Much Thinking About My Battery Bank

My inverter and battery monitor installation project has turned into a revamping the battery bank project.

I can’t believe that a high end RV like a Glendale Royal Classic does not have a proper battery compartment that makes accessing the batteries for maintenance easy. The batteries are in the corner of a narrow compartment on the front passenger side:

That picture might give the impression that there is a lot of room to work, but there isn’t. Getting in there is such a twisty business that I neglect my maintenance. For one thing, I’m very overdue to clean my battery posts. I have started to keep a cover over the batteries, but getting it off is a pain, and then you have to blindly squeeze in there to do the maintenance on the positive terminal. Getting the cell caps off to water? Augh!

What doesn’t help is that 6V batteries are taller than 12V batteries, another reason why I wanted to move back to the 12V style. But thanks to all the comments I have received, I now know that my battery information is several years out of date and that I can get two 6V with all the amp hours I need and that I will be better served by them than by two 12V. So I am eventually going to replace my two 6V with way fewer amp hours (90!!!!!) than I thought they had (150!!!!!) with the biggest Trojans (200 amp hours!!!!!) I can fit in my space. Thank you so much to everyone who beat me about the head with this information.

So all that about batteries to say that I am always going to have two tall 6V that don’t fit well in the compartment and that I am always going to have trouble doing maintenance on them.

Then, there is the design of the battery bank to keep in mind. I’m no longer going to be able to simply connect everything to my battery posts.

The addition of the 1,000W inverter means having to put in a 150A fuse on the positive side to protect my system. Such a device is not available locally, so I am shopping online and getting frustrated by the lack of sources in Canada.

I also need a shunt for the negative side, but, thankfully, that came with the battery monitor.

As for cables, ha! I need a short length (about one foot each) from the terminals to the fuse and shunt respectively, and then about six feet from the fuse and shunt to the inverter in the rig. All four cables need to be 2 gauge and will require lugs, which means crimping. I am not buying a crimper, so that means having to pay someone to make the cables for me. And that’s if I find cables. The best tip I got so far was to look for a place that specializes in car stereos, so that’s where I’ll start looking.

When I look at how others have designed their battery banks, I see that the shunt and fuse holder are often bolted to the side of the battery compartment. My compartment only has one wall and it’s not easily accessible, so forget that idea.

The more I think and research the project, the more the technical part of it becomes very clear and the more the challenge becomes a lack of sources for parts and a lack of space to work.

Relocating the battery bank is one option. But the only compartment that would be suitable is the giant passthrough at the rear of the rig. I’d be loathe to lose all that space and I’m nervous about having my batteries back there; it just feels like a more vulnerable spot than the front compartment in terms of potential accidents.

But that would put my battery bank directly under the office, so I’d be able to put the inverter in the office and avoid running the 120V wiring from the living room to here. It also seems to make more sense to have the batteries down here since the converter is in this room. I’d still have to run wiring the length and width of the rig to keep the batteries connected to the truck alternator and converter, but that should be fairly doable so long as I keep everything labeled in the dismantling process.

The biggest con for moving the batteries is the weight redistribution. My existing batteries weight 260lbs total. It seems like I will be able to reduce that weight with the Trojans, but for now, I have a battery bank that weighs 260lbs. The distribution of the weight on the axles is such that if i were to remove 260lbs from the front passenger side and move it to the rear, I would have to find 260lbs to move to the front. All the weight in the rear of the rig is inside, not in the storage compartments. I’m sure I can pull that much weight out of the storage compartment, but it won’t fit in the passthrough at the front.

So moving the batteries, while an attractive idea with a lot of benefits, is ultimately a much bigger project than what I want to get to get into.

Therefore, the idea that I am mulling over right now is being able to access my battery bank from above. Yup, I am considering building a trap door in my living room to the compartment below. I believe it could be positioned in such a way that the chair would cover the hatch, so the hole wouldn’t be immediately apparent. There would be a matter of ensuring the floor is still structurally sound, well insulated, and well sealed to keep off gassing fumes (and cold air) from sneaking in from the basement. I’m not crazy about this idea, but so far it’s a notch above using the rear passthrough.

I have to empty the rear passthrough next week so that work can be done on Miranda’s rear end. Once it’s empty, I’ll examine the space and determine which option I want to go with.

I am actually at the point where I think that AGMs, while twice (or more) the cost of traditional batteries, could be my solution since they are virtually maintenance free and once the knuckle grazing battery bank set up is done, I wouldn’t have to twist myself into the battery compartment very often. So that option is very much on the table.

If any readers have designed their own battery banks where there was no obvious place for one, I’d love some input!

