Hi

[Long unnecerery background story]
I just bought an msi gs30 laptop, which has the 2 major complaints about it being noice and batterylife. I thought I'd make a table for it in plywood, with a batterybank and a fan under the cpu. The plywood and fan I can handle, but I've never made a batterypack before, so I want to make sure I'm doing this right(don't wanna fry a 2k laptop, right?). What I've done is made some (unfinnished) designs for the laptopstand, but I know I can easaly fit 8x18650 batteries and some pcbs in there. I found some panasonic batteries, and some circuitboards on ebay, and made a schematic. I'd like any input you guys could give on this
[end]

What I found:

Voltage regulator:
http://www.ebay.com/itm/DC-DC-Verst...34?pt=LH_DefaultDomain_15&hash=item4ae6a4917e

BMS:
http://www.ebay.com/itm/4A-5A-PCB-B...324?pt=LH_DefaultDomain_0&hash=item3f4907ac7c

Batteries:
http://www.ebay.com/itm/Genuine-PAN...556?pt=LH_DefaultDomain_0&hash=item338f7c0c24

And here's picture of my circuit:

Any input is apreciated, but the only thing I can think of off the top of my head is: Do I need to limit the amp output somehow?

 

Do I need to limit the amp output somehow?

Nope, although a fuse wouldn't be a bad idea. The loads will take the current they need at the regulated voltages. You cannot control both voltage and current at the same time. Control one, the other follows.

 

okay, thanks. I was planning on makeing some hinges, and stick them in place with neodynome magnets. Good or bad idea(for both the batteries and the laptop) ?

 

Check to verify the magnets don't cause any screen distortion. I don't think that's much of a factor now that we don't use CRTs, but it's worth a quick look. I don't know of any other concern.

 

I was looking at the bms, and I saw this:

Does that means I should charge the entire thing with 4.25V, or that 4.25 is the ocercharge protection?

 

I read that as being what the BMS accomplishes for you - it's the voltage applied to the batteries under charge. It requires no action from you.

 

So I don't even need a regulator there, just straight from the charger to the bms? That would remove the low amp bottleneck on the regulator I guess, but 19V might be a bit harsh for something that small ~

 

Well, re-reading the specs I couldn't see anything about the required input voltage, so I guess it's still a question mark. It looks like it may be meant to take the power from a laptop's power adapter, which is typically 19-20V or so (and regulated). But that's just a guess. You need more info.

 

okay, thanks. I was planning on makeing some hinges, and stick them in place with neodynome magnets. Good or bad idea(for both the batteries and the laptop) ?

Aren't the magnets a threat to hard drives, or was that just old floppy disks? Are hard drives shielded against such things?

 

The platter in a hard drive is surrounded by an enclosure, and not nearly so vulnerable to a static magnetic field as to a modulated field. I wouldn't go crazy and tempt fate but there are plenty of magnets is use inside laptops.

 

The platter in a hard drive is surrounded by an enclosure, and not nearly so vulnerable to a static magnetic field as to a modulated field. I wouldn't go crazy and tempt fate but there are plenty of magnets is use inside laptops.

Good to know. Thanks for the clarification. Though, as you said,I won't go tempting the fates!