Building a LiIon Battery Pack - Connectors??

[smitty244]

Hi all, I've just build a couple of 18500 battery packs with PCB (from batteryspace). The batteris are back-to-back for a series connection, and I plan on using them in my 2C mag. I'm not good at shrinkwrapping so I just wrapped electrical tape around them, including the PCB, so all that is left are two wires (+ve and -ve) sticking out from the top and bottom of the pack. Only problem: what can I attach to be able to put them in the Mag without any major modifications? If you need pics let me know and I'll try to get some posted, but any info is apprecitated!

 

[wptski]

No answer for your question but I have a question for you!

Is there any info that came with your PCB that gives the low voltage cutoff point? The website lists 2.0V +/-.08V per cell! That a bit low for Li-Ion! It should be more like 2.8V-3.0V. Even the specs for their cells list 3.0V as LVC point.

I've emailed them with the same question too.

EDIT: They also sell a assembled pack with the protection circuit also. A three cell pack rated 2000mAh specs list a LVC of 9V but the link to the PCB is the same PCB with the 2.0V +/-.08V per cell specs! /ubbthreads/images/graemlins/thinking.gif

 

[Sway]

smitty244,

Try to find a small RC pack connector that will fit inside the light with the battery.

2C Mag 2x18650 Li-Ion with PCB

Later
Kelly

 

[greenLED]

[ QUOTE ]
smitty244 said:
18500 battery packs with PCB

[/ QUOTE ]

Please educate the noob, what does PCB stand for here? I'm confused.

 

[smitty244]

Thanks for the advice, I'm working on a sort of carrier right now so we'll see how that goes /ubbthreads/images/graemlins/wink.gif. PCB stands for Power Control Board I believe, it is to keep the li-ion batteries from discharging too much and dying.

 

[jtice]

PCB stands for Printed Circuit Board

In this case,,, the protection circuit

 

[wquiles]

Circuit packs or PCB's can be bought from BatterySpace:

http://batteryspace.com/index.asp?PageAction=VIEWCATS&Category=711

You can use these to turn bare cells into a protected battery pack. I just did that on a 3D M*g bosy using cells from a laptop battery pack. I now charge the pack as it were a "protected" cell /ubbthreads/images/graemlins/grin.gif

Will

 

[wptski]

[ QUOTE ]
wquiles said:
Circuit packs or PCB's can be bought from BatterySpace:

http://batteryspace.com/index.asp?PageAction=VIEWCATS&Category=711

You can use these to turn bare cells into a protected battery pack. I just did that on a 3D M*g bosy using cells from a laptop battery pack. I now charge the pack as it were a "protected" cell /ubbthreads/images/graemlins/grin.gif

Will

[/ QUOTE ]
Overcharge protection, yes but discharge protection, 2.0V +/-.08V per cell, no!! /ubbthreads/images/graemlins/thumbsdown.gif

 

[jtice]

Has anyone actually tested any of these to see at what V they actually cut off?

 

[wptski]

I have posted the same questions at the Battery Space Forum too!

There are FAQ's and posts from them at their site describing what the LVC should be, yet the products they sell don't conform with their own statements! Unless the specs are wrong?

I think that what used to be considered the LVC point has changed and it could be because the cells themselves have changed along the way.

 

[wptski]

Well, Battery Space doesn't respond to two emails and also doesn't reply to my post in their forum. Does that mean that my questions are valid?

 

[SilverFox]

Hello Bill,

I just got off the phone with a technical person at BatterySpace. They are surprised with that low voltage cut off listing as well.

He is going to check the original manufacturers paper work and is expecting to update the web page in a few hours. He stated that the low voltage protection should be 2.4 volts and the high voltage cut off is either 4.25 or 4.35 volts.

I was going to ask if you had tested yours, but it probably is not worth damaging a cell...

Tom

 

[wptski]

[ QUOTE ]
SilverFox said:
Hello Bill,

I just got off the phone with a technical person at BatterySpace. They are surprised with that low voltage cut off listing as well.

He is going to check the original manufacturers paper work and is expecting to update the web page in a few hours. He stated that the low voltage protection should be 2.4 volts and the high voltage cut off is either 4.25 or 4.35 volts.

I was going to ask if you had tested yours, but it probably is not worth damaging a cell...

Tom

[/ QUOTE ]
Tom:

I don't know why they'd have a 2V LVC when they(Battery Space) have a post that states taking a Li-Ion below 2.4V will cause permanent damage! I think that 2.4V is too low. I can't say how this circuit works but I know that other protected cells that I've tested that cutoff at 2.4V go far below 2.4V at higher amperages. There must a circuit design parameter that determines how fast it'll respond or switch OFF when LVC is met.

I don't have anything from Battery Space yet. The Automotive Scope that I told you about that uses 9.6V Ni-MH packs, well, I was thinking about building a three cell Li-Ion pack. A problem would be that the unit takes the pack far below 9V. I was unaware of these protection circuits till I saw this post, started to look at them and that's when I noticed the LVC problem!

They have some other questionable specs too! They sell a three cell Li-Ion 2000mAh protected pack with a max. charge rate shown as 2C(2.4A)! /ubbthreads/images/graemlins/thinking.gif Isn't 2C(2.4A) add up to 2400mAh?

I could either build a 2400mAh pack or two and parallel them. Buy two 2000MAh and parallel them.

 

[smitty244]

Just an update as to what I ended up doing... I got some cheap washers from Canadian Tire and soldered the wire bits from the +ve and -ve ends onto the washers then superglued the washers to their respective ends... works really well for anybody else looking for an easy way to get some LiIons into their lights!1

 

[jtice]

Ive had a 18650 down to about 2.13 V twice now, not much use on the cell, but its still going strong.

i think it was 2.13 V when I stopped this test,
The light dropped from reg, and was turning on and off about once a sec or so.

Ive also heard about 2.4V is the low cutoff though.