Adding House Batteries

[TayaraTravel]

Originally Posted by FlyFishinRVr

No, because for the same money, the 6v batteries have over 2x the Ah rating.

I get it, for about the same price,
One 12v has 12v x 80AH = 960 watt-hours of energy
One 6v has 6v x 220AH = 1320 watt-hours of energy

[VAtom]

Originally Posted by Ryoungca

what battery size(s) fit in the trays (Group 24)? Based on the discussion above, I am looking at replacing the existing battery box in our 2015 Interstate Ext. and adding 4 AGMs under the coach.

The battery box in my 2014 EXT is sized very tight; smaller than required for the restricted space available.

Group 24 batteries are OK. Group 27 and 31 are too long. The Lifeline GPL-4CT (6V) will fit but the reduced headroom is a struggle.

I built a gas tight wood extension for the box so I could install two additional Group 24 batteries and it was tough fitting that in without modifying any other original trim or lounge components. But in the end, it is a useful addition and includes a main disconnect.

[uncle_bob]

Originally Posted by TayaraTravel

I get it, for about the same price,
One 12v has 12v x 80AH = 960 watt-hours of energy
One 6v has 6v x 220AH = 1320 watt-hours of energy

Hi

Except you are more likely t get a 100AH 12V battery for the same cost as the 6V cells. That puts you at 1200 watt hours.

Given that most battery capacities are a bit bogus, who knows what you really get. You certainly are not getting twice the useful energy for the same money going with 6V batteries.

Bob

[Ryoungca]

Originally Posted by VAtom

The battery box in my 2014 EXT is sized very tight; smaller than required for the restricted space available.

Group 24 batteries are OK. Group 27 and 31 are too long. The Lifeline GPL-4CT (6V) will fit but the reduced headroom is a struggle.

I built a gas tight wood extension for the box so I could install two additional Group 24 batteries and it was tough fitting that in without modifying any other original trim or lounge components. But in the end, it is a useful addition and includes a main disconnect.

So you have 4 x Group 24 lifelines in the coach with your extender? I wonder about the pro or con that way versus under the floor?

[VAtom]

Originally Posted by Ryoungca

So you have 4 x Group 24 lifelines in the coach with your extender? I wonder about the pro or con that way versus under the floor?

It takes up 2 cuft (13x13x20) more of space in the EXT storage area, but it is tight to the curbside and you can stack cargo against it and on top of it.

It makes all of the battery components readily accessible for attaching shunts, monitors and other accessories, checking capacity and disconnecting for storage and swapping out.

The underslung systems I've seen seem hard to service but I might be missing something.
Keep in mind, I'm already on my third set of batteries so accessibility is important to me.
The Airstream dealer charged me $1,000 the first time and I did it the second time for $400 and now have a better chance of following correct hygiene.

Putting batteries in the "Ice Bucket" may be the best of both worlds if the bin is properly reinforced and new wiring is run, but you wind up losing that storage space without really regaining the space of the original battery box.

[FlyFishinRVr]

Originally Posted by VAtom

The underslung systems I've seen seem hard to service but I might be missing something.

It depends on your size (you, the human, not the battery ). There's not much room under the tail of the Interstate, so someone that's smaller will be able to wiggle under there and do whatever work is needed without too much fuss. If you're a bit bigger, it'll be a PITA if not downright impossible.

One solution is to remember that in this one instance, curbs are your friend (vs. evil butt-scraping villains), so if you can find a spot to back up with the arse of your rig hanging over a curb, you're golden. This makes undercarriage work a LOT easier. I refuse to work under a vehicle that's on a jack or even on ramps (bad memories), so for me it's this or nothing....

Another solution is air suspension. Some people swear it's the best thing to ever happen to Interstates (personally I find the ride of the stock vehicle to be equal to or better than my SUV, but whatever), so if you have it one of the side benefits is to be able to raise the back end up for access and service (like oil changes on the genset).

[Ryoungca]

Well I'm intrigued enough to ask for pics. Can you share anything showing the result of your add-on box inside the coach?

[VAtom]

Originally Posted by Ryoungca

Well I'm intrigued enough to ask for pics. Can you share anything showing the result of your add-on box inside the coach?

