Recommended NiCd or NiMH cells?

[HornetB]

Hi guys.

I dont want this to seem like I'm taking the short cut by just asking for the easy answer but I've been doing lots of reading and still finding myself a little confused. Like most here, I'm looking to build a bike up. I dont need huge range (5 miles to work, can charge there, 5 miles back, pretty flat riding).

I was tempted to go just with SLA, but given I haven't committed to anything yet I was thinking of putting that money into building a NiCad or NiMH pack as a cost effective option instead of lead. But the problem seems to be finding good quality cells. I dont know much about the good quality, high discharge rate cells and which ones they are so I'm hoping some people here may list what they have used. I've found Tenergy cells cheap on ebay but understand these are a pretty poor cell, seems like Sanyo have a good reputation. Where are people buying these better cells and which ones?

I was thinking of going for a 48v pack, maybe 8-10ah would do it comfortable for me. I'd likely go for a bafang or BMC hub, but maybe 408 and dont plan to have a real high current controller (20a?). So could anyone offer up any advice or which cells to purchase and perhaps a good place to buy them from? I'd greatly appreciate the help and advice as the ones I've seen, by the time the pack is made prices start to get real close to Lithium options. So, there has to be cheap Nicad out there.

Thanks. HB

 

[Ypedal]

only place i would recommend getting either nimh or nicad from is http://www.ebikes.ca, they have been selling those for a while and understand them well.

8ah should be fine, an 8ah Ni pack will weigh alot less than a 12ah SLA ( don't bother with 7ah SLA, minimum is 12 with lead, even with a 20 amp controller ) but an 8ah nicad will last you a long time if you use it right.

Cheaper is not always better. true with just about anything but drinks.

 

[HornetB]

Thanks Ypedal, I appreciate the input, it's sound advice.

I agree, there is no free lunch and cheap can be nasty and false economy. I had considered ebikes NiCad packs and still may buy one as the price is good coupled with good service and a known reputation/performance, however once delivered that starts to get awefully close to a tool pack of Konion of similar voltage and capacity, which I may still yet consider.

Guess I'm just putting the feelers out there in case there were cells available at a price that would make a good economical NiCad pack instead of SLA. I'm happy to build myself so thought there would be cost savings over buying a prebuilt pack. I understand that there may not be options much better than the ebikes packs but thought I would ask in case I was missing something and it was possible to economically get cells that were value not rubbish for a home built pack.

Many thanks. HB

 

[Mr. Mik]

Could you build a Nickel based pack with several parallel strings, with each string comprised of matched cells?

As in: Very good ćells into string one, medium into string two, lower quality into string three.

Put the three strings in parallel with each other.

Would this avoid reverse charging of the weaker cells?

I ask this because when you buy standard cells you will get a variety of quality levels in the bunch you bought; and the lowest capacity cell in a string determines the capacity of the whole string.

I hope this is different for parallel cells.

 

[julesa]

If I only had a 5 mile flat commute, I'd buy 12Ah of lead. Or just pedal.
But that's me. Is there a reason you don't want to buy lead?

 

[HornetB]

No, not really any reason not to go lead. It is definitely a very viable option and likely one that I will choose to go (at least initally). I'm just checking to see if better value can be had on the lower end of the spectrum by going maybe Nicad instead of lead (I've read it's better value in the long run because of the extended life). Perhaps of more importance than weight is size of the batteries, I'd like to get them inside my triangle and keep them kind of stealthy if possible and stick with the look of the bike (Yep, aesthetics are playing a big part. No wired mess here hopefully). 36 or 48v of lead gets bulky quickly and hanging that in the frame might be tricky. I thought Nicad might be a little smaller, slightly lighter option, plus I could triangle shape it and perhaps mount it easier really low in the frame above the bottom bracket.

5 Miles, yep that's not a far ride. In my particular situation I want to convert my only bike (a Felt El Guapo cruiser) into something a little more practical for getting to work on, but also for general fun cruising around of an evening/weekend. It would be nice to do both. The cheapest alternative of course is to get a cheap road or mountain bike, but then I'd not get to cruise on my cruiser :wink: . The 5 mile trip, while not a nasty ride in regard to hills and very easy on a road bike wouldn't be much fun on a heavy single speed cruiser and I can't really get too sweaty for the day ahead.

Hope that gives you some insight to my situation. I appreciate the feedback and comments.
Thanks, HB

 

[Zoot Katz]

For concealing the batteries you want something smaller and more flexible than lead.
For a 5 mile jaunt tool pack batteries might be the best option.
You can add more for extended cruising as your budget permits.

For off-the-shelf solutions the NiCd triangle packs from ebikes.ca might be most economical.
You can trust that the batteries they sell are at least their advertised rating.

A NiCd pack will surely last until today's newest technologies becomes more affordable and the mad hackers here are frying guinea pigs with super capacitors.

 

[pwbset]

however once delivered that starts to get awefully close to a tool pack of Konion of similar voltage and capacity, which I may still yet consider

I tell ya... keep those konions in the packs if you can. I've started my DocBassJrâ„¢ konion pack and am realizing it's going to take me weeks and weeks of working with these raw cells to get everything dialed in and built... and that's only for 120 cell pack... I can't even begin to comprehend the patience (obsession?!? haha!) of Doctorbass to construct such a huge pack as he did. After testing a little 40 cell unbalanced, throw it together 37v6ah frankenpack though I can tell it's going to be worth the effort. These are pretty awesome cells it seems. Even wildly unbalanced (4.06v - 4.32v ) the pack put out quite a bit of power and they tolerate all kinds of abuse.. though I'm sure that's effecting their life span.