<works> Battery pack find with idea for a mod. <works>

I found this pack on my favourite RC supply page:
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=6955
The good thing about this pack is it should fit into a 2D mag easily. Since it gives about 12V i thought about powering a 12V 50W halogen spot with it. The spot should fit the mag head (will test that when my host arrives) and has reflector and lens allready in place. I would connect the battery with plugs like those on my rc-planes. Low resistance mod to the switch an bulb soldered on directly should give good performance out of this <30$ mod.

This is a transmitter pack that doesnt give much current. The next step would be using a flight pack and a 100W+ bulb. That would still fit into a 2D mag easily :rock:

Re: Battery pack find with idea for a mod.

hmm...
12V 50W...I'm assuming your referring to something like a 64440 or some sort of a bipin halogen...under driven may yield a yellow beam, I'd suggest finding a 9V lamp thats more tolerant of overdrive but I dunno what to recommend :sigh:

12V 50W at 11.1V should draw 4.5amps, a cell with 2500mah capacity that would be ~2C, hmm..that would not be a issue with the pack at all...in fact you might be able to step it up to 100W

SPECS said:

Spec.
Capacity: 2500mAh
Voltage: 11.1v
Constant discharge: 3-5C
Burst discharge: N/A
Weight: 142g
Size: 100x28x23mm
Plugs: Futaba, JST-XH, JR/Spektrum

Click to expand...

I'm not a hotwire specialist, I hope mdocod chimes in
I'm not sure if Li-Po is suitable for hotwire applications, but it may very wrell provide as a reliable power source:candle:

Re: Battery pack find with idea for a mod.

These are interesting but I don't know how to read the numbers. 5000mAh 3S1P 15C.
What does 3S1P mean? there are 1S,2S,3S,...
This one has three cells.
Do the big wires pick off the batteries in series? and if so what do the little ones do?

Re: Battery pack find with idea for a mod.

Mike Painter said:

These are interesting but I don't know how to read the numbers. 5000mAh 3S1P 15C.
What does 3S1P mean? there are 1S,2S,3S,...
This one has three cells.
Do the big wires pick off the batteries in series? and if so what do the little ones do?

Click to expand...

here's a quick rundown and an example

S=# of cells in serial.
P=# of groups of serial cells in parallel.
S x P = number of total cells in the pack.
S x 3.7= total pack voltage
mah= capacity.
C= discharge rating.
the smaller wires are the charging wires to each group of serial cells(used with balance chargers to keep all the cells charged to the same voltage...
helps prevent )

so for example your 5000mah 3S1P 15C lipo
we know there are 3x1=3 cells in the pack.
3 serial cells wired in a single parallel grouping.
capacity is 5000mah
max current discharge is 15C x 5000mah = 7500mah or 75amps!
voltage of the pack 3s x 3.7= 11.1v

a 2s is 7.2v
a 1s is 3.7v
4s=14.8v
etc


now say you have a pack 3s2p
theres 2 groups of 3 cells. 6 cells total.
each cell, in the group of 3, is wired in serial.
both Groups of 3 cells are wired to eachother in parallel.

using the above 3s2p...
say you are using 6 3.7v 1000mah 5C cells in a 3s2p configuration.
total voltage is 3s x 3.7= 11.1v
total capacity is 1000mah x 2p = 2000mah

discharge of this 2p pack is now 5C x 2000mah = 10,000mah or 10amps
where as a 1p of these cells would have been 5Cx1000mah= only 5amps

thats how you benefit from cells in parallel.. you get longer runtime-capacity and a higher discharge capability.

cells in series specify voltage.

i know thats a rough description..but i hope it helps.

Re: Battery pack find with idea for a mod.

Illum_the_nation said:

hmm...
12V 50W...I'm assuming your referring to something like a 64440 or some sort of a bipin halogen...under driven may yield a yellow beam, I'd suggest finding a 9V lamp thats more tolerant of overdrive but I dunno what to recommend :sigh:

Click to expand...

I want to use those bipin halogen spots, that are assembled with reflector. They give nice white light when installed in the house. The pack is pretty empty when at 11V so it should work fine. Ill post pictures when i have all parts here.

Illum_the_nation said:

12V 50W at 11.1V should draw 4.5amps, a cell with 2500mah capacity that would be ~2C, hmm..that would not be a issue with the pack at all...in fact you might be able to step it up to 100W

Click to expand...

I wouldnt use this particular pack over 3c discharge. There are other packs available that can handle even 200W, but they have smaller capacity and would give rediculous runtime.

Re: Battery pack find with idea for a mod.

MWClint said:

here's a quick rundown and an example

S=# of cells in serial.
P=# of groups of serial cells in parallel.
S x P = number of total cells in the pack.
S x 3.7= total pack voltage
mah= capacity.
C= discharge rating.
the smaller wires are the charging wires to each group of serial cells(used with balance chargers to keep all the cells charged to the same voltage...
helps prevent )

Click to expand...

Great. Thanks.

Re: Battery pack find with idea for a mod.

It worked:

Wire directly soldered to the contact plates in the switch. High amp connector, no crappy battery spring to drop the voltage. Used another battery pack for testing (12A max). Voltage only drops .5V under load. Reading about 50W of load.
On the other hand. The beam looks pretty crappy, since the filament i not centered. I think i have to buy more bulbs and pick the best one. Another thing is that it isnt that bright, compared to my quad SSC mag (~500lumen). Theoretically it should produce about 1200 lumen, but the difference might be in the color.

I have been told that i should use irc bulbs because they are more efficient and also to overdrive the bulb. Unfortunatly that would mean another battery pack. Also a soft start should be considered. Does anyone know a soft start electronic that wouldnt bust my budget? Would just winding the battery wire in sort of a coil do the trick?