Kalkhoff: Power assistance and battery pack user manual

[10mph]

Yesterday Tim posted a link to the 50 cyles translation of the latest edition of the Kalkhoff Manual. The new manual says on the cover April 2011 edition. I carefully compared it with the manual which arrived with my Agattu in April, which is clearly an earlier edition. There is no edition date on my manual but there were some points which suggested to me when I first received it that it was a much earlier version:

1. It was copyright 2009
2. The high assistance ratio was given as 1:1.3, whereas the advertising for my 2011 model Agattu said 1:2

I just assumed that the 1:1.3 ratio dated back to the early Panasonic units, which were subsequently upgraded, firstly to 1:1.5 and for the 2011 models to 1:2.

My detailed examination should two significant new things in the April 2011 edition. Firstly the bad news:
Battery Charging Prodedure
In the procedure for battery charging the new manual has two sections, the first is for 8Ah, 10Ah and 12 Ah batteries. The second is for 18Ah batteries, which are new for 2011. The difference is that for A8Ah batteries it says that,

"When all five LEDs on the battery are lit and no longer flashing the battery is fully charged."

The phrase emphasised in bold here is as it is emboldened in the manual. It is obviously intended to make clear the distinction with the instructions for the lower capacity batteries which says,

"When no LEDs remain lit while the battery is on the charger and the charger is plugged into the mains, the battery is fully charged."

This second version is exactly the same as what it said in the manual which came with my bike and I have been following it each time I have charged the battery, allowing the automatic switch off to take place before I remove the battery from the charger. The obvious question is whether my 18Ah battery could have been damaged by not terminating the charge exactly as now instructed in the April version of the user manual.

I have charged the battery 8 times so far, and on each charge I monitor the time for each stage of the charge as indicated by the LEDs. I also monitor the power taken from the mains using a simple mains power meter, so I have a detailed record of each charge.

There is some variability but the average time to charge between the flashing of the LEDs and completion with the charger switching off has been 1hr 21 min. This last charging interval proceeds in two phases. Over the first 54 minutes the power taken from the mains rises gradually from around 67 watts to 70 or 71 watts. It then starts to reduce, slowly at first, and the charger cuts of when the power has fallen to about 29 watts.

Having now serendipitously received these new charging instructions for my 18Ah battery, I will cut down my charging time as instructed. I suppose it will not inconvenience me too much to have to rely on observation to terminate the charge, since I do keep one eye on my battery during charge while I am carrying out other tasks. This might be more awkward for someone hoping to rely on the convenience of an automatic cut-out to safely terminate the charge.

I do wonder whether this new instruction is perhaps not a critical battery safety recommendation to prevent over charging, but rather just good advice as a way of extending the life of the battery by slightly under charging. Fortunately I have ample capacity in this 18Ah battery, so for normal purposes I will be quite happy to terminate the charge earlier. But it would be nice to know that I can, if I ever contemplate an exceptionally long day out, add that extra 1hour 21mins of charging until the charger cuts off.

Now the good news:
Power Assistance Profile
There is a new graph shown in the April 2011 edition:

The differences between this and the old manual are in the speeds. The old manual shows the peak at 15kph, rather than the 22 kph shown now. The cut off is now also higher 28kph rather than 24kph. Also there are now cadence values given 56 rpm and 71 rpm.

Although when I chose the bike I was very happy with what I read about the peak output being very slightly less than my target riding speed of 10 mph, I have since had occasion to rider the bike rather faster. Yesterday I completed an 18 mile round trip to a nearby city, using maximum assistance all the way. Normally I just pootle along around 10-12 mph on minimum assistance unless I hit a steep hill. But yesterday I wanted to throw off my image as a frail elderly rider and show I could burn up the roads, cycleways, towpaths, and bridleways, on a do-good mission to sort out the digital television controls for an 85 year old who had just had her TV converted to Freeview prior to the switchover and had been left with a stupid set of instructions and a new digital controller to master.

My average speed was 13.9 mph (22.4 kph) going out when I kept a bit in hand. On the return I deliberately chose one of the major hills out of the city. The steepest section rose 40 metres (from contour counting) in 822 metres - that is 4.95% average gradient. I averaged 14.1 mph (22.6 kph) up that hill according to track recorded by my GPS. Much to my chagrin there were no bicyclists riding up whom I could zoom past. Just one lady pushing a bike - probably laden with shopping. I really must try that hill just after 5 pm when the commuters on bikes are going home. Overall on the return I averaged 14.5 mph (23.2 kph).

The point about this, especially on the hill, is the bike does seem to give maximum power around 14 mph. I find it impossible to detect when the power cuts off. Perhaps I should try an experiment of riding at 15, 16, 17, 18 mph and just switching off the power and seeing at what speed there is no difference in pedalling required. But it may be difficult to feel very low levels of assistance. Better would be to fit a current indicator. But I am a bit reluctant to pull apart my nice new Agattu to get at the wiring....... unless anyone has done it and can give me a tip.

