I've lost the thread

[coops]

I know how you feel...!

Hi Pete

I had hoped that by establishing the base power required to climb any gradient (say between 14% and 5%) one would need only the usuable output for any electric bike motor fed into an equation that contained the other vital personal data (previously considered) to conclude whether or not that bike would "DO IT FOR ONE".

Look at it another way..............
eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee..........

Peter

Hehehe! I know how you feel Peter!

A neat idea, but its just not that simple and I for one would not like to be responsible for any disappointment through error or misunderstanding that might cause..! (Though Russ (rsscott) has said that "over the next fews weeks I will try to collate the information we do have into some form of guide which will at least highlight the issues and point people in the right direction" - an unenviable task I must say!

So while its not so quick, direct or (apparently) straightforward, currently the best way to get information is to just ask, and also to get an idea from the experiences of others I guess?

Did you have a particular objective in mind (such as "how can I get up that **** 1 in 8 hill"? (insert personal choice of expletive, just don't repeat it here!) if so, then see what you think of the suggestions I posted earlier today ("some hopefully useful ideas") & post back

I hope that helps Peter.

Stuart.

 

[ITSPETEINIT]

Did you have a particular objective in mind (such as "how can I get up that **** 1 in 8 hill"? (insert personal choice of expletive, just don't repeat it here!) if so, then see what you think of the suggestions I posted earlier today ("some hopefully useful ideas") & post back

Stuart.

That was precisely it. But in a more subtle way, coaxing more and better particulars from any e-biker, "what e-bike would suit me best - taking into account my deficiences: weight, health (or the lack of It) and fitness". Rather than ask a list of questions, which might seem personal, I asked for the details of the e-bike which could then be applied to anyone.

I have gathered from the informative discussions we have had on this subject that there is no e-bike that will serve my purpose that is legal at present. I have contributed to the petition to allow motors up to about 500 watts.

I would hope that it would have a range of at least 20 miles, preferably 30.
Speed up the incline is not important provided it is above, say,4 mph.(I could enjoy the view)
The trip that I made to Shaftesbury (twice) was a round trip of 20 miles. The greatest mileage I achieved on one charge (20 miles flatish and 10 miles hilly) was 30 miles - the last 2 miles being downhill (I had already climbed it earlier on the same ride)

The Quando, apart from the only gear of 70 inches, has a lot of the attributes that I am looking for, but the small wheels would bother me unless they were a considerable convenience (as in transportability.)
Iam puzzled why the Quando has its motor in the rear wheel - if it were in the front wheel it would allow the owner to upgrade the rear wheel with a hub/derailleur gear (cost about £100 for a derailleur set up including building.
It is probably to do with foldability?

The Twist that I tried had features that I was unaware of. I knew that its owner, a diminutive body, had no trouble in surmounting 1 in 8 (maybe 1 in 7). Being local I could try it again, on his hills.
Not being aware of the programming which sensed a riders efforts then put in enough punch to keep the bike going on the grade I tried to pedal it to go faster and was left exhausted. Then it was all too late. His efforts to obtain a replacement battery and a part for the Hub gear for another twist he had robbed (virtually brand new) were very badly handled by the cycle shop where he had bought them a year or so earlier. I recall that was about October 2006. It certainly left me with the impression that cycles shops were not the best place to get service of electric bikes, at least, the electrical parts. In the event these parts were never obtained. It may be that time was right on the cusp of Giant's re-organization. I don't think he knows what valuable bikes, albeit not working at present, he has. The Shimano part for the gear hub is common to ordinary cycles: the battery could be recelled (if I have understood information on that subject on the Forum correctly).

Then my further researches discovered 50Cycles and the advertising and commentaries on the Torq seemed ideal. Here was a 'dedicated' supplier who would take charge of repairs.

For the moment I am stuck with my Torq: as pretty as it is, it does not quite fit my purpose and fundamental body statistics.
Thank you (and Flecc) for your very considerable efforts of this very heavy subject.
Peter

 

[flecc]

I don't find the 20" wheels a problem at all Peter, the fat tyres compensate with more than enough comfort on the unsprung Quando II. Regardless of your declared weight, the Quando would carry you up 1 in 8 with very light pedaling on your part, travelling at about 9 mph. However, range is only about 15 miles, so you'd need a second battery or a short charge at the halfway point.

