Backup Battery for AC200P

Hi all.

I’m new to the whole solar & battery thing, so please be kind. :slight_smile:

I have the AC200P which I charge with solar. During an extended weather event where solar can’t charge the AC200P, I was thinking of buying 12V 100Ah lithium iron phosphate battery to charge the AC200P. I understand it would be slow, but it would be better than nothing.

The manual specifically states the AC200P can be charged using a "lead acid “battery”. Does this mean I can only use “lead acid” and cannot use “lithium iron phosphate”?


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12V LiFePO4 battery would work to charge the AC200p, you would input it as a car charger but it will not charge very fast, only around 100W. Alternatively, can get the DC enhancer and it would charge it faster by boosting the input voltage.

You can use any source as long as the voltage is within the acceptable range. If I were going to do what you want to do, I would suggest a 24 volt battery since it will charge your AC200P at double the rate of a 12 volt battery.

You also have the option of getting a 24 volt battery and charging at a rate of around watts and then getting the DO50S voltage enhancer, connecting it to the same battery and then use the output of that to connect to your AC200P charging brick input port. With this setup you can see a little better than a 400 watt charge rate. It is my understanding that the DC enhancer connected to a 12 volt source will not output more than around 100 watts / hence the improvement with the 24 volt battery.

To have a simple work around, you can also get an AC inverter, connect it to your battery and charge via AC to your AC200P

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I appreciate the replies so far. I’ll purchase a “12V LiFePO4” battery as backup to solar to charge my AC200P when weather is bad.

Now when weather is good and I want to recharge my “12V LiFePO4” battery, can I connect the “DC Output 12V/10A” connector from the AC200P directly to the pos/neg leads of “12V LiFePO4” (assuming I have the right cable) to charge it back up again?

Absolutely no. You have to connect your 12 volt battery to the solar / car charging input port (aviation input port) and also have to have “car” charging selected. The input port on the AC200P has a built in charge controller which is required to step the voltage up from your 12 volts to a usable voltage the battery needs for charging to begin. I do think you will be dissappointed with the charging speed at 12 volts though.

I bought a b300 as my AC200p backup. It works well with that and it also works well for my AC200max backup. Good luck.

If you just connect your 12V battery in as is, using the car charging method, you are going to get only around 100W of charging. To get some reasonable charge rate, you will need to boost the voltage. If you boost it to 40V or so, then you can set PV mode and get a lot more power in. Bluetti sells a DC charger enhancer but it can only take 10A input, so you are still limited to 120w or so. If you can get a DCDC converter capable of 12->48V at 12A or more, then you can use that connected to your battery to charge your AC200P at a respectable 500W.

Or use a 24 battery as a base with higher stand alone charge rate and easier conversion to 48 volts as well not to mention it would work well with a 24 VDC to 120 VAC inverter.

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Can someone help me understand what the difference would be, if he’d have to charge up the backup battery anyway. Why not just charge up the AC200P from whatever source he’s got?
Not to argue the wisdom of having more backup batteries…

He would get increased run times by using the two sources. Basically increasing the battery size potential of the AC200P. Kind of like what benefit would two gas tanks be in a vehicle?..It allows you to drive further even though you have to fill both back up eventually and it would take more time to do so.

I don’t think anyone has answered the second question you asked:

The answer to the question above is a definite “no”. To effectively and safely charge any battery you have some kind of “charge controller” or “battery charger”. It’s job is to create a specific time-dependent pattern of voltage and/or current at the battery, so that the battery accepts a charge without damaging it.

If a battery is connected to a constant voltage source (like the “DC output” port of the Bluetti), then it will either fail to charge completely or it will be “over charged” (and damaged).

This is why solar panels are never (or almost never) directly connected to a battery. There is always a “solar charge controller” of some kind.

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That makes sense LandLocked. I appreciate the explanation and will look into a battery charger to keep the external battery charged safely.

Thank you!

Or you could buy another AC200P and you would have both a backup to the first one and another 2000 watt hours of battery.

I actually replied absolutely no 9 days ago to the post.