Cake Kalk - Dual Battery?

[fjefman]

I need some help. I have a Cake Kalk & and love the thing but wish I had more range. I'm wondering if I could add a second battery to the bike and use a parallel kit from these folks - https://bicyclemotorworks.com/product/dual-battery-parallel-module/

Wiring it up is straight forward enough...but I have two key questions.

How I figure out what the max AMP draw of the Cake Kalk is? That parallel kit is rated for 120amps max.

How do I know if the controller will throw a weird code if I connect this thing? If both the stock battery and an extra one are hooked up with the controller even know that the second battery is connected?

These might be simple questions but I'm new to this e-moto stuff so still learning. Any guidance is appreciated.

Jeff

 

[amberwolf]

The specs on their page (quoted below for reference if anyone needs them)
Peak Power
Kalk&, INK& 10 kW*
Kalk INK, INK Race, OR, OR Race, AP 11 kW*
Nominal power
5.8 kW

At the listing of
Voltage (nominal)
51.8 V
Capacity
50 Ah / 2.6 kWh

that means peak current should be 11000W / 51.8v = 212.4A. For a 2.6kwh pack, that's about 4C.
nominal should be 5800w / 51.8v = 112A continuous capable, which is about 2C for the 2.6kwh pack load.

So first, your new battery should be chosen to be capable of at least what the old one can do, so that if it ever ends up stuck running the whole load (old one shuts down or fails on a ride for whatever reason), the new one can handle the load without damage or stress.

This means it will probably have to be about the same size or larger than the original, depending on what cells it's made of, to have the same capacity and especially capability. They dont' say which 18650 cell they used, just "premium", so you'd have to decide what to build it from if you build it, or what to have it made from if you buy one, if you want the same "kind" of pack. You could make it (or have it made) from other types of cells like pouches, etc., but they all require compression so the casing has to be built to do this. 18650s have that as part of the cell so the case doesn't have to do it.


Next, as long as both batteries are at the same voltage at the time you parallel them, *and both* their BMSes have common port designs (same port on the BMS for both charge and discharge, rather than separate connections on the BMS for each), you don't "need" a paralleling module.

Such a module *can* add a safety feature, keeping one pack from draining the other if something should go wrong with it, but their primary reason for use is being able to plug in different voltage packs and keeping them from feeding back into each other.

If they are just modules with a pair of schottky diodes (one from each pack input) then you can parallel multiple modules to allow the amount of current you need (at least two of them for the one you're thinking of, for the currents calculated based on the specs).

If they are something more complicated, such as MCU-controlled FETs such as some of the companies selling these claim they are, then paralleling them may or may not work correctly depending on how they are designed (if one of them shuts off from some crash or limitation, the other one wil suddenly have twice the load it did before, and if it's higher than it's capability, it could just go poof and you're stuck powerless until you disconnect the parallelers and directly connect one of the battery packs to your system.


Another option that isn't as helpful as paralleling the packs is to connect them to a marine or solar battery switcher, and then when you run out with one pack, you can stop, shut the system off, switch packs, then turn on and ride away.


Now, none of this will work if your bike has a system that requires communications with the battery to work. Few do, but some are built this way. If your battery only has two wires from it to the bike's systems, it is unlikely to be built this way. If it has two main power wires and some smaller connections as well, it could be built to require this battery.

Battery​

• Cells
  Premium 18650 lithium cells
• Voltage (nominal)
  51.8 V
• Capacity
  50 Ah / 2.6 kWh
• Features
  Removable, can be charged when installed in bike or separately. Built in SoC indicator.

Brake modes​

• Freewheel
  No motorbrake or energy regeneration
• 2-stroke
  Motor brake with energy regeneration
• 4-stroke
  Motor brake with energy regeneration

Brakes​

• Brake type
  Formula motorcycle disc brakes, four piston calipers, alloy levers. Hand lever for front- and rear brake.
• Disc
  Stainless steel, 8.66" mm diameter, 0.13" thickness

Charging​

• 0-100%
  3 hours
• 0-80%
  2 hours
• Charger type
  External charger for standard 110 V outlets

Chassis​

• Frame
  6061-T6 Aluminium, Extruded, Forged, CNC machined, welded and painted.
• Swingarm
  6061-T6 Aluminium, Extruded, Forged, CNC machined, welded and painted.

