Battery Array Project

Mick of Mick'nSarah had this idea for mounting an array of batteries under the Camp-Inn. There is a large open space between the storage bins and the water tanks (right next to the axle) that could fit 2 or perhaps 4 batteries.

Even though I've got the roof mounted 85w solar panel, our battery was completely dead by the fourth day of the IRG. (We have the Dometic fridge, and the sun wasn't shining). In typical fashion, I'd like to eliminate the running out of juice thing once and for all. Forget 33 Amp hours - how about four 255AH batteries for 1020 Amp Hours total? (Then I can get two fridges, and tow one behind the trailer on skis)

So, I'd like to get some input on this idea for mounting batteries under the trailer right next to the axle.
(I will take a few photos and measure the space tommorrow.)

First, unless somebody has a great idea for how to use the original battery in tandem with the new array, I'm pretty sure the original will have to be removed. From what I've been told, batteries need to be matched pairs, or else the smallest battery will get beaten up. So, I think the simplest thing to do is just eliminate the original small battery.

Second, I did a bit of research and found that there are gel filled batteries, and then an even better battery with glass in it. Any comments on this?

Pictures and dimensions to follow...

 

Are you thinking the Optima battery? It's freaking awesome.

 

Evan,

Like Jenn, I have decided the best option for me is to hook up the tow vehicle and run for 30 minutes to recharge the battery.

Easiest method for me. Since I have never traveled to Pacific NW and IRG, why would a person need additional weight and expense when the TV is available?

Jean

 

Unfortunately for me, hooking up the tow vehicle wasn't an option because our neighbors were sleeping in their tear and the exhaust would have killed them. I tried it in the morning and by that time the battery was so dead, that after an hour of charging from the tow vehicle the meter only rose from 10.9 to 11.0

I'm pretty sure that the smaller (33AH) battery is too small for the fridge.

 

Just get a small generator. You could put it back from your unit and your neighbor and charge your battery or run all your gadgets at much less expense than a bunch of batteries that will constantly need replacing. Dave

 

Hey Evan,

'More Power Mick' has added the batteries to our trailer. We opted to do this (instead of going Solar right now), due to the fact that in the NW we just don't get enough sunny days anymore, this is where we are going to do most of our camping, and we tend to camp in more rustic spots. I don't know about any of the specs, so, I will have to defer everything to Mick. I do know he researched everything really extensively, especially the batteries, so he can give you what he learned there.

I do know that he replaced the battery that came in the trailer with another of the same (so it was brand new, but left it in its place) and added 2 more of the same in a box he created to mount underneath. If I remember right, he said I should have at least 6 days of power without recharging, with the fridge running. I am pretty stingy with my power usage, so I might get more. The recharging will take a good deal of time, and won't recharge in an hour with the car (the car still charges it, but it will take a long time). The other thing is it adds about 60lbs of weight (that's the x2 25lb batteries and the box to hold them on). He also added a voltage meter for me (I only had the one that went in the 12v outlet).

I have been out on one trip with it so far, and everything works just like it is supposed to (I didn't notice a difference, but I was only out one night). I will notice things for sure on longer trips. I have a 4-night trip coming up at the end of August.

I can have him email you what he did, if you want. He isn't on the forum.

 

Wow you better check the weight of those batteries first.
A 100 a/hr solar application AGM battery will weigh about 70-75 lbs. ea. and they are expensive for a good quality one.

 

Sounds great, Sarah. Please post pictures!

 

For comparison sake, I have the larger battery. I believe that both Sarah and Evan have the smaller battery. I arrived on Wednesday in Pamplin Grove at 3 and used only my refrigerator for the 5 days. (Used flash light and book light as needed.) The weather was cool and I set the frig at 37. When I pulled out on Monday at 10, the volt meter read 12.

If you are contemplating getting the refrigerator, you should think about the larger battery as well.

Evan, let me know if you think the above comment should be in a different thread.

