SK48V100 - charging parameters

[defed]

can anyone advise the correct charging parameters for the SK48V100's? CC's site says absorb at 57.6v, and to leave float on, but doesn't say to what...also 57.6v? what about bulk? my controller doesn't have LiFePo as a preset, so I need to make a custom one or use one of the FLA/AGM presets if they are close enough.

Thanks!

 

[MiSh]

From their manual:

• Charge Current for normal use: Up to 63A (Per Battery)
• Charge Current for fast charge: Up to 95A (Per Battery)
• Absorption Voltage: 57.6v recommended; up to 58.4v max
• Absorption Time: 15 Minutes
• Float Voltage: 55.2v
• Charging Target: 100% SOC
• Low Voltage Shutdown: 48v

 

[defed]

From their manual:

• Charge Current for normal use: Up to 63A (Per Battery)
• Charge Current for fast charge: Up to 95A (Per Battery)
• Absorption Voltage: 57.6v recommended; up to 58.4v max
• Absorption Time: 15 Minutes
• Float Voltage: 55.2v
• Charging Target: 100% SOC
• Low Voltage Shutdown: 48v

thanks.

hmmmm...i looked through the entire thing ( a few times) on CC's website, I don't recall seeing that. would bulk also be 57.6v?

oh i found it, under communications. i didn't look at that closely because i won't have comms, so i missed the part about no comms.

 

[defed]

i've read and watched a lot of stuff on charging LiFePo...it seems they don't like extended absorption cycles. my controller will only go down to 120 mins for abosrb.

i have to call CC and see what they say, but would it be advisable to lower the absorption voltage so as not to over charge the batteries? it seems that the absorb amps would just fall off to 0 as the battery reached full any way.

with absorb at 57.6v and float at 55.2v, does this mean that, during the day, when the batteries are full, and loads are being run, that they are being run off the battery until voltage gets to 55v (or whatever recharge level is) and the controller kicks back on? on my old FLA, i believe that in absorb and float, that if the battery only needed 1a but loads needed 10a, the controller would make 11a. i don't see why it wouldn't work the same for the LiFePo, but it's just something i read (for a different controller).

i believe my best settings for now (until i call CC) are:

bulk: 57.6
absorb: 57.6
float 55.2
absorb time: 120 min
recharge voltage: 55 (i'm guessing you want it just under float so if it dips, it goes back into bulk? or do you want more headroom, such as 52v?)

i will eventually look at a different controller, more tailored to LiFePo, but for now, i think i can make this one work.

 

[TomC4306]

batteries are full, and loads are being run, that they are being run off the battery until voltage gets to 55v

Bulk = Absorption
57.6 is a CHARGE voltage. NOT the resting battery voltage.
Once your charge controller goes from absorption to float, it will take less than a minute for the voltage of the battery to drop to float.
At which time, loads are powered by solar cc.

 

[defed]

Bulk = Absorption
57.6 is a CHARGE voltage. NOT the resting battery voltage.
Once your charge controller goes from absorption to float, it will take less than a minute for the voltage of the battery to drop to float.
At which time, loads are powered by solar cc.

good point, that makes sense, thanks for clarifying that.

i just checked my controller, the book says 120-360min for absorb, but i can go to 0. i set it to 25min (CC did say 15 min). the only thing left is the recharge voltage. the highest i can go is 54v, down to 48v i believe. i set it at 54v (float 55.2v).

 

[TomC4306]

i believe. i set it at 54v

Unlikely.
Charge/bulk/absorption should be higher than float.
I use 55.6 with 60 minutes of absorption and 54 float.

 

[defed]

Unlikely.
Charge/bulk/absorption should be higher than float.
I use 55.6 with 60 minutes of absorption and 54 float.

for the sk48v100, Current Connected says to use:

57.6v absorb
55.2v float
15 min absorb (i didn't think i could set that but it does go to 0 despite the book saying 120m-360m)

I was able to set those (along w/ bulk at 57.6v) so the only thing i'm left unsure of is recharge voltage (when it goes back to bulk) - the controller has a range of 48v-54v.