NiMH battery packs for regen?

electrobent

100 mW
Joined
Jun 12, 2008
Messages
49
Location
Pomona, CA 91766
Hi:

I bought a used under-seat steering recumbent a few years ago and loved it. But it was not safe once I got tired because I could not get going at lights. I figured that it would be perfect if it only had an electric front wheel. I looked around on the 'net and found expensive Canadian and cheap Chinese options. I went with the Chinese, found the Golden Motor website and emailed sales and got no reply so I emailed Raul at Perfect Team in Oakland and he eventually replied. I ordered the 36V Brushless motor kit and SLA battery pack and some very cheesy accessories that I could not bring myself to put on my beloved Turner T-Lite. I asked for a regen controller but was told that there were none available and that it would not net me much juice anyway. When it came, the motor was missing one of the pieces that go between the bearing and the fork. The wheel was horrifically out of true. And my new fork (to go from 16" to 20") needed splaying as well. With some invaluable help from the machinist at work I finally got it all put together. Oh, and I should say that Raul sent me the missing piece post-haste but it was nowhere near as nice as the stainless ones Mike the machinist made for me.

I soon discovered that it did not take a whole lot of throttle get going and get going fast. I went down a tooth in the rear from 12 to 11 if I remember right. That did not make it much faster. I rode it fast and hard and uphill and filled my giant baskets that I bought to have the giant rack to hold the silver plastic SLA case. My SLA batteries did not last long and cracked and oozed but were taken off my hands for their lead content.

I looked around at replacement SLA's and was not really satisfied with the weight and cost of the options I needed to give me the 20 Amp discharge rate necessary to go up the hill at 25 mph.

I was told that lithium would blow up and to stick with NiMH. I bought a 39.6 V 10ah D pack from Battery space. It never did seem quite right so I bought another one and put them in parallel. The Batteryspace packs are a pain because they divide them into 12V (or 13.2V in my case) segments for charging. I learned today that they do this because it works with the lower voltage charger that they are selling. So I strap their two little camera-bag cases to the front of my baskets to get the weight down below my own weight so I don't fall over again. That made it faster--a lot faster--until I melted the molex connecter on the fat power wires from the controller to the motor. I replaced the connector with a bakelite screw panel and my top speed for motor only cruising on the flats went up 2 mph.

This is great, I get paid for going to work instead of paying to go to work. With diesel at $5 a gallon this is worth about $4.50 per day for me and that will almost buy lunch . . .

All is great until my high school buddy calls and wants me to find him a motor he can use to convert a VW bug to electric. I figured I'd go back to Golden Motor and see if they had anything bigger. I did not find what I was looking for but I did see that they now have regen controllers. I transfered some money to pay-pal the slow, cheap, way and by the time I went back to make my purchase they were allowing the selection of a 48V regen controller with the 36V brushless motor kit. I emailed sales and asked if it would work with my motor. No response. Raul again. He wants $20 more and does not have the 48V model. I ordered the 48V model because I figured they would not allow it as an option if it would not work well.

Then I start wondering if it is going to blow up my 39.6V packs by trying to shove too much juice back in so I start reading here and at endless sphere and realize that my problem will also be falling below the 42V cutoff on the 48V model. So I need more batteries . . . and maybe I'll melt the wires to my motor. I am hoping it is one of the old ones. It is painted silver where it is painted and says "QUNFENSE" on it along with SWX173180A and what looks like a serial number: 52779. Does any of that make any sense to anyone?

I googled "Qunfense" and came up with this link:

http://www.made-in-china.com/showroom/successmotor/product-listjeMEwzWufncs/Brushless-Hub-Motor-catalog-1.html

The wattage there is not clear as most claim to be 500-1000W.

Anyhow, how do I tell if I need to replace my wires before they tell me?

And any body build any high performance NiMH packs to be able to take a boat load of current coming back in fast?

I happened across a Honda insight junkyard and got to see their battery packs: 120 NiMH D cells assembled into rods with 3-4 inches of airspace between them and a fan blowing over the whole assembly.

I was shocked to learn that there were less than twice as many D cells in an Insight than I had strapped to my bike and figure that this air gap must be what allows them to get away with so few cells. My own battery packs are bricks and sometimes over temp in charging.

So my plan is to take apart the two packs that I have and get enough additional cells to get to 48V (well maybe 49.2). The Honda packs are held together with shrink wrap but I think I want something sturdier--and something that can be attached to the bike in a theft resistant fashion.

So I am thinking long tubes of batteries. I walked around Lowe's trying to shove one of their D cells into various pipes and conduits and there were no snug fitting metal tubes but 1 1/4 inch Schedule 40 PVC pipe is pretty close plus its cheap and easy to work with, and if you paint it, it will last in the sun. It will retain some heat but it could be cross-drilled for ventilation. So now I am thinking of building geometric shapes with 1 1/4 sprinkler pipe and going at them with a drill press.

But then I got to thinking that its probably best to charge each cell fully (independently if I can get down that low) and then measure them and match them together in pairs of similar voltages and then put these pairs in series. That would be less elegant in the pvc pipe unless I built ladders with wires going across and that would be dangerous.

I searched on "cooled battery pack" and found some RC ones where the stand single cells up apart from each other and then sandwich them between two sheets of something with a fan on one end. So now I am thinking a couple of Harbor Freight plastic cutting boards or maybe the corrugated plastic that they use in Post Office tote tubs?

Any body done anything like this?
 
regen and ebikes.. generally not worth it. possible.. but not worth it.

You don't have enough weight, and generate enough power to gain usable power, in relation to the copmlexities it involves.

Regen has to be disabled when you frist stat your ride.. force power into a full pack and you got problems...

And most off the shelf NIMH won't like heavy amps.
 
Yes my Bionx 36v NIMH sytems have regen. Its value is more as an outstanding brake than the amount of energy returned to the battery.

On one very long hiully ride we were able to get an improvement of 1/8th battery cpacaity by using regen as much as possible.

It looks to me like the regen is current limited in the amount it will dump into the battery pack, guessing about 4 amps.

With a fully charged nimh pack, the regen is inoperative until the battery is depleted a bit, this to prevent overcharging the pack.

On certain slope hills the regen is very nicley matched to the desired speed reduction. A Lower slope and you are going too slow, a higher slope hill and the regen doesnt give enough braking. But sometimes a nice feature.

So anyway, a nice antilock brake, and can be helpful in certain siotuations. But mostly just another gizmo to distract one form the enjoyment of riding.

YMMV of course.

d
 
Lipo batteries can explode, but not LiFeP04 batteries. You would be happy with lithium.

Your Nimh cells are not bad, but they have their own problems. Do NOT put Nimh batteries in parallel during charge. Each string must be charged separately, then combined for discharge. Isolating the strings with diodes eliminates the need to unplug everything for charging.

The low voltage cutout on most controllers can be modified.

I haven't heard of that motor before. It sounds similar to a Crystalyte 400 series.
 
Welcome to Es

nimh batteries have varying resistance. You need low resistance cells for regen so the batteries won't get hot. The 6.5ah cells on the honda insight will hapily kick out 100 amps. well worth it if you can get hold of them. Failing that you can get other nimh cells with decent discharge rates if you look around for them. The important thing with nimh is to make sure they don't get too hot. Especially with regen as charging and discharge above a certain rate is exothermic so always check the temp. If you want to rebulid your pack with a better a better charger in one string. Check out ebikes.ca chargers and also matching thermistors. Also worth looking at is http://www.powerstream.com. Both the latter charging system are much better than the batteryspace cheapo 10 cell charging arangement.
 
Thanks!

The Q is definitely a Q and the "QUNFENSE" is cast into the cover plates on both sides about a half inch high and 2 + long.

It looks a little like their Climbing King model but nothing like the high speed brushless model.



How do I post photos?
 
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