Large Scale Central

14.8v 2200 MAH Lithium Ion Battery $15 Deal

Electronics Power and Sound
#21

Dennis Tetreault said:

I just came across this sale via email and thought it may be of interest. I use similar 22.2v packs without issue. Worth a shot at $15.00 each. http://www.allelectronics.com/make-a-store/item/lbat-148/14.8v-2200mah-rechargeable-li-ion-battery-pack/1.html

Dennis

Dennis - thanks for the tip - I ordered six batteries and received them a few days ago - to get a proper idea of what I can expect from them I did some tests - my notes are here:

http://www.trainelectronics.com/BatteryDischarge/

I believe that these battery packs are well worth the price!

dave

First Test

#22

Thanks for the info, David. I have six of them, too, waiting to go into various locomotives. Good info to have.

#23

Bob - it is fun to do such tests - always interesting!

I have a charge underway right now & it is building a graph – I’ll post it when it is done - probably tomorrow.

dave

#24

I added a graph of the charging that took place overnight - when charged at 200mA it took about 12 hours.

The graph is at the bottom of the page:

http://www.trainelectronics.com/BatteryDischarge/

dave

#25

Dave,

Great stuff… What equipment are you using to charge, discharge, graph and or record you effort?

There’s quite a peak at the end of charge; appears to be upwards of 19.2V which is well above the recommended cut-off or termination number of 16.8V(4.2V per cell)? Charge should terminate at no more than 4.3Vpc or 17.2V with a 4-cell battery pack to prevent overcharge and or plating of the cells.

Charging @ 200mA or .2A CC (constant current) equates to .09C charge rate… Well below the recommended OEM atypical slow charge rate of .2C or 440mA or .44A of a 2200mAh battery.

Your battery was essentially fully-charged once it realized 16.8V at the 200mA rate utilized as the cells are eventually saturated eliminating the need for the CV (constant voltage) final charge step…

I have previously suggested the use of a timer of some sort to mitigate extended charge times, it holds true with SLOW charging at the least IMO.

Generally SLOW charging Lithium cells is an acceptable practice, while TRICKLE charging is NOT!

Michael

#26

OK, I’ll bite, what is the difference between slow and trickle charging?

#27

Michael, as David said in the article the he linked to, the spike in voltage at the end of charging indicates that charging had shut down.

#28

Steve,

I should have looked at Dave’s page…

A TRICKLE charge is typically equal to the batteries self-discharge rate.

Michael

#29

Michael Glavin said:

Dave,

Great stuff… What equipment are you using to charge, discharge, graph and or record you effort?

There’s quite a peak at the end of charge; appears to be upwards of 19.2V which is well above the recommended cut-off or termination number of 16.8V(4.2V per cell)? Charge should terminate at no more than 4.3Vpc or 17.2V with a 4-cell battery pack to prevent overcharge and or plating of the cells.

Charging @ 200mA or .2A CC (constant current) equates to .09C charge rate… Well below the recommended OEM atypical slow charge rate of .2C or 440mA or .44A of a 2200mAh battery.

Your battery was essentially fully-charged once it realized 16.8V at the 200mA rate utilized as the cells are eventually saturated eliminating the need for the CV (constant voltage) final charge step…

I have previously suggested the use of a timer of some sort to mitigate extended charge times, it holds true with SLOW charging at the least IMO.

Generally SLOW charging Lithium cells is an acceptable practice, while TRICKLE charging is NOT!

Michael

Michael - the equipment for the first test was just a volt meter & a pencil & paper - each time I thought of it I jotted down the voltage as the engine slowly discharged the battery.

For the 2nd test I hooked the battery & motor up to a digital VOM that has a USB interface and a graphing application - I set it to record a data point once each minute.

The choice of 200 ma for charging was because of my not being around while the charging took place - I have charged at a higher rate but like to be in the room when I do that - since the charging would happen overnight I wanted to be conservative!

FYI, the VOM if from MCM - I have a link to it on the web page.

Steve’s comment about the spike is correct - there are more details on the web page.

dave

#30

Micheal - I didn’t answer all of your questions in the first reply.

The power supply that I used for charging is similar to this one

http://www.mpja.com/0-18VDC-0-3-A-Variable-Benchtop-Power-Supply/productinfo/9600%20PS/

I have three variants that can be set to limit current - two of them are 0-30 volts DC. Very nice for testing and other work - I use them all of the time, virtually every day.

I entered the data and did the graphs with Google Docs Spreadsheet - I have been using their software for some time and was pleasantly surprised by the maturity of the graphing function.

Let me know if you have any other questions

thanks!

dave

#31

Trickle charging are really not a well defined procedure on batteries.

In the nicad world, it was more than the self discharge rate but not much more.

the phrase “float charge” comes in here too.

As chemistry changed, a continuous low level charge also wreaked more havoc with cells, not great on nicad, not really good on nimih, and disastrous on lithium

also, extremely low charging rates on lithium is not great, I need to find the references. It’s not the same as what happens with nicad (memory “effect”), but I remember there was a problem with too light a charging rate.

Greg

#32

I couldn’t find the exact battery pack but a similar one from Tenergy recommends charging at .2c for standard charging and .5c for fast charging.

see:

http://www.tenergy.com/31026

dave

#33

Those are numbers that I am familiar with although most packs will take 1C max rate. Even my old Maha only holds that level for a short time.

Constant current charging is really old school, and not really optimal.

Greg

#34

Dave,

That is a nice little all in-one VOM so to speak… I use similar data logging programmable power supplies and electronic loads to evaluate power sources, started many years ago when I was consumed by giant scale RC aircraft (2001). When I first got involved with the big stuff we used 800mAh Tadirian Lithium Metal cells (to save weight), these worked but had shortcomings, about the same time NiMH technology was evolving as were our loads with the advent of digital servos. Li-Metal/NiMh came and went as Lithium Ion became the technology of choice. Anyway evaluating power supplies for our aircraft flight systems became a necessity with demands/loads ever increasing and many experiencing plane losses (we recorded spikes in current draw in-flight of 24A with onboard data logging). The emerging electric powered model airplanes provided another distraction for discovering the needs therein too.

Your efforts, projects and documentation are a great resource for our hobby, many thanks.

Michael

#35

Followup on these batteries. Ive had them installed in several locomotives, most notably my SD45, but also a Connie, and two geese. Zero problems with them, at all. Im going to order another pile of em.

#36

My 2 are still running strong.

#37

I’ve been using mine a lot this summer. Very good batteries.

Later,

K

#38

I am tempted by these batteries but completely unversed in the technology, so may I ask what you would recommend for a charger.

#39

This one will work quite nicely:

http://www.batteryspace.com/smartcharger15afor148vli-ionpolymerrechargeablebatterypackwithtwopinconnector.aspx

It’s pretty basic, but does the job and is cheap.

Later,

K

#40

The small wall socket chargers that came free with the 12v/6300mA Lith Ion batteries I bought from China are 12v/ 350mA output.
I have never had a problem with them (the batteries)…I did however have a charger blow when I plugged it in…frightened hell out of me I can tell you!!