 

[flecc]

The new power profile is certainly far more useful than the old for most UK riders and matches what most say they want. The old profile's early phase down was unpopular, though it did help extend the range, especially on the earlier smaller capacity batteries.

The revised charging instruction for the 18 Ah battery is a bit disconcerting and many will find it very inconvenient, having to keep the battery under observation. It will be interestig to hear any response on this from Derby Cycles/Kalkhoff or the manufacturer BMZ.

 

[lemmy]

I find it impossible to detect when the power cuts off. Perhaps I should try an experiment of riding at 15, 16, 17, 18 mph and just switching off the power and seeing at what speed there is no difference in pedalling require

I've tried that on my Tasman and I find that it's around 15mph for me. That means that the power assistance is appreciable nearly right up to cut-out point.

My bike has max assistance of 1.3x but even on the steepest bits of the North Downs like Box Hill, I've never needed more than 1:1 and a lower gear. Which must conserve battery power I'd expect, compared to higher power and higher gear.

Max power assistance on my bike is obtained at a shade under 10mph. At that speed in 8th gear and using a nice bit of leg power, most everyday hills don't require a gear change.

I spend a lot of time riding with the power off. The bike rides so smoothly and easily under Lemmy HP (Hamster Power, not Horse!) that it is quite a pleasure. The weight makes it a bit much on longer or steeper hills but hey, that's what the juice is for

 

[Blew it]

Thanks for posting this information 10mph,

My BMZ 18ah battery is being delivered tomorrow. It will be interesting to see if they include any special charging instructions.

 

[NRG]

Something doesn't seem right about this, are you saying you terminate the charge cycle manually by watching the LED status? Surely the termination should be automatic or have I missed something...if you really do terminate manually then I can only think the new 18Ah battery is not compatible with the Panasonic charger.

 

[flecc]

The way I read it that's definitely what is being said, and the continuing charge that 10mph has observed means the LEDs will have to be watched until all are first lit to terminate the charge. I'd think this was linked to the very high cell content density necessary to achieve the high capacity in such a small space. The resulting input resistance could well make the standard charger a slight mismatch.

This also calls into question the capacity. Is it 18 Ah at the rated discharge when charged to LEDs lit, or 18 Ah when charged to it's fullest extent?

 

[andyh2]

Those cadence levels are much perkier than the first Agattus. Looks like an 11t motor sprocket could be over the top on these models, 10t could be spot on though (if there is one!)

 

[NRG]

Not that I've found yet, still looking!

 

[Tim]

Evening all, I'm going to double-check charging indicators with the top man at Derby Cycle tomorrow and get back with clarification as soon as I have it.

 

[10mph]

Something doesn't seem right about this, are you saying you terminate the charge cycle manually by watching the LED status? Surely the termination should be automatic or have I missed something...if you really do terminate manually then I can only think the new 18Ah battery is not compatible with the Panasonic charger.

Yes, that is exactly how I interpret the clear statements in the new manual, and Flecc seems to read it the same way as me.

The new manual mentions the same charger as the old manual one: type NKJ38. However, I have just looked at the bottom of the charger that came with the bike. It says,
No. NKJ044B
Input Ac220-240V 50/60Hz 62 W
Output DC29.3V 1.8A

The actual mains power typically starts around 62 or 63 watts when the battery is first put on charge and then rises as it charges up to a peak of about 70 watts.

I have not yet tried to rig up some leads to measure the actual charging current and to monitor the voltage. I would need a good DVM to ensure accurate measurements. I note that the stated 1.8A for 10 hours would give 18Ah. My initial charge was 12 hours 15 mins. Subsequently, on two occasions when discharged to cut off, the charge time has been around 10hr 45 minutes.

 

[10mph]

Evening all, I'm going to double-check charging indicators with the top man at Derby Cycle tomorrow and get back with clarification as soon as I have it.

Many thanks, Tim. That will be very helpful.

 

[Kenny]

Something doesn't seem right about this, are you saying you terminate the charge cycle manually by watching the LED status? Surely the termination should be automatic or have I missed something...if you really do terminate manually then I can only think the new 18Ah battery is not compatible with the Panasonic charger.

From the Manual :

For the 18 Ah battery pack
1. Plug the charging device into a mains socket. Insert the battery into the slot
provided for it on the charging station.
2. The five LEDs on the battery will flash in turn as the battery is charging,
when all five of the lights are lit and no longer flashing the battery is
fully charged.
3. Remove the battery from the charging station
4. Unplug the charging station.

From this I take it the the signal that the battery is fully charged on the 18ah battery is when all 5 lights are steady lit as opposed to going out as with the 10ah battery.
Although it instructs to remove from the charging station it doesn't say any harm is caused by not turning off right away.