Controller​

• Features
  Best-in-class power density and state-of-the-art motor control algorithms.

Dashboard​

• Features
  
  
• Kalk INK, INK Race, OR, OR Race, AP
  Dashboard integrated in stem with battery SoC indicator, ride- and brake mode selection, warning indicator
• Kalk&, INK&
  TFT display with battery SoC, speedometer, odometer, trip meter, ride mode selecetion, brake mode selection and telltales.

Dimensions​

• Seat height
  
  
• Kalk&, INK&, AP
  35.83"
• Kalk INK, INK Race, OR, OR Race
  36.46"

​

• Wheel base
  51.57"
• Ground clearance
  11.81"
• Fork angle
  25°
• Trail
  3.44"
• Offset
  0.87" in triple clamps, 1.42" in forks
• Width
  31.89"
• Height to handle
  44.69"

Drivetrain​

• Peak power
  
  
• Kalk&, INK&
  10 kW*
• Kalk INK, INK Race, OR, OR Race, AP
  11 kW*

​

• Nominal power
  5.8 kW

​

• Torque (wheel)
  
  
• Kalk&, INK&
  252 Nm*
• Kalk INK, INK Race, OR, OR Race, AP
  280 Nm*

​

• Torque (motor axle)
  42 Nm

​

• Drivetrain type
  
  
• Kalk INK, INK Race, OR, OR Race, AP, INK&
  Direct drive, 420 chain with O-ring
• Kalk&
  Direct drive, Gates PolyChain GT Carbon

​

• Electric motor type
  Interior permanent magnet motor

​

• Front sprocket
  
  
• Kalk INK, INK Race, OR, OR Race, AP, INK&
  12 teeth chain
• Kalk&
  18 teeth, Gates mudport technology

​

• Rear Sprocket
  
  
• Kalk INK&
  72 Teeth chain
• Kalk INK, INK Race, OR, OR Race, AP
  80 Teeth chain
• Kalk&
  108 teeth belt, Gates mudport technology

Fenders & Bodywork​

• Material
  
  
• Kalk&, INK, INK&, OR
  PC/ABS plastic
• Kalk INK Race, OR Race
  PC/ABS plastic Front fender PP plastic
• Kalk AP
  Recycled fibre-reinforced plastic from Trifilon in fenders and covers.

Handlebar​

• Interface
  1.25"
• Material
  Aerospace grade 7050 aluminium
• Rise
  0.79"
• Width
  31.89"

Regulatory​

• Classification
  
  
• Kalk INK, INK Race, OR, Or Race, AP
  Off-road
• Kalk&, INK&
  Motorcycle*

​

• Licence
  
  
• Kalk INK, INK Race, OR, OR Race, AP
  None*
• Kalk&, INK&
  M1*

Ride modes​

• Explore
  The ultimate mode during exploration. Limited to 28 mph with 3-4 hours of battery range.
• Explore
  Enduro or active trail riding. 1-2 hours riding time
• Excel
  Track and race mode, maximal torque and speed, riding time up to 1 hour.

Speed & Range​

• Top speed
  +90 km/h*

​

• Range
  
  
• Mixed city riding (WMTC-II)
  53 miles*
• Trail/Enduro riding
  3 hours*
• High speed riding (43 mph)
  22 miles*

Stand​

• Kalk INK, INK Race, OR, OR Race, AP
  No stand
• Kalk&, INK&
  Side stand

Suspension​

• Front
  
  
• Kalk INK, INK Race, INK&, AP
  Upside down MX spring forks with rebound adjustment, specially engineered for Kalk. Travel 7.87".
• Kalk&, OR, OR Race
  Öhlins upside-down air forks featuring 1.50" stanchion tubes for extra rigidity and strength, specially developed for Cake. Adjustable for high-speed compression, low-speed compression and low-speed rebound. The forks are equipped with Öhlins advanced 3 stage air springs with individual setup for ride heights and bottoming resistance. Travel 8.03".

