[RE-wrenches] Lithium battery charge rate
Dave Angelini Offgrid Solar
offgridsolar at sti.net
Tue Jun 27 14:14:26 PDT 2023
Jay, I do not know/use this brand. Got this off the internet. Looks to
me like they are telling you max charge is 100A but max life is 30 - 50a
charge.
only a 5 year warranty so.... Good Luck !
Voltage 51.2V
Capacity 100Ah
Charging Voltage (Bulk/Absorb) 56.2V (+/- 0.2V)
Float 54V (+/- 0.2V)
Low DC Cutoff 47-44V (depending on load - start high, lower if needed)
Charging Current Max Constant Charge: 100A (30-50A recommended)
Discharging Current Max Constant Discharge: 100A
Dave Angelini Offgrid Solar
"we go where powerlines don't"
http://members.sti.net/offgridsolar/
e-mail offgridsolar at sti.net
text 209 813 0060
On 2023-06-27 2:01 pm, Jay via RE-wrenches wrote:
> These are 100 amp hr eg4 48v batteries.
> Tech support said their recommended charge rate per battery is 30-50
> amps.
>
> I asked because Ive never heard this and it still doesn't sound
> correct.
>
> All of the responses have been consistent and I will try to get someone
> higher up to review all this and report back
>
> Thx
> Jay
>
>> On Jun 27, 2023, at 10:07 AM, Starlight via RE-wrenches
>> <re-wrenches at lists.re-wrenches.org> wrote:
>
> Hi Steve,
>
> My experience is different. First, I don't know of any stationary
> battery systems that have C2 charge ability, many not even C1. A 20kWh
> bank C2 rate would be 40kW or over 770Amps @ 52V. I have 10 years
> experience with Li batteries, (hundreds of Li installations, mobile and
> off grid), and thousands of LiFeBlue Battery customers, low current
> charging works without issues. Most of these systems charge at the high
> end 0.35 C rate or less. Jay did not mention the bank size so we don't
> know the C rate for the 30-50 Amp recommendation. But I guess it is far
> lower than 1C.
>
> Long absorb (CV) times may cause a cell to saturate resulting in rapid
> voltage rise and the BMS protection inhibiting input current. This
> sudden loss of load (essentially a battery disconnect) can cause havoc
> with some inverter/chargers and PV solar controllers. In our
> experience, the best method to set Absorb times for any Li system is by
> trial. If the cell voltages are staying relatively close during
> discharge (6mv in the attached image), then balancing time (> 3.55V CV)
> is sufficient, whether it is 0.1 hours or much more.
>
> Larry Crutcher
> Starlight Solar Power Systems
> (GM, LiFeBlue Battery)
>
> <32ED5403-8A66-4ED5-AFFD-E308D5FC48C6_1_105_c.jpeg>
>
> On Jun 27, 2023, at 6:33 AM, Steve Higgins via RE-wrenches
> <re-wrenches at lists.re-wrenches.org> wrote:
>
> For many LFP batteries, while some say you can charge at the C1 Rate,
> most want you to charge at the C2 or C3 rate.
>
> While you don't have to get them full all the time like lead, as long
> as you are cycling regularly, it is still a good idea to get them to
> full regularly. Now if they are a backup system or not being cycled,
> they should not be held to full all the time. This can accelerate
> damage to the cells.
>
> Where we see the major mistakes are the absorb timer settings. Too
> many people are setting the absorb timers too short, especially if they
> have parallel modules and are not running closed-loop communications,
> or the batteries can't communicate with each other or the chargers.
>
> In these cases where you have 2,3,4... more batteries in parallel, the
> absorb timers can help balance them as the batteries that don't need
> balancing stop charging, while the cells that need the extra time get
> that time if you have longer absorb timers.
>
> We advise for our LFP drop in's that you have the following. Assuming
> that you are charging at least the C2 Rate.
>
> 1 Parallel Connection = 30-45 mins absorb timers.
> 2 Parallel Connections = 45-60 mins.
> 3 Parallel Connections 60-90 mins.
> 4 Parallel Connections 90-120 mins
>
> [1]
> Steve Higgins ⋅ Technical Services Manager
> t +1.902.597.4020 m +1.206.790.5840
> f +1.902.597.8447 e steve at surrette.com
> [2] [3] [4] [5]
>
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> On Mon, Jun 26, 2023 at 6:51 PM Darryl Thayer via RE-wrenches
> <re-wrenches at lists.re-wrenches.org> wrote:
> Hi Jay, Larry says is correct. My experience, with cells and there BMS
> is they need to get up to top balance voltage then the BMS will stop
> charging the full cells and bring the remainder of cells up to fill
> charge. My oldest set is about 6 years old, since I understood they
> have been fine
>
> On Mon, Jun 26, 2023, 3:58 PM Jay via RE-wrenches
> <re-wrenches at lists.re-wrenches.org> wrote: Hi All
>
> I'm wondering if minimum charge amps for lithium is common or not?
>
> Or does it have to do with the cell shape: cylindrical vs prismatic vs
> pouch?
>
> A client purchased some EG4 batteries and they are getting a bit out of
> balanced. Tech support didn't suggest higher volts or longer absorb but
> did mention they need 30-50 amps charge. It's not in the manual.
>
> Wondering what you all think and know
>
> Thx
> Jay
> _______________________________________________
>
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