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  • As I started reading this the first thing that popped into my head was a “hatch” through the floor and I was happy to see you came up with the same thought! I don’t know why we did not think of this when we talked about the original conversion to 6 volt batteries. It will take some careful measuring and planning but it is a good solution.

    You could use a swing up hinge system or just a cutout with a couple of those flush sitting, flip up rings to lift it out with when needed. Plus a system to prevent the hatch from falling through the hole when you put it back in place.

    You will come up with a workable plan, I am sure.

  • LARRY! I could kiss you! I’ve been wanting a watering system since day one and haven’t been able to find one that would fit with my height restrictions. I know I checked Camping World, even going into several stores and asking and getting blank stares.

    Now, if I can find a strong guy to lift the batteries out of the bank and put them back in, I’m in business. I could do all the wiring except the connections to the batteries without the batteries in place so I have room to manoeuvre and then I’d just have the four terminal connections to make (positive, negative, plus the series connection. With the watering system, limited access to the cells would no longer be an issue.

    $80 (watering system plus pump) and shipping to Canada sounds loads less complicated and expensive than a hatch or moving the batteries. Thank you, thank you, thank you. I am so glad I decided to mull this over on the blog!

  • Hi Rae,

    Been following your blog for a while, but this is my 1st comment.

    How about using the new lithium iron phosphate (LiFePO4) battery? The Technomadia couple used it in their bus conversion. It costs a bit more, but is so light, does not leak, and promises a longer life than lead acid batteries, AGM included. A 200Ah 12V pack weights less than 60lbs, and costs US$1500. It can also be discharged beyond 50%, compared to lead acid types.

    The LFP battery bank and inverter used by Cherie and Chris are so powerful that they can run the AC for 3 hours! Of course most people do not need something that powerful. This battery technology is new, and there is of course some risks that its promises may fall flat.

    I do not know if you can get it in Canada, but it is something to look into. Failing that, I would go for AGM.


  • To me, a more than $1,000 difference is not ‘a bit more.’ It sounds like great technology, but it’s way out of my budget.

    I did some more research on AGM and remembered why I decided against them: they need to be properly recharged regularly. Since I use solar panels, it is difficult for me to get a deep charge.

    So I’m going for two 6V Trojans with a watering system.

  • Rae – have you considered a slide-out tray for your battery bank? Might be more practical than cutting a hole in your floor? A source of trays for numerous uses.

    Good luck with the improvements/mods…


  • Mike, I did consider the sliding tray, but the way the compartment is built, the batteries are in a corner where the door doesn’t reach. My mother thought of putting the batteries on casters, but I don’t have enough height to do that.

    As for flooring integrity, I’m not too concerned. My floors are made of 1″ marine grade plywood, so a properly braced hole wouldn’t be an issue (speaking from experience as I had a mobile home with the same subfloor and a hatch).

    But the availability of a watering kit for my batteries has rendered all points moot. I can take the batteries out to put in all but the final wiring and install the watering kit, finish up the connections, and not have to worry about touching the batteries again for a good long while. In four years, this is the first time the posts have needed cleaning. So it seems like the simplest solution is the best.

  • Rae,

    For cables try a welding supply shop.

    Good luck. Bob

  • OK. You’ve scared me. I hope my solar panels will be enough to fully charge my AGMs in my about to be built rig. I don’t want to HAVE to plug in regularly to charge them. I will probably camp enough places with electricity to not have a problem but I want the freedom to not go there. This RV life is sure full of challenges. šŸ™‚

  • Bob, a welding supply shop was recommended to me, but I was told I’d have better luck getting the cables built for me if I go to an automotive shop.

    Linda, every time I kick myself for the money I lost not doing X, Y, or Z four years ago, I have to remind myself that there was no way I would have understood X,Y, or Z four years ago!

  • “So Iā€™m going for two 6V Trojans with a watering system”

    Great choice! You will be happy with the results.

    The last time I made custom cables I went to a local independent electronics supply retailer. They sold the wire and lugs, they even let me use their crimping tool to make the cables right there in the store. They also had some really cool self sealing shrink tubing that I used to seal the ends and make for a very clean and professional looking set up.

  • Hi Rae, AM SOLAR is the go to company in Eugene,Springfield, Oregon. They know the right way to do any Motorhome Solar and can give you excellent advice. Had my motorhome solar system installed there and have sent many other people there and they are all very happy with them! They could help you with the right solar wiring for the inverter also. Give them a try. Good Luck Rita Aug.10,2012

  • Rita, I completely agree about AM Solar. They installed my 150W panel in the spring of 2011! šŸ˜€

    I had them use wire gauges suitable to eventual upgrades, so all my solar wiring is good to go!

  • Gary, you and several other folks are giving me hope that I can find a place like that locally. I just need to be sure of the wire lengths I need first.

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