PCB for Battery Pack

trimixdiver

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Hi all I will have this Battery Pack arriving soon , looking for a PCB and a charger , need help
Need links please...

473910409_tp.jpg


It's a Sanys 18650 Li-ion Battery pack 14.8V 5200mAH 4S2P


Tony
 
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jspeybro

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where are you located? if in the US, you can find several PCB's at batteryspace.com etc. If not in the US, skip this site unless you are ready to pay ridiculous shipping costs.
You can however use their website to get started since they provide quite some information. just look at the 14.8V (4S) versions.

Johan
 

350xfire

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If you are going to power the XML lighthead you purchased from me with that pack, you will burn it up. The driver in the lighthead is designed for a max 7.4 volts!
 

Klem

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Capacity and voltage are two different things. 'Longer burn time' in your case relates to capacity, whereas the number of cells connected in series gives you voltage.

The drop-in head you want to use only works within a range of 2.6-8.4Volts, which is exactly the range of a two-cell. It's no coincidence and fair to assume to designers had a two-cells in mind as the optimum battery configuration.

Any higher than 8.4V and you will damage it. Your 4-cell battery is way too high for it. If you want longer burn time then get a bigger battery with more Amp hours (Ah), but whatever you get must be two-cells.

The average voltage of a two-cell is about 7.2V, so you want 'two-cell' or '7.2V' batteries.

You could break up the one in the photo and re-build it into a two-cell. It would be 7.2V and about 10Ah. The drop-in chews about 16Watts so that would give you about 4.5 hours of burn time.

Or you could buy a two-cell battery with built-in PCB.
 

jspeybro

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What Klem means is not a 2 cell pack, but a 2-cells-in-series-and-4-cells-in-parallel setup using the cellls in the original post to build a 2S4P pack instead of a 4S2P pack as shown in the picture.
That way you'll have the right voltage and more capacity.

I don't know exaclty which setup you have, but suppose you have an XML driven at 3A. If you use 2500mAh cells and a 2S4P batterypack, you'll have 74Wh (7.4V*2500mAh*4) in your batterypack. The XML at 3A has a Vf of 3.35V. multiplying that with the current gives us about 10W that the LED is using. suppose about 85% efficiency of the driver, you'll draw about 12W from the battery. Doing that continuously, you'll end up with a burn time of about 74Wh/12W=±6h.
Is that something that sounds reasonable to you? Then go for a 2S4P pack instead of a 4S2P pack.
If you still need a PCB for such a pack, get one for 2 cells instead of 1 for 4 cells.

Johan
 

jspeybro

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[copy from my private message]
Hi,

Yes, I noticed it is getting a bit confusing with all people telling different but actually the same things.
I'll try to make it clear.

In the initial picture that you showed, I see 8 cells on a table in 2 rows, but from the picture, it seems that they are not yet connected to eachoter. Is this correct?

Since you are getting the light from 350xfire, you should follow his advice. Many of the dealextreme or kaidomain LED drivers are designed to be used with 2 li-ion cells in series or 8.4V maximum. If you supply more voltage to the LED driver, you will likely destroy it because usually the capacitors are only rated up to a certain voltage.
That is why everyone keeps telling you to use a 2 cell or 2S4P batterypack. They do not mean that you should use a protection circuit for 2 cells on a 4 cells battery pack, but that you actually make a 2 cell (series) with 4 cells in parallel battery pack with a 2cell protection circuit.

Once the voltage (and number of cells) is right for the driver, you can play with burn time by putting 2 additional cells in parallel with the batterypack. The voltage will stay the same, but the capacity will add up (e.g. a 2500mAh cell in parallel with a 2500mAh cell will result in a 5000mAh batterypack which will double the capacity of a single cell battery pack and will double the burn-time of your light.

Now, for your specific configuration, you'll want to connect your cells like this:
2s4p-lipo-battery-packs.jpg


Now you have your 2S4P batterypack. For the protection circuit, you'll need a circuit that is designed for a 2S setup, like this one:
http://www.ebay.com/itm/Protection-...326?pt=LH_DefaultDomain_0&hash=item4ab86786a6
or this one: http://www.ebay.com/itm/Protection-...862?pt=LH_DefaultDomain_0&hash=item336ac821de

To connect this board to the pack, you'll need to make a slight modification to the conntections in the above picture. the connection between each 2 cells in series, should also be connected to eachother between the different strings, like in this picture which is an example of a 2S3P pack:
attachment.php


Where it says balance tap, you should connect your protection circuit and, if your charger supports it, a balancing connector to connect to your charger. You can leave out the balancing connector for now if you're unsure about that, it is there to keep the voltage of each cell the same.

Hope this helps.

Johan
 

Klem

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350xfire

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Snce this is a battery related comment and I wanted to put it in the dive light section, I will tack it on to this thread. I recently ordered the Sanyo batteries from Kaidomain (DX also has them). They are rated at 2600mah. I ordered 16 and selected 4 randomly for testing. The first was ran at 1 amp and yielded over 2.4ah. The second was a 2 amp test and yielded 2.48ah. The third cell is being run at 3 amps and is currently on the tester. I have to say for the few extra dollars I am impressed with the Sanyos. I will be switching over to these from now on.

I was usung the DX green unprotected cells rated at 2500 mah and getting about 2200 mah. They seem to really take a loss when run at higher amps. Those are just a few dollars cheaper. So I'm switching to Sanyos from now on...
 
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