The T bike - Torq Radical Update

[flecc]

When first planning the Radical battery, I intended three extra cells to bring the voltage up to 39.6 volts, the maximum that 36 volt controllers will normally reliably accept. Since there was already space for a single additional cell, I enlarged the case to make room for two more side by side below. However, the eZee controller was intolerant of the peak of voltage at the end of charge, so for a while I ran with less. I've now got a simple workaround the problem by just discharging off the peak in a few minutes after charging, so am now on the full 39.6 volts nominal. Since the battery was 8 months old and will be down to about 8 Ah, I've added cells of that capacity.

The net motor power is up from about 470 to 520 watts, gross power up from 576 watts to 634 watts, 9% less than the most powerful on the market, the F series, but the T bike is 14% lighter and has very much lower rolling resistance and coefficient of drag, so can easily outperform them. Top spot again!

Those power increases may seem modest, but the steep hill climb performance has been transformed since the normal voltage drop under load has effectively been completely cancelled. The Torq Radical now easily climbs 1 in 4.5 (22.5%), in the 60" second gear at 7 mph with me standing on the pedals making a reasonable 250 watt contribution. Alternatively, at almost 6 mph very easily in the 42" low gear, sitting on the saddle and making a much more modest contribution. So the T bike joins the Q bike in being able to easily tackle any road it could meet.

Performance on easier hills is as reported before, very competent, but the feel of more power is always very evident. Acceleration is very much faster now, the bike being willing to rapidly accelerate from zero to it's maximum of over 23 mph without assistance, though unassisted is not what it's about. All in all, the character of the bike has been added to considerably, making the fun element very much more apparent while removing the pain of it's former hill climb performance.

The original derestricted range in my hilly area with a new Li-ion was 15 miles. Although the battery voltage won't increase the range normally, I've done a range check now and returned 16.2 miles. Since the battery is 8 Ah now, that's equivalent to over 20 miles on a new Li-ion, a 33% increase. Clearly much of that is due to the bike's improvements in roll resistance, cd etc., but some will be due to the extra cells. The reason is simply that the power to gearing ratio disadvantage suffered by the 40% overgeared standard Torq has been considerably alleviated, making the ratio much more efficient, moving it towards Q bike territory.

Of course the battery can go on any eZee bike, and I've tried in in the Q bike. The same controller on that has a slightly lower acceptance voltage, so there are clearly some variations. In the Q it makes little difference, since the bike is already so competent at hill climbing, towing and load carrying. All it does is make the speed during the steeper unassisted climbs about 1 to 2 mph faster, but the slightest touch of pedalling with either battery type masks that difference.

However, this approach would be of value on a standard Torq and would greatly increase the climb ability, so within the next few days I'll publish a way in which it can quite easily be achieved for owners with NiMh battery needing that facility.

I've updated the second page on site with full details of the changes.
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[penguin]

Way to go Flecc.

Let us know when you start building to order

 

[flecc]

Thanks penguin. If there's one thing I'm bad at, it's making the same thing twice, something I can't stand. I could never be a production worker. Even building the two channels of a prototype stereo amp would drive me mad. Left channel fine and perfect on test, right channel after forcing myself to repeat the operation, not working and riddled with faults was the norm. Boredom sets in very easily, and new ventures always beckon!

That's for those who are better suited to it, and hopefully there'll be more e-bikes with better characteristics as things advance. I'm still hopeful that eZee will partially match what I've done to the Quando and put their own Q bike onto the market.

It will only need one to get it really right and start capturing a large part of the growing market for it to stimulate some real progress from rivals in supplying what's needed, rather than what suits the Chinese market and US "hand me downs".
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[coops]

However, this approach would be of value on a standard Torq and would greatly increase the climb ability, so within the next few days I'll publish a way in which it can quite easily be achieved for owners with NiMh battery needing that facility.

You read my mind flecc! Very clever idea, very neat solution in terms of a performance increase - both torque & range - for a small increase in weight . I'm glad I opted for NiMH now!

I'll wait for your "how-to" guide for more details, but could this mod be done on a newish NiMH? I've measured mine (2months old) as 40.7V hot off the charger, or 42.4V after a "boost" charge. If its possible, could you please (I'm sure you will anyway!) include details in the guide on what capacity batteries should be used for what age of battery, if appropriate? Thanks!

One other thing given that total weight reduction and lower rolling resistance originally gave the 2 biggest performance increases on the T-bike, how much performance boost would you expect from adding batteries in this way to a standard Torq, even one with, say, 38mm marathon plus tyres, with a rider who is normally ~85kg but now weighs ~100kg not including bike?! (Though I think thats what you mean when you say "greatly increase the climb ability... for owners with NiMH battery needing that facility"!)

Stuart.

 

[flecc]

Yes, I intend to include all those details Stuart, with a newish battery it's best to use the new size cells or larger if those aren't available. In your case that probably means 10 Ah, since 9 Ah ones aren't commonly available.

I was going to include a bit on the performance question with different weights too, but here's an indication of the position.

First the obvious, the climb ability will not be as good with your 126 kilos gross with bike, (the word gross not being an insult. ) as with my 93 kilos gross of course, though see further on.

Assuming you can contribute the same 250 watts on a short climb, the maximum hill you could climb at 6 mph using the 44" low gear I believe you have is 1 in 6 (17%), as opposed to the 1 in 4.5 (22.5%) for me at that power output in my 60" second gear at 7 mph. That 33 kilos extra makes quite a difference, but that's still a good climb ability. The Q bike with it's normally geared motor and matching rider gears would largely iron out the differences between us.

What I've done there is allow the gear drop to low gear to adjust for the difference in rolling resistance.

