Large Scale Central

14.8v 2200 MAH Lithium Ion Battery $15 Deal

Electronics Power and Sound
#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!!

#41

A note of caution. This experience was with the exact same Tenergy pack sold by All Battery, not the $15 special, but I would expect it to behave the same.

Yesterday I had a need for a 12-15v power source doing some troubleshooting on my RV furnace. Since I have all my LiIon packs set up with Tamiya compatible plugs and also have a mating plug to clip leads, I decided to use one of my Tenergy 14.8v LiIon packs to power the blower in the RV furnace. This is a fairly high current application, but the pack was able to spin the fan at full speed for quite some time. The first pack went into thermal shut-down after running the fan for about 8 minutes. The pack was quite warm to the touch. I switched to a second pack and kept watch of it. After a few minutes of spinning the fan I noticed the shrink wrap beginning to melt where the wires connect. I immediately discontinued using the pack and let it cool.

No damage (other than cosmetic) was done to either pack. Both took a refresh charge after waiting several hours for them to completely cool and appear to be working fine.

The caution is that while operating near the current limits of the Protection PC board these packs will get hot enough to melt things before going into thermal shut down.

#42

John,

What size batteries were in play? The typical 2200mAH 18650’s can do 4 amps continuous for about 8 minutes as you alluded to before rated voltage falls off in my experience. Chances are very good your batteries PCB are rated for more than the battery can provide typically around 5.5-8 Amps of a 4 cell 14.4v battery.

So more likely than not the PCB opened due to voltage drop verses thermal run away as these devises do not have this feature. This means the cells dipped to sub 2.4V before they invoked the PCB’s discharge voltage feature and shut down.

FWIW: The current draw of an atypical 12VDC RV furnace is about 4 Amps, newer stuff sub 3 Amps. So you were asking a lot of your batteries (early in my life I was an RV Tech, fixed this stuff all the time).

I can assure you your batteries are worse for the wear, HEAT is the enemy and greatly reduces cell life expectancy, not to mention capacity and there is the depth of discharge consideration too. At this juncture your batteries have experienced a worst case scenario for preserving cell performance.

I record battery performance at various intervals and track performance thereof, age and such. This allows me to identify anomalies and garner information over the packs life cycle. If these were my batteries a note of the damage would find a spot on the spread sheet.

Future endeavors of this type are well suited for NiCad, NiMH and or Lithium Poly batteries; or even Lithium Ion if you have larger capacity batteries with cells stacked in parallel.

Multiple batteries would allow you to wire them in parallel, to increase capacity which increases the available discharge current or ampacity too.

Thanks for sharing.

Michael

#43

Thanks for the heads up. I use these batteries for all of my motive power. They are twice that on Allbattery.com. Just placed an order.

#44

Thanks Michael. Yes, they are 2200mAh packs. I thought it was a temperature cut-off since after cooling a bit the pack had output again. Probably just recovered output voltage above the threshold.

In any case; it was probably a bad idea to use the LiIon pack when I had RV battery voltage available a few inches away. Could have just as easily run the blower directly off the RV battery lead. Oh well.

Good point on noting the damage. I’ll probably do that right on the packs so if they die prematurely I’ll have an idea why. My point wasn’t that the packs could be abused with no ill effects, but rather that they can be put in a condition that will get them warm enough to melt shrink wrap before they cut-off. BTW - The shrink melted where the wires attach to the PC board, not around the cells themselves. The cells got quite warm but not hot.

#45

Succumbed to temptation. Ordered several battery packs, to cover two or three loks plus a couple of spares, and a charger.

Clearly, I am sliding perilously close to the Dark Side.

#46

Welcome to the Dark Side, Chris. We have cupcakes.

#47

Steve Featherkile said:

Welcome to the Dark Side, Chris. We have cupcakes.

Sadly :(, I have to avoid cupcakes …

#48

ordered me 2 more this morning along with a hand full of 2.1mm ‘coax’ plugs, connectors, etc…

#49

FWIW - Michael was correct - these two packs are not well at all. They no longer hold a charge for any length of time and in use will go under-volt preventing the smart charger from charging them. I can still get them to take a charge on the dumb charger, but I’m not sure they still have any value to me as train batteries.

They will be replaced with two new ones from All Battery. At least they still have them at the $15 price :slight_smile: