dischargers

[lji86 0]

me again, im a newbie so dont know much,

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does a discharger remove all power from a battery

lewis[]

[Razer 0]

It should not remove all charge from a battery. If it does, it can cause a cell to reverse polarity which ruins it.

I was thinking of making my own discharger because it seems simple enough, but I'm not sure how to make it stop when it reaches a certain voltage nor what that voltage should be.

So, does anyone know this & can help us?

[SJoerD 2]

Light bulb, 2 wires....

Wait till the light gets weaker (voltage drop) and you are done. Having fun in a car helps too discharging! Just do NEAR emptying as much as you can. If it is totally empty and seems dead, you did it too much. Shaking the battery helps sometimes when that happens... Really! []

No expensive electronics needed, back to the good ol' days when... oh well, you get the point already! [] LOL

[BiggusDitchus 38]

For my 4 cell packs I have a 1ohm resistor bolted to a large heatsink that should do trick.

[bholio 0]

I'm no expert, but this is what I've found so far.

If you have a normal 'stick pack' battery, then you need to be careful to not discharge too much (as mentioned above). I've heard that you should not go below .9v per cell. I've also heard that 1.1v is the correct number. Not sure. What I do is hook up my cheesy timer-charger, put it in discharge mode and jam the leads of an inexpensive voltmeter into the plug and watch the voltage fall. I disconnect the battery when it hits around 5.4v (6-cell).

Cell reversal can happen if you discharge an entire pack too much. The weakest cell in the pack becomes discharged so much, that it starts to be re-charged by the (not dead yet) adjacent cells and + becomes - in that cell. When this happens the pack is damaged and the bad cell must be replaced.

Now, if you have a more 'professional' (side by side) battery pack, there are dischargers which can discharge the cells further. If the cells in your pack run next to each other, and you have access to both ends of each cell, you can place that pack in a discharger which discharges each cell individually. This type of discharger can be a bank of 6 light bulbs, each is connected to an individual cell.

If you build your own discharger, there are voltage-cutoff devices which monitor the voltage and stop the discharge when a certain voltage is reached. Check tower.

Different pack styles: [==] --> A cell

Standard pack (stick pack):

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'professional pack' (side by side?)

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[SJoerD 2]

quote:Originally posted by bholio

Different pack styles: [==] --> A cell

Standard pack (stick pack):

[==][==][==]

[==][==][==]

'professional pack' (side by side?)

[==]

[==]

[==]

[==]

[==]

[==]

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In addition to this, I found out most 'racers'at my local track have seperate cells alligned in the car like this. They call it a 'saddle pack', please don't ask me why becasue I didn't invent that silly term! (saddle pack... to mount the body on??? [] LOL )

(front of the car)

[==] (space) [==]

[==] (space) [==]

[==] (space) [==]

(rear of the car)

This has more to to with weight balance than dischargers though... Anyone remembers these??? []

([.] = circular side of cell)

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[bholio 0]

Saddle packs are named that way because they resemble packs that you attach to a horse's saddle used to carry stuff way back when people used horses to get around. Each side of the pack hangs down the side of the horse to distribute the weight better.

My Losi XX4 has one. One advantage is it allows you to have a 4WD belt, chain or driveshaft low in the chassis of the car, and still keep the weight of the battery centered.

[SJoerD 2]

quote:Originally posted by bholio

Saddle packs are named that way because they resemble packs that you attach to a horse's saddle used to carry stuff way back when people used horses to get around. Each side of the pack hangs down the side of the horse to distribute the weight better.

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[] LOL []

I was wondering. It makes sense after all. Still sounds a little silly though. [] The advantages were clear to me though, it's all pretty obvious... [|)]

[raemin 0]

As far as NiCd batteries are concenred here is a link to a very nice french website :

http://www.ni-cd.net/

with a nice how to section for building a smart discharger (with auto shut off.

http://erfred.free.fr/accus/chargeur/dechargeur.zip

Should there be some demand I may proceed with the translation.

Raoul