R Martin EVD Moped with HubMonster

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Re: R Martin EVD Moped with HubMonster

Post by ElectricGod » Feb 01, 2018 2:31 pm

John in CR wrote:
Jan 31, 2018 9:00 pm
FWIW, you wouldn't drive from the bolt flange for the rim. Just use the disc brake mount for the sprocket. That's how I'll use one for the off road moto I want. Of course there's a 2wd one planned too, but that will be with them in-wheel of course. I need to get EG's help on controller for that one though...maybe we can work a trade.
Hey! I said that too about the motor.

I've been hunting for another of these motors or moped. I did find a motor a couple of weeks ago, but it had already been sold. If I want to drive 1800 miles, I found another R Martin. I was hoping for something a bit closer. Maybe I can get the seller to crate up the bike and ship it to me.

I am preparing LIPO packs for the R Martin. Since it's 100% functional at 16S, that's what I'm shooting for right now. upgrading to 32S is more complicated, but will happen in time. Anyway, I already had 2 16S LIPO packs all made up with BMS and then have 2 20S LIPO packs that I'll reduce to 16S and add BMS to them. I might buy 2 more 10,000mah packs to complete another 16S pack and use the 2 left over packs from these 20S packs. Yesterday I received 8 16,000mah LIPO packs to make into more packs. This will allow me to vet out the moped and find any problems with it and have decent range. Later, I'll redeploy all those LIPOs into 32S. I think I have about 72,000mah at 16S right now. That ought to get me around town for now and maybe 40-50 miles of range. I need to buy more 16S BMS. Once the packs are down in the battery tunnel, they won't be easily accessible for battery maintenance or external balancing. I need BMS on all of them. This is the cheapest way to get the EV on the road without incurring massive SLA weight penalties or upgrading straight to 32S. This many LIPO packs fills like 25% of the battery space, weighs as much as a single SLA and has 22,000mah more capacity than the entire SLA pack. I bet I get zero sag too!

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These are all 10,000mah packs.

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Re: R Martin EVD Moped with HubMonster

Post by John in CR » Feb 01, 2018 11:10 pm

ElectricGod wrote:
Feb 01, 2018 2:31 pm
...This is the cheapest way to get the EV on the road without incurring massive SLA weight penalties or upgrading straight to 32S.

Actually it's not, and you can have a far far safer much longer lived pack as well for cheaper.

ElectricGod wrote:
Feb 01, 2018 2:31 pm
I bet I get zero sag too!

LOL! Don't we all wish that was possible.

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Re: R Martin EVD Moped with HubMonster

Post by ElectricGod » Feb 02, 2018 1:08 am

John in CR wrote:
Feb 01, 2018 11:10 pm
ElectricGod wrote:
Feb 01, 2018 2:31 pm
...This is the cheapest way to get the EV on the road without incurring massive SLA weight penalties or upgrading straight to 32S.

Actually it's not, and you can have a far far safer much longer lived pack as well for cheaper.

ElectricGod wrote:
Feb 01, 2018 2:31 pm
I bet I get zero sag too!

LOL! Don't we all wish that was possible.
What's this uber cheap and far superior pack option I should be looking at? Whatever it is, it doesn't use my LIPO packs that I already have. Lipo is pretty safe. I'm not overly concerned about them exploding or catching fire.

Adding a few more LIPOs to what I already have is why this is cheaper. I already own a lot of LIPO packs that will be used in the Martin for now. I'm just augmenting what I already have with a few more LIPO packs. Later, I'll build one out of 21700's or possibly LTO pouches.
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Tell me I'm insane or not...LOL

Post by ElectricGod » Feb 02, 2018 6:46 pm

I have this idea...

Please feel free to point out the flaws in my logic or where I flat out missed things, made mistakes or you know something I don't. That's the whole idea.


1. Make a custom tooth count stator. So that there is enough teeth to wind 2 or 3 adjacent teeth in the same direction and have 3 or 6 phases.

