So range and efficiency are really about controller strategies. I suspect that a hub motor with a Panasonic torque sensor and controller would be virtually identical in range to the full Panasonic system.

 

Although I agree with much you've said, I don't fully agree here, ok in theory but not in practice. Although the power/torque spread of our motors is reasonably wide, it still has a narrower area of maximum advantage and it's this area we depend on so much with the extreme limitation of power that the law permits us. So some gearing is really necessary, though as I've written elsewhere, two motor gears would suffice to cover our needs within present speed/power law restriction.

 

We do actually have the type you propose,the Kalkhoff Agattu F has the Panasonic front hub motor coupled to the standard unit's torque sensor and controller system. On test it did not have the high range possibility of the usual unit model, and that wasn't in a hilly area. In a hilly area it would be even more disadvantaged.

 

Therefore Panasonic's latest strategy on these is braking regeneration by the front motor and a large batch of these bikes are on two year trial in Japan to see if they really can do the same job more cheaply.

.

Edited November 3, 201015 yr by flecc

I don't agree either

 

If I didn't want assist I would have bought a normal lightweight bike. I want my electric bike to assist me when I need it most and allow me to cycle normally when I don't. This Panasonic system is simply more effective in what it does compared to a hub motor hence the greater range. If you look at the power plots on ES for both geared and none geared motors you will see that torque is nomwhere near flat vs RPM, power consumption rises very quickly as soon as the motor slows from it's most efficient RPM. As Flecc says a simple two speed gear setting would only be needed to greatly improve hub motors.

I don't agree either

 

If I didn't want assist I would have bought a normal lightweight bike. I want my electric bike to assist me when I need it most and allow me to cycle normally when I don't. This Panasonic system is simply more effective in what it does compared to a hub motor hence the greater range. If you look at the power plots on ES for both geared and none geared motors you will see that torque is nomwhere near flat vs RPM, power consumption rises very quickly as soon as the motor slows from it's most efficient RPM. As Flecc says a simple two speed gear setting would only be needed to greatly improve hub motors.

 

I'll have to dig out the curves for power-efficiency-torque vs rpm. The ones I've seen all have torque along the X-axis.

 

There's an old thread from Flecc http://www.pedelecs.co.uk/forum/technical/716-drive-through-gears-e-bikes.html arguing that driving through the gears is less efficient than driving direct. Curious that we're reaching a different conclusion 3 years later.

 

Multi-gear hub motors would be quite a challenge to engineer!

 

I still think the torque sensor control has a big impact on the range of the Panasonic, perhaps at least as much as any extra efficiency from the drivetrain. One other possible reason for this. Full bore acceleration from 0-10mph sucks battery capacity. It's just about the worst operating regime. Perhaps the torque sensor encourages you to accept much less acceleration and assist during this.

 

I liked your comment "If I didn't want assist I would have bought a normal lightweight bike." ... "allow me to cycle normally when I don't". Yes, that is a dream; An E-bike that compromises normal bicycle behaviiour as little as possible. So least weight, least drag, just enough assist.

I like to dream!

 

There's an old thread from Flecc http://www.pedelecs.co.uk/forum/technical/716-drive-through-gears-e-bikes.html arguing that driving through the gears is less efficient than driving direct. Curious that we're reaching a different conclusion 3 years later.

 

Multi-gear hub motors would be quite a challenge to engineer!

 

That thread was demonstrating that for many in flatter areas hub motors can be more efficient since there were none of the substantial gearing efficiency losses due to their being almost always hub gears used with crank drives like Panasonic at that time, and hardly any choice anyway. I've made the same observation about hub motors at the end of my response to David of Wisper so remain consistent.

 

However, the article still ended in the second part by saying that for optimum hill climbing, geared systems were the way to go.

 

Since then things have moved on anyway, there being a number of more efficient derailleur equipped crank drive systems now from different manufacturers. In addition we have the new generation of more efficient hub gears from Shimano and SRAM which reduce the losses I was speaking of, so that article really needs to be brought up to date in respect of the changes.

 

A two speed epicyclic hub using a single epicyclic is possible of course, but as you say, it presents some difficulty in implementation.

.

Edited November 4, 201015 yr by flecc

i think this is new kalhoff battery

 

Akku 10Ah Panasonic Mittelmotorantrieb Kalkhoff Flyer bei eBay.de: Fahrräder (endet 20.11.10 19:40:50 MEZ)

 

jim

i think this is new kalhoff battery

 

Akku 10Ah Panasonic Mittelmotorantrieb Kalkhoff Flyer bei eBay.de: Fahrräder (endet 20.11.10 19:40:50 MEZ)

 

jim

 

That is £350 at today's exchange rate (without postage)

 

maybe a 2 x 10 ah battery would be a safer option then 1x 18 ah:confused:

i think this is new kalhoff battery

 

Akku 10Ah Panasonic Mittelmotorantrieb Kalkhoff Flyer bei eBay.de: Fahrräder (endet 20.11.10 19:40:50 MEZ)

 

jim

 

I don't think that this is the new battery. The new one isn't 10Ah flavour. Only 8, 12, and 18 for the new one.

