Charge Profile for Bioenno LiFePO4 with BMS

Started by rs500cat, October 01, 2017, 08:21:51 PM

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rs500cat

I am purchasing a large LiFePO4 battery from Bioenno https://www.bioennopower.com  The battery comes with a built-in BMS and specifies a constant current, then constant voltage charge method.  The charge voltage for the battery is 14.6V.  What settings should I use with the Kid controller to achieve this method.

I would like to utilize the BMS since it is an integrated part of the battery.

Thank you,
Ron

ClassicCrazy

#1
Not sure why it would have to be constant current - maybe they don't want you to exceed a certain limit - so you could limit the top current with settings in the Kid . Once it goes from Bulk to Absorb it is then going to be constant voltage . You should check with the manufacturer to see what they want for the float voltage once the Absorb is finished. Also you may want to check with them about ending amps - which is how you would terminate the Absorb if you are not using time to end it.

It is kind of tricky to get lithium settings just right especially if the BMS needs certain current limits once it goes to constant voltage.

I just looked at their webpage but didn't see the specs . They sell a solar mppt charge controller that is designed for lithium they say .
Do you already have a Kid ?

It would be nice if there was a lithium firmware or profile for the Kid but there isn't anything specific so you would have to do the best you can with Absorb, Ending Amps, and Float settings - seems like the supplier should be able to tell you those settings .

Did you order your batteries yet ? There is also another company making that type of lithium battery in Reno called Battleborn -- unless they are the same thing with a different label on them . We all know how many different labels on same batteries exist for lead acid !
https://www.solar-electric.com/battle-born-bb10012-100ah-12v-lithium-battery.html?gclid=Cj0KCQjwpMLOBRC9ARIsAPiGeZB03oKkH36LijBY2SkOKymFfkDCUMRFqAxgJduaeGwqUJ6inS8NKYAaAj49EALw_wcB

Larry
system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

rs500cat

I have not purchased the battery, I already have other smaller Bioenno batteries and they are RF quiet and perform to spec.
  I have the Kid which is presently happily charging (6) 50Ahr batteries in parallel.  My system runs an emergency ham radio station. 

Bioenno states 'These chargers provide the required constant current, followed by constant voltage (CC/CV) charge profile for charging LiFePO4 batteries.'  The charge voltage on all of their batteries is 14.6V.

I tried contacting Bioenno a while ago and they were reluctant to offer specific advice on solar charge controller setup.  I may need to try again.

Ron

ClassicCrazy

Well they might be good batteries but geez - I don't know if personally I would  get batteries from a place that won't give even basic support like charging parameters.  That is just strange.

I am a ham too - so good  to know you don't get any noise . I doubt there would be any from batteries anyway  - the charge controller would be the issue because of all the switching stuff going on. Good to know that you don't find any noise in the Kid . Bob at Midnite is a ham and he doesn't want any RF noise in their products either !

So the way my bicycle charger on my LiFePo4 batteries works is it charges constant current - first charger was only 2 amps but second charger I have now is 6 amp . Anyway so the way it works is it gives constant current until voltage climbs to the setpoint which is the top of charge , then the charger cuts the current down and goes to constant voltage . The reason it has to cut down is also based on the BMS because the bleed resistors can only bleed off so much current to balance the cells . My charger will cycle on and off too if voltage drops then comes on back up to set voltage cuts down and it will do this until the cells get balanced. It pretty much shuts off charging when the voltage is maintained at setpoint and is not taking any more current. At least this is how I think it is working - I haven't monitored it for awhile . I just plug it in and let it do it's job.

3.65 v is the top of the charge voltage of a LiFePo4 cell so you multiply that x 4 and you get your 14.6v.
It really seems like a lot depends on exactly what the BMS in that battery is going to need or be able to handle when it is balancing.

If you have a look at the Battleborn product manual you will get more info than it sounds like your other dealer is wanting to provide.
They tell you to set the Absorb voltage and when it goes to Float at a certain voltage  it basically shuts off the charging via BMS so it won't over charge.
https://www.solar-electric.com/lib/wind-sun/Battle_Born_Manual.pdf

Larry


system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

rs500cat

I spoke to Bioenno, they confirmed that an absorb voltage of 14.6, float of 13.6, with no EQ will work fine for their batteries (actually the BMS will support any absorb voltage up to 15V).  In effect, the BMS only requires adequate current to charge the battery at a fixed voltage, it handles all voltage and current adjustments for cell balancing.  This means that essentially any charge controller should work (at least for Bioenno batteries).  I mention this for future viewers, it may make their evaluation easier.

In contrast to what the Bioenno website states, multiple batteries can also be charged in parallel, as long as they are initially fully charged.

Thanks for the advice,
Ron

ClassicCrazy

What did they say for current limits ? And  any time limits on the 14.6 absorb ?

Larry
system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

rs500cat

There are no current limits, the battery BMS will simply take what it needs.  They said it does not matter whether 20A or 5A is available to the BMS.  In the same way there is no time limit on charging.  The battery BMS is simply looking for a fixed voltage, it does all the work.

The only risk is if the BMS fails, in which case the battery could theoretically be overcharged.  That would be a risk, however, whether a battery BMS is used, or a charge controller were to fail without a BMS.  I expect that most BMS's and charge controllers would most likely stop the charge current in a failure condition.

Ron

ClassicCrazy

BMS are supposed to limit high and low voltages to the cell, help with balancing at the top charge point, and also limit the amount of current that can be discharged . Maybe that one in the battery also limits the input current . 

Larry
system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable