EVG mini E-bike 36V Ni-Mh to LiPo conversion. Orig Batt box.

Ok here's the situation. I'm talking about two nearly zero mile EVG small folding E-Bikes (20" wheels) that I bought many years ago. They both started life as 24V Lithium machines (pioneering in its' decade) from the builder. There were a few consumer charging mishaps (read fires) that forced them (big companies can't afford law suits) to recall all the 24V Lithium batteries and replace them all with the highest quality 36V NI-Mh batteries and chargers at the time (the voltage bump was to replace the peppy 24V Lithiums with saggy 36V NI-Mh for a near same riding sensation). The NI-Mh 30S Ni-Mh were sourced from "Chevon-Ovonics" pack rated at 36V 7Ah, the charger was a "High-Power" badged (typical aluminum cased charger) rated at 1.6 Amp charge rate. Case closed years ago right? No! I want to resurrect these little gems and here's my plan. All of the EVG bikes had a modular battery packs, that means you could easily remove it from the bike and charge it at home, a coffee shop, any AC outlet in the field or at work. I want the same convenience with the Li-Po upgrade so here's my plan for the mini E-Bike folders. Two of these batteries; http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=39526 in parallel.
That gets me 8Ah lithium vs 7Ah Ni-mh also a cheap 42V 2Amp charger I bought here; http://www.all-battery.com/TenergySmart ... 01338.aspx
Both batteries and the charger (2 Amp 37V nominal, 42V final voltage no BMS or balancing) will fit into the original removable battery box. I'm a little concerned about the charger being in there because it has a fan that runs while it's working. I guess I could open up the stock batt box with "vents" but I think it would be more "KISS" to keep the small charger separate (with its' 3' AC cord) and store it to the bike into a small under seat bag. That way the rider could simply unlatch the Battery box, grab the small charger from the under set bag and be on their way to remotly charge easily without the bike, light and simple.

I converted one so far of the two I have and man is it peppy and quick. The stock gearing is definitely geared for 24V applications. I don't know where to go from here. I could curb it back with 24V (29V) li-pos, I could up the front chain ring size for more assisted speed, or sell as-is as basically a moped in a tiny folding form factor. I'm betting on the latter. This little guy breaks down small enough that I could fit it in a large suitcase. I was thinking small airplane pilots or boat people but due to the the broken down size and the performance i'm experiencing.... skys the limit.
Give me your thoughts guys.
BK

Great input fellows. My real concerns is that charger being in the battery case and not having enough ventilation, second how to balance the RC li-pos from time to time, 3rd how to inform the operator about SOC "state of charge"? I think the OEM system is calibrated for a 24V SLA system, this will will work but only when the Lipo is way discharged.
BK

There's only one good solution imo, and even though I don't use them, in this case, I'd install a 10s bms in the case with the batteries, and have the charger separate, they could carry with them if needed. I'd try and get the bms cutoff at 3.3V if possible for rc lipo. That will let them use 99% soc and mot over drain the pack. I'd also install a volt meter if the bike doesn't have one and tell them to recharge when it gets to to 37V resting. That will give them the choice of running them dry to 33V, or making them last longer. And make sure you tell them not to fully charge and let sit fully charged more than overnight to extend battery life.

Thanks for the input. I was thinking about the same thing but cannot find a 10S BMS that is readily available or simple. Are you privy to these devises? Also if so, do they have the ability to prevent over charging a cell during the 2 amp bulk charge cycle and also detect a cell going south or soft during dis-charge?
TIA,
BK

For lipo, they are usually referred to as PCM's. Should be able to find lots of them.
https://www.google.com/search?client=ubuntu&channel=fs&q=10s+lipo+pcm&ie=utf-8&oe=utf-8
They limit charge and discharge voltages on a per cell basis. On discharge if any cell reaches lvc, it shuts the pack off. This seems to be a popular model.
http://www.bmsbattery.com/smart/330-lifepo4lithium-ion-smart-bms-for-513-cells-in-series.html

Hello Brian.....nice ebikes. I've got four of these, with two 36v Yellow's, and two Red 24v's.

I've used a donor 36v EVG ebike (LE) and upgraded one of the yellow 36v mini's by using the 36v controller/throttle/front/rear lights and shock seat post. I'm too using the HK Nano Tech 22.2v/8ah & a 18.5v/8ah for a 46.2v/8ah pack that fit in the battery compartment. I wired a + & - wire from controller, with 5.5mm bullets, to plug into the HK NanoTech battery pack. And am using a iMax B6AC & a cheapy 48v chinese charger with balancers to charge packs. I too will use a third 22.2v battery in parallel for a 3 pack for range. The other yellow 36v is using the stock controller and using the same 46v battery pack. One of the red 24v now uses the yellow 36v controller, and the other red 24v is using a Europa 36v controller and throttle, with both using the same 46v battery pack.