2. I want to remove the factory magnets. They are typically the same width as a single stator tooth. I want to replace them with magnets that are as wide as 2 or 3 stator teeth. That depends on the stator tooth count and if you are winding 2 or 3 teeth.

3. Start from an empty stator.

4. Depending on the stator tooth count, adjacent 2 or 3 stator teeth would be wound in the same direction. This effectively makes them into a single stator tooth.

5. Typically you wind 3 adjacent stator teeth forward/reverse/forward. I want to wind 2 or 3 adjacent teeth all forward, then 2 or 3 teeth all reverse and then 2 or 3 teeth all forward again. I also want to have 3 or 6 phases.

6. There is an implication which to my limited experience sounds absolutely fantastic. KV is based on turns per tooth. Since you are winding wire in the same direction around 2 or 3 teeth, you've effectively dropped Kv by 2 or 3X (I think). Well that's great if you want a really slow motor such as a hub, but this in an outrunner and I want something like 4000 RPMs. So then put 1/3 (ish) as many turns on the 3 adjacent teeth to get back to the original Kv. Now for the cool part. Turns of wire takes up space on the stator teeth. Since each tooth now has 1/3 as many turns on it, it's about 66% less full. Use 66% more copper per turn. This means each phase is now 66% more capable of handling current. A 10kw motor ideally becomes a 30kw motor. Right?

7. The kv is going to be higher...probably 2X or 3X higher depending on if you wind 2 or 3 adjacent teeth the same direction. This is because turns per tooth define Kv and you've reduced the number of teeth quite a lot. This sounds like it means the opposite of number 6. I frankly don't understand the implications in this area yet.

8. If there's 6 phases, then there's now half as many teeth per motor on top of the 2 or 3 tooth adjacent winds. I think this too will increase Kv by 2X.

9. Pole counts will go down significantly so eRPM constraints will matter less despite the higher Kv...hopefully.

10. Adjacently wound teeth in the same direction and lower pole counts also means fewer transitions per rotation and therefore less iron losses.

Conclusion: Wont this make for a motor that has 2-3X more current handling, probably has a somewhat higher Kv and has a much lower overall stator and magnet count so fewer transitions per rotation which reduces iron losses.

Like I said earlier tear it apart, point out the logic flaws or missteps I made, add additional ideas, corrections and so on. I'm certainly no expert on this. I've wound 2 outrunners. I just found out about 6 phase motors a few weeks ago. What do I know? LOL!

I also posted this in the motor tech section.
Last edited by ElectricGod on Feb 02, 2018 10:13 pm, edited 2 times in total.
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Re: R Martin EVD Moped with HubMonster

Post by fechter » Feb 02, 2018 7:29 pm

Most brushless motors will have a stator tooth count that is a multiple of 3. Magnet count is always a multiple of 2.
If using overlapping windings, each winding counts as one tooth, even if there are 3 teeth inside the winding.
The iron losses are largely from hysteresis and eddy currents, so by reducing the magnet count, iron losses will be less for a given RPM.
Overlapping windings will have more copper losses in the end winds compared to salient or concentrated pole winds. The increased copper losses might cancel out reduction in iron losses.

I'll have to think about this a bit more, there's a lot going on.
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Re: R Martin EVD Moped with HubMonster

Post by ElectricGod » Feb 02, 2018 7:49 pm

fechter wrote:
Feb 02, 2018 7:29 pm
Most brushless motors will have a stator tooth count that is a multiple of 3. Magnet count is always a multiple of 2.
If using overlapping windings, each winding counts as one tooth, even if there are 3 teeth inside the winding.
The iron losses are largely from hysteresis and eddy currents, so by reducing the magnet count, iron losses will be less for a given RPM.
Overlapping windings will have more copper losses in the end winds compared to salient or concentrated pole winds. The increased copper losses might cancel out reduction in iron losses.

