Beware

[Mark-VA]

Learned a very valuable less this past week.
Ordered 2 battery protection circuits from
https://www.batteryjunction.com/li-p...FJRdaQWVqstbtZ

Wired the unit up according to their instructions scroll down on the link above.

The units would not work correctly, wouldn't charge or discharge, by then I'm half mad.
Went to Tenergy's web site to research the circuit, found this technical diagram
http://www.tenergy.com/32010

Hoping I had not ruined the circuits I re-wired according to Tenergy's specs.
You really have to read carefully to see the differences.

Now I've got output, yea.
Yea to soon.
Now It won't charge
Contacted Battery Junction to point out the difference and they refused to talk about the matter.
Buyer Beware.

[ivconic]

That's valuable information, thanks!
But i miss to find the wiring on:

"...Went to Tenergy's web site to research the circuit, found this technical diagram
http://www.tenergy.com/32010..."

[ivconic]

I am using these most frequently:

But the wiring is accurate and everything works like it should.

[Mark-VA]

Wiring description is on the right hand side of the page.
This looks identical to the wiring diagram you posted here. I might need to look into finding one like your.

[Jim in Idaho]

Seems to me that the wiring description is wrong. If you connect the P+ and P- to the B+ and B- respectively, how can the controller regulate the charge current? The charger, connected to P+ and P- would be connected directly to the 4 battery cells, with no controller regulation? On mine, I have the output on B+ and B-, and the charger socket connected to P+ and P-. No connection between the P's and B's except thru the controller circuitry.
EDIT: Oh, I see....the P+ and P- are the power output, and charger input. Ok, I'll buy that. I'd forgotten how I wired mine. So, according to Tenergy, I've got mine wired wrong? I should have both the charger input and power output connected to P+ and P-. Seems I goofed that up, though my pack is working fine. Wish I could find the diagram that came with mine!
Jim

[ivconic]

Here is a example of application.
Super "light weight" solution with 4x18650, 2.4A batteries.
Finally provides ~16.2V.
Charging with ~16.8-17v.
FelezJoo PI is having sort of "battery alert" function in code, taking "18v" as right supplying voltage.
And alert activates when voltage drops bellow 14.xx volts. That is author's decision.
Although it can work just fine with voltages under the 14v too.
In order to avoid alert annoyance and suit what's written in code; i only had to adjust the "voltage sensing" (single resistor to ADC) value.
So when BMS provides 16.2V ; detector takes that value as "18V" and displays it on screen.
As the voltage drops by 0.1V; "18v" display acts accordingly displaying "17.9V, 17.8V...." etc
The only tricky part using this BMS was to pick proper power supply for charging.
Advised 16.8V is not standard value that you may find easily. So what to do?
I have some universal laptop power supply with adjustable (by multi switch) outputs.
So i could pick between 16v and 18V.
I picked 16V. I am afraid to let it on 18V longer, not sure if it can damage something.
With 16V it will charge batteries quite alright up to 85-95% of capacity.
Something i can live with.
Until i find exact 16.8V power supply, small and suitable package.
I don't have some experiences with these BMS's .
I wander would it be safe to charge with voltages above 16.8V? Say 18V?

[Carl-NC]

Yes, P+ & P- should be both power out and charger in.

Mark, I assume you are building custom battery packs. Are you using button-top cells or flat-top cells? Button-top cells usually have their own internal protection circuit -- they are intended to be used and charged individually, just like NiMH or NiCad cells -- whereas flat-top cells don't because they are intended to be used in a pack with a separate protection circuit. If you have button-top cells, there could be an issue with the 2 protection circuits.

[Jim in Idaho]

For a charger, I just use a buck converter with adjustable max voltage and current. Generally I limit the charge on my 4-cell pack to 16v. That gives about 80% of the max run time, but can triple the number of charge/discharge cycles before the pack is worn out.
Jim

[Jim in Idaho]

Yes, P+ & P- should be both power out and charger in.

Mark, I assume you are building custom battery packs. Are you using button-top cells or flat-top cells? Button-top cells usually have their own internal protection circuit -- they are intended to be used and charged individually, just like NiMH or NiCad cells -- whereas flat-top cells don't because they are intended to be used in a pack with a separate protection circuit. If you have button-top cells, there could be an issue with the 2 protection circuits.

Strangely enough, Carl, I mentioned that very thing to him yesterday...LOL
Jim

[Jim in Idaho]

Yes, P+ & P- should be both power out and charger in.

Mark, I assume you are building custom battery packs. Are you using button-top cells or flat-top cells? Button-top cells usually have their own internal protection circuit -- they are intended to be used and charged individually, just like NiMH or NiCad cells -- whereas flat-top cells don't because they are intended to be used in a pack with a separate protection circuit. If you have button-top cells, there could be an issue with the 2 protection circuits.

Yeah, I'm not sure how I missed that! I wired mine with the output on B+ and B-, and the charger input on the P's. I'm guessing the effect of that is I have overcharge protection, but no overdischarge protection. My pack works fine, as is, and the lack of discharge protection is no big deal as I rarely run the TDI for long periods of time, and have two packs, so swap them out at about 4 hours.
Jim

[ivconic]

For a charger, I just use a buck converter with adjustable max voltage and current. Generally I limit the charge on my 4-cell pack to 16v. That gives about 80% of the max run time, but can triple the number of charge/discharge cycles before the pack is worn out.
Jim

That answers my doubts.
I have choose wisely... the 16V option!

[walkman]

I use this.

[rickb]

Ivconic, put a series combination of silicon and schottky diodes in series with the dc output to get what you want.

[Carl-NC]

Yeah, I'm not sure how I missed that! I wired mine with the output on B+ and B-, and the charger input on the P's. I'm guessing the effect of that is I have overcharge protection, but no overdischarge protection. My pack works fine, as is, and the lack of discharge protection is no big deal as I rarely run the TDI for long periods of time, and have two packs, so swap them out at about 4 hours.
Jim

More critically, you have no short-circuit protection. Lithiums can catch fire if short-circuited.

[Mark-VA]

Flat top batteries.