Project: Carrera Kraken conversion with BBSHD

[mephisto]

Hi guys,

I'm beginning the project to convert a Carrera Kraken which is about 6 years old I believe and has been gathering dust for a while. After researching a lot I'm thinking about a mid drive motor as if later on I feel like using in another bike I can easily do. My idea was to first get a commuter bike in place as I ride a road bike every day, but it seems I can have some more fun converting first a spare bike and see how it goes offroad. I'm a bit geek so I spent the last week researching about what works best.

Here are some pics of the bike:


What I have in mind is to use a BBSHD and a large battery pack 52v 14.8ah (Samsung 30Q cells). Do you guys see any issues judging by the pictures and the bike model? I've come with a list of things that may be an issue:

1. Will I have problems with chain wheel touching the rear side of the frame?
2. Is there a aftermarket plastic/nylon sort of derailer to help keep the chain in place as I've seen some bikes using on single wheel chain?
3. I'm thinking to begin with a 46T lekkie wheel chain, considering I use 54 on my road bike I think 46T or 42T should be a good start?
4. How PAS works? Is it going to work based only on wheel speed using the mag sensor?
5. What connector the 6V volt output uses for lights? I'm thinking about buying some strong LED lights so I'm wondering if there is any reayd to use solution?
6. The gear sensor from gearsensor.com, does it really work well when shifting gears to cut off motor power?
7. Can I connect brake and gearshift to the same cable? I have Hydraulic brakes so I'll need to use some mag sensors.
8. What are the battery connectors like? I'm wondering if I should customise them at both battery and motor or should I follow some recipe/ready connector types?
9. Specific tools required: bafang midrive installation tool, crank arm puller, bottom bracket remover, plastic bonder to glue brake sensors, torque tool to tighten things to the right torque

I've looked at a few suppliers so far:

1- em3ev

• BBSHD + DCP14 = £463
• Lekkie 46T £70
• Gearsensor £35
• 52v 14.8ah 40A (14S5P) battery (30Q) £388
• 58.8v 5A charger with 90% switch £47
• total £966 + £124 shipping = £1091 + possible £20-30 from customs

2- electronbikes

• BBSHD + DCP14 + gear sensor (not sure model) + hydraulic brake sensor = £625
• 52v 15ah 40A battery (30Q) £499
  
• if purchase both as part of a kit with 2A charger£1050
• similar to lekkie chain whell 42T £60
• total £1110 shipped from the UK

I've also seen eunorau-ebike.com, ebikebatteries.co.uk, eclipsebikes.com but it seems they don't offer 52v batteries. Alibaba and aliexpress prices seems similar to em3ev.

I like what em3ev does to the batteries, you really know what is inside and the video that brunopower made in their factory show how much attention they have given to the batteries, that makes me feel inclined to buy from them even though it may take longer. As I'm not in a hurry that would be an option for me.

I understand the weight of BBSHD is around 6.5kg and the battery another 5kg, I've got no problem with that.

Some video tutorials about BBSHD installation that I'll use to guide me through the process:

1. luna cycles #1
2. luna cycles #2
3. rev ebikes

I'm open to ideas, suggestions and any general advice about problems I may face with this setup

Thanks!

 

[Nealh]

Advantage of only charging to 90% is all but lost unless the bms is programmable, cells over time will loose balance.

 

[mephisto]

so the BMS itself is not always balancing the charge? pardon my ignorance as I come from a LIPO background for remote controlled cars, I use to balance charge the battery but the controller itself and balancer is in the charger. The battery only has a wire to inform the voltage delta between the cells.

Is that the same way these batteries for ebikes work as well or the controller that actually balance the cells (BMS) is what actually balance them, meaning every charge is always a balance charge?

 

[awol]

The gear sensor from gearsensor.com, does it really work well when shifting gears to cut off motor power?

1. Can I connect brake and gearshift to the same cable? I have Hydraulic brakes so I'll need to use some mag sensors.

The gear sensor works quite well. I tried without and could not get the hang of pulling the brake for a second on every gear change so I like the sensor, some people say they manage without it.
A splitter cable like this one allows you to connect the gear sensor and the brake cutoff to the same connector.
https://www.ebay.co.uk/itm/Y-Splitter-1T2-Cable-for-Gear-Sensor-Brake-Bafang-8Fun-BBS01-BBS02B-BBSHD/253475428039?hash=item3b045016c7:g:PSMAAOSwhQtaoN1x

 

[Woosh]

so the BMS itself is not always balancing the charge?

we call them BMS but the Chinese tend to call them PCM or protection board.
Their balancing circuit is passive, via bleed resistors Cells with highest voltage are bled until they reach the same voltage as the lowest cell. This function is activated at the end of the charging. The main function of the PCM is to protect the battery from overcharging and under voltage. It makes economic sense when you consider that batteries are usually not serviceable (except for replacing the PCM) but unsatisfactory from the customer's point of view because the battery's life can be extended with the use of active balancing circuit.
Typical passive balancing using 200 Ohms (Rbal = 201 SMD resistors) resistor:

 

[awol]

Is there a aftermarket plastic/nylon sort of derailer to help keep the chain in place as I've seen some bikes using on single wheel chain?

