What is the best BM out there? No I am not trying to start a fight LOL

[Deleted member 9967]

I was tracking the AH I was putting into the battery with the Chargery and another stand alone monitor I have. I was assuming the batteries were 30-40% charged when I got them. Once I thought I was close to full charge, I was checking every 15 minutes or so. I would shut off the charge manually when I wasn't able to monitor it. I was probably a little too paranoid, but didn't want to take any chance I was going to ruin my battery while initially testing the BMS and getting the initial full charge on the battery.
Even though I had the BMS, I wasn't fully comfortable with it's functionality yet. I initially set the LVD at 3.4 just to make sure it would disconnect and so I would know I was starting up the knee. At that point, I set the Chargery to start balancing and reduced the charge current even more and kept reducing it further to 1-2 amps and allowed balancing to finish.
I had purchased a 0-30V 10A adjustable power supply. With it, I could parallel balance if I needed to .... but the pack was within 15mv by the time one cell reached 3.65V.
Overall, it took me several days with an abundance of caution to finish the initial charge/balance.

Wow, a long time then.
And you were trying for 3.4 and got 3.65? Or did I miss something again?
Or did you try for and get 3.4 and they try for higher after doing so?
Was it easy to get to 3.4 just by watching?
By that I mean no equipment was used to stop the charging once it hit 3.4.

Every 15 minutes eh? Better than me. I was thinking checking every half an hour LOL.

 

[Bob B]

Wow, a long time then.
And you were trying for 3.4 and got 3.65? Or did I miss something again?
Or did you try for and get 3.4 and they try for higher after doing so?
Was it easy to get to 3.4 just by watching?
By that I mean no equipment was used to stop the charging once it hit 3.4.

Every 15 minutes eh? Better than me. I was thinking checking every half an hour LOL.

I initially set the Chargery to cut off if any cell got to 3.4. Once that was achieved and it worked as it should I raised the value to 3.65 and set the charge current very low.

 

[Deleted member 9967]

I initially set the Chargery to cut off if any cell got to 3.4. Once that was achieved and it worked as it should I raised the value to 3.65 and set the charge current very low.

Ah ok then. So the Chargery turned it off then. Not you.
The problem I have is that I become the "shut off". So I will have to monitor it very closely.
This is where my OCD will come in handy LOL.
Some call it a disorder. I call it a help
Thanks Bob for your help.

 

[drwormy]

Might not be what you are after, but a cheap charger solution is to use a HP server powersupply, such as the DPS-600PB. Its nominal 12.5V, but applying a -2.5-2.5V takes the output to 10 - 15 V (but with builtin over voltage cutoff at 13.8V - so perfect for a ~ 3.4V/cell charge). It also has an 0-10V output proportional to current (0-10V ~ 0-50A). They are sub $20.

Im running mine via an arduino using simple PID control for constant current, and terminating when current drops below a setpoint.

 

[Deleted member 9967]

Might not be what you are after, but a cheap charger solution is to use a HP server powersupply, such as the DPS-600PB. Its nominal 12.5V, but applying a -2.5-2.5V takes the output to 10 - 15 V (but with builtin over voltage cutoff at 13.8V - so perfect for a ~ 3.4V/cell charge). It also has an 0-10V output proportional to current (0-10V ~ 0-50A). They are sub $20.

Im running mine via an arduino using simple PID control for constant current, and terminating when current drops below a setpoint.

50 amps? Sounds like a lot for computer psu.
And for only 20 dollars? cool.

 

[Bob B]

Might not be what you are after, but a cheap charger solution is to use a HP server powersupply, such as the DPS-600PB. Its nominal 12.5V, but applying a -2.5-2.5V takes the output to 10 - 15 V (but with builtin over voltage cutoff at 13.8V - so perfect for a ~ 3.4V/cell charge). It also has an 0-10V output proportional to current (0-10V ~ 0-50A). They are sub $20.

Im running mine via an arduino using simple PID control for constant current, and terminating when current drops below a setpoint.

Would you be willing to start a new thread about the details of how you are doing this? .... wiring, Arduino code, etc. maybe post a link to it here.
I've been wanting to experiment with an Arduino to start learning it and this might be a good one to get my feet wet.

 

[Deleted member 9967]

Would you be willing to start a new thread about the details of how you are doing this? .... wiring, Arduino code, etc. maybe post a link to it here.
I've been wanting to experiment with an Arduino to start learning it and this might be a good one to get my feet wet.

As the originator of this thread. I am ok with that.

 

[drwormy]

50 amps? Sounds like a lot for computer psu.
And for only 20 dollars? cool.

They are server PSU's, so high quality and rated for high power. The DPS-1200PB is 100A; its more expensive as the Crypto miners have adopted it as one of their go-to power supplies.

 

[drwormy]

Would you be willing to start a new thread about the details of how you are doing this? .... wiring, Arduino code, etc. maybe post a link to it here.
I've been wanting to experiment with an Arduino to start learning it and this might be a good one to get my feet wet.