For 2 additional Group 24's

[VAtom]

Originally Posted by VAtom

For 2 additional Group 24's

inside the box

[Ryoungca]

After lots of reading and discussion on Airforums and locally, I'm embarking on an upgrade/expansion for the house batteries by re-purposing the rear storage compartment. Many thanks to Phaeton313 who led the way earlier in this thread and to Lewster and FlyFishinRV for advice and technical info.

My plan is to add 4 X 6 volt 220-230 Ah Golf Cart style lead acid batteries and then remove the existing internal battery box and the 2 X Group 24 12 volt 75 Ah batteries. The goal is to have about 220 usable Ah of capacity versus 75 Ah today.

Step 1: It looked like the rear storage compartment in my 2015 AI Ext Lounge would be easily removed for modification and it was. The pics show the compartment and the rear of the coach with the opening and spare tire below. Next step is new holes for drains, vents and cables. I'll keep you posted as progress continues.

[wachuko]

Originally Posted by Ryoungca

After lots of reading and discussion on Airforums and locally, I'm embarking on an upgrade/expansion for the house batteries by re-purposing the rear storage compartment. Many thanks to Phaeton313 who led the way earlier in this thread and to Lewster and FlyFishinRV for advice and technical info.

My plan is to add 4 X 6 volt 220-230 Ah Golf Cart style lead acid batteries and then remove the existing internal battery box and the 2 X Group 24 12 volt 75 Ah batteries. The goal is to have about 220 usable Ah of capacity versus 75 Ah today.

Step 1: It looked like the rear storage compartment in my 2015 AI Ext Lounge would be easily removed for modification and it was. The pics show the compartment and the rear of the coach with the opening and spare tire below. Next step is new holes for drains, vents and cables. I'll keep you posted as progress continues.

This is great!! Do share as many photos of the process as you can.

[wachuko]

Originally Posted by Ryoungca

...My plan is to add 4 X 6 volt 220-230 Ah Golf Cart style lead acid batteries and then remove the existing internal battery box and the 2 X Group 24 12 volt 75 Ah batteries. The goal is to have about 220 usable Ah of capacity versus 75 Ah today...

Replacing, not adding? Any reason to not keep the Group 24 batteries as well? Is the reason because we must use batteries that are the same?

[Tincampers]

Originally Posted by wachuko

Replacing, not adding? Any reason to not keep the Group 24 batteries as well? Is the reason because we must use batteries that are the same?

Different battery types have different charging profiles.

[wachuko]

Originally Posted by Tincampers

Different battery types have different charging profiles.

I suspected that was the reason behind it...

I am just trying to plan ahead on how I will modify mine... LiFePO4 Lithium Iron Phosphate Batteries are out of my budget right now... so I was thinking of using the existing tray, add the second one on the passenger side, use the rear storage compartment like Ryoungca is doing... just trying to see how much I can accommodate... I want to eventually have a setup that would allow me to also use the A/C if needed... so based on the above, I would have to swap all batteries for the same type as those being added.

I want to make the changes necessary to support current batteries and also support LiFePO4 batteries in the future, without having to redo everything... so that I just buy once... makes sense?

I know I will need a new inverter... still need to figure out what model that should be based on my intended use of running the A/C...
I know I will need a new controller... need to know if the one I selected will support my ultimate goal of running larger battery banks or if I need to change to different model...
I am hoping that the wiring in the AI does not need to be upgraded...again, need to validate...

So even if I stick with just the two factory batteries for now, I want to upgrade the infrastructure supporting the Solar system to be able to cope when I move to the additional battery banks and then when I move to LiFePO4

[Protagonist]

Originally Posted by wachuko

Replacing, not adding? Any reason to not keep the Group 24 batteries as well? Is the reason because we must use batteries that are the same?

If you mix 12v and 6v batteries— or mix battery groups like Group 24 and Group 27, for example— they cannot be recharged at the same time without damaging one or the other.

Either the batteries that are finished recharging first will be cooked while the others are still charging, or the ones that would finish recharging last will never reach full charge. Or both. And yet the BIM allows shore power— through the inverter/charger— to recharge both the Group 24 house batteries and the Group 49 chassis battery, though neither one to the optimum charging profile. So clearly there are other factors to consider.

