Sourcing parts for my first eMoto build

[robertehlers]

I plan on converting a 197X Honda CB 125 into an eMoto for my first build because I want to get more hands on experience with electronics to improve my understanding. I have owned a few Japanese bikes from the 70s but am looking forward to snagging one for an eMoto build.

Being in the US it seems a foolproof system is just to buy a kit from Electro & Co but it sounds like there are a lot of software issues with the Votol EM controllers so I'm not sure if that is still the best idea. My plan here was to get their QS138 70H V3 motor, with a EM260sp controller, and an undetermined battery but roughly 72V 40ah and 280A+.

I originally wanted to build my own battery pack but after watching and reading many build posts I think I should save that for later after I become more familiar with all of this. The Electro & Co kit has the option to add a 76V 40ah 300A battery but this seems slightly non-standard? Seems like nominal voltage is usually 72V then 96V and I didn't want to run into any issues with charger incompatibility. Is there a good source in the US for batteries in the range I am looking? Amazon has a lot but that just seems like it could be hit or miss on quality.

 

[amberwolf]

What job do you want the bike to do for you, under what riding conditions? You'll need to define those to find out how much power it will take to do those things, so that you get sufficiently capable parts.

When you've decided what you want it to do and examine your terrain, wind, etc., you can take that info to simulators / calculators like those at ebikes.ca. With that sim, you can either play with existing setups with your conditions, or define custom setups per the instructions below the graph/chart section, and then see how many watts it takes to overcome worst-case conditions and do the job you need done under them, and then average conditions as well. Then you can also see about what the wh/mile would be for various conditions to get an idea of how big a battery you'll need for the required range minimums.


Battery is the heart of the system, and if it can't supply all the voltage and current the system needs, worst-case, the system can't do what you need it to.

Most randomly-found batteries out there are not very good, at their best. EM3EV makes good batteries, but they're typically meant for ebikes, not motorcycles. Don't know if they still do custom ones. There are probably other good ones out there, but I couldn't point you to any--there are other discussions about good battery sources around the forum, though.

If you were able to build a battery, you could use used large-EV modules (there are a number of threads and posts for packs made this way), and be likely to get better performance and lifespan from those even though they're used, just because of the quality difference between the cells they use and those generally found in separately-sold battery packs for ebikes, scooters, mc's etc.

Regarding battery voltages...you'd have to ask them why they call it a 76v, and get *complete* specs for it including which specific cells are used (and how many series/parallel), BMS model/details, etc. If they won't provide that information, they're hiding something and should probably be avoided. If they don't know that information, then it means they don't have sufficient technical information about their products to properly support them, and they don't make their own stuff either, and are just buying from some other reseller (and may have different sources over time, so you can't even be sure of getting the same replacement parts when needed).

Normally the nominal cell voltage is multiplied by the number of cells in series to give a pack voltage. But not everyone does that, especially when their marketing department gets involved and chooses to use some other number that makes it sound better than it really is (and also incidentally makes it impossible to compare to other sellers/manufacturers).

 

[floydr]

This pack? https://www.electroandcompany.com/product-page/high-power-76v-40ah-li-ion-battery
High Power Stainless Steel Enclosed Battery packs manufactured by Eon Lithium. A 72V charger goes to 84V might even extend the life of the battery only charging it to 4V/cell. 21s @ 3.6 nominal is 75.6V nominal, 21s @ 3.7V nominal is 77.7V nominal. no mention of what cells are used.
later floyd

• 76v (88.2v Max)
• 40ah
• 21s10p 21700 Configuration
• 300A Cont Discharge
• 400A Peak Discharge
• 500A Peak Rated ANT BMS
• 8.25" x 6.25" x 11" Dimensions
• QS8 Discharge Port
• XT90 Charge Port
• 40 AMP Fast Charge Capable
• about 40lb

 

[azeus17]

There is a youtube video where they discuss these batteries. At one point, you can see the label where is states they are Lishen 21700 LA cells in a 21s configuration. E&C has also developed their own controllers for the Razor kits. It seems like they are phasing out of the Votol, but maybe not available for the higher amperage systems yet. I'm just guessing as I have no affiliation.

FWIW, I cobbled together my own components for a dirtbike build. QS 138 v3, fardriver 96850, and a custom battery I had built per my specs. I was able to put it together for less than the QS kit on E&C, but not by much and I do think there is some value in the pre-programming, simplified wiring, etc. that comes with the kit. If you plan to have a custom battery built, I would say skip the kit and order your own components separately. I'm not a fan of the Votol controllers. I have both Votol and Fardriver and I find the Fardriver easier to program, but that's just my opinion...lots of Votols out there, obviously.

 

[robertehlers]

Yes floydr correct, that is the battery I was looking at from E&Cs website.

I just heard from Eon Lithium about my request for more info on the battery. Here is what I received

We use Lishen LR2170LA
Lishen 21700 4000mAh 45A Battery (LR2170LA)

We use fusion strips with copper laser welded on top the nickel taps and we use ANT bms for the models depending on the P group cell count and discharge rate needed.
IP64 304 stainless steel case with silicon seal around the seams.
We source the materials and assemble here and for bulk orders we outsource the lengthy process.
The nickel/copper fusion strips are cut to size to fit the connection points so there is no particular method or design to it unless there is a model we specifically design, and we spot weld each tap to the cells with kweld at 10 joules.
Then the leads it depends on what your connection preference is, we have connectors that people prefer, XT90, XT60, QS8, QS10, etc.