Battery and system upgrade questiin

[Life In The Dog House]

Hi everyone, I have not been around for quite some time, but I have some questions about upgrading my skoolie RV solar system.

Currently, I have 380 watts of solar panels, with a 20amp mttp ccharge controller and 2-100ah AGM batteries. Basically, I followed Will's 400watt solar blueprint. When setting up the system.

I was not kind to my AGM batteries over the padt few years especially in the winter months so they don't work great.

Now, I am ready to upgrade the system. I would like to move up to 800 watts of solar, with 100amp mttp charge contoller, and 2-206ah lithium batteries.

THe new batteries arrived today, and I am wondering if I can hook both of them up to my current system until the other parts arrive to be installed.

My current load on the current AGM batteries is mostly dc items, so there really isnt much in the way of loads depleting the batteries. Fortunately, I can plug into shore power on a daily basis at my workplace.

Your sage advice would be most appreciated. Thanks, and have a great weekend!

Clyn

 

[rmaddy]

With 800W of solar on a 12V system you only need a 60A MPPT charge controller. A 100A controller would be good if you plan to upgrade to 1200-1400W of solar panels. But a 100A controller is expensive.

Use a LiFePO₄ friendly 12V battery charger and fully charge each of your new batteries before you wire them into the system. Once charged you can then remove the AGM batteries and wire in the new batteries. Then update the settings on your current charge controller for LiFePO₄.

If you don't have a 12V battery charger you could remove the AGM batteries, hookup one of the new batteries, and get it fully charged via solar (again, make sure the charge controller is setup for LiFePO₄). Once charged, swap it out with the other new battery and charge it. Once both are fully charged you can wire both in place.

Just make sure you have the proper sized wire and fuses for all of the new stuff.

 

[Life In The Dog House]

Hi rmaddy,

Thank you for such a wonderful and informative response! I am still new to all of this and sincerely appreciate the information you provided.

I don't plan to move out of the 12v power sector, and I don't think I need to go over the planned 800 watt stotal upgrade to my system. My power needs are not gluttonous where I need to power a 85 inch TV or other stuff. I try to keep it pretty simple.

I do have a 12v battery charger- it is NOCO 15000 that will charge/recover 12/24v flooded, agm, and lithium batteries. The charger is also used as my shore power. Keeping it simple.

Yes, it is my understanding that I need to charge both of the new batteries to 100%; unhook my solar panels before installing them, and also changing the settings on my charger controller. I was more worried about frying something in the system, without double checking with someone who is more informed that me.

I do remember that my fuse is 200amp and the circuit breaker is 50amp. I will have to dig out my system schematics (I drew a picture of everything, what connected to what and where, along with each wire sized used, etc.) to remember what the wire gauges I used, and if I need to upgrade them.

I hope the weather tomorrow will cooperate so I can get the batteries charged and installed. Tonight weather is 70mph wind gusts with temps dipping down to zero.

Thank you again rmaddy for you help, and have a great weekend!!

Clyn

 

[Life In The Dog House]

Hi again rmaddy,

I am sorry, I forgot to add... Thanks for saving me some money by letting me know about only needing a 60amp charge controller versus the 100amp one.

Clyn