I'll have to think about this a bit more, there's a lot going on.
I knew what typical BLDC stator and magnet counts were. I should have stated that up front. I assumed that was obvious what with number one mentioning making specific tooth count stators. Of course my statement about finding a 26 tooth outrunner was incorrect. I've revised this thing 4 or 5 times. I missed that one. I edited it to correct this over sight. There's probably 3 or 4 more mistakes I've made and missed.
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Re: R Martin EVD Moped with HubMonster

Post by John in CR » Feb 02, 2018 9:55 pm

You diving down a rabbit hole. When you divide the slot and pole count by half (everything else the same), it will significantly increase Kv, maybe by more than 2x (I haven't chased that rabbit far enough to say exactly). For someone who can do their own controllers there's no benefit to going 6 phase over 3 phase.

If you want to design a motor then I'd suggest starting with a look at Miles' thread in the Motor section where he shares a lot of the process in designing his very high efficiency lightweight motor.

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Re: R Martin EVD Moped with HubMonster

Post by ElectricGod » Feb 02, 2018 10:19 pm

John in CR wrote:
Feb 02, 2018 9:55 pm
You diving down a rabbit hole. When you divide the slot and pole count by half (everything else the same), it will significantly increase Kv, maybe by more than 2x (I haven't chased that rabbit far enough to say exactly). For someone who can do their own controllers there's no benefit to going 6 phase over 3 phase.

If you want to design a motor then I'd suggest starting with a look at Miles' thread in the Motor section where he shares a lot of the process in designing his very high efficiency lightweight motor.
The idea spun off of what you said about the hubmonster. SO I thought is it possible to make a motor that's 6 phase or 3 phase that winds multiple stator teeth as one tooth and apply larger magnets that span that same amount of teeth. Then I thought what's the implications of doing this?

Increased Kv was clearly one of my suspicions.

Designing my own motor...yeah I guess you are right...that's where this is heading. For now, it's a mental exercise to get my mind wrapped around some of the implications that I find interesting.
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Re: R Martin EVD Moped with HubMonster

Post by MrDude_1 » Feb 03, 2018 11:02 pm

ElectricGod wrote:
Feb 01, 2018 2:31 pm

I've been hunting for another of these motors or moped. I did find a motor a couple of weeks ago, but it had already been sold. If I want to drive 1800 miles, I found another R Martin. I was hoping for something a bit closer. Maybe I can get the seller to crate up the bike and ship it to me.

If you happen to find one in the southeastern US, could you send me a PM?

My brother is a bit of a moped/scooter fan and hes showing an interest in electrics. Id love to get him out of his modded GY6 stuff and into EVs... and if he doesnt like it, I'll ride the thing. lol.
Warning:This post is being read via light, a substance known to the state of California to cause cancer.

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Re: R Martin EVD Moped with HubMonster

Post by ElectricGod » Feb 04, 2018 12:19 am

MrDude_1 wrote:
Feb 03, 2018 11:02 pm
ElectricGod wrote:
Feb 01, 2018 2:31 pm

I've been hunting for another of these motors or moped. I did find a motor a couple of weeks ago, but it had already been sold. If I want to drive 1800 miles, I found another R Martin. I was hoping for something a bit closer. Maybe I can get the seller to crate up the bike and ship it to me.

If you happen to find one in the southeastern US, could you send me a PM?

My brother is a bit of a moped/scooter fan and hes showing an interest in electrics. Id love to get him out of his modded GY6 stuff and into EVs... and if he doesnt like it, I'll ride the thing. lol.
Google for "Rmartin for sale". I found one in Alabama.
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Re: R Martin EVD Moped with HubMonster

Post by Voltron » Feb 05, 2018 6:00 pm

Craigslist is great for that...
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Re: R Martin EVD Moped with HubMonster

Post by ElectricGod » Feb 05, 2018 6:33 pm

Voltron wrote:
Feb 05, 2018 6:00 pm
Craigslist is great for that...

scoots.JPG
where are those located? How much?
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Re: R Martin EVD Moped with HubMonster

Post by Voltron » Feb 05, 2018 8:27 pm

They're in Santa Barbara... sent you a pm about maybe selling.

