Large Scale Central

14.8v 2200 MAH Lithium Ion Battery $15 Deal

Electronics Power and Sound
#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: