Solar project thoughts.

GpnAZ wrote:
Holy smokes, what a bank of batteries and you probably need a bank to buy all those!! What type batteries are you using and what's the weight on all of them? How many total watts do you have for solar panels? I can't help with wiring or monitoring needs but we have some pretty knowledgeable people on this forum when it comes to solar, BKA being one of them. Nice project!

The batteries are manufactured by CALB They are prismatic LiFePO4 cells. The individual cells are 3.2v so placing 4 in series yields 12.8v battery. They can also be configured to 24v, 48v etc..

The cells weigh about 7.3 pounds each, so this bank weighs in at 175 pounds. Only a little more than what the generator that would occupy this same compartment weighs. By removing the (2) 6v from the battery compartment the end result is a reduction in camper weight compared to genset and stock batteries.

As far as cost. The batteries cost me landed with busbars $550 per 100AH. 100AH CALB cells arrive tested to +/- 15% over stated capacity, so you do have a usable 115AH. I will probably make my own cut off at 90% and that will probably be infrequent to drop that low.

zb39 wrote:
Are the batts in the basement? awesome system.

I considered building everything out in the basement but decided to use the generator compartment for the batteries and the battery compartment for the inverter. The camper already has ducted heat to the basement so it will be easy to keep the batteries warm in the winter. I will also be working on a temp sensor fan that will circulate air from the cabin though the battery compartment in hot weather.

600 ah. Not bad, considering you have about 80% of that useable. Does wiring dilemma mean you're considering higher voltage?

2oldman wrote:
Not sure what 'battery wiring dilemmas' means.

There are different ways I can connect the cells. The picture above shows 2 banks with 3 in parallel and then 4 in series. They could also be configured as one battery 6 in parallel 4 in series. They could also be as shown in the schematic 4 in series 6 in parallel. Each style presents pros and cons.

work2much wrote:
Each style presents pros and cons.

Consider higher voltage. That way you can run air without things heating up. :)

2oldman wrote:
600 ah. Not bad, considering you have about 80% of that useable. Does wiring dilemma mean you're considering higher voltage?

These cells are very conservatively rated. They come from the factory with a data sheet showing the cells actual capacity. Typically 15% higher or more. So 90% is a safe number based off the 100 AH rating. This will give 540 usable AH's. Not sure I will ever drain them that far though.

2oldman wrote:

work2much wrote:
Each style presents pros and cons.

Consider higher voltage. That way you can run air without things heating up. :)

Inverter is only rated for 12v. In retrospect I should have gone to 24v system and stepped down to feed the 12v house circuits. Oh well.

A couple more pics.

Basement with stock charging converter and transfer switch removed. Farther down added a junction box to splice in 110 from magnum inverter/charger.



Solar Charge controller. This is at the back of the basement very close to battery bank.



This board will be the front part of the battery clamping system. Not a lot of space to work with. Still playing with design.



Roof combiner box. I decided to run panels in parallel which requires more wiring. The panel wires are 10 gauge housed in 3/8 liquid tight flexible conduit. The conduit really isn't necessary but does allow me to raise off the roof a bit to allow better water run-off. The main feeders down are 2 gauge flexible welding cable.



All sealed up. A weather tight gland added after this picture for the cell booster cable.

I thought all prismatic LFP cells needed mechanical constraint to keep them from expanding. Are you going to do this? I don't see it in the picture.

HMS Beagle wrote:
I thought all prismatic LFP cells needed mechanical constraint to keep them from expanding. Are you going to do this? I don't see it in the picture.

Not built yet.