Parallel li-ion with lifepo. Possible?

[Boeckstyns]

Hi all,
Is it possible to parallel connect these two chemistries? I have 2 10Ah 24v packs i would like to combine to not overextent them by driving them individually. But would i do more damage by connecting them in parallel? They both have individual BMS.
Any thoughts appreciated.

 

[dogman dan]

Yes, no, maybe.

The main thing is that you need to have the one that charges to the highest voltage discharged to match the one that charges to a lower voltage before you hook them up parallel. In other words, match the voltages at top of charge before you parallel them. So maybe you ride 1/2 mile, then make that connection. Whatever works so you don't overcharge one of the packs. So if one pack charges to 27v, and the other 29v, you have to hook up when both are at 27 v.

Then, step two is to never discharge too deep for one of the chemistries. The bms helps of course, since you have it able to shut off the pack when it needs it to shut off. Main thing is, know when that shutoff is going to happen, so you know you are now running on just one pack.

Some will say you need diodes, some will say not. I just say I don't understand the whole diode thing. I'm just a holder of an agriculture degree.

 

[dnmun]

you can connect them in series if you wanna do that. you don't have to include diodes if the batteries are in series.

you can connect them in parallel if you use some low voltage high current diodes able to handle the current. the 8S li ion is higher voltage than the 8S of lifepo4 so you would put the cathode of the diode (or diodes if you need to use more than one to get the current rating needed which should be 2X max) on the li ion and the anode on the lifepo4 side. that way current will not flow back into the lifepo4.

what kinda BMS do you have on the li ion? you should be able to charge them both at the same time with separate chargers without disconnecting also.

 

[migueralliart]

I think another member called etriker said he had some sort of combination like this. But it was connected at the main leads only.

 

[etriker]

I think another member called etriker say he had some sort of combination like this. But it was connected at the main leads only.

Not using a bms though,

With bms's you would need diodes for sure I would think ?

Just saying....

I have not tried.