Chain guides like these will help keep the chain in place but you might not need it with a lekkie ring.
https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p4712.m570.l1313.TR12.TRC2.A0.H0.Xchain+guide.TRS0&_nkw=chain+guide&_sacat=0

 

[mephisto]

The gear sensor works quite well. I tried without and could not get the hang of pulling the brake for a second on every gear change so I like the sensor, some people say they manage without it.
A splitter cable like this one allows you to connect the gear sensor and the brake cutoff to the same connector.
https://www.ebay.co.uk/itm/Y-Splitter-1T2-Cable-for-Gear-Sensor-Brake-Bafang-8Fun-BBS01-BBS02B-BBSHD/253475428039?hash=item3b045016c7:g:PSMAAOSwhQtaoN1x

That is exactly what I was looking for thanks! Good to know the gear sensor is useful, so definitely will be on my checkout

we call them BMS but the Chinese tend to call them PCM or protection board.
Their balancing circuit is passive, via bleed resistors Cells with highest voltage are bled until they reach the same voltage as the lowest cell. This function is activated at the end of the charging. The main function of the PCM is to protect the battery from overcharging and under voltage. It makes economic sense when you consider that batteries are usually not serviceable (except for replacing the PCM) but unsatisfactory from the customer's point of view because the battery's life can be extended with the use of active balancing circuit.
Typical passive balancing using 200 Ohms (Rbal = 201 SMD resistors) resistor:

That makes sense, with my LIPOs each cell has a wire back to the charger to balance it, not sure if it just a sensor or if there is actually some sort of electric switch that the battery switch on/off depending of the voltage on each cell?

Chain guides like these will help keep the chain in place but you might not need it with a lekkie ring.
https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p4712.m570.l1313.TR12.TRC2.A0.H0.Xchain+guide.TRS0&_nkw=chain+guide&_sacat=0

another one nailed, thanks!

 

[awol]

If your a bit of a geek and want to charge and balance your battery cells up to 90% then you want a Neptune15 BMS, I think it's great and use it with my Lipo's at the moment and will work with 18650 cells too.
https://www.speedict.com/

 

[richard beadle]

Never slipped a chain with my Lekkie or the standard chain wheel on my bbs02

 

[richard beadle]

Also i would suggest that with the bbshd and its extra weight you might want to consider a full suspension bike, I have two mid drive bikes, one hardtail frome ripley 1 bought brand new, with a tongsheng 500w and a second-hand giant yukon 2 full suspension bouggt for £180 with a 750w bbs02, suffice to say I never us the hardtail now

 

[richard beadle]

1. Possibly the lekkie 46t has about 20mm offset but you can always add a spacer.

2. Not required

3. 46t would be fine for road use I like my 36t for off road stuff

4. Cadence sensor Starts working when you turn the pedals

5. Pass

6. Other people use them I've never bothered.

7. Don't get what you mean, as for hydraulics why not get the hydraulic set off em3ev extra £74 well worth it if your spending that sort of money, they are in the options list.

8. I used andersons and good quality shrink tube on mine I believe if you contact em3ev they will do it for you but you will probably still want to shorten the cables.

9. bafang midrive installation tool absolutely essential in my opinion, otherwise you'll be squeaking after a few 100 miles.


10. You will almost certainly have to re-route your rear derailleur cable from going under the bottom bracket, get some jagwire gear cable housing and run it the full length from shifter to derailleur.

11. Buy plenty of long cable ties and one of those down tube mud guards is a great place to hide wiring behind

 

[anotherkiwi]

The bike taxi guy here has one of those weird trikes with a seat at the back and a roof (IIRC someone on here bought one a couple of years ago). It has a BBS02 36v 500 W motor and the trike weighs 147 kg. He has moped rims and tyres, very large diameter hydraulic disk brakes, a nuvinci hub driving a differential and a very strong single speed chain. Add a couple of passengers (only slim ones fit) and the rider who must be all of 72 kg soaking wet. He is not setting any speed records but that is what that motor is capable of hauling around St-Jean-de-Luz. There are places he will not go because the percentages can get up over 12-13%. A BBSHD would be a good fit for that thing, or any other cargo bike, but I don't seen any use for one on a road bike.

