# battery maintenance questions



## PWA (Aug 14, 2005)

I'm getting back into the sport with my kids and have a few battery maintenance questions. What should I be doing to maintain my batteries? If I'm storing them for a few weeks at a time what should I do to the batteries? I have GP3700 cells, an Ice charger, I currently don't race since we have no local track, and I just built one in my back yard for me and the kids to play on.

My biggest thing is I got a good investment in battery and want to be getting the most out of them. There are so many battery related Item out there I'm not sure what’s needed and what’s not.

Thanks for your time
PWA


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## Trixter (Oct 8, 1998)

Charge tham as normal at 5 or 6 amps. Run them till you notice a drop in performance then take them out and put them aside till next time. If you only run for a short time (not till battery is dead) then you can just wait till next time. They will discharge on their own over time. The Ice charger will detect that they will have some charge in them and charge them appropriately. You can discharge them with something that uses 20 to 30 amps. I sometimes use a bulb type with a cutoff. If I remember right, the Ice has a discharge function but only 10 amps. Not too good fro the calibur of cells you have. Pick up a Tekin Discharge tray and put them on it once in a while. This will keep them balanced.


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## DJ1978 (Sep 26, 2001)

Manufacture guidelines for Nickel Metal batteries is to store them with a full or partial charge if you are not going to run them for a while.
Also if it is months in between, It is a good idea to cycle them once and a while.


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## Guest (Jan 5, 2006)

Read some of the battery care information posted on most of the battery matching sites, then try a method that works for you.
Generally I just leave the packs discharged to a .90 volt level, then equalize them before charging. Even for competitive racing I haven't noticed that much of a decline in runtime for stock and 19turn racing, but any cell may show too big of a decline to still be competitive.
For side by side backs a strong of bulbs should suffice for discharging install a cutoff device that stops the load when pack reaches a certain voltage levels (Racer's Edge sells both the bulb and cutoff device in a 20, 24 amp load available direct or on Stormer Hobbies). For equalizing trays Integy sells 3-4 types with the Octane2 being fine, the Zero30 is more expensive but requires a power source if pack is more than half charged, there are other brands too Trinity, Novak, Tekin, Duratrax, Reedy -LRP. For stick packs pack equalizers, single bulb or discharge resistor can help. 
There doesn't seem to be a right or wrong way in storing NIMH but discharging the cells before charging tends to help cells charge better when you use them each additional time, as cells don't always discharge to the same levels when pack is used. The imbalance in cell voltage sometimes leads to much of the false peaking problems associated with NiMh. With the GP brand of NiMh you can leave pack in tray until it has cooled enough to be charged or if you are trying to maintain runtime remove the pack within 5min after the bulbs have gone out which brings the voltage to around .05 - .15 volts per cell depending on load tray uses to discharge each cell.

Personally I've left packs stores for as long as 8 months with a .90 volts per cell level. Only problem I encountered was pack didn't charge to normal voltage or MA rate was low, in racing situations it didn't have the snap it did. But in most cases after pack saw active use in 1-3 cycles it was back to normal.


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## DynoMoHum (Sep 25, 2001)

If your not racing... I'd actualy advise buying some GP3300 packs... perticularly if you can find a good price on them. GP3300s are alomst indistructable...

I'm not that firmilar with GP3700 cells... So I can't give any specific advice on the maintaince of those...


In general... for use in situations where your not trying to be ultra competitive... Charge the packs, run them till the vehicle shows signs of slowing down, then STOP. Don't keep driving till the vehicle is barely moving, this could damage some of the more sentitive batteries that are on the market today. Let the packs sit for at least a hour before charging again... idealy you should probably only use the same pack twice a week (or less). For NiMh cells you might consider puting a little bit of charge back into the cells before storing them for a extended period of time (weeks). For not competitive use, there is really no reason to 'cycle' a pack even during long term storage. Packs will generaly re-juvinate themselves from a period of non use, by simply useing them a couple times, better to get some fun out of the pack in your vehicle, even if it isn't operating at 100% after that long storage period...

For non competitive use, it's really a waste of money to buy expensive 'matched' packs, and you should look for a pack made from cells that are very durable... Some of the newest high capacity matched packs, are NOT really very good for your average backyard RC user... (but then the absolute cheapest packs are often not great either).


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## DynoMoHum (Sep 25, 2001)

Oh... if you want to get into more complicated battery maintaince procedures... I think ICE is capable of the following...

Once every 10-20 uses, you could discharge each cell in a pack individualy, using the ICE discharge function. (This assumes you have battery packs where you have full access to both positive and negitive sides of each cell in the pack). Set the ICE to discharge, at it's highest discharge rate for a single cell, set the cutoff voltage to .9 volts. After you've run a pack down to the point where the vehicle slowed, start discharging each cell seperately... it may take a minute or two for each cell depending on the discharge rate, and how much capacity they had left in them when you took the pack out of the vehicle. Discharging each cell to exactly the same voltage (.9 volts) insures your cells are fully discharged, and ready to take on anohter full charge... This is said to 'equalize' the pack... 

Many racers do this same procedure after each use of the pack. They tend to use a somehting commonly called a equalizing tray, to do the whole pack at one time. These trays can be somewhat expensive for a good one. For backyard RC use, this type of procedure is probably overkill, perticuarly when doing this each and every battery use. Even so, you may consider buying a Equalizing tray... Just make sure you get one that actualy stops discharging at .9 volts... Many of todays best cells don't like to be discharged bellow .9 volts for extended periods of time, so you can hurt your cells with the wrong tray, or the wrong procedures of this type... This really is 'advanced' stuff, and may cause more harm then good if not done correctly.


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## CDW35 (Jan 17, 2006)

Well what I do I charge my batteries at 5 amps. I discharge at 20 amps. if you are going to let the batteries sit I would keep alittle charge in them and then every now and then cycle them

CD


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