One alternative is the eZee Chopper, also 20" wheeled. That's the best hill climbing hub motor bike of all, due to it's 20" wheel gearing down the powerful Sprint front hub motor that it has. Basically a small wheeled Sprint, it shares with it the 7 speed hub gear, so is a "proper" bike, albeit with maximum motor assist at about 13 mph. Where the Quando's maximum hill climbing power comes in at about 8.5 mph, the Chopper's comes in at around 6.5 mph, so as there's less power needed at that speed, it's hill climbing power is prodigious, further aided by the rider having that 7 speed gearing. Rated at 500 watts peak and a Hall effect motor, the net power is probably about 400 watts, more than enough with that reduced motor gearing.

As you've guessed, I'm sure the Quando's rear motor is because it's a folder, but that said, I'm glad it's rear motor since it makes it a great tow bike and more comfortable as well. With the lack of weight on the front, that powerful motor if in the front wheel would just wheel spin when towing uphill.
.

 

[coops]

Wot, no twist?

Regardless of your declared weight, the Quando would carry you up 1 in 8 with very light pedaling on your part, travelling at about 9 mph. However, range is only about 15 miles, so you'd need a second battery or a short charge at the halfway point.

One alternative is the eZee Chopper, also 20" wheeled. That's the best hill climbing hub motor bike of all, due to it's 20" wheel gearing down the powerful Sprint front hub motor that it has. Basically a small wheeled Sprint, it shares with it the 7 speed hub gear, so is a "proper" bike, albeit with maximum motor assist at about 13 mph. Where the Quando's maximum hill climbing power comes in at about 8.5 mph, the Chopper's comes in at around 6.5 mph, so as there's less power needed at that speed, it's hill climbing power is prodigious, further aided by the rider having that 7 speed gearing.
.

Good call Flecc! Do you think though that the Twist, if available, affordable & repairable at reasonable cost, is also an option? Or is there a good reason (or three!) that you didn't mention it - e.g. that it needs parts/maintenance, lack of a good repair service (though as you say the twists are reliably well engineered), or most of all maybe its not best suited to your riding style/input Peter (having tried it and found it not intuitive for you?).

I'm only saying this to be sure that Pete & others are fully informed of the options in these sorts of circumstances, you understand , and apologies if this topic has been covered a million times in this forum .

Just out of interest, (I'm assuming the twist would handle the hill at or above the ~4mph Peter said?) do you think the twist would handle the round trip on one battery, with any "comfort zone" for battery deterioration over time? It seems to me that the efficiency of Twist over hub motors could be handy in the circumstances?

If the twist is an option, and can be made roadworthy affordably, you could always make the owner an offer for it, and tell him you know of a good place where he could put the other up for sale if he wants .

Stuart.

 

[flecc]

The Twist is an option, but on a 1 in 8 hill with the Twist, I climb at about 5.5 mph. Since I weigh 74 kilos, Peter might find it a bit slower, so close to his marginal point. It's also a bit more effort when climbing than the Quando/Chopper options.

The Twist's gain is in the ultimate steepness that can be climbed and limit of weight carried on a given hill, where it can beat the other two. This shows up most with trailers though.

While it's extremely reliable normally, I'm getting a bit nervous about Giant's position on supporting the old Twist. Breakdowns aren't the only factor that's important. They've now scrapped any intention to continue with the increased capacity 9 Ah batteries and are selling only the old 6.5 Ah ones, presumably old stock so with shortened life anyway. Prices are getting daft, £250 for those old batteries (incidentally £600 for the pair fitted on the new Twist I), and a new 14 tooth motor chain sprocket, an item that needs replacing from time to time, is now a ridiculous £30. These things, and whether support will continue, make it difficult for me to carry on recommending buying it, despite it's qualities.
.

 

[coops]

Shame.... Oh well, they don't make 'em like they used to...

 

[ITSPETEINIT]

Yes, I appreciate that the Torq's most appropriate use is very much a power-assisted bike, not pure motor powered, and I'm sure it wasn't too happy on those gradients unassisted, its just to get an idea of the useful limits of the motor alone, taking the bike's drivetrain gearing out of the equation to allow analysis of rider & motor's separate contributions to performance of bike as a whole .

