KID setup with LiFePO4

[jamesb]

I've just purchased a KID black and am having trouble with my setup for my LiFePO4 calb batteries. 
12 calb 3.65 v 100ah batteries wired parallel for 300ah @ 12V
3 x 100W solar panels
House Power BMS

I picked the lithium configuration during setup which set the absorb to 14.0 and float to 13.9.  What I'm finding though is that I'm getting a float charge most of the time which is fine voltage wise, but the amperage is too low (about 4.5A when 15+A are available).

So in talking to support I said that I wanted the batteries charged to 13.5 volts and then stop, so they had me change the absorb to 13.5, float to 8.5v and set the absorb time to 4 min and rebulk to 13.5.  This has essentially disabled all charging, so I put it back so that I'm at least getting some amps from float.

At one point, as a test, I increased the voltage to 15 and started getting full amps out of the panels, but this is too high for the battery so I couldn't leave it in that state, but what it did tell me was that there was nothing wrong with the panels providing the power.

I don't know where to go from here, is there someone out there that can help a newbie?

Thanks,

James

[dbcollen]

When you are in float it only puts out the amount of amps that the batteries need to maintain float volts. You should only get full amps when the charger is in bulk. The charger should be put back to the default lithium settings, it is working properly.

[Westbranch]

what  are your loads on those cells?  That kind of short charge sounds like a fully charged battery...

[ClassicCrazy]

These are the settings I have for my Calb LifePo4 pack at 48v
But notice - this is for Bottom Balance .
Which means they are drained out from start to basically flat -  each individual cell is balanced empty so to speak. Then when they are put together they fill up to about 80% and then the Ending Amps cuts off Absorb and it goes to Float.
I don't have a BMS on mine which I wish I did cause I  screwed up a few times and got voltage of cells too low but caught it quickly and they seem to be okay - been running my refrigeration loads fine . So wish I had minimum something that would cut off at 40v . I thought inverter would do that but not reliable because its no load current and  Classic itself can take the voltage down below critical stage.

Anyway this is how I have it for 16 cells
bottom  2.5v x 16 = 40v
Absorb 3.5v  x 16 = 56v
ending amps = 5 amps
Float  54v

When it changes from Bulk to Absorb it is really fast and then goes to Float .

Your settings are probably going to depend on how you are trying to charge the batteries - top charging with BMS or Bottom balancing, etc.

Larry

[jamesb]

I found a poor connection, I had accidentally slipped a washer in between causing a poor connection.  Once I resolved that I started getting 9A from the 3 panels.  I measured the voltage on the leads and found it was 13.5 with my 14.0 Absorb setting, when I increased the absorb to 15.0 it increased the lead voltage to 14.0 and my amperage jumped to 15A+.  It seems somehow that the amperage is in direct relation to the voltage, but it could just be my cloudy day.  Your setting of 3.5 correlates to my 14.0, so it should behave the same way.  I have also set the ending amps = 8 amps, and the absorb time to 4 min, and rebulk to 13.5.

ClassicCrazy, do you get 56v across your leads from the controller? or is it lower?

Any help / thoughts would be appreciated.

Thanks,

James

[ClassicCrazy]

Do a search on the main page of the forums for Lithium batteries - there was a detailed discussion o  Calb batteries in the past and a lot of the charging setpoints were discussed.

There are a lot of different perspectives on how to charge Calb LiFePo4 batteries.
Top charging with BMS balancing the top voltages and bleeding off high voltage cells to let low cells come up  - but then you rely on the BMS or bleeding devices to not fail and let cells overcharge or get unbalanced.

The bottom balance approach is to initially once  discharge each individual cell flat just above the critical low 2.5 voltage point. You need to let them rest and recheck them a few times. Then if you go to the 3.5v top range they are not 100% full but it stays away from the top 3.65v range above which is bad for the cells. Since they all started out empty then even if some are a bit unbalanced there is no harm at 3.5v at the top . That is the theory anyway .

You certainly don't want to be charging them to 15v  which is above 3.65v top voltage point. 

Did you check your cells before you charged them to make sure they were all balanced ?  I think they recommended putting them all in parallel for a few days to equalize all the voltages. 

At this point you probably want to run some loads on your battery pack and check individual cell voltages to make sure they are balanced and that none to go below 2.5v while other remain high.

I think with lithiums there is a lot of work ensuring they are working right and balanced at first before you can really trust everything goes smoothly and works properly
Larry