 

I like the idea of maybe one more battery. The deep cycle Optima battery is what I would like to install. It's been an amazing battery in my Element. What about mounting a battery box to the tongue right in front of the propane tank? Just so its easier to access. Evan, I too have been stressed for power. The solar works well, assuming you got sun! Most the campgrounds we frequent are very wooded (not much sun), also have rules against running a generator. Don't quite understand how charging from the tow vehicle doesn't take everyone 10 hours of idling? No thanks, I don't want to idle that long....someone is sure to get annoyed with it.

 

Hi all-

Mick wrote Evan an email and thought I should post it here. I am adding the photos in a minute, so if you don't see them, they are coming. I just didn't want to lose this info switching back and forth between screens.

Sarah

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Hi Evan,
                Sarah mentioned you ran your battery flat on the teardrop recently. I did the modification we talked about and added a couple of extra batteries. Below is a little write up of what I did, if you think it will help others then feel free to post it to the forum.
 
First, a little battery 101, I am not an expert but it’s handy to know the basics. When linking batteries in parallel you need to make sure all the batteries are of the same type and size and all of the same age. As you correctly stated when you link batteries, you are making a bigger battery (each 12v batteries are made up of six 2v cells in series) and a weak link will bear the burden of the current sink and be the first to fail. When you link batteries in parallel the best way to connect them is to have equal length wire running from each negative and positive terminal to a common point ensuring that the resistance of the wires is matched. Matching resistance means matched current draw from each battery. Of course it's not always possible to do based on battery locale, true in our setup. My goal was to triple the capacity of the system by adding two batteries in that space between the boxes and the axle. The third battery stays in the stock location. When you hook up batteries that will have unequal lengths of wire from terminal to terminal, it's important to take the positive source from one end of the chain and the negative from the other. While this setup is not perfect it balances the current draw a little. Below is a diagram of the battery connections.
 

 
I’m sure someone won’t believe this makes a difference because they have done it in the past and it worked, so for those people read this: 
http://www.smartgauge.co.uk/batt_con.html
 
The single battery went flat in about two days with the fridge running so with three batteries in parallel we *might* get 6 days of use. The battery which came with our Camp Inn was the EnerSys Genesis NP33 (33 AH) deep cycle battery. (Amazon $64 each + shipping search for Genesis NP33-12B) It’s a sealed lead acid deep cycle battery which is actually a good fit for this application as you can drain it dead and have some chance of it not being damaged. Typically you should not drain a battery down lower than 20%. The other advantage is that it’s a small battery and based on measurements I was going to be able to build a box to store them, and it would fit in the space between the axle and water tanks.
 
Here is a picture of the box I made
 

 
As with everything I build, its overkill. I was worried that with 60lbs of battery hanging from the trailer that I would want to secure it very well which is why the angled metal is along the long side of the box. If I was to do it again I would increase the size of the box making it easier to route the wires and have the brackets at the end. I used wood screws but if I did brackets at the end I would have used a couple of small bolts countersunk into the floor under the mattress. My box worked fine and fit like a glove but it would have been nice to have a little more room in the box to pad the batteries. The wires come out at the top on one side and the bottom on the other. This was so that if the batteries vented, yes even sealed batteries can vent, the gas could escape via the top hole. Also the batteries are raised on little ¼" feet so that if water got in they are not sitting in it and the water can drain out the bottom hole.
 
Also, see the size of the wire I used, that’s automotive 0/1 gauge wire, huge ($40 for 25 feet). The larger the core of the wire the less resistance and with the two batteries a little distance from the third I wanted to minimize any voltage drop between them. Again overkill, I would recommend 4 gauge if you are doing the same but nothing smaller.
 
The box is made from ¾" cabinet grade, external glue plywood with 4 coats of marine grade finish on it. Screwed with brackets made from aluminum angle.
 
The box attaches to the bottom of the trailer and only sticks down lower than anything else by about 1”, hence the metal edges.
 

