Old School Marin Build

[billsy]

Hi Guys

I'm in the planning stages of my second ebike and thought I'd start a thread cos I'm going to need a bit of guidance this time round and of course others might benefit. I have decided I need to have full suspension and just happened to have a Marin Rift Zone sat in the garage gathering dust. I never really considered converting it before as there was just no easy way to mount my 48v 20ah ping pack on the bike. Then just recently I started looking into a DIY battery pack made up of Headway 38140S cells, 16 in series to make 48v 12ah, and was surprised how cheap you can find them. The best quote I have so far is from BMSbattery.com which came in at £224 delivered to the UK. For those that don't know, these 12ah cells are good for 120A continuous discharge. You can get bigger capacity Headways but the price climbs pretty quick after the 12ah one's. My commute is about 8 miles round trip and my current bike uses around 8/9 AH so I figure the 12ah capacity will be just about right.

BMSbattery gets mixed reviews, has anyone used them recently?

Motor
I plan to use one of the latest Nine Continent rear hubs, just need to figure out which number of windings to go with to match or better my current bikes top (no pedal) speed of 31/32mph.

Controller
Infineon 40A probably

Brakes
I would like to keep the hydraulic disc brakes on if poss. I will need to check the clearance for the 9C hub!


Ok here are some pictures.
The bike as it is now. I bought the frame, forks and rear shock off eBay a couple of years ago and had it built up by a local guy that runs a bike shop from his shed. He's very good!

The next few are my first mock up of where I think the pack should go. I still need to figure out how to mount, protect and cover the battery in this location. I want it to be solid so I can go off road and not be limited to commuting as with my current bike.

I will try and keep this up to date.

Cheers

Chris

 

[LI-ghtcycle]

Looks like a good start! Are those cells bare or in a case? I don't know what motor would give you 32 with that battery, but I would imagine, it would be on the slow side getting there. I can tell you with that battery and a standard 30A controller, I get 27 MPH with a 9 X 7, but if you run higher amps/volts I'm sure you can get the speed you want. I know there are different windings of 9C motors, but it seems most of the faster windings suffer at the low end, but with the 9 X 7 it seems you can just add a higher amp controller and voltage and still keep the low-end torque. I know that some have achieved 40 MPH with 60A and 72V, so I imagine you could scale that down a bit for 32.

 

[billsy]

Looks like a good start! Are those cells bare or in a case? I don't know what motor would give you 32 with that battery, but I would imagine, it would be on the slow side getting there. I can tell you with that battery and a standard 30A controller, I get 27 MPH with a 9 X 7, but if you run higher amps/volts I'm sure you can get the speed you want. I know there are different windings of 9C motors, but it seems most of the faster windings suffer at the low end, but with the 9 X 7 it seems you can just add a higher amp controller and voltage and still keep the low-end torque. I know that some have achieved 40 MPH with 60A and 72V, so I imagine you could scale that down a bit for 32.

Yes the cells are bare in the mock up. The only thing I added was the orange building blocks. I think I will be attaching them to a back plate mounted on the frame and then box them in some how.

Is the 9 x 7 you refer to an older 9c or is that another name for one of the current range of motors? If so which one? I intend to use a 40A controller, so based on what your saying, I should hit 30 (hoping)

Cheers

 

[billsy]

Quick question chaps

I was just about to order a BMS from Ping to go with the 16S Headway cells from BMSbattery (not ordered yet) and the Ping charger that I already have, and remembered reading that the Ping chargers are set at quite a high voltage. Thinking about it I'm sure my ping charger is set at 60V which is obviously above the recommended 58.4V for the Headway's. Is it going to be a problem charging the Headway cells to 0.1V above the recommended? I'm thinking 0.1V is nothing to worry about. What are your thoughts on this?

 

[BIG BEAM]

I think the 38120S Headways are 10ah batteries

I tested mine and none made it to 10ah but a few were close.(3.60v charged to 2.50v discharge)
DON

One more thing I learned about Headways,when you're charging them,when they get to 3.55v or so they are almost charged.Mine only take about 250ma-300ma to get from 3.55v -3.60.

SORRY I JUST REREAD YOUR POST AND YOU'RE GETTING THE 38140S HON,WHERE'S MY #* GLASSES

 

[BIG BEAM]

This might help
http://ebikes.ca/simulator/
DON

 

[billsy]

This might help
http://ebikes.ca/simulator/
DON

Thanks for the link Don. I've had a play with that and I'm a bit confused. The simulator reports a much higher MPH for the 2805 than for the 2807 9C motors, I was under the impression that more windings meant higher RPM? Have I got this wrong?

