Plans for the Battery Pack

[pmhendry]

Hello All. I was wondering if someone would be able to put together a list of parts/plans for the battery pack from episode 1. I want to have a supplemental battery for my laptop and cannot afford an a second Li-Ion battery. Im hoping that this works. Thanks

[hillwog]

First you need a battery (http://www.batteries.com/productprofile.asp?appid=265094)
Then you need a charger (http://www.amazon.com/Battery-Tender-Junior-Volt-Charger/dp/B0000C7FJ7)
After that you need a connector (http://www.radioshack.com/product/index.jsp?parentPage=search&pg=1&summary=summary&cp=&accessories=accessories&productId=2062272&kw=12v+accessory+adapter&techSpecs=techSpecs&currentTab=techSpecs&custRatings=custRatings&searchSort=TRUE&features=features&sr=1&y=10&retainProdsInSession=1&origkw=12v+accessory+adapter&support=support&s=A-StorePrice-RSK&x=10&tab=summary)

These are just examples shop around.
The outlet usually has instructions with it. The Radio Shack one is easy connect the red wire to the red terminal and the black to the black. You should use a lower amp fuse based on the draw of your device.

The higher the Amp Hour rating the more the battery can handle and the longer it will last, but the heavier it will be.
AMP-HOUR RATING. This is a unit of measurement for battery capacity, obtained by multiplying a current flow in amperes by the time in hours of discharge. (Example: A battery which delivers 5 amperes for 20 hours or 20 amps for 5 hours, = 100 ampere-hours.) The faster you drain it the harder it is on the battery and the shorter the overall life.

Hopefully this helps. I am not real good a explaining things.

[scienceking]

Yeah, but that works only if you have a charger for your device that runs off 12VDC, like a car charger. Otherwise, you will need to throw in a voltage regulator to take the 12 VDC down to the voltage your device uses, and thats assuming your device doesn't use too much power. The best example would be putting a 7805 between the battery and a F-type USB connector to make it a nifty usb power source for changing. Just make sure you throw a switch on the line coming out of the battery into the 7805, or it will slowly discharge even when you aren't using the charger. Sometimes your device will have a voltage regulator built-into it and the wall wart that came with it will not give out a regulated DC voltage. In that case, so long as the regulator in your device can handle a 12 V input(probably if it is lower than that), you CAN just run the battery voltage into it through the connector.

[hillwog]

Yeah, but that works only if you have a charger for your device that runs off 12VDC, like a car charger.

Valid point if you do not have the proper 12 volt power adapter or know how to make one you should not use this set up. The wrong adapter or battery set up could damage your device, like when my son thought any adapter would do and burned out his portable cd player that needed 6 volts not 12. :eek:

A little bit of knowledge can be dangerous use caution and do your research. That said I have fried my share of components in the learning process. :rolleyes: Watching the smoke roll out of a device and then figuring out why will make more of an impression on you than just reading it in a book. taking a chance can be good if you are willing to pay the price if it fails.

[KKL]

Another way to resolve that is, just have the lighter plug connect to the seal lead acid, to feed out 12 volt.
If you have car adapter for the device, use it,
otherwise use a power inverter that you can get from hardware store.
Make sure you leave place for inverter air flow (since most of them have a fan)

also, a good idea/practice is throw in a fuse on the battery line. The lighter plug socket is BIG, if you drop a quarter/penny inside, it might short the battery...
those thing heat up alot due to the short circuit current is REALLY high (or internal resistance is small).

[KKL]

The best example would be putting a 7805 between the battery and a F-type USB connector to make it a nifty usb power source for changing. Just make sure you throw a switch on the line coming out of the battery into the 7805, or it will slowly discharge even when you aren't using the charger.

That indeed probably one of the simplest way to get 5V out of 12V, and by far the most stable too.
but when you do that, make sure you check how hot the 7805 get before stuffing it in to the bag (just by quickly touch it / smell it / feel it by letting it run for a bit with your device connected). 7805 is not a switching device, it basically "consume" the extra power when it bring 12 down to 5. Meaning, if your device draw 150mA @5V, it will still consume roughly 150mA at 12V with the 7805 inline.
the extra power will dissipates as heat. so for the sake of an example, 150mA * (12-5V) = 1.05W. It is some countable heat on a tiny package like the TO-220. and last thing you want is the regulator melt the nylon bag and fell out...

just my 2 cents...

Cheers

[scienceking]

That indeed probably one of the simplest way to get 5V out of 12V, and by far the most stable too.
but when you do that, make sure you check how hot the 7805 get before stuffing it in to the bag (just by quickly touch it / smell it / feel it by letting it run for a bit with your device connected). 7805 is not a switching device, it basically "consume" the extra power when it bring 12 down to 5. Meaning, if your device draw 150mA @5V, it will still consume roughly 150mA at 12V with the 7805 inline.
the extra power will dissipates as heat. so for the sake of an example, 150mA * (12-5V) = 1.05W. It is some countable heat on a tiny package like the TO-220. and last thing you want is the regulator melt the nylon bag and fell out...

just my 2 cents...

Cheers

You should use the little heatsink that came with your bundle of 7805s. Better yet, put your little PSU unit in a small aluminum project box or altoids tin and use some thermal glue to glue the metal part of the 7805 to the case, making it a big heatsink. The 7805 will not overheat this way unless the inside of the bag is getting pretty hot from an external source of heat.

[l33twire]

This battery is going to be great with my ideas on my forums at l33twire.com ^^

[Lobelto]

I found these links to DIY mobile power packs, which one would you guys consider best and would you change anything? I like the first link, is it missing an inline fuse?

http://forums.dpreview.com/forums/read.asp?forum=1025&message=22855258

http://www.kr1st.com/powerpack.htm

[awbgeek10]

Does anybody know the brand of the bag that Patrick used or a store where they are sold?

[hillwog]

Does anybody know the brand of the bag that Patrick used or a store where they are sold?

The pack is made by maxpedition (http://www.maxpedition.com/). I believe it is one of the Versipacks
(http://www.maxpedition.com/store/pc/viewCategories.asp?idCategory=4)