Dry Box To Charging Box

by SlowPass | June 13, 2015 | (15) Posted in Projects

I wanted a good way to charge my LiPo batteries in the field without being dependant on my vehicle’s battery. After searching through RC forums for guidance I found that many people focused on getting the largest amount of charging capacity available per dollar. Coming out on top with that criteria were deep cycle marine batteries. The EverStart Maxx Deep Cycle 125 Ah battery costing ~$100.00 is a common recommendation for getting the most capacity/dollar.

 

I currently fly small foam airplanes and a mini quad so my ideal charging solution is not a large 60+ lbs (~27 kg) lead acid battery even if it is the most bang for my buck. I’m not going to haul around such a heavy battery given what I fly. After thinking about my average flying time and the typical batteries I needed to charge, I came up with the following requirements for my field charger:

  • Relatively small

  • Not extremely heavy or unwieldy to carry

  • Decent battery capacity so it can charge ~6 1400Mah LiPos before needing to be recharged

  • I can use it not only run my LiPo charger but also charge USB devices

  • I can easily see the source battery capacity and know when I’m getting close to 50% discharged and I need to recharge


With a little bit more research I found that for those wanting a lighter solution, car jump starters were recommended. Here are a few examples:

PowerAll PBJS1600R

ABN PowerAny 12000 mAh


These are definitely light and portable but I was not sure how well a lithium ion battery would hold up over time or if they were deep cycle batteries. Since I wasn’t very confident in these I decided to build my own charge box with a sealed lead acid battery that would have less capacity but would be lighter than the large marine batteries.


Finding the battery I wanted to use was pretty easy. For ~$37.00 at Amazon I found a 18Ah deep cycle sealed lead acid battery that weighs 12 lbs (5.4 kg)

Finding a box to put this battery in was a bit more difficult. After running around to a few stores, trying unsuccessfully to modify a Plano tackle box, and looking online, I finally found the Flambeau Outdoors Dry Box with the proper dimensions.


With the base requirements out of the way I picked up the other items I wanted:

Banana Plug Jacks

Battery Capacity LCD Indicator

Momentary Push Button Switch

Dual USB / Lighter Socket


With a bit of measuring cutting and gluing this is how it turned out:


Charging Box ~$40.00

18Ah Battery ~37.00


Parts List:

 

Edit: Multiple commentors have requested pictures of the wiring connections so I've included them below.

COMMENTS

FrankB on June 24, 2015
Very nice, I am gonna have to build one too I think after my next copter build.
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SlowPass on June 24, 2015
Thanks!
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llharper on June 24, 2015
Outstanding !!

