Battleborn's statement on recharging LiFepo4 needs 14.4v

[hemiallen]

Some of you may already know this tidbit, I finally got my PD4575A to produce more than 13.6v to fully recharge my BB-400Ah bank. More info before this clip, but this is the defining statement of the need for the BMS to get over 14v to balance multiple batteries

https://youtu.be/ultUAyv-XQs?t=117

Hope this helps. 13.6V may be 99% recharged, but it seems long term life needs higher recharging voltage.

Allen

[kowbra]

Originally Posted by hemiallen

Some of you may already know this tidbit, I finally got my PD4575A to produce more than 13.6v to fully recharge my BB-400Ah bank. More info before this clip, but this is the defining statement of the need for the BMS to get over 14v to balance multiple batteries

https://youtu.be/ultUAyv-XQs?t=117

Hope this helps. 13.6V may be 99% recharged, but it seems long term life needs higher recharging voltage.

Allen

Hi Allen,

Thanks for the info!
Can you share how you got the PD to produce more voltage? I think I'm having that issue also...

Brad

[hemiallen]

I wish I knew what changed Brad. I may be jumping the gun saying the PD is fixed..... but wanted to post this when I found it.




I spoke to Dennis at PD many times, in my other thread I think it's detailed.

Our last conversation was Dennis saying to "do the PD troubleshooting guide
https://www.progressivedyn.com/wp-co...LESHOOTING.pdf

He said my 13.3v as read on the Victron smart shunt was cable losses. I added another cable to simulate a 1/0 cable reducing battery recharge cable losses, and it made little difference, from my numbers.

And when I added batter 4 and cut individual 1/0 wires to join them with the shortest length wires, I of course shorted the system and blew all 4 reverse polarity fuses ( dummy mistake)

After finishing the wires I found and replaced the 4 15A fuses and proceeded to recharge the batteries, and it worked! I still need to let them settle ( disconnected from shore power) and I need to run them down to maybe 60% and do a recharge to see if it immediately goes to 14.4 / 50+A of charging, which I will post my results.

I just found this BB info and wanted to post it up, for those that replied theirs don't recharge AT 14.4v, and 13.3-6 is ok. I am hopeful, and everything I have been told from PD to BB is a recharging system NEEDS to be putting out 14.4v the entire recharging time, not just when the bank is near 100%.

[carlrx7]

Sorry hemi, but you are not understanding the basic charging characteristics of LiFePo4 chemistry correctly. You are referring to Constant Voltage charging by saying it needs to be 14.4 the entire time. NO manufacture recommends CV charging. In order to perform a CV charge, your charger must be capable of putting out 100's of AMPs in order to push the voltage up that high.

The charger is putting out Constant Current but 13.6 voltage you are seeing is because the charger is maxed out of what it can deliver and it only pushes the voltage up that high. It will read 13.6 until it gets to at least 90% SOC, then rise very rapidly.

The reason you are seeing 14.4 now is because it is finally full. see graph:


The video you linked mention that 14.2-14.6 needs to be reached to allow cell balancing. It does not state, the entire charging period (because that is almost impossible).

https://www.solacity.com/how-to-keep...tteries-happy/

[PNW Fireguy]

A bit off topic but actually by charging them at the lower voltage coupled with lower DoD increases their lifetime number of cycles.

[hemiallen]

Thanks for the graph.

On topic
My link was about the need to FULLY CHARGE TO 14.4 so the BMG does it's balancing, these other discussions are not related to my post topic. I believe BB's post was due to some only using a charger that does 13.6V ( lead-acid w/o charge wizzard) as I have read some say it is ok to not recharge above 13.6v. Sorry for the confusion of my post.





Thank you

Allen

[66 Galaxie]

They only need to go that high occasionally to "cell balance". When you set inverters with large chargers that high, they can ramp up too quick and create a spike in voltage that suits the batteries down. I like to set the solar for that voltage and leave the main charger around 14.2

[PNW Fireguy]

The FET charge spike is something only experienced witht BB batteries that I have seen. It is a result of limitations of the internal BMS. I have no such issues with my RV pack nor the LIon Safari batteries used in my truck APU. As far as balancing and the charge voltage goes the subject would be a long one. If you don't balance the cells the proprietary internal BMS on drop in batteries can be susceptable to drop out due to low cell voltage vs low pack voltage. Balancing will only occur once the batteries have reached absorption.

[hemiallen]

Thanks for the additional information.

I wasn't sure if this was solely a BB or Lifepo4 issue.

Allen

[bcrvman]

Originally Posted by hemiallen

Some of you may already know this tidbit, I finally got my PD4575A to produce more than 13.6v to fully recharge my BB-400Ah bank. More info before this clip, but this is the defining statement of the need for the BMS to get over 14v to balance multiple batteries

https://youtu.be/ultUAyv-XQs?t=117

Hope this helps. 13.6V may be 99% recharged, but it seems long term life needs higher recharging voltage.

Allen

Here are the graphs of my BB batteries being used and charged. The top chart shows the voltage and current, the bottom chart shows the state of charge. Look at the right edge first, notice that when the current starts to flow out of the battery the state of charge follows that curve and the voltage goes from float (13.6) to nominal (13.2). 13.2 is the normal resting voltage when neither charging or discharging are happening. 13.6 is where it goes after the absorb cycle is complete. Lithium batteries don't really have or need a float voltage, but since almost all chargers have a setting, then use 13.5 or 13.6. If you also have a solar charger, I think you are supposed to set it higher so you prioritize solar over mains charger but I am not 100% sure of that. The absorb voltage can be anything between 14.2 and 14.6. LiFePO4 is not anywhere as sensitive to this setting as FLA is, many FLA's have been destroyed over the last 5ish years due to people setting them to 14.6 or 14.8. For LiFePO4 a good compromise is 14.4. This makes sure the BMS does its job in balancing the cells.

[hemiallen]

Thank you very much

Allen

[bcrvman]

Originally Posted by hemiallen

Thank you very much

Allen

I forgot to mention, those charts are part of the Victron system. I have a GPS and a WiFi module installed on my Multiplus so I can monitor the entire system from anywhere in the world.