Li-ion Battery Problem

[J Cameron]

Hi Guys I need some help please,

I bought 4 Li-ion battery packs, 12v, 4800mAh each. I then connected these in parallel to give me a 12v, 19.2 AH battery pack for my 50w halogen torch.

As soon as I try to turn the light on, each of the battery packs trip (they come with an on/off switch and LED power light)

The batteries work when I use a low wattage bulb but trip with anything above 10W power.

Anyone got a solution to how I can get these batteries to power my torch ?. Each battery pack has a very small circuit board attached to it which I suspect is limiting the drawdown current.

thanks.

 

[DM51]

Welcome to CPF, J Cameron

As this is purely a battery issue, I'll move your question to the Batteries section.

 

[alpg88]

you need soft start, there are few ways,
inrush current limiter, mosfet, and inductor and a diode.
use search box here and you'll find pbly dozens of threads on how to make a soft start.

 

[Battery Guy]

Each battery pack has a very small circuit board attached to it which I suspect is limiting the drawdown current.

I suspect that you are correct, but your current requirements on each pack are pretty modest at ~1 amp (I get the 1 amp value by taking 50W/12V=4.1 amps for the 4 batteries in parallel).

Where did you buy these battery packs? Can you provide more information, including manufacturer and model number of the pack?

Cheers,
BG

 

[J Cameron]

The batteries were purchased from ebay, Hong Kong site but I think they came direct from China.

Details:
Super Rechargeable Li-ion Battery
12.6 VDC input
12.0 VDC output 4800mAh
Model: T-12480.

Thats all the information I have on these.

cheers

 

[Battery Guy]

The batteries were purchased from ebay, Hong Kong site but I think they came direct from China.

Details:
Super Rechargeable Li-ion Battery
12.6 VDC input
12.0 VDC output 4800mAh
Model: T-12480.

Thats all the information I have on these.

cheers

Is this it?

 

[mdocod]

If it is those packs, then they likely used a protection circuit with a very low tripping point since the pack is intended for use in a low drain device.


There may not be any way to use the packs to drive your bulb unless you upgrade the protection circuit.

I don't see any balance taps... wonder if the charge control is part of the global protection or something.... odd.

Eric

 

[Mr Happy]

It looks like the charge balancing and charge control would be internal to the battery, using the pictured wall wart charger...?

As others have said the batteries don't look like they are intended for high power applications.

 

[J Cameron]

Hi Guys, Yes thats the LI-ion battery packs that I have as shown by "Battery Guy".

I'll have a look around for protection circuits and see if I could replace the existing circuit.

 

[alpg88]

I'll have a look around for protection circuits and see if I could replace the existing circuit.

bad idea :shakehead

 

[Battery Guy]

bad idea :shakehead

I think I have to agree.

I am having a difficult time figuring out what cells would be in this pack. The pack dimensions are 60mm x 80mm (thickness isn't specified). I had initially thought that each of these packs probably has 6 18650 lithium-ion cells in a 3S/2P (3 series 2 parallel) arrangement, but the dimensions are wrong. It might contain 3 26600 cells. In that case, running four of these packs together in parallel is a total of 12 26600 cells. Any way you arrange it, 12 cells is the minimum, and you will have a >70 Wh pack. That is A LOT of lithium-ion cells, and I think that even the most experienced hobbyists would be very leery of assembling and using such a pack. This is especially true since you really have no idea if these are high or low quality lithium-ion cells. Actually, considering the origins of this pack, I can pretty much guarantee that the cells are not made by well established, top tier lithium-ion cell manufacturers.

To put it simply, this sounds like a very, very scary endeavor.

My recommendation is to punt on this particular design and look for alternative options. Personally, I would not even consider building a pack this big without using very high quality lithium-ion cells.

One possibility you might consider is going with four NiMH packs in parallel, with each pack containing 10 sub-C Elite 5Ah cells in series. This would get you your 12V 20Ah you are looking for. This is just an example off the top of my head, and there are probably better cell sizes and options. I am sure that some people on this forum could give you tips on making large battery packs.

J Cameron: I am sorry that I have not been very helpful in answering your original question. However, given the current information, I think that using these packs for this application is too risky.

Cheers,
BG

 

[Robert UK]

I have just purchased the same battery detailed above to power a 2 or 3 led bike light inline with bikeled.org design (aluminium tubes) using cree XPE's and buckpunk 3023 with potentiometer.

Being a newby and looking for a 'project' I'd be grateful for some advise:

1. whether this will power a 2 or 3 unit light?
2. Is this a safe Li-ion when used with the charger supplied?
3. Is this a safe Li-ion when used with 2/3 unit cree configeration?

The other half may take offence if I burn the house down using a cheap battery/charger to save a few pounds.

Battery is DC 12V 4800mAh Super Rechargeable Lithium-ion Battery from depotzz on ebay

Any thoughts would be gratefully received.

 

[MikeAusC]

The current for a cold Halogen lamp is usually TEN TIMES its rated current - so 40 amps for a 50 watt lamp, until the filament heats up.

An FET constant-current drive is your best bet - or change to LEDS !!!!