There's a changeover point effect in this climbing though. If a hill is just inside your combined capabilities with you comfortable with the effort needed, the nature of the Torq tends to encourage participation and boost your input, making the hill seem easier than it was as you rise to the challenge.

Conversely, if it's just beyond that exertion level, the effect is the opposite and giving up results. That's how I find this model's effect on me, and judging by other's postings I think it might be common to most. It seems to have that all or bust character.

Therefore the calculated result could vary according to how you react to the bike in climb situations. My guess is that you could get a bit better than the calculated result.
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[coops]

Thanks flecc

17% would be a very healthy climb ability .
Not sure I'll always want to put in 250W but then again a limit of ~17% or so would put most climbs within reach . I'll have to digest the figures properly, but that sort of big improvement seems scarcely believable! Much better than I'd hoped for!
No comment on the weight issue, except to say it does feel rather gross from time to time .

Stuart.

 

[flecc]

I was surprised by the degree of improvement on the Radical hill climbing too, but subject to that 44" low gear being there for you, I think you'll get near what I've indicated. It fits with what I've always maintained about how seriously the extreme overgearing affected the Torq. Any offset of that quite severe power to gearing mismatch is likely to produce a big improvement.

You can do as I did and get three D cells, charge them and lash them together first. Then cut the switch to controller return wire below the battery and solder 15 amp cable to those and onto that cellpack end. Then you can see how it works for you before doing anything more drastic. You can solder the switch return wire back together and insulate it after.

If you do that, ride a bit of charge off your battery first for five minutes to ensure you're below the voltage acceptance point of the controller.

Doing this test doesn't realise the full power, that only coming once the system has been altered and goes through a full discharge/charge cycle, but it gives a very good indication for a few minutes work and the cost of three cells, which can later be used in the full mod. You'll need a charger which is capable of fully charging those D cells though.

P.S. Did you get up very early, or have you just come in?
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[coops]

Thanks flecc

I'll re-read those instructions to make sure I've understood; how will combined battery + 3cells voltage be within 39.6V though, when my charged-flat range is 40.2V (rechecked yesterday) to ~36.5V flat? Aren't the 3 cells adding ~3.6V+ to that?! Does that mean I may need to use less, but 1 or 2 extra cells still seem to put it over 39.6V on even a few miles pedalling (still around 39V)? Am I missing something, or do I need to wait for my battery to age some more?

Still, a neat way to add torque to the torq .

P.S. Did you get up very early, or have you just come in?

Errrr... somewhere in between I think

P.S. Yes, my lowest gear is 44.8" thats 40T front & 25T rear, but I may always alter the rear derailleur & mech if I need to .

Stuart.

 

[flecc]

That difference is due to the voltage change per cell Stuart. Fully charged you have 1.34 volts per cell, so fully charged after adding three cells it will be 44.2 volts or thereabouts, the purely nominal 39.6 volts being the official convention in rating NiMh at 1.2 volts per cell.

The discharged equivalents at 1.22 volts per cell are 36.5 volts as you stated before, and 40.1 volts after. But of course the controller will not cut at that 40.1 volts, it will still try to cut at 36.5 volts as before, equal to 1.1 volts per cell, so that's where a bit of the extra range comes from, albeit at the old performance for that last little bit of use.

You shouldn't need to alter the gearing. If it goes too low, the corresponding lower road speed could drop the high geared motor right to the edge of the lowest useful power and into the growling region, not good for the nylon gears and wasting loads of current.
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[coops]

Ok, thanks flecc

I think I see now (apologies if I seem a bit slow on this today ): the 39.6V is not the actual maximum voltage the (obviously, now I think about it, since I use 40V+ on a full charge no probs) but the max "nominal" figure based on 1.2V per cell, as you said, so 33x1.2V=39.6V should be ok .

EDIT: double apologies, since I now see you updated your site's T-bike pages with all this info already. I'll try to read things properly first in future . Clear now .

I'll try to let all this sink in now .

Re: gearing, I may in time extend the gear range for my pedalling, as you did with a "get me home" gear, but mine may well be a bit lower & slower to reduce the power needed to shift the extra weight! .

Stuart.

 

[flecc]

Re: gearing, I may in time extend the gear range for my pedalling, as you did with a "get me home" gear, but mine may well be a bit lower & slower to reduce the power needed to shift the extra weight! .

Stuart.

Or you could break the Chippie's heart!
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[frank9755]

Flecc,

I've seen you give a view of the advantages and disadvantages of rear and front wheel hub motors, which give a fairly mixed picture with (from memory) 2-wheel drive and weight distribution in favour of front and lighter steering / less juddering in favour of rear.

Given that both the Q and T-R bikes have rear wheel drive, is it safe to infer you think that is generally a better option?

I've not ridden a rear wheel drive bike (yet) so don't have a rounded view. Do others have strong feelings either way?

Frank

 

[coops]

Here's the front vs rear hub summary I think you're referring to Frank .

I haven't tried a rear hub motor Frank, but overall it looks to me to be better for comfort and efficiency so long as gear range isn't limited, the only downsides being back-heaviness and no two wheel traction, although better traction on uphill poor/slippery surfaces .

Stuart.

 

[flecc]

Enough for me not to want another front one Frank, but that is strongly coloured by my personal usage. That includes a high proportion of heavy load towing when the traction and weight control of the rear motor is clear winner and much safer. The other factor is that I don't personally like sprung forks, but front motors really do need them for comfort. The Q and T are indeed rear motor now, and my Twist mid motor.

For many others, the majority not towing but most probably liking sprung forks, the front motor is a good choice for the much improved gearing options.
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