 

[Nealh]

so the BMS itself is not always balancing the charge? pardon my ignorance as I come from a LIPO background for remote controlled cars, I use to balance charge the battery but the controller itself and balancer is in the charger. The battery only has a wire to inform the voltage delta between the cells.

Is that the same way these batteries for ebikes work as well or the controller that actually balance the cells (BMS) is what actually balance them, meaning every charge is always a balance charge?

No, only near the end of the charge 41.5v and above.
The Speedict/Neptune allows you to configure/programme the balancing voltage lower.

With Lipo the balance charger uses the sense/jst wire to monitor the cell voltage, it is the balance charger that reduces the amp charging rate to balance off cells equally. Lipo's have no switching capacity it is purely down to how good the charger is.​

I have a bc68 and a bc168 two totally different balance chargers , one of my lipo's one won't charge as it say's and detects a fault yet the other happily charges and balances it perfectly and in use it discharges perfectly.

 

[anotherkiwi]

My LiPo charges are 35 odd minutes charging and the last 5-8 minutes balancing. You can watch it happen on the LCD on the charger.

 

[mephisto]

If your a bit of a geek and want to charge and balance your battery cells up to 90% then you want a Neptune15 BMS, I think it's great and use it with my Lipo's at the moment and will work with 18650 cells too.
https://www.speedict.com/

that would be for a 2nd project for sure, I've read a lot about it and it seems interesting, just a bit too time consuming for me at the moment considering other projects I have

Never slipped a chain with my Lekkie or the standard chain wheel on my bbs02

ok, that works for me then, so many reports like yours a lekkie sort out many of the problems with chain coming off, I'm sold on that.

I'll check the other replies tomorrow, working flat out today, just got back home after 2 hours on the M25 from Kingston.

 

[awol]

I have a bc68 and a bc168 two totally different balance chargers.

BC168 two - a new version ?

My LiPo charges are 35 odd minutes

What are you using to get the time down to 35 mins?

 

[Nealh]

Don't know why I said I had bc68 & bc168 , confusing myself or cracking up !!!

I have the bc168 which is quite good until it intermittently develops a mind if it's own and often randomly gives erroneous voltage readings on one or two cell banks but still does the job.

The bc68 should have read cb86 which I didn't end up buying and got the SKYRC D100 instead which is quite good.

 

[anotherkiwi]

BC168 two - a new version ?

What are you using to get the time down to 35 mins?

Charging 2 x 10 Ah bricks at 1C with a couple of 20A Turnigy Reaktor chargers (iCharger repackaged) and a 540W power supply. Total charge time with balancing from about 37v is in total 40 minutes for Graphene and 45 minutes for Multistar.

Other stats: the chargers draw 21-22 Amps (total for both) at the beginning and as they get hotter that goes up to about 27 Amps so 82.5% efficiency. If I take the Graphene 36v battery all the way down to 3.65v per cell it takes 58 minutes to charge up to 4.15v per cell. The 10 Ah Graphenes are good for about 9200-9300 mAh in the real world which is fine by me, Multistars 8700 mAh tops.

At my current state of fitness the 36v "9.2 Ah" battery gives me a range of just over 60km.

 

[awol]

Charging 2 x 10 Ah bricks at 1C with a couple of 20A Turnigy Reaktor chargers (iCharger repackaged) and a 540W power supply. Total charge time with balancing from about 37v is in total 40 minutes for Graphene and 45 minutes for Multistar.

Oh you got 2 Reaktor's on the go, lucky you, I've got one of those. Incidentally what volts/rating are your power supplies at?I'm sure my psu was
also when/if you eventually switch to welding cells are you going to continue balance charging as you are doing now or switch to using a BMS ?

 

[anotherkiwi]

Oh you got 2 Reaktor's on the go, lucky you, I've got one of those. Incidentally what volts/rating are your power supplies at?I'm sure my psu was
also when/if you eventually switch to welding cells are you going to continue balance charging as you are doing now or switch to using a BMS ?

18v on the power supply, 30 Amp job so enough juice to keep both happy at 13.5 Amps each counting losses.

I am going to make a 3P10S battery with BMS for a custom battery box on Number Two and will use my 2 Amp charger for that.

For the trike I am going to make a couple of 5P6S bricks without a BMS and balance charge them with the Reaktors then series them for 5P12S 44.4v. My choice is firm on Sanyo 20700 cells. If the balance charging works for me and as my intention is to use the trike for long range I'll weld up another set so have 1.77 kWh on board. With my goal of 250 km a day I'll have 7.1 Wh/km to play with which is more than I use on the upright with the GSM at the moment. Factor in 20 kg of luggage I think I am within reasonable expectations, especially as I am much more efficient on the trike. And I will also carry another 400 Wh of LiPo as a "get me to the next hotel" range extender.