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MPPT for Non-Standard *51.2V* CATL LiFePO4 Battery Pack

Mark1988

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Joined
Sep 6, 2021
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Hi,

I'm interested in purchasing my first solar battery pack (together with a handful of used 500W panels) and since I can't quite afford Tesla's PowerWall, I decided to go with a Chinese PowerWall instead :cool: .

1) I'm ready to pull the trigger on this bad boy since it comes with CATL cells and 20 years warranty (spec attached). The only thing that concerns me is that it appears to be using a rather non standard 51.2V battery configuration? Should I be worried about that and does it mean I won't be able to use a standard 48V MPPT?

2) I can see that Victron/SmartSolar MPPTs can be configured to deliver around 55-57V which should hopefully work for the 56V required by the battery pack but is messing about with a custom config worth it? Full spec attached.


Any input would be hugely appreciated.

Thank you,
Mark
 

Attachments

  • GSL ENERGY 51.2V 100Ah Wallmounted lifepo4 battery-16S CATL(下单之前确认回签的).pdf
    570.6 KB · Views: 4
  • Datasheet-SmartSolar-charge-controller-MPPT-150-35-&-150-45-EN.pdf
    203.8 KB · Views: 2
It uses 16 cells in series, so 16 cells x 3.2V nominal = 51.2V, if the batteries are charged up to 3.6V, then the pack Voltage will be about 57V is normal Voltage for 48V LiFePO4 pack. You just have to set the charging Voltage needed which is what we do here when we use the LiFePO4 batteries, I do not see any problem with making the settings to what you want, most people here will charge the battery to about 3.35 ~ 3.40V per cell instead of trying charge up to 100%
 
Thanks for a swift replay!

That's right, it's most likely 16 cells and I suspect the reason they did it that way was to get the unit to a full 5KWh (15x3.2V=48V x 100A=4800KWh so that's not enough but would have given them the 'standard' 48V).

Do you think it's worth getting one of those 48V SmartSolar MPPTs and try and configure it to a slightly higher charging voltage OR should I get a simple inverter instead. I would imagine an inverter would be easier to configure since it's not set to 48V but I'd be missing out on the charging profiles provided by an actual charge controller...?

Again, thanks for taking the time to help me with this.

Mark
 
Thanks for a swift replay!

That's right, it's most likely 16 cells and I suspect the reason they did it that way was to get the unit to a full 5KWh (15x3.2V=48V x 100A=4800KWh so that's not enough but would have given them the 'standard' 48V).

Do you think it's worth getting one of those 48V SmartSolar MPPTs and try and configure it to a slightly higher charging voltage OR should I get a simple inverter instead. I would imagine an inverter would be easier to configure since it's not set to 48V but I'd be missing out on the charging profiles provided by an actual charge controller...?

Again, thanks for taking the time to help me with this.

Mark
"Standard" lifepo4 48v pack is >52v with 16 cells.
There's nothing unusual about it.

You're overthinking it.

In fact if they had given you 15 cells that would be shortchanging you and could result in a dangerous overvoltage condition with a normal lithium battery charger.

Same goes for a 12v pack. 4 cells. 12.8v at 3.2v per cell but they can be charged up to 3.65v per cell which is 14.6 volts.

24v pack is 29.2 volts.

And 48v pack is 58.4v.

Many chargers will give you ~58v. Dakota lithium sells a 48v charger that's 57.6 volts, which is on the lower side, but gives you 3.6v per cell with 16 of em.

If you had 15 cells that charger would likely destroy the pack, because 57.6/15 = 3.84v per cell which is above the maximum charge voltage of 3.65.
 
Also, the odds of getting your 20 year warranty exercised from a Chinese seller is virtually zero unless you happen to be in China.

I wouldn't count on that.
 
Amazing, thanks guys appreciate your help and expertise and yes, 20 years is probably on the optimistic side but with the CATL cells I should be alright.

On a separate note, I note that the finished product is 2-3x more expensive than the batteries alone so maybe for my next project I'll build a battery pack myself...

Cheers,
Mark
 
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