Are the reported speeds based on the maximum RPM of the motor, for example with the wheel lifted off the ground?

Cheers

Chris

 

[liveforphysics]

Each turn creates an additional chunk of BEMF increase. All these blocks stack in series to equal the total BEMF. As BEMF increases, it acts the same as if pack voltage decreased.

Therefore, the less turns, the slower BEMF grows, and the higher RPMs are capable or a given voltage.

More turns means each amp of phase current creates a stronger magnetic field, and higher torque output. However, it requires a proportionately higher voltage to get the same current draw, so they end up exactly balanced.

What doesn't balance is the stress placed on the controller, but these motors are very easy on controllers anyways, so it's not a big factor here.

If you can find it, the 8-turn 9C is the motor capable of the highest continuous torque. (64 pieces of wire in each slot). The 9x7 is a close second with 63 pieces in the slot.

 

[LI-ghtcycle]

Looks like a good start! Are those cells bare or in a case? I don't know what motor would give you 32 with that battery, but I would imagine, it would be on the slow side getting there. I can tell you with that battery and a standard 30A controller, I get 27 MPH with a 9 X 7, but if you run higher amps/volts I'm sure you can get the speed you want. I know there are different windings of 9C motors, but it seems most of the faster windings suffer at the low end, but with the 9 X 7 it seems you can just add a higher amp controller and voltage and still keep the low-end torque. I know that some have achieved 40 MPH with 60A and 72V, so I imagine you could scale that down a bit for 32.

Yes the cells are bare in the mock up. The only thing I added was the orange building blocks. I think I will be attaching them to a back plate mounted on the frame and then box them in some how.

Is the 9 x 7 you refer to an older 9c or is that another name for one of the current range of motors? If so which one? I intend to use a 40A controller, so based on what your saying, I should hit 30 (hoping)

Cheers

The 9 x 7 motor that I am referring to is the specific type of 9c motor. You can get one the cheapest probably from Cell Man or in the used section here. I have one I would be willing to sell if you are interested, but I'd want to sell it as a kit, not just the motor.

Your probably going to get really close to what you are looking for with a 40 amp controller, but IMO, if I am going to expect 30 MPH under most conditions, (cooler temps, strong winds, up most hills, hauling cargo, etc.) I would actually build it for 40 MPH, and then you can just use your throttle to keep it closer to 30 since a under-stressed motor, controller and battery are going to be much happier than one being pushed more to it's limits. The other thing you really need to consider too is aerodynamics, I forget the practical cut-off, but I think most people find that 30 MPH+ is where aerodynamics really start to come into play.

Good luck, and post pictures!

 

[billsy]

Each turn creates an additional chunk of BEMF increase. All these blocks stack in series to equal the total BEMF. As BEMF increases, it acts the same as if pack voltage decreased.

Therefore, the less turns, the slower BEMF grows, and the higher RPMs are capable or a given voltage.

More turns means each amp of phase current creates a stronger magnetic field, and higher torque output. However, it requires a proportionately higher voltage to get the same current draw, so they end up exactly balanced.

What doesn't balance is the stress placed on the controller, but these motors are very easy on controllers anyways, so it's not a big factor here.

If you can find it, the 8-turn 9C is the motor capable of the highest continuous torque. (64 pieces of wire in each slot). The 9x7 is a close second with 63 pieces in the slot.

I had to resort to Wikipedia to understand that my friend. So basicaly the Counter-electromotive force, opposes the original applied voltage and so more turns require more input voltage to get the same end result. Or something like that

How would one identify a 9x8 and 9x7 motor? I suppose they look the same on the surface?

Thanks

 

[billsy]

Looks like a good start! Are those cells bare or in a case? I don't know what motor would give you 32 with that battery, but I would imagine, it would be on the slow side getting there. I can tell you with that battery and a standard 30A controller, I get 27 MPH with a 9 X 7, but if you run higher amps/volts I'm sure you can get the speed you want. I know there are different windings of 9C motors, but it seems most of the faster windings suffer at the low end, but with the 9 X 7 it seems you can just add a higher amp controller and voltage and still keep the low-end torque. I know that some have achieved 40 MPH with 60A and 72V, so I imagine you could scale that down a bit for 32.

Yes the cells are bare in the mock up. The only thing I added was the orange building blocks. I think I will be attaching them to a back plate mounted on the frame and then box them in some how.

