NiMH Care

[Jman_15]

I have just bought a new GP 3300 battery pack for my RC10T3. I have been reading about NiMH battery packs on the internet for a while, but I am still not 100% clear on everything. I read some places that you should discharge them, and others where you shouldn't and ect. I understand the basic concept that you need to keep a charge on them when storing and I also understand the memory effect. I just want to know if I should discharge them with my bulb discharger before I charge it up again on a race day. Also, is it correct that I should cycle them 3 to 5 times in order for the pack to be broken in? Thanks

[insano]

I have had several packs of gp3300's and they all needed a couple cycles before they would take a full charge. But once they were "woken up" they worked excellently. I leave my packs charged about half way if I am going to store them, and I think gp recommends storing them with .9 volts of charge per cell, so thats 5.4 volts. Which is discharged beyond when the battery dumps which should be somewhere around 7 volts, so yes you should use the bulb discharger according to gp. I always store mine with around 7 volts of charge in them however, and my gp packs are still strong after many many months of hard use. So I guess its up to you. Gp is a high quality manufacturer, and it seems that no matter what you do to the cells (besides deadshorting, which you should NEVER do with nimhs') they will last a long time. All my packs have been very punchy as well.

[Grizzbob]

Jman, the reason why you've seen conflicting reports is because the cell themselves have changed a bit since NiMh's first came out. With the first generations of NiMh's, yes, it was absolutely neccessary to leave a fair amount of charge in them when you're done running it for the day. But with the latest batches of GP's cells, it seems they respond pretty well(in racing applications) to go ahead & discharge them to .9 volts/cell, much like we used to do with NiCd's, & they can keep for at least a week or so like that(btw, you really can't tell how much charge is in a cell by the no-load voltage you read in it, as all rechargable batteries tend to recover their full voltage after a load has been removed from them. But that voltage will drop FAST as soon as a load is placed on them). And because of the newer batches, it's also becoming more popular to use the newest discharge trays on them(like Novak's new one & Rayspeed's as well) that can be set to discharge each individual cell to a preset point, & it's common to tray the pack shortly before you start charging the pack nowadays. Also, while it's apparently possble now to dead-short them too, I've been told that it really doesn't help them much for voltage, & that it's not worth the loss in run time for it.... :cool: