fozjared

tonight i was at wal mart and had this mini epiphany, i have been looking to buy a new rx battery so i can keep my plane in the air all day! i thought to myself, self, make your own battery.. so i found myself in the battery section in electronics and picked up some nimh 2650mah 1.2 volt AA duracells so i bought them.. (4 of course) i have a soldering iron, solder etc. just not exactly sure how to get started.. do i strip a wire bare the length of the four batteries for the positive and negative sides? where does the third wire come in? i know for servos it is a signal wire (the orange one since i fly spektrum dx-7) and the red and brown are hot and ground.. so do i take the red (i have a spare extension i can cut one side off of) and strip it for the length of the 4 batteries, then solder the wire to each individual pos. terminal of the four batteries and do the same to the ground and just not use the orange signal wire? when i am done doing this will i have a 4.8v 2650mah rx battery that i can charge with the wall charger that came with the spektrum system? also can i just wrap the four batteries really well with electric tape from top to bottom or do they need ventilation considering they shouldnt be used too hard as a rx battery.. 2650mah will most likely keep me in the air with consecutive flight refuel flight refuel flight time of maybe 1.5 hours? sorry i am so full of questions, thanks for the help in advance.. also are the duracell nimh batteries i bought worth fooling with? will a 30watt soldering iron do the job if i solder directly to the positive terminal will i most likely mess up the little nylon seal, or can i just drip the solder onto the wire/battery top? thanks again.

mrasmm

you'll probably get plenty of this, but you might be putting your plane at risk with those duracell packs. Like red has stated many times, it's not in duracell's or energizers interest to make a good rechargable battery, so the bid always goes out to whoever will do the packs for the least amount of money.

With that said, you wire them in series, making sure not to heat them very much and melt the nylon vent cap (which is approeaching difficult to impossible), and then the negative goes to the black or brown wire, and the positive goes to the middle wire that is usually red.

sounds like you know what you are doing though because you've already mentioned several of these things. There is no 3rd wire on receiver packs, just the two wires. You're right servo's do have 3 wires and the lightest colored one is usually the signal, like you already said.

your pack would look something like this

pos lead-----+=============-
|
-=============+
|
+=============-
|
neg lead-----=============+



lol, well that didn't work, it deleted all the spaces I put in

fozjared

so it is negative positive neg. pos. orientation not straight across pos terminals and straight across negative terminals huh? boy i had that wrong.. so as far as wrapping them in electric tape when i am done soldering them together anything wrong with that or do they need venting of some kind?

mrasmm

with a receiver pack they wont need much venting because it's usually only like a 500mA draw or something, but venting wont hurt as long as something doesn't get in there and short something out or whatever. Usually these kinds of packs are totally encosed in heatshrink. Electrical tape will probably work just fine, you just have to be aware that it is thicker so it will add more weight and will also hold in the heat more.

yeah, sounds like my pic worked =)

Good luck =)

you can also check out www.rcbatteryclinic.com and look at red's info (which will pretty much tell you that it's not worth it to do it, it does give many why's, and will give some things to watch out for incase you want to do it anyways).

Khatsalano

Why doesn't a manufacturer just make Lipos for us where we can select what connectors we want, and BOOM, the Fedex guy brings it to your door with no soldering. : )

- K

fozjared

mrasmm so in your drawing, would it be beneficial to set the batteries like you have shown in reverse order (pos neg pos neg) and run a wire all the way across all four batteries top and bottom, sure would be easier but would it work fine or better? let me try your diagram to help show what i mean..
and just run the wires off of the end to the rx as shown here.. thanks!

ok the diagram didnt work for me it wont display it, hopefully you can understand what i mean though.. just stack the batteries like you showed me and run a red wire down one side and a black down the other and where the black ends make that join to the neg. and where the pos ends on the last battery's pos. terminal make that go to pos on the rx.

Capt Lou

foz:

My experience with making your own flight packs is that it is not worth the money you think you are saving. To properly solder the connections, you have issues including overheating the battery and causing its seal to open, whether or not you accomplished a good solder connection, and most of all you are never certain that you did it correctly. I'd rather leave it upto the battery manufacturers' expertise and testing and buy a pack for peace of mind. There are guys on this forum that I am sure have done this successfully, but I'm not one of them and most people who I know who attempted this regret wasting their money.

Jazzy

fozjared,

The batteries must be wired in series (+ to -) such that the result is one unconnected pos end and one unconnected neg end. Sort of how batteries are put into a flashlight except side-by-side. In the side-by-side arrangement, since the battery ends are not making contact, a small wire or piece of conducting material is used to bridge the gap or connect the ends.
Play with the flashlight arrangement in your mind and on a piece of paper. It will get you on the right track.

I have made quite a few different battery packs out of loose cells without any problems. It can be tricky at first but you'll get the hang of it.

Use the search function here on RCU to find other information on how to make your own packs.

I've been planning on doing a step-by-step tutorial on how I solder my packs together. I'll try to get it posted soon.

BTW, electrical tape works ok at first but the end invariably peals up. Other possible things to use are: box tape (a wide roll of clear cellophane tape) and old covering material from the scrap box.

JNorton

My Feedback: (2)

Fozjared
I have been an electronic hobbyist since I was 12. I've been soldering since that time too. I do not believe it is worth the risk in soldering my own packs. I much prefer to buy welded packs from vendors like No BS Batteries. I cannot believe that saving $10.00 is worth your plane, but to each their own.

It sounds as if this is your first effort. Sometimes pictures help. This is a pretty good tutorial. http://www.yourzagi.com/battery.htm

John

fozjared

jnorton, super tutorial! thanks for that, you know as paranoid as i get sometimes, i think i can spare a couple extra dollars for a factory made battery.. thanks for everything guys!!

mrasmm

I didn't really get what you were saying, but it sounds like you've got it all figured out now =)

good luck!