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SlowPass on June 25, 2015
Thank you very much llharper!
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HilldaFlyer on June 15, 2015
Excellent Project, creative and very nicely done! I like the ease of use and portability. The battery you selected is an excellent choice. I have 8 of these hooked up in 4 pair (24 v system) in parallel and I'm able to charge all day long. They've been resourced from APC UPS. They'll last a long time.
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SlowPass on June 16, 2015
Thanks HilldaFlyer! I'm glad to hear this battery is a good choice.
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Bellows on June 14, 2015
Very Nicely Done!
I like it!. May build one myself.
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SlowPass on June 15, 2015
Thank you very much Bellow & SGRacer.
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Gsimpson2g on June 17, 2015
Very nice! I can see attaching some solar panels to it to help charge the battery :).
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SlowPass on June 17, 2015
Good idea. I'll have to check into getting a small panel and charge controller. Maybe even a small inverter if I want to get fancy.
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Dadman on June 24, 2015
I built a Charge Box out of 1/4 " ply. like a Field box. I used a Power Chair Batt, ( Gell-cell Deep cycle ) Cause I had 1. I like the Batt level meter , and the USP port (is it hooked up to the full 12 volts ? ) Let me know if you guys are ever in Northern California (not Cali. I'm no yuppie.) I belong to the Red Barons Model Flying Club. Marysville Calif. area. Would love to fly -w- you guys.
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SlowPass on June 24, 2015
Hi Dadman. The USB port does hook directly up to the 12 volt source and steps down the voltage to 5 volts.
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mb3987 on June 16, 2015
If you watch Harbor Freight you can get their 3 in 1 jump starter on sale for 39.99 -49.99. Depends if you are one of their club members. Also, coupons. The battery is a 12 V, 17 ah or 18 ah depending on the lot. It comes with a built in charger both 110 v and one you can charge from your car which I transfer over, a volt meter, 12 volt power port (cigarette Lighter) socket, and a light if you want to move that over. I keep one of their inverters in my box for a soldering iron and a glue gun.
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SlowPass on June 16, 2015
That is a sweet deal. Do you have a link to the HF jump starter? if it has some storage as well it might be better than this box I put together.
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SGRacer on June 15, 2015
This is great! I was looking at this same battery for a while, but this is a perfect solution! I'm going to save up and make this!
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SGRacer on June 15, 2015
Would you send a picture of the battery connections?
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SlowPass on June 15, 2015
I can send one later tonight. It isn't anything special and I left the connections pretty lengthy so I can take the battery out of the box easily without disconnecting all the plugs etc.
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gecko20 on June 25, 2015
would it be possible to get a picture of the connections too? Thank you
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SlowPass on June 25, 2015
Hi Gecko20. I forgot to send the pictures to SGRacer but I did go back and add them to the article so you can see my sloppy wiring. :)
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gecko20 on June 26, 2015
thank you very much for the pictures
in 2-3 weeks everything will arrive at my doorstep (I ordered the buttons and the battery indicators from China, in the European Amazon they are way to expensive) and I will try to build my battery box too :)
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Charley24 on November 12, 2015
I found a ready made box with one 12v port, battery life indicator, etc. on www.walmart.com for $34.00. They also have a double port for a little over $50.00. I bought the cheaper one, added a second cig lighter female port, and put a trolling motor battery in it. It was way to heavy, so I bought the battery shown here, put it in the box, and filled around it with expanding foam insulation. Worked perfectly. The battery will still come out if needed because the foam doesn't stick to the box or the battery for some reason.
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TexasPilot71 on July 16, 2015
I just built this box. The battery took 19 days shipping to Texas via Amazon. Gotta be a better source for battery. But it's a great box and looks good too!
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SlowPass on July 17, 2015
That's great! One addition I did have to make is to put a switch in line with the lighter socket / usb ports. Without switching it off it was slowly drawing power from the source battery even though devices where not plugged into the USB ports.
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Chefinator on July 27, 2015
Hey SlowPass,
thank you for your article. I must say very inspiring, even though I had something like this in mind for a while a.) for use with my camper, and b.) to use for rc flying.
I have ordered some parts already, but think I will be using 2 batteries in parallel rather ta=han one.
Question 1. How do you charge the batteries? trickle or car charger or your rc charger?
2. I can not figure out how many amps I can draw out of these batteries? there must be a max, not that I want to reach that anyways, but would be good to know. Where do I find information for that.
3. If I will be using it for my camper I would be considering a solar charger, any recommendations?

Keep up the good work, all the best. Fly high land soft!
Chef
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SlowPass on July 27, 2015
Hi Chef,

Thanks for the comment and questions!
1) I normally just hook the box up to my Accucell 6 every now and again to charge it up.
2) The specs on the UB12180 are available at https://www.1000bulbs.com/pdf/ubD5745-spec.pdf It has a discharge chart that shows amp draw.
3) I haven't pulled the trigger on a solar charger but I think a decent 30Amp 12/24 volt charge controller and a decent sized solar panel will keep it topped off nicely. Something like this starter kit: http://www.amazon.com/Renogy-KIT-STARTER-100D-FBA-Mono-Starter-Kit/dp/B00BFCNFRM/ref=sr_1_1?ie=UTF8&qid=1438049208&sr=8-1&keywords=solar+panel

Let me now when you get it done especially the solar solution if you go that route. Thanks!
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Dry Box To Charging Box