Help me Frankenstein a battery expansion for the eb3a

[Jack Mmkay]

I have a blueti eb3a. It has 268wh, which is nice.

I have two 100W renogy solar panels on my van's roof.

I'd like to purchase a 50 or 100 AH lifepo4 as a battery expansion for it. Id use it through the bluetti and Ideally id like to also charge it with solar trough the blueti.
It may be not the most eficient way as im deteriorating two batteries at once, but it gets the job done and it would be a long time until i need to replace anything.

What cables would i need to purchase / Frankenstein?

Is it possible to charge the external lifepo4 through one of the 12v barrel plugs? And If I wanted to use it I'd plug it into the solar socket? ( probably at night when there's no solar)

How would you do it? Do you have a better idea? Cheers from Spain

 

[time2roll]

Any chance to open the eb3a? I would be inclined to run a cable direct from the internal battery to connect the additional battery in parallel.
Of course this would void any warranty.

 

[Jack Mmkay]

Any chance to open the eb3a? I would be inclined to run a cable direct from the internal battery to connect the additional battery in parallel.
Of course this would void any warranty.

Is it possible?

 

[Jack Mmkay]

Is it possible?

Apparently its a extremely dangerous idea

 

[Vibe]

Well first off, the EB3A has a 7s2p battery pack and the normal 24v batteries are 8s. So there's a problem with the voltage right off. There are 7s BMS boards available, so a suitable expansion pack can be built. I'm not sure what an 8s packs higher voltage would do to the inverter board though. I looked at doing the same thing and was informed of this descrepancy. It may have been originally designed for a 7s lithium ion 3.7v per cell pack instead of the 3.2v LiFePO4 cells currently used, and rather than add 2 more cells, just changed the boards to the lower voltage instead.

 

[ejfluhr]

Why not charge the external batteries directly via MPPT and have those feed the solar input to the power station?

I've not seen any non-hacky ways to enable the power station to charge external batteries via solar and have those batteries also charge the power station once solar is gone.
You certainly could manually charge the external batteries via a DC->DC or AC->DC charger when solar is available, then change the connections over to support batteries into the power station via the solar input port. That seems, to me, like a pain to manage: better to go with the unidirectional approach.