Battery Compatability Problem.

[acrosteve]

Well, I decided to repower my spotlight.
http://www.candlepowerforums.com/vb...ix-my-old-LSI-Nite-Tracker-or-get-a-new-torch


The bulb is a 12v 100w 48696 Narva and the battery is a 12v 2.8ah lead acid. I have also tried a regular 55w h3 bulb, with the same results.

Anyway, I decided to replace the LA battery with a protected 2200 mAh Li-ion pack. I will admit that I did not look into what "protected" meant. I just assumed that it meant that the cell would be protected against over discharge. I never thought about anything else.

So, I get my pack and it says it has a rated current of 5A, and "over current detection current" of 5.7a - 7.7a. That right there is my problem. The 100W bulb draws a little over 7.5a - way too much. But the 55w bulb I have draws right around 5.5a or a little less when connected to a different battery. I suspect that the protection is kicking in on my new pack too soon. The filament in the bulb never even begins to glow.

Now, i suppose I could return the pack, but I would be out the shipping and a 15% restocking fee. I would bet it would total nearly half of the $27 I have in this pack.

If I can get the to negotiate an acceptable exchange, I could return the pack, and exchange it for a 4400mAh - possibly it would have a higher amperage rating. But that pack is $30 more - over twice the price, so it is not quite the value of the smaller pack.



Anyway, anybody ever modify the protection circuits of a Tenergy pack? I just wonder what I would be into.

Thanks

 

[acrosteve]

Another ?? on the larger pack.

I am assuming the 4400 pack would have a higher current rating than the 2200. Would that be correct?

I have contacted Battery Junction, but do not expect an answer today.


Thanks

 

[fivemega]

Main problem is "cold fillament current spike" which is way more than 7.5A and shut down the PCB
If there is a room for 2 parallel packs, this will split the total spike into 2 battery sets, otherwise try lower wattage such as 35 watt bulb.

 

[qwertyydude]

My suggestion is return the the pack and get a battery more capable of the discharge current. A 3 cell 5000mah lipo battery can be had rather inexpensively such on hobbypartz.com

search for "Sky Lipo 5000mah 11.1V 20C"
http://www.hobbypartz.com/77p-sl5000-3s1p-20c-3333-hardcase.html
It's capable of a 100 amp discharge and only costs $30.50. It won't sag it's voltage as much as li-ion chemistry would. Plus at 5000 mah it'll last longer. If you want to try over volting the bulb to get even more power, get a 4-cell of the same construction capable of up to 16.8v on a full charge. The only other issue would be buying a charger for it as these need a hobby charger to charge.

 

[hellokitty[hk]]

It's certainly not going to put up with 100A, even though it's rated at such. Generally, you'd estimate that the max real continuous discharge to be at around 60A - 70A.

 

[qwertyydude]

Nope that's a real 100 amps I use 3 sets of them in my RC boat, it's a 6S motor, and my clamp on ammeter will read a continuous 80 amps or so and can spike to about 140 or so and the battery has survived just fine. They're rated at 20c continuous and 40c burst so they'll theoretically do 200 amps for a short burst. They're quite amazing really and I even charge them at 10 amps, that's a 2C charge rate. Haven't lost very much mah yet on my discharge tests after a year.

 

[acrosteve]

I did get a response to my message at Battery Junction, but only to tell me someone else would be responding later.

Getting another cell and running them in parallel would work, I suppose. However, I want to charge them together so that I would not have to disassemble my light for charging. Anybody see a problem with that?

I do have a couple of hobby chargers, so the 3s lipo would not be an issue, but the form factor on the batteries is. I only have so much to work with inside of my current light.

I am prepared to compromise and run a 55w bulb, rather than the 100w. However, I do not think I want to run a 35 unless it is a last resort.

But, come to think of it, I suppose the 35w would work with my current pack. Maybe I will get one and try it while I am waiting for the response from battery junction.

 

[acrosteve]

I got a rather confusing response.

Thank you for your email and purchase with our company. The maximum discharge current for the 4400mAh is 1C (about 4.4A). Unfortunately we don’t think this is going to work for your needs.

I don't want to argue with them about their product, but that seems to contradict what is printed on the label of the 2200. And i would think that the 4400 would be 2x that.


What's up with that?

 

[acrosteve]

Main problem is "cold fillament current spike" which is way more than 7.5A and shut down the PCB
If there is a room for 2 parallel packs, this will split the total spike into 2 battery sets, otherwise try lower wattage such as 35 watt bulb.

I wonder what the spike is on those bulbs.

 

[acrosteve]

At this point, i wish I had just gotten another lead acid.:sick2:


I asked about running in parallel and double checking the ampacity. They only partially addressed my questions, which does not make me very comfortable.

I double checked with my product supervisor and by running them in parallel, it would increase capacity and max the discharge current. The only thing is that you will need to charge the packs separately.

The separate charging is enough to be a deal breaker.

So at this point, i either need to go forward and cobble together a long-shot, or cut my losses and stop.

I figure I will stop. But what to do with my 3x18650 battery pack???

Maybe I need to disassemble the pack and get a new light.:huh:



Now, what is the brightest thrower that will run on 3 18650's?? I want something more powerful than my TK41:naughty:
I need a Jetbeam Raptor, but i don't think the 1200 lumens will suite me. :ironic: