Warning Upland 26 problem

[Grizzly Bear]

Hi Everyone
I have only just joined pedelecs forum, and I wrote about converting my Giant into an e-bike using a cheap chinese donor e-bike called an Upland 26, that I bought off Ebay. Please beware I am having battery issues. I will keep you posted on developments.

Grizzly Bear

 

[flecc]

Thanks for the warning Grizzly Bear. Keep us updated, and share what the issue is if you wish, we're always interested.

However, I hope you get it sorted it without suffering any loss.
.

 

[Grizzly Bear]

Re Upland battery

Hi Flecc
my converted giant has been really good, but all of a sudden the performance dropped off, I have some electrical knowledge and investigated the problem. The charger was doing some strange things, and I thought it was faulty. I did not have my multimeter so I wasn't able to check the system. When I did check it I found that the battery voltage was in excess of 40 volts, the bike was advertised as having a 36 volt NiMH battery. I stripped out the battery, which is located in the rear wheel hub, what I found was that there was only 29 cells in the battery pack! and this was producing in excess of 40 volts, I found one cell had burned out too. I checked the voltage of each cell and found it to be in excess of 1.4 volts, I have assumed that they were in fact normal dry cell batteries, they were however tagged? I am planning on replacing them with 11 amp D cells, fingers crossed this will resolve the problem.

Regards Grizzly Bear

 

[Ian]

I used to have an Upland/Sybergie branded bike with the battery in the rear hub. The bike was a pile of junk which I scrapped after a catastrophic controller failure. I did salvage the cells however, all 29 of them which are now doing service (with one addition) in an Ezee battery casing. The cells are normal (albeit cheap'n'nasty) NiMh cells with a fully charged voltage of about 1.35V. This is a perfectly normal voltage, only falling to the nominal 1.2V when almost discharged and is exactly the same as the original high quality Ezee batteries which are about 41V when fully charged (30 cells)

Data sheets for batteries can be downloaded from RS components, and it can be seen from these that the correct voltage for a fully charged NiMh cell is 1.4V. Sanyo 9Ah Stock number 400-7207

 

[flecc]

A 36 volt nominal NiMh battery with 30 cells will have around 41 to 42 volts when fully charged, that's normal.

Cheap Chinese bikes often cheat in having one or two cells short like that one, and it should peak at just about 40 volts. However, the matching of cells in series in these batteries is very important, and clearly that's where this one has failed. It should be tagged cells so that they can be soldered safely, as pressure contact using those cheap 11 Ah ebay batteries is unlikely to be able to carry enough current, and we know nothing of their consistency. Therefore there's a risk of another failure.

The other problem with these button end cells is that they are slightly longer than the tagged ones, so might not fit into the case.

Sorry about all these warnings, but these high power batteries can be tricky to deal with. That's why the decent ones start at about £200.

P.S. Post crossed with Ian's, hence some duplication of advice.
.

 

[allotmenteer]

Hello Grizzly

The 36 Volts is a nominal figure (made up of 30 cells x 1.2 Volts nominal). When fully charged the each cell will be slightly more than 1.4V, so about 42V+ for the pack.

The 29 cells is cheeky, one would expect 30 cells to give the nominal 36V.

The tagged batteries are the normal type used for battery packs though.

Paul

P.S. Post crossed with Ian's and Flecc's hence some additional duplication of advice!

 

[Ian]

A Further Warning

Be advised Grizzly that if that rear hub is the same as the one I had then it has no fuse protecting the battery, an inexcusable and potentially dangerous omission.

When my controller failed and shorted the supply the lack of any protection melted much of the wiring, if a relay in the rear hub hadn't melted and broke the circuit it's likely that the cells would have dangerously overheated.

 

[Grizzly Bear]

Hi
Thanks for the info, as I previously wrote I have transplanted all the running gear onto my Giant mountian bike, I am aware of tagged cells and I am planning on using them, also the need to match individual cells of a battery pack.
Indeed there was no fuse fitted on my battery pack either. I have just checked the voltage of these cells again and they are approx. 1.4 volts, I then checked some other NiMH batteries I have and they are 1.2 volts fully charged. Surely the voltage rating of 1.2 volts for a NiMH battery, is for a fully charged one? I think the battery in the rear hub is a great idea, and I want keep this, I even tranfered the Giant's 7 speed gear set onto it.

 

[Ian]

All the manufacturers data I have ever seen which is freely available from reputable manufactures and suppliers quotes the open circuit voltage of NiMh cells to be approx 1.4V when fully charged only falling to 1.2V at about 85% discharge. This is what I have measured on a number of occasions, which is exactly in line with the experiences of Flecc and Paul above. As NiMh cells are deemed to be fully discharged at 1.0V the quoted 1.2V is a nominal average.

From my experience with Ezee bikes I can say that when the no-load pack voltage falls to 36V the battery meter yellow LED illuminates indicating almost discharged.

Obviously you like the the idea of a hub mounted battery, while it does have advantages it didn't work for me. I prefer a removable battery to simply swap with a fresh one to increase range. I also found the inability to lighten the bike by removing the battery to be a disadvantage when there was a need for manhandling.

 

[flecc]

I concur with Ian. Those other NiMh batteries that you have clearly aren't fully charged at 1.2 volts. If they are a very old type they wouldn't reach the 1.45 volts that modern cells reach, but 1.2 would still be low.

Originally NiMh batteries used a mixture of rare metals for the hydride of the content, and they tended to decline to lower voltages quite quickly and didn't have very long effective lives. Modern ones use a mixture of rare earths in place of the metals, and they are much longer lasting and also attain the higher voltages.

Strictly speaking, they should now be known as NiEh.
.

 

[Grizzly Bear]

Hi Everyone
thanks for the advice, I will keep you posted on my project, be assured I will be fitting fuses when I re-build it. It's a pity the batteries suffered meltdown, as it was really good performer, and it looks great.

Thanks again Grizzly Bear

 

[gerfried]

Hello,


I'm just wondering if there is a Patent on hub mounted batteries (now with matra)- this would put the Chinese in problems...


Gerfried


Title here!

 

[giguana]

the battery *might* come up as 1.4 on a multimeter on standby, and then drop to 1.2 as soon as a few amps are drawn from it.