My 12v packs

[Tinkerer]

Hi everybody,

long time lurker here. I thought it might be time to share what I’ve done so here it is.

my 3s34p battery packs made from Samsung 35E cells extracted from bad BMS ebike packs, all test 100% capacity and internal resistance is according to data sheet. It’s designed for low current, less than 200W hence the nickel busbars and 14 gauge wire. This battery sits in a steel ammo can. BMS is external and is in use when charging and discharging but can be removed if necessary. Every cell is fused to 3 amps and fuses are spot welded to cells.

This may sound like overkill, but each ammo can is gonna have its own on board arduino controller hooked up to mosfets and programmed to shut off the power in and out if any parameters such as temperature, voltage, and maybe humidity levels are breached...sounds like a BMS on top of a BMS...


Can anyone suggest any improvements?Always want to be as safe as I can be.

 

[italianuser]

Looks good, lucky to find such good cells. Soldering looks great, very clean job.
I woudn't ever remove BMS. It happened to me that a very low power device (actually, two small displays used to show Voltage&Amps, 40mAh) connected to a solar MPPT regulator, had what I supposed to be and over-current problem which melted negative 26AWG wire. I then added an extra protection circuit, described here.

If it's ok with you, you could share the Arduino project (even a high level schematics or something). I'm doing a similar job, what do you use to shut off power in case of an out-of-range parameter (temp, voltage, ...), a DC relay?

 

[Tinkerer]

Looks good, lucky to find such good cells. Soldering looks great, very clean job.
I woudn't ever remove BMS. It happened to me that a very low power device (actually, two small displays used to show Voltage&Amps, 40mAh) connected to a solar MPPT regulator, had what I supposed to be and over-current problem which melted negative 26AWG wire. I then added an extra protection circuit, described here.

If it's ok with you, you could share the Arduino project (even a high level schematics or something). I'm doing a similar job, what do you use to shut off power in case of an out-of-range parameter (temp, voltage, ...), a DC relay?

That’s what i thought about the BMS. I have not yet designed much of an arduino circuit and no idea how to make a digital schematic, lol.

 

[Rodsterman]

Hi everybody,

long time lurker here. I thought it might be time to share what I’ve done so here it is.

my 3s34p battery packs made from Samsung 35E cells extracted from bad BMS ebike packs, all test 100% capacity and internal resistance is according to data sheet. It’s designed for low current, less than 200W hence the nickel busbars and 14 gauge wire. This battery sits in a steel ammo can. BMS is external and is in use when charging and discharging but can be removed if necessary. Every cell is fused to 3 amps and fuses are spot welded to cells.

This may sound like overkill, but each ammo can is gonna have its own on board arduino controller hooked up to mosfets and programmed to shut off the power in and out if any parameters such as temperature, voltage, and maybe humidity levels are breached...sounds like a BMS on top of a BMS...


Can anyone suggest any improvements?Always want to be as safe as I can be.

That’s what i thought about the BMS. I have not yet designed much of an arduino circuit and no idea how to make a digital schematic, lol.

Hi everybody,

long time lurker here. I thought it might be time to share what I’ve done so here it is.

my 3s34p battery packs made from Samsung 35E cells extracted from bad BMS ebike packs, all test 100% capacity and internal resistance is according to data sheet. It’s designed for low current, less than 200W hence the nickel busbars and 14 gauge wire. This battery sits in a steel ammo can. BMS is external and is in use when charging and discharging but can be removed if necessary. Every cell is fused to 3 amps and fuses are spot welded to cells.

This may sound like overkill, but each ammo can is gonna have its own on board arduino controller hooked up to mosfets and programmed to shut off the power in and out if any parameters such as temperature, voltage, and maybe humidity levels are breached...sounds like a BMS on top of a BMS...


Can anyone suggest any improvements?Always want to be as safe as I can be.

hello,
Since i was scared by the explosive battery hype, I delayed getting into building my own packs.
However, I am not as concerned with that issue as much now.
I programed an Esp2866 (Wemos D1 Mini) to monitor the temperature of my 3S8P packs. These sit in an ammo box as well and it is programmed to sound a loud piezo as well as notify me via wifi of a temperature rise. The esp goes to sleep after taking a measurement every minute. That way it draws minimum power from the pack.
So far it is working well.