Recommend me couple of 200ah Lithium batteries for my backup system

Just as the title says, but let me explain my setup:

I have lived 100% offgrid miles from the grid for 6 years in a small log cabin. The cabin is 100% operational meaning it has all the normal appliances, but the kitchen stove, dryer, water heater, etc run on Propane. My typical electrical usage is in the ~300w range at any given time.

The main solar setup is 100% Renogy: 2400w of panels, 48v inverter/charger/controller and 8 AGM batteries. This works extremely well for my needs, but I lack on battery storage.

I have another solar array for my backup system. This backup system charges the main 48v inverter when I turn the backup inverter on. The backup system consists of 500w panels, small charge controller and a bunch of extremely tired and worn out Optima Blue Top 12v AGM's. This uses a Renogy 3000w 12v inverter with a remote power switch that charges the main system when I turn it on.

All of my solar equipment is in the basement of the cabin and will NEVER get below ~45 degrees F, so I have no battery heating requirements at all.

I wish to replace the old Optima 12v batteries with some Chins, Ampere Time, etc Lithium batteries from Amazon. I will probably get a couple of these batteries at the same time.

So, which one of these should I get? I'm just dipping my toe into the Lithium battery area.

FYI I live in a 100% offgrid mountain community where 99% of the people up here still run lead acid batteries, usually those huge 2v batteries wired up to 12v and they seem very happy. I 'broke the mold' so to speak by going with AGM's so me getting some Lithium batteries will be a big of a conversation piece up here.

thanks guys!

I just replaced my AGM's with 2 - 220ah lithiums from Trophy Battery. Do some research on several brands, but I would recommend looking at trophybattery.com. Dan, the owner, was super helpful. And, as he had said, the batteries are sold as 220ah, but actually is built out & displays 230ah on the battery displays.

No other recommendations?

Why do you have a "backup" solar system? Why not put it all on the main system?

I would DIY a battery and get 4 LF280k batteries from a reliable source and a JK BMS, or whatever flavor of BMS you are comfortable with.

Hi Blakes, just a couple things to consider:

For those AGM type batteries you use, the maximum depth of discharge is 80%, while with newer lithium chemistries you can get up to 95% DoD with some frequency without too much lifetime capacity impact. There are also two separate methods of communication between the inverter and the battery, open and closed loop. Open loop involves just the inverter reading the voltage of the battery, charging and discharging with respect to the loading and the amount of PV power supplied and the voltage parameters programmed into the inverter. The second closed loop method involves a serial communication line to the inverter, and the inverter and battery talk to each other and keep track of each watt-hour as is goes between the two, allowing for a safer operation with fewer chances for battery malfunction. Lots of people run open loop for many many years and never see an issue, I however ran into problems with it during my first build, looking back it was probably due to a bad cell in the battery I was using, but ive avoided it since. Like I said though, just my two cents, lots of people use just voltage control no problem.


As far as brands go, there are a couple options. The cheapest DIY solution would be buying 16 individual cells, preferably grade A from a good source like CATL for longevity's sake. A BMS can be purchased for these cells and installed, and there are plenty of videos about this online already. There are also companies like you have seen like LiTime, Eco-Worthy, OSM etc that will package these cells and a BMS together for you and sell it in one package. There are also companies that go further and install more complicated BMS and safety systems like breakers, fire arrestors, etc like EG4 that feature closed loop controls. Obviously all of this comes with an increased cost as you go. Personally speaking, I wouldn't cheap out on batteries. It only takes one bad cell to impact the performance of the entire battery. Some rack mount form factor options are aolithium, SOK, and EG4. Hopefully some of this is helpful.

Blakes said:

No other recommendations?

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Uhhhh ….Lithionics, Battleborne , Dakota, SOK, Victron, and more There are many solid brands… it all depends on your pockets…

Thanks guys.

I needed to buy today, so I got a couple of 200ah chins from Amazon.

As for the question about: why not expand my current system....well...I'm running 8 renogy 200ah AGMs that are 2 years old. I'm trying to prolong their life for a couple more years while I finish this log cabin. Then, I will have the $$$ to buy whatever is good at the time. I'm floating the cost of building this offgrid log cabin paycheck to paycheck....

It's funny to answer this question for you, if it's convenient, please tell me the specification of your current battery (voltage & capacity); and how the battery is connected, then I will recommend our lithium battery for you

Baintech

Blakes said:

I needed to buy today, so I got a couple of 200ah chins from Amazon.

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These batteries and similar priced are so cheap it’s hard to resist. And many people run them for years without issue. It all comes down to whether or not you won the quality control lottery. If you win, it’s a good deal, if not, it’s an expensive lesson unless you’re willing to tear it open to try to replace whatever failed (cells or BMS).

The higher priced batteries tend to come with not only better build quality but better quality control and warranties.

We went with middle of the road with the Powerurus, but low temp protection was a must have for us, too, which the CHINS doesn’t have.

Tomthumb62 said:

These batteries and similar priced are so cheap it’s hard to resist. And many people run them for years without issue. It all comes down to whether or not you won the quality control lottery. If you win, it’s a good deal, if not, it’s an expensive lesson unless you’re willing to tear it open to try to replace whatever failed (cells or BMS).

The higher priced batteries tend to come with not only better build quality but better quality control and warranties.

We went with middle of the road with the Powerurus, but low temp protection was a must have for us, too, which the CHINS doesn’t have.

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yeah, I think you are right.

They will be delivered on Monday and will be installed into my secondary array and put into use. I'm hoping they are 'good' and I won't have to mess around with returning them or opening them up...

Blakes said:

opening them up...

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Hopefully you'll never need to do that. It does NOT look like fun. If you do, be sure to watch a lot of Will's videos on him doing just that, so you do it as safely as possible. Here's one of him tearing open a CHINS: