Putting LiFePO4 in an Oxygen Lepton
Hi, I'm a newbie and I've recently purchased an Oxygen Lepton. My first order of business is to extend the range and upgrade to LiFePO4. Second order of business will be to make the scooter faster, but I will deal with that later. Right now I am asking everyones help to figure out the best combination of batteries for my application.
My needs: I need a 48V (do leptons react well to over-volting to 60v?) battery pack with at least 40-50Ah. The battery pack must also be easily removable (this shouldn't be a problem because of the location of the battery compartment on the letpton) so that I can take my battery into my apartment to charge it.
Restrictions: -Battery pack dimensions must be less than 19.5 cm wide X 17.5 cm tall X 65 cm long
-Scooter has regenerative braking (how does this affect the BMS?)
-Controller takes an input voltage of 48v and 70 Amps constant and 120 Amps peak
-Controller outputs 35V and 60Amps constant 100 Amps peak
-Weight must be less than 30kg
-Price must be less than $2000 with shipping, charger, and BMS. I would be willing to pay $2500 for higher Ah and/or proven quality. However, if the quality is dubious I would prefer to pay as little as possible.
I have minimal experience with electronics, so I would appreciate any help any of you can provide.
There used to be a number of lepton owners here, and I don't think anyone ever figured out how to modify them for more speed or torque. The lepton uses a smart controller and speed control system, so even if you upgrade to 60 volts, and even if it will run on 60V it will yield no more performance.
As far as LiFePO4's, there are lots of options, if you have enough money, about $3000 you can get Valence U-charge batteries which come in the same size as the batteries that are probably in it now. or for cheaper, you might be able to fit 16 Thundersky 40 ah cells - but they will require some home-building of a battery management system. Thunderskys can be had from Electric Motorsport for $100 each. Valences can be had from Runaboutcycles.com (Josh Kerson) Just google these.
Don't be fooled with these bring rated at 40ah. They will actually deliver considerable more usable range than 40ah lead acid batteries, as LiFePO4's exhibit little Peukerts effect.
To make it faster you may be able to fit the biggest tire on the rear that will fit the rim but this will hurt hill climbing some and may require modifying scooter for extra clearance. The speed increase will not be dramatic though. As far as lithium batteries, there is an ebay seller pingping227 who could make you a custom pack. You should also ask for a quote with a 5-10 amp charger instead of the 2 amp standard charger. You would likely need 48V and at least 40ah of capacity just to handle to the large current draws especially if you will be using the scooter on a lot of hills and in a lot of stop and go traffic.
Todd already pioneer in this method....ask Electric motorsport for more experience.....we have 4 pcs Lithium battery sample in hand of Todd too,it is much bigger torque and quicker speed than lithium Oxygon .
Are those the thunderskys? Last time I measured they would not fit. Also what is the discharge rate of the thunderskys?
what is your required range? Some SAFT NiMH might work. I found some decent prices on some here:
http://www.septechnologies.biz that I may consider for a range extender on my bike.
I'm not really interested in NiMH, but I am considering the thunderskys. If I was to use 16 thunderskys, which BMS should I use?
BMS's are not very available right now. Some people, aren't using BMS's at all, which isn't advisable unless you have money to burn replacing over charged and over discharged cells (at least the LFP cells won't burn violently or explode).
Two people in the endless sphere forum are developing a good BMS, which may initially be just in kit form. Go here:
On the thundersky group on yahoo!groups they tend to like a BMS from reap systems. www.reapsystems.co.uk
Some answers about the Lepton:
I have a few, more than 20,000 miles combined. There were two versions sold in the US; one with an external charger (Zivan, mounted under the seat) and internal in the controller (7 amps). Basically you can use any battery you want if you are willing to forego the Autonomy (range) display.
A lithium pack is the best. It shaves ~80 lbs off the lead pack (better acceleration, easier to handle), and has more capacity. I am running HiPower 50 Ah cells; 16 fit comfortably in battery space (room left over for a BMS). Thundersky 40 Ah also fit well.
Charging? Even though I built a BMS, I use it rarely. After 5 years on the HiPowers, one is dead, and one is reversed (uh-oh). I don't care. I still get better than 30 miles of range, plenty enough for around town and the occasional concert in Golden Gate park, where parking is a bitch unless you have a scoot.
Overvolting? Don't waste your time. It doesn't go faster, and is in fact slower because of increased weight. And you'll get the pesky Over voltage alarm.
Make it go faster? Unless you are an expert in TI DSP programming, know JTAG inside and out, move on. There is a mod where you can overclock the controller and get about 35 mph - but the bike is perfectly designed to do what it does forever - overclock it and it will overheat on long (>20 mile) rides.
Just recognize it for what it is - a great bike. Limited? Sure. But in California, under 30 mph means no registration and no insurance. Throw some good batteries in, and enjoy for years.
Questions are welcome, and happy scooting.