I think my estimate of 8-9% for the torq + 76kg rider unassisted was a bit optimistic: with different guesstimated corrections for "drag" at the different speeds of the quando & torq (say 80W @ 12mph & 40W @ ~8.5mph)
and with the peak power output @ ~475W, the predicted gradient limits for a 100kg (bike+rider) unassisted would be:

Torq ~ 7.5%
Quando ~ 11%+

Which, while not exactly what you have found in reality, is near enough (about 1% gradient difference) for me, as a rough guide to motor limits in each bike.

Incidentally, applying the same to your case, Peter, would give (Torq @12mph):

limit of motor alone ~ 6.5%
limit with 100W rider input ~ 8%
limit with 150W rider input ~ 9%

- check my figures & take with a pinch of salt .

Stuart.

Hi everyone who has contributed to this discussion.
Today was a day better than most for weather - Breezy, Sunny, Temp 7C.
Fully charged Li-ion batteries (recharged Last Sunday) were used, stored in an unheated garage.

My first tests were on a CHOPPER:
Weight Bike 25 Kgs + Spare battery + Rider 90kgs = about 120Kgs
1st Hill 7% (1 in 14) Motor Cut out at 8 mph unassisted - restarted after switch off/ then on.
2nd Hill 3% (1 in 30) Motor cut out at 9 mph unassisted - restarted after switch off/then on.
VERY DISAPPOINTING.
It is also worth noting that even on gradients of 1% or 2% (no steeper) the unassisted road speed falls from 12.5 mph to 11mph.

My second Tests were on a Torq (restricted to 15.5 mph);
Weight: (more or less the same as above).
1st Hill 7% (1 in 14) Motor laboured at 8.3 mph but still produced some assistance.
2nd Hill 10% varying to 9%(1 in 10/11) Motor assisted by rider input (very slight) Lowest gear 39 inches - Cadence about 70 rpm Motor produced useful output at 7.8 mph.
I had to rest every 150 metres (or so) when the red light appeared.
VERY ENCOURAGING
The Total Miles covered out and back on one battery (yellow light on at finish when stationary) was 18.5 miles. I was too tired to do more flat miles to see how far the battery would go.

When I recover fully from the virus and get 'limbered up' I shall be able to tackle 10% grades with a rest to recover my breath (legs are OK) every 150 metres, or so.


Peter

 

[flecc]

Hello Peter

Those Chopper tests were very odd and had to be due to either dud battery contacts or a Li-ion battery problem. A correctly working Chopper would never cut on on any hill with an NiMh battery and clean battery contacts, and cut-out shouldn't be that likely with Li-ion on that model. That said, I have had similar cut-outs with Li-ion on both Torq and Quando. The drop to 11 mph is only to be expected though, as it's only geared to do just above that maximum.

The Torq is as expected with that reduced gear set that's on that one. It produces around 280/300 usable watts at about that 8 mph mark, rideable with that 39" gear.

A pity about that Chopper fault, you would have been quite impressed at the hill climb capability of that bike.

I'm pleased that your health is now permitting you doing those tests though, good progress.
.

 

[coops]

ditto

Hi Pete

Glad to hear you're back in the saddle in the better weather & have some encouraging results Thanks for the info.

Ditto Flecc's comments re: the chopper, no personal experience but from what I've read it should be one of if not the best hub motor climbers? Li-ion, again from what I've read, not quite as effective for long/steep hills as NiMH, but all the same, results look suspect to me too...

I didn't allow for your lower gearing (& possible sub 12mph hillclimbing) in my guestimate of gradient limits on your Torq, so better results at 8mph may be possible and that seems to me a reasonable compromise speed.

I've just started a thread here asking how the Torq limiter may affect things like hill-climbing power output, and since you use the Torq restricted you may want to look in in case its useful to you .

Stuart.

 

[ITSPETEINIT]

More Torq and Chopper Tests

Hello Peter

Those Chopper tests were very odd and had to be due to either dud battery contacts or a Li-ion battery problem. A correctly working Chopper would never cut on on any hill with an NiMh battery and clean battery contacts, and cut-out shouldn't be that likely with Li-ion on that model. That said, I have had similar cut-outs with Li-ion on both Torq and Quando. The drop to 11 mph is only to be expected though, as it's only geared to do just above that maximum.

The Torq is as expected with that reduced gear set that's on that one. It produces around 280/300 usable watts at about that 8 mph mark, rideable with that 39" gear.

A pity about that Chopper fault, you would have been quite impressed at the hill climb capability of that bike.

I'm pleased that your health is now permitting you doing those tests though, good progress.
.

