How do you feel about "mixing" batteries?

[LewisB]

I've seen numerous discussions regarding 6V vs 12V batteries. But I have seen very little discussion regarding using a mix of BOTH voltages.

My 2018 Raptor 353TS came with three (3) battery trays – there is no room to add a fourth tray. So it looks like my options are:
> Three 12V batteries in parallel or
> (Two 6V batteries in series) + (One 12V battery in parallel)

Has anyone done a “mix” of voltages as above?

Along with three battery trays, the trailer has 50A shore power, a 5500W Onan/Cummins generator, a 200W solar charging system, and a 2000W inverter system. We do a lot of boon docking (dry camping). It would be nice to take advantage of the 6V storage batteries to power my inverter system but also have at least one isolated 12V battery for trailer mechanical systems (slides, levelers, etc.). Additionally, I would need to connect these through diodes or other devices that would allow both the solar system and the trailer converter to recharge all 3 batteries but isolate the 12V battery from long term discharge (from the inverter).

Any comments or equipment suggestions?

[chuckster57]

While I suppose it would work, I'm not so sure I would try. IS there enough room on one of the shelves for a pair of 6V batteries? If all the trays had enough room for 6V batteries I would go with six 6V otherwise three 12V would be my recommendation. Not based on any experience or research.

[Snoking]

Three 12Vs, all fresh from same batch. Don't mix battery types, sizes or age.

[KSH]

Don't mix, is probably what he was saying above..

[JRTJH]

I'd ask this:

How do you feel about loading a shotgun with two 12 gauge shells and a 20 gauge shell ??? It's essentially the same as trying to connect two 6 volt batteries and one 12 volt battery. They will "discharge and provide power" but when it comes to attempting to recharge them, they have different charge rates, different charge capacities and different charge characteristics. So, while you can "empty them at 12 VDC" you can't effectively "fill them at 12VDC" (the 12 volt battery will likely burn up while it's fully charged and the pair of 6 volt batteries are still "cooking away, gathering electrons to store for future use).....

[foldbak]

Ya what they said. Bad idea! Use all the same batteries. It's recommended that if you have to replace 1 battery that you replace them all.

[GHen]

Agree, don’t mix.
I have two 6volts and two 12 volts, but I have switch that is A, B, BOTH and none. I use the six volts normally, but when I run low on power I switch to the 12 volts. Never both. It’s a little bit of a pain switching, the the 12 volts are still good so I use them as back up. Once the 12volt age out, I’ll replace them with Two 6 volts, but I may need to continue the switching since they will be of different age and they may be charging to different voltages. Different battery’s mixed will always charge to the lowest level of the group.

[flybouy]

Batteries should not be "mixed". They should be initially installed as new, "matched" (as in same capacity) and when one fails replace both. My truck has dual batteries and the same applies per the owner's manual.

Here's the why. Given a parallel connection, say you have one battery say rated at 85 amps and one rated at 105 amps then the 105 Amp capacity battery will only be charged to the 85 amps.

Now say you have two 105 Amp batteries and one fails. The other battery may be charging to only 80% of it's capacity due to age or deep discharging cycles. So you replace only the failed battery and now it will only charge to the same 80% of it's paired battery's capacity.

Hope this helps to explain how it works.

[Roscommon48]

why would someone even start mixing?????? use the same battery types and enjoy life.

[LewisB]

Batteries should not be "mixed". They should be initially installed as new, "matched" (as in same capacity) and when one fails replace both. My truck has dual batteries and the same applies per the owner's manual.

Here's the why. Given a parallel connection, say you have one battery say rated at 85 amps and one rated at 105 amps then the 105 Amp capacity battery will only be charged to the 85 amps.

Now say you have two 105 Amp batteries and one fails. The other battery may be charging to only 80% of it's capacity due to age or deep discharging cycles. So you replace only the failed battery and now it will only charge to the same 80% of it's paired battery's capacity.

Hope this helps to explain how it works.

Thanks to all for responses - I Suspected this might be the case but figured it didn’t hurt to ask. I appreciate all the input. Sounds like 3 ea 12V batteries is the way to go. Thanks again.

[flybouy]

why would someone even start mixing?????? use the same battery types and enjoy life.

Simply put experience. I can't speak for the OP but if a person has never experienced having multiple batteries then they don't know. I can clearly understand someone having space for 3 batteries but only have 2 6v batteries. Logically you would assume that it might be OK to just add a 12v to the existing.

The OP acted intelligently by asking the question and in my opinion doesn't deserve criticism for not having the experience to know.

[MrEnto]

I put two AGM 6v for the trailer power and a 12v to start the Gen. I did wire a trickle charger to 12v since the gen does not “back charge” the starter battery. The Gen battery charges only when the 110 is live via the inverter or shore power.

[sonofcy]

I've seen numerous discussions regarding 6V vs 12V batteries. But I have seen very little discussion regarding using a mix of BOTH voltages.

My 2018 Raptor 353TS came with three (3) battery trays – there is no room to add a fourth tray. So it looks like my options are:
> Three 12V batteries in parallel or
> (Two 6V batteries in series) + (One 12V battery in parallel)

Has anyone done a “mix” of voltages as above?

Along with three battery trays, the trailer has 50A shore power, a 5500W Onan/Cummins generator, a 200W solar charging system, and a 2000W inverter system. We do a lot of boon docking (dry camping). It would be nice to take advantage of the 6V storage batteries to power my inverter system but also have at least one isolated 12V battery for trailer mechanical systems (slides, levelers, etc.). Additionally, I would need to connect these through diodes or other devices that would allow both the solar system and the trailer converter to recharge all 3 batteries but isolate the 12V battery from long term discharge (from the inverter).

Any comments or equipment suggestions?
If you are full time get 3 Lithium 12V. Lifetime cost is comparable to FLA plus a bunch of other benefits. If boondocking a lot you will want to up solar to maybe 800 watts. If you just want the 12V to power the hydraulics for the slides and landing gear then build in some isolation switches to keep the 12V very separate. Maybe leave the existing converter to charge the 12V and get a proper charger for tbe Lithium although Lithium can be recharged with any old charger if you don't have a Lithium specific uit.

[cliff]

As everyone else says, don't mix voltages or ages if possible. We carry two 12 volt, but got the 2x batteries from Auto Zone. If you had 3 it would be equivalent to 6.

[fbird77]

Yes it would work. But long term you're better off with a matched set and cables all the same length and gauge. That way the batteries charge evenly. Other wise one tends to overcharge and one undercharge reducing their lifespans.