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TL;DR What's the best way to care for NiMH when it comes to charging, use, and storage? This is for 1:14 trucking, so I don't need high-current demands, I just want a set of packs that will take as many cycles as possible before going the way of the recycling centre. I don't need to fast charge - I'm happy to slow charge before events, two packs per truck will last a whole day. Long Version It's been a while since I seriously used NiMH batteries in anything - since moving to LiPo I haven't looked back. But I've got a big truck event this weekend, and due to an administrative error some new LiPos didn't arrive on time, so I bought two new Ripmax 3000mAh NiMH packs from the LHS. They cost me a fair bit - as much as the non-delivered LiPos, which have almost a 40% higher capacity and are, well, LiPos. Back in the good old days, my charging technique for NiMHs was "run it until it slows down, then crank up the clockwork dial to 15 mins and let it run." Remember those clockwork chargers? Terrible, weren't they? When I was racing (and even bashing) on NiMHs, the general attitude was "do a race, then stick it on the fast charger, it'll shut off when it's done." I ran for a few years like that, but mostly I had around 10 packs to choose from and at any one time, a couple of those would be suspect - i.e. not holding a charge or dumping very quickly when used. While some NiMH packs would give me several years of use before heading for the bin (or light duties powering LED displays on the shelf), others would become troublesome within a few months, especially if they were being raced hard and charged hard. The label on the battery says to charge for 14-16 hours at 0.3A (10%). Yesterday I charged both brand new and unused packs at 0.3A and one had a false peak after 70 mins, the other charged for over 7 hours before peaking. This morning I topped off the early-peaked pack at 1A and it took another 60 mins or so of charge. Slightly worrying that these are both brand new packs yet exhibit different characteristics on the same dual charger. So, what's the best way to keep them living long? Should I trickle-charge them at 10% and let the better cells thermal off any excess? I've heard NiMH cells can be damaged even on a trickle charge. Would I be better charging at 0.1A if I'm going to trickle them? That's a very long charge time Should I charge them at 1 - 2A and let the delta peak stop the charge? Or even fast-charge at 3A? What's the best delta to use to protect the battery (vs getting max voltage when the start buzzer sounds?) Should I discharge them before recharging? Should I build a discharging board to discharge each cell individually, or hook the battery up to a low-current application (like running the truck's lights on the workbench for a few hours) to zero all the cells before charging? Is there any mileage in charging each cell individually with a probe, or is that only worth doing if the pack starts to exhibit poor charging / capacity characteristics later down the line? I know there are people here who religiously use NiMH all the time and don't complain about the kind of problems I used to have 10 years ago, so there must be a way to treat them well, especially if I'm not fast-charging them four times a week between races and topping them off until they're boiling to get the very best performance off the starting box.
I got a new 8.4v 3800 nimh pack from overlander last week. Used twice on my Thunder Dragon but found it made the car too hard to drive with 120a esc and 10.5t brushless. ESC has now died so want to go back to 7.2. Has a deans connector installed by overlander. I have tamiya adaptor for both a charger and/or tamiya esc plug. Maybe good for a big wig rere? Cost me £29 for the pack and £3 for each adaptor. It's this pack but with a deans plug. https://www.overlander.co.uk/premium-sport-3800-8-4v-power-pack.html Make me an offer before it goes on eBay? Now on eBay. A bit of research reveals it will fit any Thundershot chassis buggy, but will also fit any hotshot variant if you get part 50296 Look at this on eBay http://www.ebay.co.uk/itm/263000080384 I have deans to tamiya adaptor leads if needed too.
Evening all. Thought occurred to me: If I could move the extra cell on a hump pack 8.4V NiMH battery from the centre to the end, it would fit in my DT03 buggy which might be a giggle. Don't want Lipo or any of the associated hassles, but if I could cut open the pack and move the extra cell then I could get a bit more pep in my Grasshopper 3. Anyone done this? Any advice? Cheers!
Hey guys - anyone know of the best deal on 5000mAh NiMH batteries? There are some cheap ones I see on eBay but I'm reluctant to buy them since I don't know if they are decent quality... and I'm notoriously concerned about the dangers batteries can pose. That being said - I'd like to find a source for good, high capacity NiMH batteries for less than $30-35 apiece, which seems to be about the going rate. Anyone know of any hookups? Had experience with some value brand(s)?