I dont have much to report as its still in the messy breadboard phase. A link to another one i modified with Voltage control only is here:

RC Groups - View Single Post - DPS-600PB Builds - hints, tips and build plans

RC Groups - the most active Radio Control model community: electric and fuel rc airplanes,rc helis,rc boats and rc cars. Features discussion forums, blogs, videos and classifieds.

www.rcgroups.com

I have since changed that to give 10-14.5V. That 100 page thread has all kinds of details on these powersupplies.

The one im working on for a programmable battery charger is currently using an Arduino MKR1010 using the SAMD chip - this has 6 12bit analogue in and 1 10 bit analogue out. I wanted wifi monitoring. I also have a seedino Xiao (like $5 with the same chip but no wifi) that ill probably end up using.

Im doing the actual control in EPICS (https://epics-controls.org/ - because thats the control system i have some experience with), communicating to the Arduino via USB using this command language:

cmd_response — cmd_response 2014.0521.0 documentation

Bascially that maps the arduino's hardware to simple text based intrepreted commands like ?ao1 (report back the voltage of analogue input 1 in units of 0-4095/3.3V). !ao0 512 (set the voltage on analogue output 0 to 512/1023*3.3V).

The Arduino is acting as a external data acquisition device, and im using a PID record within EPICS to set a constant current which i read from the "current share" pin (11). Its not that accurate at low current; 0-10V corresponds to 0-50A. To set the voltage i supply a voltage to pin 9. 0V = 12.5V, 1V = 13.5V etc. As the Arduino only does 0-3.3V i dont have control under 12.5V yet - still building a op-amp based inveter circuit to get -2.5 - 2.5V.

The DPS600PB is the most suitable power supply i found to use as its over current, temperate and voltage protected, can be remote started, but importantly has linear voltage input controls and output. 10-13.7V available without needing to mess with the circuit board. I got mine for $21 AUD ea including shipping.

I do plan to put the PID and control on the Arduino with a little LCD display and to be able to read and set the Voltage and Current setpoints via potentiometers. When i get that far ill writeup a bit of a howto.

 

[Bob B]

I dont have much to report as its still in the messy breadboard phase. A link to another one i modified with Voltage control only is here:

RC Groups - View Single Post - DPS-600PB Builds - hints, tips and build plans

RC Groups - the most active Radio Control model community: electric and fuel rc airplanes,rc helis,rc boats and rc cars. Features discussion forums, blogs, videos and classifieds.

www.rcgroups.com

I have since changed that to give 10-14.5V. That 100 page thread has all kinds of details on these powersupplies.

The one im working on for a programmable battery charger is currently using an Arduino MKR1010 using the SAMD chip - this has 6 12bit analogue in and 1 10 bit analogue out. I wanted wifi monitoring. I also have a seedino Xiao (like $5 with the same chip but no wifi) that ill probably end up using.

Im doing the actual control in EPICS (https://epics-controls.org/ - because thats the control system i have some experience with), communicating to the Arduino via USB using this command language:

cmd_response — cmd_response 2014.0521.0 documentation

Bascially that maps the arduino's hardware to simple text based intrepreted commands like ?ao1 (report back the voltage of analogue input 1 in units of 0-4095/3.3V). !ao0 512 (set the voltage on analogue output 0 to 512/1023*3.3V).

The Arduino is acting as a external data acquisition device, and im using a PID record within EPICS to set a constant current which i read from the "current share" pin (11). Its not that accurate at low current; 0-10V corresponds to 0-50A. To set the voltage i supply a voltage to pin 9. 0V = 12.5V, 1V = 13.5V etc. As the Arduino only does 0-3.3V i dont have control under 12.5V yet - still building a op-amp based inveter circuit to get -2.5 - 2.5V.

The DPS600PB is the most suitable power supply i found to use as its over current, temperate and voltage protected, can be remote started, but importantly has linear voltage input controls and output. 10-13.7V available without needing to mess with the circuit board. I got mine for $21 AUD ea including shipping.

I do plan to put the PID and control on the Arduino with a little LCD display and to be able to read and set the Voltage and Current setpoints via potentiometers. When i get that far ill writeup a bit of a howto.

Do you know if you can connect the output in parallel with another one?

Edit ... Never mind, the info is in the linked thread .... Thank You

 

[drwormy]

Do you know if you can connect the output in parallel with another one?

Edit ... Never mind, the info is in the linked thread .... Thank You

I think you can - did you find the answer? They are used that way in hotswapable servers, with the current share pins connected together. I know there is a god howto to isolate the ground and float them so they can be put in series. For 100A, find a DPS-1200 PB, or the 800GB (80A) seems readily available, with a nice howto

 

[Bob B]

I think you can - did you find the answer? They are used that way in hotswapable servers, with the current share pins connected together. I know there is a god howto to isolate the ground and float them so they can be put in series. For 100A, find a DPS-1200 PB, or the 800GB (80A) seems readily available, with a nice howto

Yes ... found it in that thread. Apparently you can parallel several if you want and just jumper that current share pin.