Is the 9 x 7 you refer to an older 9c or is that another name for one of the current range of motors? If so which one? I intend to use a 40A controller, so based on what your saying, I should hit 30 (hoping)

Cheers

The 9 x 7 motor that I am referring to is the specific type of 9c motor. You can get one the cheapest probably from Cell Man or in the used section here. I have one I would be willing to sell if you are interested, but I'd want to sell it as a kit, not just the motor.

Your probably going to get really close to what you are looking for with a 40 amp controller, but IMO, if I am going to expect 30 MPH under most conditions, (cooler temps, strong winds, up most hills, hauling cargo, etc.) I would actually build it for 40 MPH, and then you can just use your throttle to keep it closer to 30 since a under-stressed motor, controller and battery are going to be much happier than one being pushed more to it's limits. The other thing you really need to consider too is aerodynamics, I forget the practical cut-off, but I think most people find that 30 MPH+ is where aerodynamics really start to come into play.

Good luck, and post pictures!

What would the kit contain? It'll be a pain to post it to the UK tho right?

I think having a 30ish MPH limit at full throttle will be fast enough for me to be honest.

Cheers

 

[billsy]

I have ordered the following from BMSbattery. Here's hoping for a speedy service!!

18 x 12Ah 38140S cells
22 x 38120 Holders
22 x 38120 Connectors

I thought it would be good to order a couple extra cells for obvious reasons.

I'm also assuming that the Holders and Connectors will fit the 38140S cells even though they are labelled 38120 on the site, the two cell types have the same diameter. Ordered a few extra of these too.

 

[knoxie]

8)

Love the old Marins!! my mate had a B17 that was awesome and another friend had an East Peak in red which is one of the nicest bikes I have ridden it was so smooth.

9C is a good choice, there is a dealer in Europe for them now but they look like they only ship the kits not just the wheels, I think they make a good alternative the X5 motor as they are a lot lighter, still love the X5 though.

Just saw you ordered the Life cells after I wrote the text below however if you do decide to go lipo at any point

*****************************************************************************************************************************************************************************************

Batteries look ok but have you thought of Lipo? I run 50V of lipo, so light and easy to stash on the bike!! I got 50V at 10AH from Hobbyking, use a 4 channel RC balancing charger to charge them and buzzers to monitor them cheap and easy and not messing with BMS (they can be more trouble than they are worth to be honest)

The German warehouse is stocking them at the moment, make sure you select the order as a gift and its under 15 dollars worth else you will have to pay a bit to the post office

Less connections to make off! only 4 in total, look at my build thread to see how I did it. I could in theory pull 60C from this pack 8)

http://endless-sphere.com/forums/viewtopic.php?f=14&t=19399&hilit=knoxie+gets+some+new+toys

you could get 4 packs for 240 dollars thats £151! 30 quid to ship roughly. weigh roughly 7lbs for the whole thing with no like a volt sag under 40A loads 8)

Good luck with the build will be watching with interest

 

[billsy]

9C is a good choice, there is a dealer in Europe for them now but they look like they only ship the kits not just the wheels, I think they make a good alternative the X5 motor as they are a lot lighter, still love the X5 though.

Knoxie

Which European supplier are you referring to for the 9C motors? I’ll check them out.

It looks like there are some good deals to be had on Lipo at the moment. I should have done a bit more research really. Is Lipo as volatile as all those YouTube vids make it out to be?

Cheers

 

[knoxie]

http://www.ebikewheel.com

They may sell you just the hub? worth an ask.

Lipo is great! I have been using Lipo for 5 years or so just started using these RC packs, they are amazing in both terms of price and performance and weight, go check out the dimensions and the performance on hobbyking, their site was down last night but checking back the german site has these in at the moment.

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=10357

60 dollars and if you hang about looking at the page without doing nothing they sometimes offer you a better price! box will just pop up saying not sure how about x amount! pretty cool

I ordered mine from Hong Kong which was a little stressful at the time as they were in the midst of cracking down on shipping Lipo by air, they dont seem to have the same issues coming from Germany, postage is a lot cheaper as well and they will get to you much quicker, I can get stuff shipped from Germany via my work over night for AM delivery which is cool! I doubt I would be that desperate for lipo but you never know!!

Never had a single pack catch fire and I have abused them, the worst I have had is a pack puff up on an old big old tech lipo battery (not an RC battery) you have your batts on order and they look fine, but you can always make an excuse for another pack...a range extender ha ha.

