Battery Discharger, build it yourself, plans in Mo

[Not2Night]

Battery Discharger, build it yourself, plans in Model Aviation Oct. 2003

Along with RC cars, I also fly an electric RC airplane. As a member of the AMA (Academy of Model Aeronautics) I get their magazine. The October issue has a article on building your own battery discharger, by Bob Kopski, called the "Dump'r".

From the article: "Dump'r is a safe, one-size-fits-all Ni-Cd/NiMH battery discharger." ... "Dump'r is a relatively simple device that safely discharges four- to 18-cell ... Ni-Cd and ... NiMH batteries at a fixed 1/2 amp- rate." Included is a parts list and Bob's article describes how to build it. Most parts come from http://www.mouser.com and RadioShack. Bob says anyone with soldering experience can build it. Well, I have soldered leads to a battery, so I will give it a try. I figure parts will cost about $35.

Anyone else seen the article? I searched the web for a link to it. Best I could find is http://www.modelaircraft.org/mag/1003/toc.htm Which is only the cover page and incorrectly calls Dump'r a battery charger.

It will take awhile but when I am done I will let you all know how it went.

[DJTheo]

I think you can get a ready discharger from companies like LRP with auto shut off to prevent too high discharge & cell reversion for less then $35, except if you need it for more then 7 cells.

[trabbi daz]

I can vouch for wldnas' discharger, He made me one and it works great!! Keep your hi-tec dischargers just a b ulb and two bit's of wire for me[]

[DJTheo]

Just remember to disconnect them before they completely dim out, as otherwise you can get voltage reversion on some cells... Otherwise they work as good as expensive special ones, only those shut down automatically...

[madbad jezza]

surely the easiest and cheapest way to make a battery drain, would be to use an old motor?. if you wired in a battery connector on the motor, you could plug it straight up to the battery pack - hey presto, instant flat battery.

i,m no rocket engineer though.....

james.

[bleep]

madbazz i think that would only flattern the battery so much as the motor would need "x" amount of power to spin in.

The best and cheap solution is a bank of bulbs or as state above 1 bulb.

just out of interest what is this voltage reversion ?

[DJTheo]

quote:madbazz i think that would only flattern the battery so much as the motor would need "x" amount of power to spin in.

id="quote">id="quote">

No, a motor discharges even when it doesnt turn, actually its power consunption is max when it doesnt rotate, if you for example just help it a bit to start rotating with the empty battery, you will see the current fall...

quote:just out of interest what is this voltage reversion ?

id="quote">id="quote">

The phenomenon in battery packs consisting from cells which arent equally charged, when you discharge them too much, the cells with the less charge may reverse polarity.

[Not2Night]

I have yet to start building it, but winter is on its way. About cell reversal, (from the article) Dump'r automitically stops when the pack reaches the epuivalent of .9 volts per cell. Dump'r is fuse protected from cell reversal. Dump'r was designed for the Electrics enthusiast.

Building Dump'r should be part of the fun. Enjoy.

[raemin]

quote:Originally posted by Not2Night

Building Dump'r should be part of the fun. Enjoy.

---

id="quote">id="quote">

Easy, place in serie :

9 x 0.6v/6Amps diodes

1 x 3ohms resistor (with heat disipator and 50w capacity)

The idea is to roughly use 1.5 diodes per cell, so you could adjust the system to discharge 4.8v packs (6 diodes), and 9.6v radio packs (12 diodes).

Raoul

[raemin]

quote:Originally posted by Not2Night

Building Dump'r should be part of the fun. Enjoy.

---

id="quote">id="quote">

Easy, place in serie :

9 x 0.6v/6Amps diodes

1 x 3ohms resistor (with heat disipator and 50w capacity)

The idea is to roughly use 1.5 diodes per cell, so you could adjust the system to discharge 4.8v packs (6 diodes), and 9.6v radio packs (12 diodes).

Raoul