The front chainring on all have been upgraded to a 46t and using a rear 7 spd 11t/30t rear freewheel for high end pedaling.

Oh, I've also got 14 other EVG ebikes in all the combinations available. My favorites being the 36v SX and LE (Police version). These are cheap to purchase used (excellent condition), though are limited to only a 20mph top end limit with the stock controller and the stock noisy heinzmann brushed geared rear hub with the 46v Nano battery packs. These too have been upgraded to 46t front chainring (some case trimming needed), and 11t/30t rear freewheels.

BTW, is that a Tidalforce IO 750 cruiser seat you've got on your yellow mini? I also have 7 of these ebikes. Which are my first choice to ride.

I have an original 36v (42v charged) lithium battery box. I've been meaning to upgrade it with fresh 18650 cells, once I can find someone local that is qualified to set it up.

KEEP THE BIKES.

Kit
S.CA

Kauaikit, that's some collection. I think I should rename myself Mililani-kid (Oahu) for respect or comfortableness, (is that a word)? I have two EVG E-Bike mini folders, one yellow one black, they are like new and stored indoors. I also have 5-7 full size 26" wheeled bikes from the same maker, all in differents states of operation, again all indoor stored. My Tidalforce collection is; #1(One) iO stepthrough bought for my mom, I transplanted 2 HobbyKing 8AH 5S into the front hub. 3 years of use and never balanced, works great. #2 (Two) iO (male) cruiser with many modifications, mostly aesthetic. Installed a Imperial 3G springer fork w/triple clamps working a 24" Sun Rhyno lite rim with a Sturmey Archer drum brake via black spokes and a 2.4" tire filled with a 2.4mm tube from the downhill folks, it's my daily driver pulling the dog. #3 (three) an off the shelf red S-750 with nearly no use, it's still stock and works great. Lastly and my favorite, #4(four) the WHIP! The 1st TF bike I ever bought was a Montague folder with the "X" software installed from a de-linceded DUI convicted driver, he used it to get to work and back. He said he moved and the bike couldn't fill his needs anymore, whatever!! I bought it and have been happy as a clam ever since. I transplanted this power system into a "Giant WARP DS" brand full suspension bike. I sold the Montague folder locally at asking price. Ah shit the kids are calling, i'll TTYL
BK

kauaikit said:

Hello Brian.....nice ebikes. I've got four of these, with two 36v Yellow's, and two Red 24v's.

I've used a donor 36v EVG ebike (LE) and upgraded one of the yellow 36v mini's by using the 36v controller/throttle/front/rear lights and shock seat post. I'm too using the HK Nano Tech 22.2v/8ah & a 18.5v/8ah for a 46.2v/8ah pack that fit in the battery compartment. I wired a + & - wire from controller, with 5.5mm bullets, to plug into the HK NanoTech battery pack. And am using a iMax B6AC & a cheapy 48v chinese charger with balancers to charge packs. I too will use a third 22.2v battery in parallel for a 3 pack for range. The other yellow 36v is using the stock controller and using the same 46v battery pack. One of the red 24v now uses the yellow 36v controller, and the other red 24v is using a Europa 36v controller and throttle, with both using the same 46v battery pack.

The front chainring on all have been upgraded to a 46t and using a rear 7 spd 11t/30t rear freewheel for high end pedaling.

Oh, I've also got 14 other EVG ebikes in all the combinations available. My favorites being the 36v SX and LE (Police version). These are cheap to purchase used (excellent condition), though are limited to only a 20mph top end limit with the stock controller and the stock noisy heinzmann brushed geared rear hub with the 46v Nano battery packs. These too have been upgraded to 46t front chainring (some case trimming needed), and 11t/30t rear freewheels.

BTW, is that a Tidalforce IO 750 cruiser seat you've got on your yellow mini? I also have 7 of these ebikes. Which are my first choice to ride.

I have an original 36v (42v charged) lithium battery box. I've been meaning to upgrade it with fresh 18650 cells, once I can find someone local that is qualified to set it up.

KEEP THE BIKES.

Kit
S.CA

Click to expand...

Hey Brian....BTW, I too have 8 of the Tidalforce ebikes.

