I have a Ac200max, can I use the 30A output to charge a 12v lifepho battery?

Product Discussion BLUETTI AC Series
1

I have camper that has 2 100aH lifepho batteries. I was just looking for option if the ac200max can charge that using a dc aviation to xt60 using the 30A output

2

12 volt output directly is to low for loading lifepo or other batteries 12 volt and up. You can use a 12 volt mppt charger from the dc output. Or an ac charger from the ac output.
Sigi

3

Hi @bluetti_blueice_pvfyahoocom

as @sigi-und-so mentioned. 12V is not enough to charge a 12V Battery. You need atleast ~14V. The only thing you can do is to step up the voltage with a DC-DC Step Up module.

But im not a electrian and wouldnt recommend to cut cables and “build something” yourself.

I do have a similar idea with my EP500. But i just leave it.

greetings

Erik

4

Thank you erik.
Attention: You do not need only more volt than the voltage of your batterie. You need a real charger. Otherwise the lifo can explode.
A 12 volt booster (12 volt mppt charger) would do that. They are normally build in mobile homes to charge the car batterie and/or vice versa. The most buyed a from victron and there scale are from 5 to xxx ampere. That is a secure use. Also for you erik. ;)
Sigi

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5

I would think that the batteries being charged would pull in excess of the 30 amp output and would overload the circuit.

6

I have an AC500, the measured voltage on the 30A outlet is 13,65V.

With this voltage you can top up the LFP batteries but not fully charge them as LFP’s need at least 14,2V for cell balancing.

@Bluetti: is it safe for the power station to do this ?

7

@Bikerwally Allowed but not recommended. BLUETTI machine is a constant voltage output and it will easily cause overcurrent by doing this.

8

@Bluetti, what do you mean “causing overcurrent” ?
Overcurrent for the power station or overcurrent for the batteries ?
Can the power station give more than 30A ?

9

Over current for the power station. Your outlet has a maximum of 30 amp output and when you connect a discharged battery, there is nothing from stopping your batteries being charged from demanding much more than 30 amps. Kind of like you get an allowance of $30 per week maximum with no way to save it week to week. Your wife opens your wallet and wants $100 but it isn’t there and your wallet is overloaded.

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10

I was also thinking about that. But when I look at the 12V/30A Aviation Plug cable, which is 12 AWG only?!

For 30A I would use at least 8 AWG in my RV.

So, the only way to know is to try. I connected a 300Ah LFP battery to the 12V/30A Aviation Plug.

SOC of the battery was 68% (to be on the save side) and the voltage was 13.2V.

This is the result:

  • Outgoing voltage dropped from 13.65 to 13.4V
  • 11.3A flowed into the battery
  • DC load on the AC500 = 141W

When SOC reached 70%:

  • Voltage 13.4V
  • Amps = around 8A
  • DC load on the AC500 = 100W

You are correct, a more discharged battery will pull more amps.

I stopped this test after a few hours with SOC 76%.

I’ll continue testing this with a more discharged battery another day.

11

The output voltage will remain steady under a given load since it is a regulated voltage and not direct battery voltage. I think the small voltage difference from the supply vs the battery being charged is resulting in the lower amp / watt draw.

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12

Correct ! That’s why I was not afraid to try it out.
Today I continued the test.

SOC of the 300Ah LFP battery was 45% @ 13.1V.

Once connected to the 30A outlet, 25A went into the battery, this dropped very fast to 20A @ 13.2V.

I left it like this for some hours until the SOC was 70%.

Conclusion:

  • The 12V/30A can be used to top up LFP batteries but check the amps at the beginning, it shouldn’t be higher than 30A.
  • No appliances/consumers should be running on the LFP as this will increase the amps.
  • Lead/acid batteries have a lower voltage, consequently the amps will be higher.
  • Put a 30A fuse in the red wire close to the LFP battery.
  • Charge the LFP battery at least once a month at the voltage recommended by the manufacturer in order to balance the cells.
13

Hello @Bikerwally
the only secure and good way to charge a external battery is to use a dc/dc booster (charger) I described before. That would pull out only 20 amps (as sample) when that is set to the dc/dc booster and would never overload the powerstation by doesn’t matter if the battery is empty or not. And it would take care of the correct power (volt) the external battery needs to be charged. I would NEVER connect a regulated output from a powerstation directly to a battery.
Sigi

14

Conclusion…The only reason you had this short term success is because your LFP battery you were charging was not at a low enough voltage to overload the regulated output circuit. If you go low enough on the voltage you will overload.

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