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Re: R Martin EVD Moped with HubMonster

Post by ElectricGod » Feb 09, 2018 11:24 pm

I've been putting together batteries for the RMartin.

I had all of these 10,000 mah LIPO packs except for 2 so I bought a couple more to make this 30Ah pack. There's 3 banks of 16S so they each get their own BMS. I had 2 identical 16S BMS and one from another source. I've bought another 16S BMS for another 10,000 mah pack.

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Partly into building the 30Ah pack, I thought it looked really close to the same size as a 50Ah SLA. Sure enough, they weigh almost the same amount too. Except that it's 30Ah at 66 volts as compared to 50Ah at 12 volts or 3.3X more capacity than the SLA at the same weight.

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I also have 26 LTO cells. I'm still waiting for hardware to arrive for screwing the tabs together and I'm getting super cap protection boards to protect the LTO cells from over charging. I'm toying with the idea of going with LTO's for the entire 131 volt pack. They are heavier than any other lithium solution and have less capacity, but they also don't have problems with the cold, are 50% the cost of Multistar packs per Ah and have about 10,000 charge cycles. This could be very compelling despite the weight and size.

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All of this will go into the moped at 66 volts for now until I have the electrical mods done and am ready to move to 32S or 131 volts. It's about 62Ah total.

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There's also 8 16,000mah LIPO packs that I might put in the Martin for a while. The idea is use what I have now and slowly build out the permanent pack as I have money for more batteries. All of these LIPO's can be reconfigured however I want.

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Re: R Martin EVD Moped with HubMonster

Post by John in CR » Feb 11, 2018 2:48 pm

ElectricGod wrote:
Feb 09, 2018 11:24 pm
Partly into building the 30Ah pack, I thought it looked really close to the same size as a 50Ah SLA. Sure enough, they weigh almost the same amount too. Except that it's 30Ah at 66 volts as compared to 50Ah at 12 volts or 3.3X more capacity than the SLA at the same weight.
More like 6X the real world capacity of lead. That 50ah for the lead is at a 20 hour discharge rate, and Peukert's Effect hits lead hard. Plus if you discharge more deeply than 80% you kill lead rapidly. That means lead only has about 50% of its rated capacity as useful capacity.

The LTO's otoh sound great. Is there a public source to buy them at half the price of the MultiStars? You may not be afraid of the lipo, but you should be with that size pack. I had a brand new balanced pack of lipos stored in a climate controlled room flame out after sitting untouched for a month. Sure I've used RC lipo's, but I charge where a fire can do no harm.

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Re: R Martin EVD Moped with HubMonster

Post by ElectricGod » Feb 11, 2018 5:57 pm

I can get LTO's in the USA for $8.33 per 11Ah cell. Probably a bit cheaper if I bought lots more at the same time. Since there's no need for a BMS, this makes for a cheap power storage source. I've read stories of them getting damaged, smashed and punctured and nothing happens.

I've never had an issue with LIPO...not ever and I have hundreds of LIPO cells. Some are in RC packs and others are individual cells. They don't do anything, but sit there. Your incident makes me wonder if something else happened...like your BMS shorted out or a cell had a weak spot in the pouch that gave way. Some reason for the failure beyond "catching fire just sitting there."

Maybe my LIPO pack is already going to be way better than the SLA's and do it at 1/5th the weight. And I have more LIPOs too.
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Re: R Martin EVD Moped with HubMonster

Post by John in CR » Feb 11, 2018 7:12 pm

Yes, the little 4s RC lipo pack was just sitting there for at least a month on a table with each pack spaced apart about 5" after I checked a new shipment of 20 packs for balance. It was in our fan ventilated guest house that no one but me entered, so I know for a fact that they were undisturbed. I was just lucky that I didn't trust any RC lipo pack until I've used them for some cycle, which is why I had the packs spaced apart, and thermal runaway isn't too big a deal with just four 5ah cells as long as there's ventilation for the smoke.