Interesting how you put 2 HK lipo batteries in the front hub. Personally I removed the front battery hub, installed a 26" shimano dyno hub disc wheel to power a Planet Bike LED light (w/blinky). Then installed an Avid BB7 caliper for upgraded braking. I'm using the HK Nano tech lithium, with one 22.2v/8ah and one 18.5v/8ah for a 46.2v/8ah and then run an identical pack in series for a 46.2v/16ah pack that I put on a topeak spring loaded rack. It only weighs 10lbs.

This gives an X bike a level speed of 31.5mph (195lb) for a easy 12 mile ride, though generally I cruise in the 25mph range. This too included a 52t front chainring for increased pedaling assist.

Golden Motor has just brought out their newest MP4 rear hub, though they are now using an internal sine-wave controller. The same style used on the TF. It too is dead silent vs the noisy heizmann geared brushed hub. I installed a "kit" on a EVG PE (Police Edition) ebike. With a 50v lithium (2 22.2v/8ah Nano Tech) battery it pulls right up to 25mph and cruises again in dead silence. A 60v battery will give it a 28mph level speed.

I mention this, because they make it too in a 20" wheel. I almost order a second hub to try on an EVG ebike mini. I'd still to try one.....soon, as I'm told it goes right to 22mph. But I ordered a second 26" MP4 hub in a High Speed winding to get another EVG PE ebike to 34mph.

The 24v/400watt hub on the mini's can take 50v, and it's simple drop in of two HK 22.2v/8ah batteries, after runninga + & - wire with 5.5mm bullets soldered to connect to the battery.

Though you could too setup a 18650 cell battery pack, with BMS, @ the 50v range and install in the original battery box.

Kit
kauaikit@earthlink.net

Kit,
You're killing me. 1st off bravo for being an ebike nut. 2nd for trumping my collection. We should talk.
Brian
PS I've tried most makes and models but my hands down fav is the TF X with RC Lithumn

you really should not be selling lipo based stuff to novices who have no idea of what they are getting. you mentioned early in the thread about companies getting sued but act like you cannot be sued. that could be a surprise for you.

i doubt if the original lithium packs were lipo. i would assume they were poorly made lifepo4 packs that had problems remaining balanced until they finally had to give up because of the need to replace so many of them, not from lawsuits. you may see a lawsuit though if your hack causes a fire.

A copy of my latest email about selling the EVG min folder. FYI
Hi Mike,
Your questions. "What condition is it in? How long have you had it. How much are you asking for it, etc?".
The condition is like new, Original tires have perfect tread and even the warning label on the folding feature control arm is still attached, a true time capsule of this model. This was an original release of one of the 1st "Lithium" powered electric bikes from any large company. They had a recall due to some safety issue or concern and replaced (at no cost to owners) the removable (small lunch box sized) 24V Lithium battery and separate charger, with a 36V nimh battery (Chevron-Ovonics cells, top of the line pack then) and separate charger, the reason for the voltage change was to account for voltage "sag" of nimh batteries under high load or amp demands vs. the "stiff" discharge characteristics of lithium to give the owners a similar riding experience. Nimh batteries have mortality over time or "shelf life". No matter how well you treat them, they will lose muster over time, period. I've owned this bike for about 7 years (your 2nd question), that was enough time to let the nimh battery become useless, i'm very well versed on batteries and tried every trick I could to keep it going but time said no. That was a blessing in disguise, you see I got into a new hobby of remote controlled cars, helicopters, planes and quad-copters/drones about 5 years ago. The battery advancement in that arena has been fantastic (size, weight and cost) and I have recently applied it to this bike (well all of my bikes) and it's a win-win-win. The removable (small lunch box sized) 36V 7 amp-hr. aged nimh battery I replaced now sports a 36V 8 amp-hr Lithium battery and charger all within the same convenient quickly removable case! It's a fantastic upgrade. 1st, Light as a feather compared to what the old battery weighed and with the built in charger you can pop into a Starbucks for a coffee and a top up charge discreetly without a bulky separate charge unit and its wiring. 2nd the power of the new tech battery is amazing, very quick acceleration and higher top speed all the way till the end of the charge. 3rd range, 36V 8 amp-hr (new lithium) vs. 36V 7 amp-hour (old nimh)may not seem like much but it's not that simple, i'd guesstimate a 50% improvement while enjoying near fresh off the charger performance the entire time. That's why I called it a win-win-win.
Price....????
Brian

So, Brian......you still ebiking?!? I am, and in fact the "collection" has grown!

KB