Lol so true, I even swapped out the stock 15t pulleys for 20t pulleys and still problem free. Gear ratio of 1.6:1 versus stock 2.13:1 or 2.53:1 (optional 38t drive gears) I definitely can’t pull this off in a hilly area, especially with 97mm flywheels. With the Kegels, it climbs hills quite okay considering the gear ratio.
I’ve been quite a bit of battery research the last few days. And It really seems to do with the amps getting too high for the battery pack. If you run an efficient drive train system (like enertion), you can do very low amps. I use hubs mostly, so that means amps are even more of a problem. I’m thinking of make a super thick board that has a hollow 2 hollow channels 36 x 330 x 76 mm each. You could fit a vesc-x and 60 cells for a 12s5p (without a bms, which is how I’ve ridden since July with no issues or balancing needed), or a 10s5p with a charging only bms. Total cruiser dimensions will be 34 inch x 8.5 inch x 42 mm chubby board. That would push the amp limit up to 100a con, which should help with the sag.
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10s8p/12s7p packs no sag to report here
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Haven’t been able to get on a long ride since Bara helped me out with my battery issues. Prior to that, high headwinds on flats could cause the low voltage cutoff to trip.
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My daily work commute is 11kms making it 5.5kms each way.
On the way back home from work, the battery would read 89% before leaving the work depot, but at the last main hill at the 4 Km mark, I can actually sag the battery to cut off. After I stop at the top of the hill, the battery would read 60%.
When ever I approach that hill, I have to actually monitor the % and let go the trigger a bit when it hits 2% and it would go up to about 12% till I get to the top. It sure would be nice to just leave that to a program and enjoy the ride.
This issue have got me thinking about going DIY for an AT board if I can find something that would manage the sag by auto slowing down. Would try to keep the GT AT wheels and maybe use that with Enertion motors and a longer board.
Evolve info and weight - Bamboo GT with AT wheels in FAST mode and my weight with backpack is at 100kg/220lbs.
you can see the battery voltage readout by pressing reverse button then scroll down 2 steps. Can even see individual cell voltages.
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That sounds like a really bad technician they have working for evolve… How can they even make a such mistakes?
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I never knew that, i will check it out once i get home later today. Thanks for the info.
I run 12S1P A123. It’s absolutely excellent.charges super fast and I never have enough voltage sag that it’s even noticeable.
edit: by voltage sag I mean a noticeable lack in power/top speed due to a lowering of charge from use or from strain.
awesome. I’m going to do it. what bms are you using? Just gotta find some cells now!
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keep in mind lifepos are a bit heftier and aren’t as energy dense as liion
Hi, we’re wondering why the discussion is around bigger packs when the real problem is that voltage reading alone is an inaccurate fuel gauge? The DIY already has two open source BMS that monitor current and profile battery resistance (Impedance Track, sorry for the caps, but it’s a Texas Instruments trademark. ;-)), DieBieMS and Battman (both are in threads elsewhere.)
Fun (if you’re into it) educational video here: https://youtu.be/A6oeL2ltKL0
An update coming soon will talk about Mellow’s own BMS. Yes, we use all three methods. The BMS is located in the (removable) battery pack itself.
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Many are likely getting readings from inaccurate fuel gauges. How, with the new iphone app I have been developing (Vesc Status), I can monitor sag in live time with the data that the vesc is seeing. This data seems to be accurate, and has shown me that even with a 12s4p 18650 LG HE2 in my config, I sill have a voltage sag of around 25-30% on hills of 20%+ grade. I will add a specific tool in my app to measure voltage sag specifically in the background while you ride so that this can be monitored more accurately in the future by the community. I do agree those fuel gauges are often surprisingly inaccurate. I also use volt monitors on my board which have been very accurate. I calibrated them, and have noticed every time I check, they are within .1 volt of accuracy.
Thanks for dropping in though and giving some perspective 
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I’m working on a company, we use a custom BMS. I will be posting a thread on the forum introducing the brand when we have a date for our Kickstarter.
When discussing voltage sag, it would be helpful to mention terrain. Voltage sag on flats is minimal but can be significant when climbing hills (high current draw). If you live in, say, Florida, you won’t be pulling much current. Hilly terrain is a whole different story, and you may draw in excess of 60A, depending on your setup and current limitations.
An A123 18650 battery has a continuous discharge rating of 30A. Check out the voltage sag in this published diagram. It just seems hard to believe that a 1P pack wouldn’t have noticeable voltage sag, even at 12S
You’re looking at the wrong A123 cell. 26650’s is the lifepo cells people typically talk about which is rated for 70A discharge.
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Roger that. Thanks for the correction
A123 26650
http://www.a123systems.com/Collateral/Documents/English-US/A123%20Systems%20ANR26650%20Data%20Sheet.pdf Samsing 25R 16650
More charts for 25R here: https://www.powerstream.com/p/INR18650-25R-datasheet.pdf