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Old 01-15-2008, 01:40 AM   #1
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Default help - charge / discharge / equalise

up until now i have been charging and discharging my 4200 stick packs on my ice charger.

i have now bought some matched side by side 4200 packs. i have just bought a novak smart tray to equalise the batteries,

my question is,

if i use a pack for a 5 minute run and its still got plenty of mah left in it, but i want to discharge and recharge it for another run, can i discarge it from that point on the novak smart tray to bring each cell to 0.9V or do ihave discharge it on my ice charger first,

but i am worried by doing that it will pottentially discharge the cells below 0.9V.
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Old 01-15-2008, 06:26 AM   #2
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After a 5 minute run a 4200-even with a mod motor will still have a good 1500-2500 mah left in it, depending on the driver and track and gearing. It would take forever to discharge to 0.9v on the Smart Tray. Set your ice discharge to cutoff at 0.9v, then tray the cells. The Smart Tray will still be discharging for a good 10-12 minutes. If you are worried you shouldn't be, once you set the Smart Tray to 0.9v/cell it absolutely won't discharge below that, so you will not hurt your cells.
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Old 01-15-2008, 08:26 AM   #3
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The ICE will discharge so fast the pack will hit .9V/Cell or 5.4V before you hurt the cells. They will recover to a higher resting voltage quickly. The Smart tray only discharges at 2.7amps so it willl take a while longer. The lower discharge rate allows for a more accurate cutoff.

With the new NiMh pack it is recommended to discharge and equailaize BEFORE you charge the pack. Always store the batteries with some charge on them. For most people that race on at least a monthly basis the charge left in the pack after a 5-7 min run is more then enough to keep the pack fresh. If you plan to not run the batteries for longer (winter shut down or going on Vac etc.) put a full charge on the pack for storage.

If you are going to run the pack for a second time in the day and do not want to discharge and equilize it is fine to just recharge the pack. Just make sure it has cooled back down to room temp. I would make a point of discharging and equilizing each pack at least once per day of racing though.
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Old 01-15-2008, 09:52 AM   #4
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Quote:
Originally Posted by Casper View Post
If you are going to run the pack for a second time in the day and do not want to discharge and equilize it is fine to just recharge the pack. Just make sure it has cooled back down to room temp. I would make a point of discharging and equilizing each pack at least once per day of racing though.
Casper is right, you dont have to discharge it after you have run it already., tray it, let cool for 1+ hours then recharge. Todays cells do not like heat buildup as much as possible.

Here is my charging/storing/traying process... I run 2 packs per class. I have Pulsar 2's for chargers, a DPD for my 30 amp pulse discharge rate, and I either use the DPD traying function or my smart tray. Running EP4600 cells, charge at 7 amps, delta peak set at 20-30mV depending on ambient temp where you are racing at. or adjust it to cutoff around 120 degrees. Run the pack in the race, If I have to use the pack again in a shorter amount of time, ill elt it kool after the race, then recharge it back up, but if i have a long time again, I will 30 amp pulse discharge and tray it, let kool and run it for the race.

Storage, leave whatever you have left in there from your race. 1+ month storage, fully charge

*People that posted for forgetting something. The Ice only discharges at 10 amps i believe. In order to keep you pack performing great, you need to discharge at a higher rate, like 20-30 amps, then hit the smart tray to .9 after that. I have been using the DPD 30 amp pulse discharge then using the 5 amp linear tray mode on it after.
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Old 01-15-2008, 10:10 AM   #5
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higher discharge does nothing but save time and build heat.

10amp discharge on the ice is plenty to maintain the packs.
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Old 01-15-2008, 10:27 AM   #6
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Quote:
Originally Posted by Casper View Post
higher discharge does nothing but save time and build heat.

10amp discharge on the ice is plenty to maintain the packs.

Yep...


I am so glad lipo is legal at my track now I hate this ritual, Just waiting on the weights so i can use them.
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Old 01-15-2008, 10:32 AM   #7
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Just make sure you have your voltage cutoff set on your speedo so you do not over discharge your new lipo. It is easier to kill a lipo from over charge and discharge then it is NiMh.
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Old 01-15-2008, 10:49 AM   #8
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Quote:
Originally Posted by Casper View Post
Just make sure you have your voltage cutoff set on your speedo so you do not over discharge your new lipo. It is easier to kill a lipo from over charge and discharge then it is NiMh.

Of course i do at 140 a pop, i aint playing games.

I am more cautious with my nimh to keep them tip top for almost 6 motnhs now. I ruined 4 packs i first bought..... Never again.
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Old 01-15-2008, 10:52 AM   #9
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Does teh shpere have teh lipo cutoff?
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Old 01-15-2008, 10:57 AM   #10
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I just looked at the LRP site and it does not mention anything?

Not sure

http://www.rc10.com/lrp/esc_brushless_80500.htm

The competition might but I could not get to that page.
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Old 01-15-2008, 11:09 AM   #11
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I have 2 '07 comps and they have automatic mode which has lipo cut off. will cut off with nimh too in that mode. the cutoff sucks because you feel like a small loss of punch with the lipo for like 18 - 30 sec and then it just stops.
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Old 01-15-2008, 11:16 AM   #12
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Sounds like it works then!
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