I have been in touch with 50Cycles (Jim) and we are working on a diagnosis of the problems. Both the Chooper and the Torq are displaying similar symptoms but the diagnosis may well be different because of the basics of each bike (the Chopper has better climbing ability because it has 20 inch wheels). Here are my test results - not entirely scientific but the best an amateur can do:

E-ZEE CYCLES TESTS – 13th MARCH 2007.
Rider Weight 92.8 KG (204 lbs)
Weather: Dry – Sunny –Temp 10.8ºC – Wind Negligible.
EZee Chopper
Hill 6.5% (no variation on climb) - 260 yards long
Test 1. Battery miles 3.57
Stopped at 8.8 mph unassisted
Diagnostic LED did NOT flash

Test 2. Battery miles 3.88
Did NOT stop – 8.5 mph to the top

Test 3. Battery miles 4.23
Stopped at 8.5 mph unassisted
Diagnostic LED did NOT flash

Test 4. Battery miles 4.57
Did NOT stop – 8.4 mph to top

Test 5. Battery miles 4.90
Stopped at 8.2 mph unassisted
Diagnostic LED did NOT flash

Hill 3.5%
Test 6. Battery miles 7.11
Stopped at 8.8 mph unassisted
Diagnostic LED did NOT flash

Hill 2.5%
Test 7. Battery miles 7.6
Stopped at 9.4 mph unassisted
Diagnostic LED did NOT flash

Total mileage 8.55 miles – Green Light on at rest – last mile stopped 5 times even at 10 mph downhill 1%

EZee TORQ – de-restricted
Hill 6.5% x 260 yds long
1st Test: 11 mph unassisted – stopped after 194 yds – Diagnostic KED did NOT flash

2nd Test: 7.6 mph unassisted – did NOT stop – Red Light on at 17 mph

3rd Test: 8 mph unassisted – did not stop – Red light on at about 16 mph

On the return journey 3.57 miles to 7.14 miles the red light was on at 17,16, &15 mph on the level road.
Your views would be appreciated.
Peter

 

[flecc]

I'll remark on the Torq first, as that is simpler. At 11 mph when it cut out, it's almost at it's maximum current drain against load situation, so that would provoke the greatest voltage drop, with cutout at about 32 volts. This is a situation I recognise well from my own experience with two batteries. This can happen even with a new and healthy battery if the load is applied for long enough

At around 8 mph, the load has lessened and the current demand can be a bit less. In theory, the current demand will be the same, but with some of it wasted at that speed, being well below the power band, only around 300 watts are realised as usable power, so tolerances or resistance could make the current drain fall just short of cutout point.

The Chopper situation is much more difficult to judge. It seems it's marginally near to cutout all the time, and the characteristics suggest chemical exhaustion. It may be that one cell is failing in the affected batteries, this being enough to cause this sort of failure on such low loadings, but equally there might just be a slight controller problem, since the results don't quite fit what's happening with the Torq. It may be that it's cutting out too early.

On the first battery that started to fail for me, it behaved just as badly in the Quando as in the Torq, despite it being the better hill climber as with your Chopper model, and that became unusable in the end, even for the shortest journey on either bike. Since I had an NiMh battery as well, I was able to satisfy myself that the bikes were ok, and that is was solely the battery at fault.

Therefore I still favour it being at least one battery problem.

The Li-ions can show some inconsistency. 50cycles kindly replaced the faulty battery for me, and after that was run in, on a long climb up the downs, it cut out towards the end. As usual then, it cut out three further times before I reached the top, this being due to the fact that time is needed to recover from chemical exhaustion. If I'd waited 15 to 30 minutes after the first cutout, it would have completed the climb without any problem. Since then it's never cut out again in either bike, showing the odd inconsistency I mentioned.
.

 

[ITSPETEINIT]

I'll remark on the Torq first, as that is simpler. At 11 mph when it cut out, it's almost at it's maximum current drain against load situation, so that would provoke the greatest voltage drop, with cutout at about 32 volts. This is a situation I recognise well from my own experience with two batteries. This can happen even with a new and healthy battery if the load is applied for long enough

At around 8 mph, the load has lessened and the current demand can be a bit less. In theory, the current demand will be the same, but with some of it wasted at that speed, being well below the power band, only around 300 watts are realised as usable power, so tolerances or resistance could make the current drain fall just short of cutout point.