Good luck with the bike, it looks great love those Marins

 

[billsy]

Guys I need some help finally deciding which 9C motor to go for. I have studied the simulator at ebikes.ca but I’m unsure how to relate the results to the real world. However I do want one of the new motors (that Justin is just about to get a shipment of) and will probably buy a kit plus extras from him. I'm definitely leaning towards a 2806 mainly because it is labelled as "NC26R_Fast" on his site.

I'm 80% convinced that the 2806 will do 30mph (no pedal) with 48V and 40A controller. Does 30 sound about right?

 

[billsy]

Anticipating a delivery of headway cells in the next few days (fingers crossed), I have a couple of questions.

Firstly can anyone tell me how much heat (if any) the 12AH cells will generate at 3C? I will be boxing them in with either 0.8 titanium or 1.0 Aluminium sheet so I guess this will act a bit like a heatsink. Or will I need a vent?

Secondly I am thinking of using a light thread locking compound on the terminal screws, the sort of stuff that you would use on your spoke nipples so they don't vibrate loose but you can still make adjustments. I can't think of any problems doing this as long as the electrical bond between the bus bar and the cell remain clean. Anyone else doing this?

Edit 1. Just found this. Look at page 18. They have a strip type insert along a given length of the thread. I used to use something similar on milling cutter inserts.

http://www.longloklocking.com/pdf/handbook.pdf

Edit 2. If only they did a metric version There must be someone selling them!!

 

[999zip999]

I think you well love the headways at lest it is 16 cells not 64 or more. and a high c-rate. What bms ? What a bms ? Would that be a 60amp. ? If one is used ?

 

[billsy]

I think you well love the headways at lest it is 16 cells not 64 or more. and a high c-rate. What bms ? What a bms ? Would that be a 60amp. ? If one is used ?

Yes I will be using a BMS. I've ordered a V2.5 from Ping and a 2A charger set to 58.4V

 

[BIG BEAM]

I use 12 Headways in a sealed wooden box and also use a 9c and draw 25A max .The batteries never even got hot.The black box got hotter than the batteries.I'd say that the hottest they got was 90F and the outside of the box was the same.

But I'm changing to 2 saddle bags from leather up.Going for that elitist professor look.Now all I need is a pipe!
DON

 

[billsy]

I use 12 Headways in a sealed wooden box and also use a 9c and draw 25A max .The batteries never even got hot.The black box got hotter than the batteries.I'd say that the hottest they got was 90F and the outside of the box was the same.

But I'm changing to 2 saddle bags from leather up.Going for that elitist professor look.Now all I need is a pipe!
DON

Nice one. I'll just seal em up and monitor temps for the first few rides then.

While I'm here. The high rate Ping BMS will allow 60-70 amps continuous and 100 amps peak for 1 second. It also has a much lower working temperature than the standard Ping BMS.

 

[Mark_A_W]

At 25-30A continuous, my 20 headway cells sealed in a fibreglass box get very warm to the touch. You can hold your hand on them, but they are really quite warm (IR thermometer is on it's way).

But they are over 2yrs old now (12,000km) - the old paper wrapped 10Ah cells.


I wouldn't really pull more than about 40A peak/24A continuous out of a 10Ah cell - unless they have drastically improved.

 

[billsy]

At 25-30A continuous, my 20 headway cells sealed in a fibreglass box get very warm to the touch. You can hold your hand on them, but they are really quite warm (IR thermometer is on it's way).

But they are over 2yrs old now (12,000km) - the old paper wrapped 10Ah cells.


I wouldn't really pull more than about 40A peak/24A continuous out of a 10Ah cell - unless they have drastically improved.

Mark
Are your 10ah cells still rapped in tape inside the fibreglass box? Nice build by the way.

 

[billsy]

I'm thinking of copying a friends idea of using one of these as an on/off switch. They are rated at 100 amps continuous at 24 volts which sounds good enough to me for a 48 volt setup can anyone see a problem with this? Appart from me being a copy cat! :wink:

 

[999zip999]

I had many problems with 40 amps. on my bmc it would give a hmmmm. in a graling tune. It finnaly got a c.a. turn it down to 25amps. I would ask how many amps a 9c can take a solwer high torque would take more ? If using on hills and that is it use or a tailor not speed. I think if you over amp. it will not only over heat but it has some rambling inside the motor hmmm. Of coarse I just made that of but I do beleive it ? I do hear it. Yes ?