 
Ok, now for the tough bit, I have three 0/1 gauge wires to run into the trailer (this is where 4 gauge would have been so much easier to work with). As we do not have the hitch mount on the rear I just decided to run it in right there in the middle. No need to pull the tanks out of the way (but I did remove them for the install). I just drilled a hole up into the trailer which goes into the sink side area. This will be a problem for people with the hitch. You *may* be able to get 4 gauge wires in next to the hitch, I’m not sure what the hitch mount looks like inside.
 
Here you can see the wires running inside. Rubber gasket and extra sealer just in case.
 

 
Inside the trailer these poke in on the side with the sink, as I said. The floor of that side is already raised so the wires are hidden and you then run them into the other side through a hole.
 
The other side I built a raised floor so I could run the wires over to the electrical area. See picture below, you can see the 2x2 which raise the floor. It’s only a small loss of space. Remember the battery below in the stock space is also a new one so it’s matched with the other two. The battery I took out was still good, so I used it to replace the battery in one of my race cars which always needed to be jump started (waste not want not, as they say).
 

 
Once the wires are inside of the electrical area it’s just a case of hooking them up the right way. Note that I have three wires as I am taking the negative off from the other end of the battery set.
 

 
I added a negative bus bar on the side so you can hook the negative wire to the trailers negative. Remember which wire is from which end of the battery set. Note the positive goes straight to the battery in my case, and the trailer source hooks directly to it. Also note no fuses. With batteries in parallel if you want to be perfect you would put a fuse between each battery and then a cut-off switch. The trailer has a fuse so it’s protected and if the batteries fail then a fuse between them is not going to do that much, IMO, so I didn’t bother. But at this point you are basically done.
 
Finally, the side panel with fuse panel needed a little modification due to the now false floor. It’s got a little rubber gasket on the bottom just so it seals better and crumbs don’t get in. The false floor is ½" cabinet grade ply with again the 4 coats of finish. It’s not a perfect fit but does the job.
 

 
Our trailer has the built in 5amp trickle charger so you can work out how long the battery bank will take to charge up if drained to zero. (About 20 hours in theory but have yet to drain the batteries that much so not sure yet.) They will also charge as normal by the car but again take much longer to get to full.
 
Anyway that’s how I did it, I am sure it can be improved upon. You could just stick a 100Ah deep cycle battery in the storage area and call it done but it will take up so much space. I liked the idea of using that gap between the axle and the tanks.
 
Feel free to ask questions. I’m sure I left some details out.
 
Cheers
 
Mick

 

Mick and Sarah, can I borrow your lift or jacks? How did you get that under the camper?

 

Mick has a dual post car lift in the garage that she went up on for this.

 

That is some nice work! Very well done Mick. Let him know that Sarah.

I like how Mick duplicated the plumbing spacer on the battery side to run the cables through under the new false floor. Ends up looking factory like that.

He also did it perfect by matching up the batteries exactly. That is the proper way to string batteries.

As a note, what Mick did can only be done on a 560. The space between the axle and tanks only exists on a 560. The axle is 9" further back on the 500 and 550.

Cary

 

Thanks everyone!

I will tell Mick. He let me have a little say in what was going to happen since the galley is really my space. I told him I wanted the wires hidden, and we worked out a scheme, and he perfected it. Otherwise, all of this is his baby. It took a lot of work to sort everything out, but I think it will work well for us.

 

Mick'nSarah unbelievable, great job you are a true craftsman.

 

Nice job! Very inspirational need to drill some more holes now!

 

I told Mick about all of the nice comments, and he wanted me to say thank you for him. I will say, he is a very handy guy to have around, and I am one lucky lady to have landed him! Funny thing, destiny.

 

Cary,

Do you have any ideas about how to fish the wire up to the battery box if you have a hitch like I do?

Also, any comments on the gauge of wire? As Mick said, he probably went a bit big. I may not have that luxury.