The Chopper situation is much more difficult to judge. It seems it's marginally near to cutout all the time, and the characteristics suggest chemical exhaustion. It may be that one cell is failing in the affected batteries, this being enough to cause this sort of failure on such low loadings, but equally there might just be a slight controller problem, since the results don't quite fit what's happening with the Torq. It may be that it's cutting out too early.
Therefore I still favour it being at least one battery problem.
The Li-ions can show some inconsistency.
.

Thanks for the quick response Flecc.
I did say that the "science" of the tests were amateurish.
I realize now, reading your observations: the Tests I did last week were on both bikes on the SAME battery (a Li-ion).
The Tests today were done on two different batteries (both Li-ion).
The Chopper and its battery have done 91 miles.
The Torq and its battery have done 333 miles.
They have both been keept charged up after each use whether of 2 or 3 miles or 10 0r 20 miles.
Does that put a different interpretation on the results of the Tests?
I did notice (but did not report because it was subsequent to those first two rides) this "recovery" factor. On the Torq: Riding a hill about 4% with me assisting in my limited way, I had the red light on. After I had stopped to post a letter (about 2/3 minutes - I wear so many clothes it takes a while to search all my pockets to recall where I put things ) the Green light was more in evidence and even under acceleration only the yellow light came on. But as soon as I reached another "Hill" (2%) the red light was back on until I coasted down the other side, it was back to yellow (Not green).

I had a feeling it was cell exhaustion. My previous experience is only of Lead Acid Batts. When you get a dud cell it's OK when the batt. is fully charged
(as fully as it can be with a dud cell) but as soon as one has given the batt. some grief as with the starter motor on a cold morning the decline in power is quite apparent. Then, after a good drive (like 40 miles) it's back so that you don't know anything is wrong until you try to start the next day and put some real load on it.

Peter

 

[flecc]

I don't think that really alters what I've said Peter. As you've said, this is clearly chemical exhaustion, which these Li-ions show when they are under too heavy a load, or a high load for too long. The cutout guards against the first instantly, while it comes in later with the second as the high load gradually increases the exhaustion to the low voltage point.

The second case is the most common, but I did get the first very dramatically with the Torq when new once. I'd pointed it at a hill which was impossible for both the Torq and me, and we both cut out together in protest! Very much an instant stop on that 20%.
.

 

[ITSPETEINIT]

Torq - The Power to climb hills.

Hi Peter,

(Excuse the lateness - .........

Additionally, it would seem that roughly 8-9% for Flecc or 7-8% for you Peter, is do-able unassisted on a Torq, as a conservative estimate...? How does this compare in reality?

I hope that helps?

Stuart.

I apologise in that I might not have acknowledged your efforts Stuart.
This is the result of a test I ran on my Torq with a fully charged battery less 3 miles to the test ground:

EZee TORQ - de-restricted

Hill 6.5% x 260 yds

1st Test: 11 mph unassisted - stopped after 194 yds - Diagnostic LED did NOT flash

The motor was derestricted. 'Stopped' means the battery cut out.
See my profile for personal data.
I am going to find a 5% hill for a test run as soon as the weather improves
Thanks
Peter

 

[flecc]

Re: Coops quote entry Peter, that Torq climb figure from me was a theory one, I've previously stated that in practice the Torq will barely scrape 7% with a battery straight off the charger, and only 6% is moderately manageable.

So your result on 6.5% is quite normal.
.

 

[ITSPETEINIT]

Torq on hills

Re: Coops quote entry Peter, that Torq climb figure from me was a theory one, I've previously stated that in practice the Torq will barely scrape 7% with a battery straight off the charger, and only 6% is moderately manageable.

So your result on 6.5% is quite normal.
.

Thanks for that Flecc - since I became fixated with the trouble with the Chopper and its battery, every time the Torq stops I get very nervous.
With so many variables (particularly with the riders) there seems to be no normal range of behaviour on hills.
So if the motor unassisted cuts out on hills 6% or above - taking into consideration Health, Age and Strength (see my profile) I propose not to worry. Anyway, there's always the flat.
Peter

 

[flecc]

One final note on the Quando re: our discussion on gears Peter. I've had the Quando rear wheel out as I had a suspicion about the freewheel. My suspicion was correct, it's a BMX freewheel with it's smaller thread size, so a multi sprocket freewheel isn't an option, it's stuck with single speed.
.

