Battery selection help

[Nickruby]

Hello, I'm a solar rookie. I bought the Renogy 12v starter kit with the 30A pwm controller with 2 100w panels and it works good for my cabin. I have been using a 12v deep cycle rv battery but would like to upgrade as that battery needs to go back in a camper. I have about a $250 budget should I go with 2, 6V golf cart type batteries to run in series or something better in that range? Any ideas appreciated.

 

[Just John]

Hello, I'm a solar rookie. I bought the Renogy 12v starter kit with the 30A pwm controller with 2 100w panels and it works good for my cabin. I have been using a 12v deep cycle rv battery but would like to upgrade as that battery needs to go back in a camper. I have about a $250 budget should I go with 2, 6V golf cart type batteries to run in series or something better in that range? Any ideas appreciated.

Depends on your needs, and how soon you need them.

Luyuan 4pcs Eve 105ah Lifepo4 (lfp) 3.2v Cells 12v Battery (fully Matched)--genuine Grade A - Buy Eve,Lifepo4,Rechargeable Battery Product on Alibaba.com

Luyuan 4pcs Eve 105ah Lifepo4 (lfp) 3.2v Cells 12v Battery (fully Matched)--genuine Grade A - Buy Eve,Lifepo4,Rechargeable Battery Product on Alibaba.com

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Add in shipping and a BMS, you will probably top out over $300, so just a suggestion.

My total was just over $500 for 8 cells, including shipping and Alibaba service fees.

 

[Bubba1]

I made a 78amp battery with cells from battery Hookup. Cheap bms and few other parts for about $200. Does your cabin go below freezing when you're not there?

 

[Nickruby]

Yes it's in the mountains and gets very cold. I realize the budget is small so appreciate the help!

I really have no idea what I'm doing but learning alot looking around the forums

 

[Bubba1]

In the forum there's a sub forum for harsh environment. Look there and you will get some ideas. Some take their batteries home when they leave cabin so the battery is fresh when they come back. If you get good winter sun perhaps you could make a passive solar heater to warm up in the day and leave the batteries on charge.

 

[MichaelK]

A better way to go about this is to first outline what it is you want to power, and design the system to meet those needs.

Most likely, if going with golf-cart batteries, your solar will be adequate to charge them. Let's assume you have 210Ah batteries at 12V and you want to charge them with at least 1/10th capacity, or 0.1C. That's 120Ah X 0.1C X 13Vcharging X 1.175fudgefactor = 183W. 1/8th C would be 120Ah X 0.125C X 13Vcharging X 1.175fudgefactor = 230W. So, your charging rate is between good and best.

My very first system was 12V/PWM with 12V panels, and I was happy to get rid of it. If you can save up a bit, you might get much better performance upgrading to 24V, with grid-tie panels and an MPPT controller.