LFP explained that what must have happened was a tiny bit of grit or whatever got in one of the layers during manufacture and eventually it lead to a microscopic reaction creating a short or local temperature change that led to thermal runaway. While my event was quite rare, my research turned up other such incidents, so it's not unique. No doubt most lipo fires are due to human mistakes and/or charger failures, but the "I've had lots of lipo packs and nothing ever happened, so they must be safe." attitude is one that can get you killed. I still have several kwh of lipo, but they're stored or unattended while on a bike in a place where they can do no real harm, but especially considering their relatively short life I won't be buying any more.

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Re: R Martin EVD Moped with HubMonster

Post by ElectricGod » Feb 12, 2018 4:28 am

John in CR wrote:
Feb 11, 2018 7:12 pm
Yes, the little 4s RC lipo pack was just sitting there for at least a month on a table with each pack spaced apart about 5" after I checked a new shipment of 20 packs for balance. It was in our fan ventilated guest house that no one but me entered, so I know for a fact that they were undisturbed. I was just lucky that I didn't trust any RC lipo pack until I've used them for some cycle, which is why I had the packs spaced apart, and thermal runaway isn't too big a deal with just four 5ah cells as long as there's ventilation for the smoke.

LFP explained that what must have happened was a tiny bit of grit or whatever got in one of the layers during manufacture and eventually it lead to a microscopic reaction creating a short or local temperature change that led to thermal runaway. While my event was quite rare, my research turned up other such incidents, so it's not unique. No doubt most lipo fires are due to human mistakes and/or charger failures, but the "I've had lots of lipo packs and nothing ever happened, so they must be safe." attitude is one that can get you killed. I still have several kwh of lipo, but they're stored or unattended while on a bike in a place where they can do no real harm, but especially considering their relatively short life I won't be buying any more.
Good points...still...never had a problem and there have been a few times that I've done some awfully stupid things with LIPO's.
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Re: R Martin EVD Moped with HubMonster

Post by John in CR » Feb 12, 2018 8:15 am

I hope your luck doesn't run out. I'm glad I learned the lesson with nothing more than losing one pack and having to clean soot off of a table. Plenty of others haven't been so lucky, and it's quite likely we've lost at least one forum member to lipo and never known about it.

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Re: R Martin EVD Moped with HubMonster

Post by ElectricGod » Feb 12, 2018 12:06 pm

John in CR wrote:
Feb 12, 2018 8:15 am
I hope your luck doesn't run out. I'm glad I learned the lesson with nothing more than losing one pack and having to clean soot off of a table. Plenty of others haven't been so lucky, and it's quite likely we've lost at least one forum member to lipo and never known about it.
I've heard the LIPO FUD before. LIPOs catch fire, LIPOs explode, and so on. Everything can kill you including death. If a meteor falls on my head, then it will happen and fearing it happening won't stop it from happening. I choose to NOT live in fear of the "maybe could be's". I'm going to continue using LIPO for various things and of course explore other options too. Ever see the super car wreck that Top Gear host Richard Hammond had? That was on LION and the battery fire went on and on. It happens, but it's NOT the normal thing to happen. If it was, then LIPO would never get used EVER. Controllers fry from time to time. You won't see people stop using motor controllers becasue a random one stops working or a cap blows up inside. I used to do a lot of RC stuff. I've had so many high speed wrecks that destroyed my heli or plane, that I've lost count. Not once, not EVER did I have a LIPO battery fire or even the possibility of a fire. I don't believe in luck. I own far more LIPO's now than I did back in my RC days. My so called "LIPO fire risk" is easily 10X higher now than it ever was 10 years ago. Not only do I have far more LIPO packs now, but they are for the most part 10,000mah or higher and put together into 16-24S strings. Things go wrong...they do...but that's not the typical behavior.
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