 

[coops]

Hey, don't worry Pete I just hope you find a bike solution which meets your requirements. As has been said those figures are at very best only a rough guess, and performance will vary according to level of battery charge etc. etc.... besides, the Torq is I think best used while pedalling.

How's the battery situation now? Did you try the Chopper on your hills with the ok battery, or was that never an option?

Stuart.

 

[ITSPETEINIT]

Chopper Test

Hey, don't worry Pete I just hope you find a bike solution which meets your requirements. As has been said those figures are at very best only a rough guess, and performance will vary according to level of battery charge etc. etc.... besides, the Torq is I think best used while pedalling.
How's the battery situation now? Did you try the Chopper on your hills with the ok battery, or was that never an option?

Stuart.

The more I learn about these bikes (Torq and Chopper) the more anxious I get. It comes from having feeble legs (see my profile) so even pedalling will not make up the neccesary difference to surmount the obstacles in my path.

No, I did not try the Torq with the Chopper's battery (yet), nor the Chopper with the Torq's battery. I must do that: it will tell me a lot. I was on my way to my nemesis (Shaftesbury Hill from the east A30 = 10%) when the "whatever it was" died on the 6.5% hill half way to my project. I tried the hill seven times (without assistance to test the theeory that it would climb almost anything [a garage wall was mentioned at one point but I think that was a motor driving chain, driving cassette 12 - 32 teeth]). Naturally I was disappointed with the result that I did not get up 5 times out of the seven.

For my next trick I took the Torq out unlimited and performed the same test.
The motor stalled at 11 mph on that hill 6.5% x 260 yards when I reached 194 yards.

Here are the full result of the tests;

E-ZEE CYCLES TESTS - 13th MARCH 2007.

Rider Weight 92.8 KG (204 lbs)
Weather: Dry - Sunny -Temp 10.8ºC - Wind Negligible.
EZEE CHOPPER
Hill 6.5% (no variation on climb) - 260 yards long

Test 1. Battery miles 3.57
Stopped at 8.8 mph unassisted
Diagnostic LED did NOT flash

Test 2. Battery miles 3.88
Did NOT stop - 8.5 mph to the top - unassisted

Test 3. Battery miles 4.23
Stopped at 8.5 mph unassisted
Diagnostic LED did NOT flash

Test 4. Battery miles 4.57
Did NOT stop - 8.4 mph to top - unassisted

Test 5. Battery miles 4.90
Stopped at 8.2 mph unassisted
Diagnostic LED did NOT flash
Hill 3.5%

Test 6. Battery miles 7.11
Stopped at 8.8 mph unassisted
Diagnostic LED did NOT flash
Hill 2.5%

Test 7. Battery miles 7.6
Stopped at 9.4 mph unassisted
Diagnostic LED did NOT flash
Total mileage 8.55 miles - Green Light on at rest - last mile stopped 5
times even at 10 mph downhill 1%

EZEE TORQ - de-restricted
Hill 6.5% x 260 yds

1st Test: 11 mph unassisted - stopped after 194 yds - Diagnostic LED did NOT flash
I could not have caught the Key (that can happen but not recently) with my heel 'cos I was not pedalling.
2nd Test: 7.6 mph unassisted - did NOT stop - Red Light on at 17 mph
3rd Test: 8 mph unassisted - did not stop - Red light on at about 16 mph

On the return journey from 3.57 miles to 7.14 miles (on the computer) the
red light was on at 17,16, & 15 mph on level road

After all this I was too bushed to do any more - I recharged the batteries - sent details of the test to Jum at 50 Cycles- and cooked dinner.

The weather on the Wednesday 14th March had changed for the worse - no biking!

Cheers
Peter

 

[coops]

I've read somewhere on this forum about some of the different characteristics of Li batteries, especially on hills, so that's one possibility. If I find the thread, I'll link to it from here.

Since Jim at 50cycles is dealing with this, I wouldn't like to suggest anything which might interfere, but to me common sense would dictate to firstly check if both your Li batteries are performing similarly and also to make sure its not a poor battery connection in the Chopper.

Maybe charge both batteries & check voltage of each when fully charged, meanwhile ensure battery contacts are dry & clean in both bikes (tips aplenty from Flecc).

If you suspect one battery performs poorer than the other, try the better one in chopper in particular, to see if that improves performance.

Hope that helps Pete

P.S. Don't know if you saw my suggestion in your "index for threads" thread, so just thought I'd mention it here for you .