Discussion Batteries

[Gman]

Calibrating the low battery indicator circuit will make you go insane if you try and try to get it exactly where you want. The "sweet spot" on the multi turn potentiometer for around 6.2v is not large and easy to under/over shoot. And just when you think you've got it, the temperature changes, or the batteries settle in finally and now the timing is different. I'd say if you can get it to turn on 6.2v or a little over that is generally pretty useful.

 

[jefflongo]

Does BM on a protection circuit serve a purpose other than to connect the two middle terminals of a set of batteries? If not, can you just run a wire instead of wiring to BM? For a 2s2p configuration, running wires to BM would require 4 wires on 1 pad.

 

[Aurelio]

Does BM on a protection circuit serve a purpose other than to connect the two middle terminals of a set of batteries? If not, can you just run a wire instead of wiring to BM? For a 2s2p configuration, running wires to BM would require 4 wires on 1 pad.

It’s needed for proper battery protection. Just wire the batteries together, and then have only one wire going to it

 

[link270]

http://modretro.com/xen/index.php?t...sion-of-daftmikes-low-battery-indicator.3640/
This one is probably the most used, the red light will turn on at whatever voltage you've set it at with the potentiometer. You could use that or wait for something like PowerMii Full

I feel kinda dumb for asking this, but I’ve been looking around a lot and just can’t find a good answer.

On this schematic it’s got a pot at the end with three leads going into it. Which one goes to which pin on the pot? Will I use all three pins or just two?

Where should I be measuring the voltage from? Do I just wait till my batteries get to the voltage I want then adjust the pot so the light comes on then? Or is there a better way to properly adjust it?

Thanks for the help!

 

[Gman]

I feel kinda dumb for asking this, but I’ve been looking around a lot and just can’t find a good answer.

On this schematic it’s got a pot at the end with three leads going into it. Which one goes to which pin on the pot? Will I use all three pins or just two?

Where should I be measuring the voltage from? Do I just wait till my batteries get to the voltage I want then adjust the pot so the light comes on then? Or is there a better way to properly adjust it?

Thanks for the help!

The three pins on the schematic symbol correspond to the three pins on the potentiometer. Here is a diagram I googled http://www.regiscoyne.com/tech/potwiring/potwire.jpg

Just like you said, wait for the batteries to deplete and then turn the potentiometer so the light comes on. It may take a few iterations for you to figure out the sweet spot.

 

[jefflongo]

It’s needed for proper battery protection. Just wire the batteries together, and then have only one wire going to it

So this?

 

[Aurelio]

So this?

View attachment 3892

Yeah, that's correct.

 

[Stitches]

So this?

View attachment 3892

It's supposed to be like this:

 

[Gman]

It's supposed to be like this:
View attachment 3898

That's the same thing smh

 

[Aurelio]

It's supposed to be like this:
View attachment 3898

That's the same thing smh

@Stitches pls

 

[Stitches]

Oh fuck it is as well, sorry.

 

[Nold]

So this?
View attachment 3892

Awesome! I was thinking about how to do this, too.. I would have used two BMS-boards... so this saves me one BMS

 

[martinwels]

I am trying to connect 2 3.7v lipo batteries to form a 7.4v, so do I leave the two protection circuits on and solder the wires together to make a series? or remove the protection circuits and wire it after I connect the batteries

 

[cheese]

I am trying to connect 2 3.7v lipo batteries to form a 7.4v, so do I leave the two protection circuits on and solder the wires together to make a series? or remove the protection circuits and wire it after I connect the batteries

You should get a 7.4v protection circuit and connect both batteries to the one board (there should be instructions to tell you where and how to connect the batteries).

 

[GingerOfOz]

How do I charge my 4 Panasonic NCR18650B in the cheapest way? I looked at the one in the BOM, but it's kind of expensive for my budget and I'd prefer something that uses a some sort or usb adapter instead of AC (if possible), so its not bulky and can be plugged-in in the car and the house easily.

Unfortunately, there isn't a cheap way to safely charge 18650 cells. You are able to use special boards to charge batteries with generic DC power supplies (though likely not anything as handy or convenient as micro USB or USB C, you'd probably still have to use something a bit more powerful) but a board for four cells costs $50, which doesn't really help with price. So using the BOM smart charger and a PCB is probably your cheapest option for charging your batteries.

 

[Enrique]

What kind of pcb for charging do you recommended

 

[cheese]

It depends on how many cells and what voltage you want. Generally, there will be a pre-made board out there

 

[Enrique]

It depends on how many cells and what voltage you want. Generally, there will be a pre-made board out there

I'm using the batteries from the BOM
And what would be the best voltage

 

[cheese]

7.4v or 11.1v, depending on your setup.
Probably best to do 7.4 since that would give you multiples of 2 cells vs 11.1 would be multiples of 3

 

[Enrique]

So I would have to look for a 7.4v pcb charger?