Simple BMS wiring question
 

I haven't been on here in a great while, so thanks in advance for your patience.

I purchased some leaf lithiums a long time ago with intention of installing them in my old CC DS. Batteries I had did not go on it before I sold the cart. Now I am in the process of getting the battery pack ready for my wife's Yamaha G22 with regenerative system. I have a cheap Chinese BMS and would like to wire it for charging only. Last year, I had been following several lithium builds but have since strayed away and have forgot more than I learned from the forum. In my 70's so I like to use that as an excuse.

Question: (BMS has connections labeled P-, C- and B-)

Please correct me
I wire C- to negative charger lead?
I wire B- to negative battery terminal?
I was planning to leave P- empty?

At the charger I planned to wire Pos to battery.

I tried to search on here several times but could not find the wiring diagram for the "charge only" thread. I apologize for bringing this up again and appreciate the help. I just plan to use the Chinese charger and BMS to charge the battery pack, nothing fancy. After I get the charger adjusted to give it a safe charge, I will bypass the OBC. I seem to remember (and may have downloaded) the wiring diagram for bypassing the OBC.

Once again, thank you for your assistance and patience.

Re: Simple BMS wiring question
 

Two diagrams for the Chinese BMS and Leaf modules. One with only charge protection thru the BMS for high cell protection under charging. The other shows the Sergio relays added for extra protection for HV and LV situations.

Re: Simple BMS wiring question
 

Thank you., but I probably was not clear. My mistake. I have a simple BMS board with the three solder pads, P-, C- and B-.
I plan to wire C- to the negative on the charger
I plan to wire the B- to the negative battery terminal
And I plan to leave the P- empty.
Just wondering if I am doing that correct for Charge Only.

I don't have one of those fancy BMS like Sergio, just a plain old Chinese circuit board BMS.

Re: Simple BMS wiring question
 

If your BMS does not connect to each individual cell, it isn't monitoring cell voltages or balancing. I would not run with a BMS like that!

Re: Simple BMS wiring question
 

Yes, I understand that. I have the BMS connected to the individual cells but I have it on the bench and wanted to charge it. I wanted to know if I would solder the negative connection from the charger to the C- tab and the negative line going to the battery pack to the B- tab. I planned to connect the positive line from the charger to positive battery post.

If I was then to install the battery into the cart, I planned to hook the load up to the battery negative and positive battery posts.

The idea was to set up the BMS for CHARGE ONLY, protecting the battery cells by shutting them down individually when the achieved the max charge limit allowed by the BMS to avoid overloading one cell.

Maybe the way I am describing my plan is not clear, so I apologize. And I do plan to use an Anderson connector to the charger.

Re: Simple BMS wiring question
 

Connecting the charger negative to BMS C- is correct.

The BMS B- to pack negative wire needs to be 12ga or better depending on your charger output current.

The BMS will stop the charging if any cell goes above your maximum cell level setup.

You should also consider protecting the cells (not entire pack) from going into low voltage while driving.

Re: Simple BMS wiring question
 

As Sergio says - the BMS cannot stop charging individual cells - only the entire pack. It should stop charging if any individual cell gets above the set max voltage during charging.

Re: Simple BMS wiring question
 

Thank you. That's exactly the info I needed. I apologize for not keeping up on this. I had been following these lithium builds last year but got away from it for months and found out that I had forgotten a lot. I guess it was because I did not have a need to convert my wife's golf cart over yet. And I had sold my golf cart. Now, her batteries are starting to get weaker and I have to start thinking of converting it over.
I wanted to put the battery on charge on the bench while I start planning the conversion, so I had questions.
I REALLY appreciate the assistance. Now, I will have time to study some of the different builds to see what might work for my wife's Regenerative Yamaha G22.
Thanks again.