​

• Rear
  
  
• Kalk INK, INK Race, INK&, AP
  Direct mounted shock for simplicity and robustness.
• Kalk&, OR, OR Race
  8.07" Öhlins TTX22 shock with CAKE internals and spring. Used with linkage for optimal performance.

Weight​

• Dry weight
  
  
• Kalk INK
  132 lbs
• NK Race
  134 lbs
• Kalk OR
  115 lbs
• Kalk OR Race
  128 lbs
• Kalk AP
  139 lbs
• Kalk INK&
  146 lbs
• Kalk&
  137 lbs

​

• Battery weight
  37.5 lbs

​

• Max. permittable load
  397 lbs (bike + battery + rider)

Wheels & Tires​

• Hubs
  Forged and CNC aluminium CAKE hubs with 25 mm axle

​

• Rims
  
  
• Kalk&, INK, INK&
  19"x1.85” custom designed 7116-T6 aluminium motorcycle rims
• Kalk INK race, OR Race
  Front, 19"x1.40" aluminium mx rims Rear, 18"x1.85" aluminium mx rims
• Kalk AP
  Front & Rear, 1.85"x18" aluminium rims.
• Kalk OR
  24" (bicycle standard) re-inforced, triple chamber, 6061 aluminium.

​

• Tires
  
  
• Kalk &, INK&
  19"x3.00" dual sport motorcycle tires
• Kalk INK Race, OR Race
  Front, 70/100-19 mx tires Rear, 3.00-18 mx tires
• Kalk INK
  19" off-road motorcycle tires
• Kalk OR
  Custom made 24" lightweight off-road tires for durability and minimum trail wear.

​

• *Disclaimers
  The street legal bikes are homologated for the specific country the bike is delivered to. That means that lights, blinkers and other "street legal necessities" might differ in look, style and dimensions, everything to meet the local regulations. Accordingly, details might look different from the product photo. • Images show fully specced vehicles. • The specs, such as range, speed and power are not estimated by CAKE. The numbers are the result from the European homologation test, WMTC-II. (performed in a controlled environment and might differ from regular use) • Peak power is the maximum power the power supply can sustain for a short time. • The actual energy storage capabilities of the battery can vary from the nominal rated capacity. • Torque values based on motor specifications. • Charging time may differ depending on the voltage in the local grid. • All specifications are subject to change without notice. • It is the buyer’s/owner’s responsibility to ensure all local rules, regulations, classifications and license requirements are followed.

 

[calab]

Just use one battery until the battery runs out, disconnect it, and connect the new battery, takes all but a few seconds.

wish I had more range. I'm wondering if I could add a second battery to the bike and use a parallel kit

Louis Rossman made his own parallel adapter with his ebike. I am sure he did not cheap out on the components when he made his own. I am sure he did not do any short cuts in the name of profits.

 

[fjefman]

Just use one battery until the battery runs out, disconnect it, and connect the new battery, takes all but a few seconds.

Huh, so essentially use one of those Marine dual battery switches to switch between one and the other? I like that idea.

 

[fjefman]

@amberwolf thanks for the detail. You know only helped with the answer but laid out the logic so it is easier for me to follow. I suspect you were good at "showing your work" in math class.

I ready it 5+ times and it mostly makes sense. A few comments and some questions.

Can you explain the 4C and 2C comment and why it matters to me?

I can't have a battery as big as there is no room. The battery is huge and takes up all of the space in the center of the bike. I was thinking I can build a triangle battery about 50% of the capacity, but still capable of the same amp capacity (not sure if that is the right way to describe it) and mount it in the space under the seat/against the downtubes.

I do like the switch idea...that would make it easier to manage. But, how do I figure out for sure if the bike needs to talk with the battery? I know there is 5 big wires and a couple small ones going to the main connection points on the controller as well as the multipin connector. I've not followed them straight back to the battery yet to find how where they go...But even if I do trace them how do I know what they do?

 

[amberwolf]

Can you explain the 4C and 2C comment and why it matters to me?

the "C" number is what they call C-rate, which means how high a current the cells can support. It sounds complicated (but isn't) because capacity doesn't in and of itself affect the current delivery, but the C-rate sounds like it does, in that C-rate means how many times the capacity of a cell that it's current capability is:

a 2.5Ah 4C cell can supply 10A (4 x 2.5). A 1C 5Ah cell can supply 5A (1 x 5). Etc.

