OP is proposing. He wants to place a deep cycle in a start situation.

first line in op post:

I know this is not an optimal solution, but has anyone put a deep cycle battery with a starting (chassis battery)

put & with implies parallel to me, maybe op will clarify

[Pigman1]

Originally Posted by gatorb8

first line in op post:

I know this is not an optimal solution, but has anyone put a deep cycle battery with a starting (chassis battery)

put & with implies parallel to me, maybe op will clarify

Agree. It's not the most optimal solution, but it is doable. Two years ago I brought the 2013 coach with 450hp Cummins from Albuquerque to Delaware with one of the two start batteries completely dead and the other weak. (bad alternator charging for 5 hours at 19+ volts) Again, not optimal but it worked. Do you want design perfect, or is good enough good enough?

[gatorb8]

Originally Posted by Pigman1

Agree. It's not the most optimal solution, but it is doable. Two years ago I brought the 2013 coach with 450hp Cummins from Albuquerque to Delaware with one of the two start batteries completely dead and the other weak. (bad alternator charging for 5 hours at 19+ volts) Again, not optimal but it worked. Do you want design perfect, or is good enough good enough?

well yes it will get you going but the article says if you deep cycle the pair, you will severely limit the life of the starting battery. I was only commenting based on that. My guess is if you don’t often deep cycle your “house” batteries with this configuration it would be good enough, but, I am only guessing! so many parameters, so little data.....

[Gary RVRoamer]

What's long term? You've already conceded it's "not optimal". There are multiple factors at play, i.e. the differences in size, type, age and condition. However, you know the one chassis battery is bad, so your left over 12v house battery is surely better than that. But what about the other chassis battery - is it much better? If not provably superior, I might be inclined to use both your old house batteries. But that raises the question of why you replaced the house batteries - were they also showing signs of weakness? Maybe you just need to bite the bullet and buy two new ones.


I've used a variety of leftover used batteries in my fishing boat, for both cranking and auxiliary power. Works fine in the short run, but not something I would do if I was depending on long term, reliable performance.

[Winemaker2]

Originally Posted by Ray,IN

This will explain in detail why it is not a good practice: The 12volt Side of Life (Part 1)

Originally Posted by twinboat

Didn't see pairing used deep cycle and used starting batteies mentioned in the article.

Agree didn't see it mentioned.
How many people have used their "Combine" switch to parallel your house and starting battery bank and nothing terrible has occurred.
Deep cycle starting battys cab be used for starting without major problems. Agree that deep cycling a true starting FLA is not a good practice and will cause premature failure but the opposite is not detrimental.
And the above only applies to FLA - when using AGM a GP31 (normally thought of as starting) can be deep cycled just as well as an AGM GC2. Check the specs and you find E Penn Duracell specs both AH and CCA.

[jabassmaster]

wanted to provide update. Today I pulled my old chassis batteries and cleaned them up. I finally found the date of both these batteries and was shocked. I bought my 2006 Journey in May 2017. The battery date on both was 12/09!!!
So I threw Iout the idea of placing my deep cycle battery in parallel with the starter battery. I quickly drove to Sam's Club and bought 2 commercial 31C batteries ($109/ea) and will put them in tomorrow. A sincere thanks to everyone's input!!

[Pigman1]

Originally Posted by jabassmaster

wanted to provide update. Today I pulled my old chassis batteries and cleaned them up. I finally found the date of both these batteries and was shocked. I bought my 2006 Journey in May 2017. The battery date on both was 12/09!!!
So I threw Iout the idea of placing my deep cycle battery in parallel with the starter battery. I quickly drove to Sam's Club and bought 2 commercial 31C batteries ($109/ea) and will put them in tomorrow. A sincere thanks to everyone's input!!

Good move. Decide on some possible solutions, collect as many differing opinions as possible, completely evaluate what you presently have, and make a decision based on the facts you find and future needs. That type of decision making is as good as it gets.

[THenne1713]

Originally Posted by jabassmaster

I know this is not an optimal solution, but has anyone put a deep cycle battery with a starting (chassis battery)
and had long term success. I replaced my 12v house batteries with 6v golf cart batteries and now have a couple of good deep cycle batteries. I have just discovered that my trip back from Utah (and the terrible roads entering and leaving Colorado) has produced a bad chassis battery (11v).

SUSPICION would be that a piece of plate broke off and shorted some other plates, but I would remove, check water, and attempt a bench charge? If new enough (12-24mo old?), may still have prorate credits against replacement? Luck