 

0-10mph sucks battery capacity. It's just about the worst operating regime. Perhaps the torque sensor encourages you to accept much less acceleration and assist during this.

 

Actually the opposite on the standard Panasonic system. Maximum power is only available from 0 to 9.4 mph, then phasing down towards no power at just under 15 mph. Coupled with this is that the magnetic flux torque sensing system used is most sensitive at low rotations means power delivery and current consumption are maximised in that acceleration phase. In practice that means I've been able to do the odd wheelie off the mark on the flat with the lighter Panasonic equipped bikes like the Lafree Twist Lite.

 

By contrast I'm unable to wheelie on the flat with my rear hub-motor bike that's ideally suited to it, short frame, heavily weight biased at the rear, saddle near to the rear wheel axis, 20" wheel leverage advantage, peak 1000 watts power. It will wheelie up a 1 in 4 hill though.

 

Panasonic unit power delivery explanation

.

Edited November 4, 201015 yr by flecc

i think this is new kalhoff battery

 

Akku 10Ah Panasonic Mittelmotorantrieb Kalkhoff Flyer bei eBay.de: Fahrräder (endet 20.11.10 19:40:50 MEZ)

 

jim

 

10 Ah is the existing Panasonic battery Jim, the new Derby/BMZ ones will be 12 and 18 Ah in the same casing.

 

Meanwhile Panasonic have announced their own 12 Ah which is presumably in the existing casing, in addition to their wider case 15 Ah one which will be changing to 16 Ah soon.

.

Edited November 4, 201015 yr by flecc

I've just posted more information and prices for the batteries here. We're taking advanced orders and deposits on these items now so that we know how many to order in for next Spring.

 

http://www.50cycles.com/images/kalkhoff/new-kalkhoff-battery.jpg

 

Kalkhoff New Battery Technology - 8Ah, 12Ah and 18Ah Lithium electric bike batteries

 

PS The German caption reads "For every need, the right battery".

Edited November 12, 201015 yr by Tim

I've just posted more information and prices for the batteries here. We're taking advanced orders and deposits on these items now so that we know how many to order in for next Spring.

 

http://www.50cycles.com/images/kalkhoff/new-kalkhoff-battery.jpg

 

Kalkhoff New Battery Technology - 8Ah, 12Ah and 18Ah Lithium electric bike batteries

 

PS The German caption reads "For every need, the right battery".

 

Nice graphics showing double the number of charge cycles, nearly double the capacity and double the shelf life. It's disappointing to see that these brave and groundbreaking claims aren't backed up with any increase in warranty period. Is this an indication of the confidence the manufacturer had in these claims?

 

For now, I'll take it as five hundred quid for 2 years cycling. I don't mean to be rude, but blow smoke up someone elses chuff with the meaningless charts.

Nice graphics showing double the number of charge cycles, nearly double the capacity and double the shelf life. It's disappointing to see that these brave and groundbreaking claims aren't backed up with any increase in warranty period. Is this an indication of the confidence the manufacturer had in these claims?

 

For now, I'll take it as five hundred quid for 2 years cycling. I don't mean to be rude, but blow smoke up someone elses chuff with the meaningless charts.

 

Almost all Panasonic 10Ah batteries have lasted well beyond their 2-year warranty. There are many 2007 vintage batteries still giving useful service. They don't suddenly dematerialise after 2 years have elapsed you know. We haven't had final confirmation of the new battery's warranty cover, so you are jumping to conclusions.

Almost all Panasonic 10Ah batteries have lasted well beyond their 2-year warranty. There are many 2007 vintage batteries still giving useful service. They don't suddenly dematerialise after 2 years have elapsed you know. We haven't had final confirmation of the new battery's warranty cover, so you are jumping to conclusions.

 

Good evening Tim

 

It depends on how you define lasts. When a consumer buys a battery with a specified capacity and specified life expectancy guaranteed for two years, that is what they are buying into. Experience shows the batteries are falling short of this.

 

If I only wanted to go to the top of my garden and back, then the battery may, "last" for many years beyond the warranty period. However, if you want to do anything approaching a 20 mile round trip, it won't last 2 years.

 

I suppose what I am saying is, that these batteries are a massively expensive consumable item. Some of the claims made regarding their performance is approaching the misleading. As a rule of thumb, my experience tells me to divide all claims by 2 and only expect to use the battery for the warranty period.

As a leisure cyclist, the battery longevity problem is not so noticeable. Having only covered 1200 miles in 17 months, my battery deterioration through age is quite small compared to a daily commuter who's battery suffers deterioration from both age and a large amount of recharges. I'm reasonably happy with my battery but would maybe be less so if I was a daily commuter.