Charging 14S lico lipoly with a CC-CV 48v lifepo4 charger?

[voicecoils]

The charger in question is from BMSBattery (King Power?) designed for 16S lifepo4, so it outputs 58.4V at up to 10A in the CV mode.

I'm thinking that a 14S2P pack can be made out of 2S1P 5Ah packs from Turnigy, Zippy etc from HobbyCity. I'd rather 6Ah but can't seem to find any decent priced ones.

Using this charger would mean the maximum each cell in the 14S group would receive is 4.171V. Can anyone comment on how conservative this is?

I'd like to charge to a conservative safe level and only discharge down to 80%. I don't plan on using any active BMS but likely a low voltage buzzer device on each cell.

It's unlikely I'd ever pull more then 100A from the pack.

I don't want to buy any dedicated RC charging equipment if at all possible.

Any thoughts?

 

[GGoodrum]

The charger should work fine for a 14s setup, but I think if I was going to do a 14s2p pack, I would use four 5s and two 4s packs instead fourteen 2s packs. With 14 2s packs, you will have a crapload of 3-pin balancing pigtails and 10-gauge main power leads to deal with, which is going to be a rat's nest.

I know you said you don't want to use any sort of "active BMS", but you did say you would use a low voltage "buzzer device" on each cell, and this is much easier to do if you parallel the cells first, and that is easier if you have six total plugs instead of 14. Fewer devices too.

-- Gary

 

[voicecoils]

The charger should work fine for a 14s setup, but I think if I was going to do a 14s2p pack, I would use four 5s and two 4s packs instead fourteen 2s packs. With 14 2s packs, you will have a crapload of 3-pin balancing pigtails and 10-gauge main power leads to deal with, which is going to be a rat's nest.

I know you said you don't want to use any sort of "active BMS", but you did say you would use a low voltage "buzzer device" on each cell, and this is much easier to do if you parallel the cells first, and that is easier if you have six total plugs instead of 14. Fewer devices too.

-- Gary

Thanks Gary for the response.

The reason I was thinking of 2s1p packs is that then I could get 14 of them that all had sells which came off the same production line. If you reckon the 4s1p and 5s1p packs from the same manufacture would use identical cells then that would simplify things quite a bit.

When I said 'active bms' I should have said 'active balancing' I suppose. I'd like to be informed (visually or by a buzzer) if any individual cells gets pulled too low. If so, I'll just stop riding and return home to recharge. I can set my controller's LVC through the Cycle Analyst and watch as the watt-hours tick over so I can stop when 80% of the pack's energy capacity is depleted.

I have two further questions:

What's the suggested way to charge up a single cell if it's week or goes out of balance with the rest of the pack? Are single cell charges easily found and the suggested method?

* Is it safe to charge in my apartment if I'm home to monitor it? At 10A charge current the pack should charge in under an hour anyways. I don't have a garage.

 

[Hyena]

I agree with Gary on getting less packs to cut down on the wiring mess.
Buzzer wise you want to get 3 chargery BM6's or 2 of the cell log 8's from hobbyking. Also grab a few of the pig tails while you're at it to cut up simplify your balance connectors.

Yeah that charger should be fine and that's a fairly safe voltage to charge to. I have my power supply set to about 4.17/cell and without balancing the highest any 1 cell has hit is 4.22v which is still ok. Thats after 100 charges without balancing, prior to that they never got more than 0.02v apart. You probably should get atleast 1 of Garys (or another) balancers though to balance periodically. I had a 6S hyperion one I used for a few months but it melted into oblivion for no good reason and the shop I got it from wouldn't replace it under warranty so I've gone without for now.

Any reason you're going with 14S - just because of the chargers voltage ? I think those ones can be easily set to another voltage if you open them up.
You could either go with 12S for a simpler set up or if you're going to have 3 lots of batteries and monitors anyway, go with 18S for more powaah

 

[voicecoils]

I agree with Gary on getting less packs to cut down on the wiring mess.
Buzzer wise you want to get 3 chargery BM6's or 2 of the cell log 8's from hobbyking. Also grab a few of the pig tails while you're at it to cut up simplify your balance connectors.

Yeah that charger should be fine and that's a fairly safe voltage to charge to. I have my power supply set to about 4.17/cell and without balancing the highest any 1 cell has hit is 4.22v which is still ok. Thats after 100 charges without balancing, prior to that they never got more than 0.02v apart. You probably should get atleast 1 of Garys (or another) balancers though to balance periodically. I had a 6S hyperion one I used for a few months but it melted into oblivion for no good reason and the shop I got it from wouldn't replace it under warranty so I've gone without for now.

Any reason you're going with 14S - just because of the chargers voltage ? I think those ones can be easily set to another voltage if you open them up.
You could either go with 12S for a simpler set up or if you're going to have 3 lots of batteries and monitors anyway, go with 18S for more powaah

Cheers Hyena, I'm looking into the option to trim the charger voltage up or down now.

I'm tempted not to touch it since I'd be able to continue using the charger with lifepo4 packs then too.

If I can and do trim the voltage I'd probably go for 15S if I can trim the voltage up and then just have 5s1p packs.

18S will be pushing my new BMC hubmotor past it's comfort zone.

Thanks for all the advice.

 

[Hyena]

Ah so you got the BMC ? Where did you end up getting it from ? Locally or overseas ?

I went with 15S too, running at the max limits of my controller and wattsup meter.
I also liked the 5ah packs for being able to run 15S2P most of the time but switch to 10S3P when I need the extra range.

 

[voicecoils]

Ah so you got the BMC ? Where did you end up getting it from ? Locally or overseas ?

I went with 15S too, running at the max limits of my controller and wattsup meter.
I also liked the 5ah packs for being able to run 15S2P most of the time but switch to 10S3P when I need the extra range.

I got it from Ilia @ ebike-sf on this forum. Sent from San Fransisco, US$75 postage.

Good idea about the extra range pack reconfiguring