If you wanted to have two separate and independent house battery banks, one composed of 6v batteries in series and one composed of 12v batteries in parallel, you can get a three-way selector switch from retailers such as West Marine, and keep the two sets of batteries independent, as a main set and a reserve set. But you would probably want two separate selector switches, one for use and one for charging, to allow you to charge one while using the other. Or to let one house battery bank power the inverter while the other feeds just the 12v systems. Or whatever.

I'm just spitballing here; I haven't explored the possibilities and limitations inherent in maintaining two independent house battery banks. You might need a second BIM as well, for all I know. Electrical engineering isn't my forte.

[wachuko]

Originally Posted by Protagonist

If you mix 12v and 6v batteries— or mix battery groups like Group 24 and Group 27, for example— they cannot be recharged at the same time without damaging one or the other.

Either the batteries that are finished recharging first will be cooked while the others are still charging, or the ones that would finish recharging last will never reach full charge. Or both. And yet the BIM allows shore power— through the inverter/charger— to recharge both the Group 24 house batteries and the Group 49 chassis battery, though neither one to the optimum charging profile. So clearly there are other factors to consider.

If you wanted to have two separate and independent house battery banks, one composed of 6v batteries in series and one composed of 12v batteries in parallel, you can get a three-way selector switch from retailers such as West Marine, and keep the two sets of batteries independent, as a main set and a reserve set. But you would probably want two separate selector switches, one for use and one for charging, to allow you to charge one while using the other. Or to let one house battery bank power the inverter while the other feeds just the 12v systems. Or whatever.

I'm just spitballing here; I haven't explored the possibilities and limitations inherent in maintaining two independent house battery banks. You might need a second BIM as well, for all I know. Electrical engineering isn't my forte.

I want to keep it simple ... I will use all the same type of batteries when I add/replace for the upgrade...

[Protagonist]

Originally Posted by wachuko

I want to keep it simple ... I will use all the same type of batteries when I add/replace for the upgrade...

I don't blame you. That's the way I would go in your shoes.

However, I am reluctant to tell people "No, you can't." I'd rather tell them, "No, you shouldn't. But if you want to go ahead and do it anyway, here's what I think you should keep in mind…" And then they can make their own, more informed, decision about whether to go ahead.

[Ryoungca]

Regarding a 6 volt bank and a 12 volt bank in the same set-up, I think there are inverter chargers that will monitor and charge two or more separate battery banks, each according to its needs. I haven't looked into that option for now. I want to monitor boondocking performance with the planned 4 X 6 volt set-up and avoid the expense and hassle of replacing the Magnum for a least a while.

[uncle_bob]

Hi

If you go to a battery system with 4 T-105's in it, you will want a 100A converter/charger to match them. They "enjoy" being charged at that sort of rate for best performance.

If this is a re-wire job and you are in the "thinking" stage - consider a 24V system instead of a 12V one. Put the T-105's all in series. The cables will be smaller. The 24V inverters and converter / chargers will be more efficient. Boats run 24V so LED lighting and appliances are all available at 24V. So are solar gizmos.

Maybe keep one group 24 to run the brakes and the propane detector. Trailer brake lights and turn signals are all run off the TV power so they really don't matter in this case. Charging a 4 x T-105 bank off of the TV is sort of silly so it also is not a big drawback.

Bob

[Boxster1971]

Originally Posted by uncle_bob

Hi

If you go to a battery system with 4 T-105's in it, you will want a 100A converter/charger to match them. They "enjoy" being charged at that sort of rate for best performance.

If this is a re-wire job and you are in the "thinking" stage - consider a 24V system instead of a 12V one. Put the T-105's all in series. The cables will be smaller. The 24V inverters and converter / chargers will be more efficient. Boats run 24V so LED lighting and appliances are all available at 24V. So are solar gizmos.

Maybe keep one group 24 to run the brakes and the propane detector. Trailer brake lights and turn signals are all run off the TV power so they really don't matter in this case. Charging a 4 x T-105 bank off of the TV is sort of silly so it also is not a big drawback.

Bob

With all due respect Bob, your comments are not right for owners of an Interstate B-van in the sub- forum it was posted. Your comments only apply to an Airstream trailer.

T-105 are flooded lead-acid batteries that just don't work in an Interstate with our special access and venting.

While going to a 24V system has advantages it also requires more than switching out a few LED light bulbs. You would also need a 24-12V DC converter to handle all the 12V systems in the Interstate.