Samsung 30q Batteries, BMS and Vruzend Kits - Atlanta Georgia

[roadrich]

I bought a couple Vruzend kits and attempted to make my own battery. Not sure if the BMS is faulty or if I just have no idea what I'm doing (probably the latter) but somehow I killed 7 of the batteries. I tested the others (21) and they are all around 3.4v so the rest seem fine. If you want all of the following make me an offer. I have about $250 into this so far and am looking to recover some of the funds, but obviously not all.

- 21 working Samsung 30q batteries (~3.4v each)
- 7 dead (0-0.05v) Samsung 30q batteries
- 1 brand new unopened Vruzend kit
- 1 used Vruzend kit
- 1 BMS (52V 14s Battery Management System)
- 1 roll of shrink tube, approx 3 feet

Make me an offer! Local pickup preferred but if you want to get it shipped you pay the (probably high) cost of shipping batteries

 

[Patdown45]

would you take $100 as I am thinking about building my own as well but not willing to take a big gamble just yet.

 

[tomjasz]

You were building a 14s 2p? 52V?
Sadly the BMS and 7 batteries have no value.
Where are you located?

 

[MarkF]

3.4 is over discharged.

 

[mako]

3.4 is over discharged.

Believe that is incorrect. More like 2.5v if you believe in spec sheets.

 

[MarkF]

Storage is 3.8 resting voltage, 90% discharge is 3.7(resting voltage) and should never go under that. You can go down to 3.4 while under a load.

 

[mako]

Sorry, was thinking vco under load

 

[harryS]

They ship new out of factory at 3.6V per cell. Every new battery I've purchased comes in there. Mako is correct. Lithium 18650 has a minimum of 2.5V for min discharge, but no one goes there.

Most ebike controllers would run them down to about 3.0V per cell if you just rode til the bike stopped. If you want your battery to last longer, 3.6V which is around 50% charge is a good place to stop, but it doesn't hurt to go down to 3.0 volts once in a while if it gets you home.

 

[stanmiller]

Where are you located?

Thread starter is in Atlanta, GA.

 

[tomjasz]

Thread starter is in Atlanta, GA.

I'd get Micah Toll's book and try again rather than lose more of the investment. I can't imagine how the OP trashed the batteries, but find a 14s2p build to be ill-advised anyway.

 

[stanmiller]

I'd get Micah Toll's book and try again rather than lose more of the investment. I can't imagine how the OP trashed the batteries, but find a 14s2p build to be ill-advised anyway.

I have both of Micah's books. The battery book is great! to learn more about Li-ion battery technology and applications in e-bike tech.

As many may know here, Micah is a partner/investor/principle in Vruzend. https://vruzend.com/about/

Early on I considered building a battery with a Vruzend kit, but for my first go I went with an off-the-shelf battery from Junstar.

 

[tomjasz]

Early on I considered building a battery with a Vruzend kit, but for my first go I went with an off-the-shelf battery from Junstar.

Good idea to start with an already built battery pack. Building isn't for the faint of heart or those not detail oriented. Best to be bust riding while contemplating a build.