 

[10mph]

In my original post I wrote:

Perhaps I should try an experiment of riding at 15, 16, 17, 18 mph and just switching off the power and seeing at what speed there is no difference in pedalling required.

This morning I found a suitable short hill with a uniform gradient, perhaps around 5%. On the flat before the hill using top gear, I got up to a steady 26 to 26.4 Kph on my GPS, which is 16.15 to 16.4 mph. I maintained the speed up the hill and then hit the power button, instantaneously substantially more pedal force was needed to maintain the speed.

When I rode definitely above the cutout at 29 kph (18mph) there was no noticeable changed when I hit the off button.

This confirms that power profile for the ramp down has been changed from the 2009 versions of the Agattu as is now much more as shown in the April 2011 edition of the Kalkhoff manual, here:


It confirms my suspicions that the peak output is just under 14 mph rather than around 10 mph which my handbook shows for the old model. No wonder I am finding the bike so good at higher speeds!

 

[flecc]

This confirms that power profile for the ramp down has been changed from the 2009 versions of the Agattu as is now much more as shown in the April 2011 edition of the Kalkhoff manual, here:
View attachment 2312

It confirms my suspicions that the peak output is just under 14 mph rather than around 10 mph which my handbook shows for the old model. No wonder I am finding the bike so good at higher speeds!

I had learned of the change a little while ago and tentatively altered some details at the start of the article in my Pansonic website on how these units work, though it needs further amendment now.

The change seems to have probably coincided with the altered chainring and rear sprocket, the chainring now 35 tooth from 41 tooth with the cadences different now.

The alterations eliminating the influence of Japanese e-bike law seem to have been designed to suit the export markets better.

 

[Blew it]

Is this right?

The BMZ 18ah battery arrived at lunchtime.

The charger was switched on and the battery inserted into the charger at 12.20 hrs, first light solid, second light flashing and the consumption meter showing 53 watts. At 1915 hrs the fifth light went solid so the battery was removed from the charger which had consumed 319 watt-hours. At this point I expected the five battery lights to go out, but they didn't.

The battery was then fitted to the bike and the system switched on. The first handlebar light flashed once followed by all three lights solidly lit. While the system is switched on, the battery lights go out, but when the system was switched off all five lights on the battery came back on, and they are still on now.

I have tried a press-and-release, and a press-and-hold of the battery test button, but still the five lights are shining away like a Christmas tree. Needless to say, this battery is spending the night in the garden.

 

[10mph]

The BMZ 18ah battery arrived at lunchtime.

The charger was switched on and the battery inserted into the charger at 12.20 hrs, first light solid, second light flashing and the consumption meter showing 53 watts. At 1915 hrs the fifth light went solid so the battery was removed from the charger which had consumed 319 watt-hours. At this point I expected the five battery lights to go out, but they didn't.

The battery was then fitted to the bike and the system switched on. The first handlebar light flashed once followed by all three lights solidly lit. While the system is switched on, the battery lights go out, but when the system was switched off all five lights on the battery came back on, and they are still on now.

I have tried a press-and-release, and a press-and-hold of the battery test button, but still the five lights are shining away like a Christmas tree. Needless to say, this battery is spending the night in the garden.

That does not sound right, or at any rate it is different from mine.

My BMZ 18Ah arrived in a deep sleep and discharged I think. It took 15 minutes for the first LED even to start flashing and around 12 hours 15 minutes total for the first charge.

When not on the charger the battery lights are off unless I press the battery button and then they stay on for a few seconds only.

If you get no other advice, why don't you try using the bike and watch the discharge pattern. Perhaps it will correct itself on the second charge.

 

[Kenny]

That does not sound right, or at any rate it is different from mine.

My BMZ 18Ah arrived in a deep sleep and discharged I think. It took 25 minutes for the first LED even to start flashing and around 12 hours 23 minutes total for the first charge.

When not on the charger the battery lights are off unless I press the battery button and then they stay on for a few seconds only.

If you get no other advice, why don't you try using the bike and watch the discharge pattern. Perhaps it will correct itself on the second charge.

My battery arrived at 3pm also fully discharged. I expect the charge time will take around twice the time of the 10ah battery so i am going to charge overnight.
Will post tomorrow how I get on.

 

[10mph]

Good luck, Kenny.

 

[Kenny]

Thanks, I just hope Bob's battery is OK. We've all waited a long time for these batteries to arrive and could do without any hitches.

 

[Blew it]

Spending the night in an outside building appears to have awoken the BMS, the lights are now out and the test button functioning correctly. Battery voltage stands at 28.8, having fallen from 28.9 fresh off the charger.

Due to other comittments, it will be Friday before I can carry out any road tests. Confidence in this battery is not particularly high at the moment.

EDIT:

I'm thinking that removing the battery from the charger immediately all lights go solid is interrupting the cell balancing phase of the charging sequence, at constant voltage. It appears the cell balancing continued after the battery was removed from the charger.