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Old 11-07-2006, 03:04 AM   #1
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As the title says
Just wanted to ask why do you decharge your battarys wouldnt running your car tilll its dead do the same

Forgive ,e if its a stupid question but im new to electric cars
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Old 11-07-2006, 03:30 AM   #2
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first of all, its not called decharging, its called discharging.

each RC battery cell is 1.2v and most 6 cells packs r thus 7.2v. most people use a discharger or discharge tray and discharge to 5.4v which is equal to each battery cell being 0.9v. running the battery in the car til the batt goes dead isnt good since you can still drive and drain the battery below 5.4v which isnt good. basically drive the car until it gets fairly slow then u recharge it.
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Old 11-07-2006, 03:48 AM   #3
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thanks mate
ive seen the bulb trays that are used is it poss it made somthing like thus instead of buying one or are they cheap to start with
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Old 11-07-2006, 05:42 AM   #4
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first of all are you racing or just bashing? if you race do you have SxS packs? SxS packs are where the cells are next to each other and held together by tabs made of silver which go from + to - to + to -, etc. they are made of 6 cells. or do you run packs which are long and have 6 cells but are in 2 columns of 3? like this:

IIIIII (SxS pack) or II (stick pack)
II
II

u can only use discharge trays on SxS packs. if you do use SxS packs a novak smart tray will be good for equalising ur packs and discharging them or if you race stick packs just get a car globe and put it onto the male type plug that you run in your car, such as a tamiya plug, and then plug it into the battery and when the light goes fairly dim the pack is discharged. or get a proper discharger. if racing SxS are better since there is less resistance meaning more power and voltage so that you go fast and longer.

just ask sum1 at ur LHS or local race track
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Old 11-07-2006, 05:48 AM   #5
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Is it a bad thing to discharge to 0 and quickly charging it afterwards? Does it still need to rest if it's discharged at 1 amp?
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Old 11-07-2006, 08:23 AM   #6
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Quote:
Originally Posted by MK_Arbiter
Is it a bad thing to discharge to 0 and quickly charging it afterwards? Does it still need to rest if it's discharged at 1 amp?
Most current cells do not like to be dead-shorted (discharged to 0 volts) ... dropping voltage down to 0.9 volts per cell is the safest method to get ideal performance out of the cells. Some more experienced racers are doing something different - however, these racers are also buying new batteries more often as well.

As for resting after being discharged at 1 amp, it depends on the battery temp. Basically, you want the batteries to be at room temperature before you charge them up. If they come off the discharger hot, let them cool and then charge them up ... at 1 amp, the temp of the battery should be pretty cool after discharge.
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Old 11-07-2006, 10:46 AM   #7
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Hi Guys

The ones ill be using are the ones that are packed in a plastic sleve. the ones that have two side by side and 3 down.
If you get what i mean As i dont now which ones these are called
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Old 11-07-2006, 10:58 AM   #8
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yes what you have are generally refered to as "stick" packs or "shotgun" packs. The bulb discahrger mentioned earlier is fine for these packs. just plug it up, wait till the lights get dim, take it off, let the pack cool off, then your ready to go again. Sorry, not sure on how to make one, but i do know that racers edge sells them for about $20.
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Old 11-07-2006, 12:05 PM   #9
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Since the cells are wired in series and you are discharging them in series, you can only measure the series voltage of the 6 cells, and not really know what individual cells are being discharged to. All six cells don't fade equally. If you run them too low in series, you run the risk that a cell is now zero and is being reversed in voltage as a result of the current being pushed through it by the other cells. Reversing polarity on the discharged cell is distructive, and it is the reason you don't want to run the stick pack down to zero by either running it in your car till it stops, or hooking it to lights and running it down completely. You can either monitor the voltage with a digital multimeter and stop at 5.4 volts, or buy a discharger that has a cut off. Packs that are side by side and have the ends exposed are better because you can put them on a discharge tray that monitors and discharges each cell individually to the voltage you sellect (0-0.9 volts). That ensures equalization and no reverse polarity.

Do yourself a favor and buy a charger that will charge by delta peak and discharge packs at up to 20 amps down to 5.4 volts. If ur on a budget, there is lots of yesterdays technology available for cheap, such as a Reedy Quasar Pro that might sell used for as little as $50.00.
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Old 11-07-2006, 02:56 PM   #10
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How would I know when to unplug the battery with this discharger?
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Old 11-07-2006, 03:21 PM   #11
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for the stick packs you might want to look at the
Integy Reactor 20
Integy Reactor 30

Or as suggested Bulb Discharger but you should also use some sort of voltage cutoff device. In the end it'd probably cheaper and more reliable to buy the Integy Reactor.
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Old 11-08-2006, 01:50 AM   #12
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Thanks for the info guys
what are the standard chargers that come with the kits like are they any good for charging the higher spec battarys
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Old 11-08-2006, 05:35 PM   #13
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Quote:
Originally Posted by gazf
Thanks for the info guys
what are the standard chargers that come with the kits like are they any good for charging the higher spec battarys
Usually not. You'll need a decent charger for those expensive battery packs.
But seriously, if you are new to the racing scene, buy some sport packs and practice/race with those believe me they be more than enough. Don't get caught up in the gotta have the best to race it will get very expensive very quick. Most new people leave because of this reason.
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Old 11-09-2006, 04:26 AM   #14
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Quote:
Originally Posted by minicooper
for the stick packs you might want to look at the
Integy Reactor 20
Integy Reactor 30

Or as suggested Bulb Discharger but you should also use some sort of voltage cutoff device. In the end it'd probably cheaper and more reliable to buy the Integy Reactor.
i am not so techie and adventurous...so the bulb discharger is probably out of question altho' some bashers have made their own...not too sure whether there is any voltage cut-off built in...perhaps the only reliable way is to disconnect the packs once the bulbs are off...

coming back to stick pack, i do have a spintec battery manager version 1...but it is taking me donkey minutes for my IB3800 pack to be conditioned/discharged...you reckon the integy reactor 20 with spintec BM will do justice for my stick packs? in other words (correct me if i m wrong):-

i. discharge/condition using BM;
ii. charge the battery;
iii. after run, immediately discharge using Reactor 20;
iv. condition using BM.

by the way, i am running stock motor (23 turn). does the reactor 20 has a build in auto voltage cut-off?

assistance very much appreciated,
Regards
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Old 11-09-2006, 04:39 AM   #15
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another noob question...

is there a real benefit to discharging at a high amp rating? i just recently let go of my CTX-D with has a 30A pulse discharge... i'm now stuck with the 10A max discharge from the Cell Master. I can still equalize the batteries before charging with my Rayspeed though.
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