Author Options:

deep cycle battery pack Answered

Does anybody know what parts I'd need to make a 12v rechargeable battery pack for an upcoming road trip? I also need to know where I can find deep cycle sealed lead acid batteries for this project.

I waited long enough to make a lithium ion pack, but now I changed my mind on the battery type to get 12v, and now I have no idea of what protections and electronic components I need for it.

I'l post more info on available casing later, but I'll tell you now that it's like a small blue lego briefcase from when I was little. It's about the size of a texbook and I'd like to be able to put it in a small backpack to carry around school sometimes for my windows tablet.

Update: I am available to buy any particular case, but wiring in a case can sometimes look bad, so I'd like it to store all wires internally and have a friendly look. Appearance was part of why I switched my plan from li-ion 18650s to lead acid. A block with printed volt and amp information looks better than a group of oddly sized cells. Also, no clocks.


If you're really serious about deep-cycle, you should look for Hawker Cyclon cells

Thanks, steve. I know you helped my with my initial idea.

How many do you think I should get? For the number, what level of amperage should I get on the charger?

Also, what kind of wiring will I need and will I need any circuits?

I looked them up and clicked through different dimensions to fit as many as I can. I found a regular lead acid battery here: http://www.amazon.com/volt-4-5-Rechargeable-Battery-Electronics/dp/B002QGVW3K/ref=pd_sim_p_4

Not counting circuits, which can still fit on top, I can fit 6 of those in my case, with room for ports. 3 batteries on each side in parallel, 2 cells in series.

I still need help with information on how to wire and charge the pack

Well the nice thing about Cyclon's is that the form allows you to put batteries into nicer packs than the slabby rectangular ones. What capacity do you WANT ?

I want to get 10 ah if I can. If I can't, I can drop down to 8. I need it to be portable, though, and that includes weight.

Where would I attach wires to the Cyclon's?

Here's the best deal I found:

I can fit 2 of these. What other parts besides the batteries and case will I need? Do I just wire it to charge and discharge ports? Which charger? What can I use to measure a % remaining power?

I now realize that lead acid is pretty heavy. What do you think?

Any 12V charger will handle them. They're going to weigh 6 pounds, not too bad in my view - and a lot cheaper than Lipo

Please, what wires and circuits will I need?

I need 12 volts, meaning I'm putting 2 cells in series. I'd be wiring a positive and negative together, and the other two to another part of the circuit. If I want to charge my tablet directly, I'd need 12V @ 3.3A. The car charger has no brick.

So you want to run the computer and charge the battery at the same time ? What's the maximum input that the computer can handle ?

Can I use this charger? http://www.atbatt.com/product/22714.asp#tabs

BTW, I can. If I need t't find the max input. If I need to maintain a constant 12V, is there a way to regulate it?

Does the charger itself provide all the necessary protection? Are there any fuel gauges available to determine how much of a charge is left?

Terminal volts on lead acids are a reasonable indication of capacity.

I don't want to charge them at the same time, that would just be a bonus.The tablet runs the same voltage as the battery. Now that I think about it, I should buy an extra charger for the tablet, cut the tip, strip the wire, and connect both the input and output to the same terminals. They wouldn't charge at the same time because it's the same i/o voltage and wattage.

What I really need to know now is whether I need protection or regulation circuitry in between like I'd need for lithium ion.

output of the charger connected to both the battery input and the discharge input.

That's at least 12 lbs of dead weight that you will be lugging around. May not sound like much but carrying a large bowling ball around all day is no fun.

average weight of a textbook is 3.5 pounds, and I carry 3 textbooks at any given time at school. 3*3.5 is 10.5. You're right, that's damn heavy.

Li ion is much lighter. If I use a voltage regulator and figure out how to wire it, can I keep it at 12V? that was the other reason I switched.

Here's my cost list:
Lead Acid -
Insulation tape: $5
Batteries: $50
Charger: $23
Fuel Gauge: $8
DC port: $5
TOTAL: $91

Li-ion -
Insulation tape: $5
Batteries: $80
Battery Holders: $23
PCB: $15
Charger: $26
Fuel Gauge: $8
DC port: $5
Wire terminals: $5
Balance Cords: $4
TOTAL: $171

What do you plan on running off the battery pack and for how long? Tablets usually use 5v off of usb power. Lead acid batteries can be found for motorcycles but they are heavy and kinda large.

I'm going to be using the samsung ativ 500t, which has a 40w charger, meaning much more power and higher voltage needed than usb.

ah, more of a portable power brick for a netbook/tablet device. I do imagine Windows 8 being a power hog.

Yes, but it definitely charges much faster than an ipad. I need this external power source mostly for road trips and campouts, but it will be kept in my school backpack for charging convenience until I can charge between classes next year in college.

My teachers will know what it is before I use it.