LiFePO4 charging current

[teddysx3]

Hello everyone,

I just wanted to ask if I'm on the right track.

The battery I'm planning to buy is a 100ah lithium iron phosphate battery. It has a Charge rate at 50A, so I thinks this means it's .5C.

My question is, if I buy two batteries, and hook them up in parallel connection, they will become 200ah. Does this mean that the charge current can now be 100A? which is still .5C of the whole pack?

This info is needed in order to program my inverter/charger not to put out 80A if I only hook up one 100ah battery.

Thanks!

 

[A.Justice]

That's correct. You would be good to charge 2 in parallel at 100 amps.

 

[Steve_S]

There's a catch.
Whatever is charging the batteries it MUST be CC (Constant Current) AND CV (Constant Voltage) Capable.
Yes you could charge 2 batts at 100A BUT with Constant Current you can only get to 90% Full then CV has to finish it.
IF one battery cuts off then the other takes the full shot, this has to be accounted for.

A 100AH Battery can discharge up to 1-C / 100A for One Hour (it will warm up doing so).
It can take a 0.5C Charge Rate of 50A for two hours (which will also heat the cells and cause deviation between cells)
Batteries in Parallel will divide & split both Load & Charge.
Each Battery should still be Fused (150A per is fine), have to allow for surge and LFP is capable of 2C+ Burst Discharges.
!! Use identical length & gauge battery wires, remember to keep the wires close together to cut EMI/RFI. You'd be amazed how much noise DC can generate.

*NOTE, the Higher the C-Rate during charge the more cells will heat up & deviate between each other. A Battleborn Battery with Matched & Batched A+ Cells will handle this reasonably well BUT the cheapo offshore batts "Not so Much". FYI: Watch will's vids, he never charges them at 0.5C and the discharging is also tricky because LABEL VALUES are not always real (see the AOL Battery he just reviewed, NOT 200A Discharge capable as stated per label, cells are max 150A). QUITE OFTEN people will use 0.25C as the Charge Rate simply because the cells take that the best with least quirks.

IMPORTANT:
Be cautious with PreBuilt Batteries. Top Brands like Battleborn, Relion, SimpliPhi and similar you can depend on the honesty of their labeling and specs. Many offshore PreBuilts are "GOOD" but there are just as many if not more that are "Dubious" at best. Due Diligence & Caution is always warranted.

 

[teddysx3]

There's a catch.
Whatever is charging the batteries it MUST be CC (Constant Current) AND CV (Constant Voltage) Capable.
Yes you could charge 2 batts at 100A BUT with Constant Current you can only get to 90% Full then CV has to finish it.
IF one battery cuts off then the other takes the full shot, this has to be accounted for.

A 100AH Battery can discharge up to 1-C / 100A for One Hour (it will warm up doing so).
It can take a 0.5C Charge Rate of 50A for two hours (which will also heat the cells and cause deviation between cells)
Batteries in Parallel will divide & split both Load & Charge.
Each Battery should still be Fused (150A per is fine), have to allow for surge and LFP is capable of 2C+ Burst Discharges.
!! Use identical length & gauge battery wires, remember to keep the wires close together to cut EMI/RFI. You'd be amazed how much noise DC can generate.

*NOTE, the Higher the C-Rate during charge the more cells will heat up & deviate between each other. A Battleborn Battery with Matched & Batched A+ Cells will handle this reasonably well BUT the cheapo offshore batts "Not so Much". FYI: Watch will's vids, he never charges them at 0.5C and the discharging is also tricky because LABEL VALUES are not always real (see the AOL Battery he just reviewed, NOT 200A Discharge capable as stated per label, cells are max 150A). QUITE OFTEN people will use 0.25C as the Charge Rate simply because the cells take that the best with least quirks.

IMPORTANT:
Be cautious with PreBuilt Batteries. Top Brands like Battleborn, Relion, SimpliPhi and similar you can depend on the honesty of their labeling and specs. Many offshore PreBuilts are "GOOD" but there are just as many if not more that are "Dubious" at best. Due Diligence & Caution is always warranted.

Hmm, interesting. Thanks for the detailed reply!

I have purchased the Renogy 100ah self heating battery, I know they have pouch cells. Also I will probably be using the Victron Multiplus 2000va inverter/charger, which has a max 80A charging current. I'm sure this is CC and CV specific.

So what do you think the best charge rate will be, regardless the aH capacity I will have in the future, .25C?

Also what do you think of the Renogy pouch cells, I'm sure they are not Battleborn quality, but I'm sure they are not sure cheap either.

Thanks all!!