I can't have a battery as big as there is no room. The battery is huge and takes up all of the space in the center of the bike. I was thinking I can build a triangle battery about 50% of the capacity, but still capable of the same amp capacity (not sure if that is the right way to describe it) and mount it in the space under the seat/against the downtubes.

To be capable of the same amps, it will need much better cells than the ones in the original. (at least twice as good.. at least twice the C-rate). Usually that means that they will be of lower capacity (usually high current cells are low capacity, and vice-versa, for the same physical size).

I do like the switch idea...that would make it easier to manage. But, how do I figure out for sure if the bike needs to talk with the battery? I know there is 5 big wires and a couple small ones going to the main connection points on the controller as well as the multipin connector. I've not followed them straight back to the battery yet to find how where they go...But even if I do trace them how do I know what they do?

That's the catch--you won't know what they do. If there are more connections from the controller to the battery than just main + and -, then it probably communicates with it in some way, and will only operate with that specific battery.

You can do some testing to find out what they do, but messing with them risks causing problems that could prevent the system from operating at all.

The most common way of "communication" is actual serial data over one or two wires plus a ground (if it doesn't use the battery negative as ground). This kind of connection is difficult to work around, as you either have to know what it's asking and what answer to give, or if it is always exactly the same data to "clone" the data with a serial data reader and make something that spits that data out whenever the controller asks.

Another method is not true communication and is much easier to emulate, if the controller is just monitoring an enable line on the battery, which changes from one voltage level to another when it stops working, vs when it is working.

Another is just monitoring something like a temperature sensor of a specific type and resistance range, and if it's outside the limits the controller is programmed for, it errors out.

There are other variations on these, and probably more we haven't seen yet.


If there is only main + and - from controller to battery, it's probably just a regular battery.

 

[leffex]

I second this. My current information is that it will work but I have no way to test it yet or before buying. Also I have other things that will need to be correct if I can use it

 

[fjefman]

@leffex do you have a cake? And are you saying that based on your research it should be possible to run a second battery on a Cake?

@amberwolf thanks again or the explanation...I'm learning fast and your explanations are helping.

My strength is strongly mechanical vs electrical, and I'm more of an experiment and see, rather than calculate and do math kinda guy. So, that said, would it be a stupid idea to get/borrow a decent 52v battery (the voltage of the current cake battery), hook it directly up to the controller with the current battery pulled out of the loop , and with the bike off the ground, see if everything works? I can go easy on the throttle and with no resistance to the wheel I can test this without needing to worry too much about the current delivery of that temp 52v battery.

If that does work then I can make a good second 52v battery and install it with a marine switch in the middle and just switch from one to the other when I need that extra range.

Is this sound logic? Thoughts on a better plan?

Jeff

 

[leffex]

I don't know for sure but I have an older Super Soco that works. But as you can understand something might not work like SoC level on the speedometer display but that is not cruicial for me. I can fix it easy but that ain't the first thing I do usually.

First I want to know if it works and then make it work before going on to fix the last details.

I need a 100% larger battery which means about 4kwh of usable energy. That will make it an option for me. I will build the second battery myself or a whole new battery with the full capacity I need.

 

[fjefman]

Just following up on this one...Can anybody confirm that on my Cake if I talk the current battery out of the system and then wire in another known good 52V battery that this is the best way to test if the controller has to talk to the battery? Seems simple to do this...any specific care I should take?

 

[amberwolf]

No reason it should cause a problem, it'll either work, or not.

Just make sure the test battery connection polarity is correct, voltage is sufficient to run the system but no higher than the full charge voltage of the original, and that the test battery can handle whatever load you're going to put on it during the testing.

 

[fjefman]

Perfect, thanks, let me get my supplies together and try this out. I’ll report back once I do.

I am currently waiting on a new display from cake so this may take a few weeks.

 

[leffex]

Perfect, thanks, let me get my supplies together and try this out. I’ll report back once I do.

I am currently waiting on a new display from cake so this may take a few weeks.

Any news?

My guess is that older models are open whilst the newest bikes may have some other connectors on battery side or both on the battery side and bike to make only their battery compatible.