betarambo

Has anyone done it yet? I have a 20" and it is absolutely amazing. It has way more power than an 80cc bike, great suspension and light weight. For my previous electric bike builds I have a bunch of 6s1p and 3s1p packs. Oset US turned me on to a drop in solution that uses Lifepo4s packaged as a direct replacement for Osets. They even sell them in a kit with batteries and charger. They are very cool as they have a battery management system built in so they are as easy to charge as the standard Oset SLAs. They list a kit for 24v and 36v and will probably have the 48v soon. http://earthxmotorsports.com/products-page/etx-batteries/oset-36v-kit/ They are more expensive that HobbyKing Lipos, but when you take into account having the BMS built in I think this is the way I would go if I was starting from scratch. However, I already have a ton of batteries. I would start with running the 6s packs, 2 series and 2 paralell, in a 12s2p configuration. That would give me 50.4V hot of the charger and maybe 45.6V when they are about done. From my experience running 6s2p on a 24v bike (25.2V - 22.8v) I found that as soon as you drop below nominal voltage the bike really gets sluggish. In fact I ended up changing batteries after using about 40% of the charge. I solved it by running the 24v bike on 9s1p (37.8v - 34.2v) and she reported no feeling of power loss throughout the discharge cycle. I expect I will have the same problem with 48V since everything is doubled. Given the batteries I have this means that I would want to run it with 2 6s pack in series plus a 3s pack in series. I would run two in paralell to meet the current and range requirements so I would be 15s2p for 63v hot and 57v when they are done. This happens to be the setup I currently run in her home built bike so it works nicely for the batteries and cables I have. I have not been able to confirm a real voltage limit for the new 20" Oset controller. I would feel pretty safe ffiguring that anything rated at 48v can handle 60v, but I don't want to pump in 63v without knowing I won't smoke her brand new bike. I understand that some experiments with the 20" prototypes run up to 75v, but I have no idea what controller that might have been with. So... Can anyone confirm that the 20" controller can handle 63volts input? Thanks!

I became on Oset dealer and just got my first 20". After my kid rode my home built one for 7 months while we waited I can confirm that the 20" Oset knocks the socks out of my home build. It is 5 pounds lighter even though my bike is Lipo and the Oset is SLA. The suspension is better, the controller is awesome, and the weight will probably be like 15 pounds lighter once I convert it to Lipo. She had a hard time getting wheelies out of the bike I built. I think this is mostly due to the really heavy fork and the overdesigned 4 piston caliper and adult sized disc that Gas Gas puts on the front. On the 20" she is getting the wheelies figured out. In fact, with the power turned all the way up I almost looped it when I wasn't even going for a wheelie! And I am no small boy at 230 pounds. So, to wrap up my story, I am happy I built her bike. It was a fun project and I learned a lot. She enjoyed the bike for over half a year while we waited for the 20". Now it is retired and will probably become a pit bike for me.

I ran my kid's 16" 24V on 36V of lipo for a couple years with no issues. I did it on 9s lipos so it should be 37.8 volts hot off the charger. I think gwhy is onto the issue. The relay may not be happy with it. Do you hear the relay click? Also, I would guess that 12V SLA batteries hot off the charger might have 13V so maybe you have 39V and you are right at the limit somehow. I would bypass the relay and see how it works.

A couple of details: I managed to ditch the 20" bicycle Creepy Crawler idea and go with a Vee Rubber 14"x3.0. This gives a bit more sidewall and more width so I think it finds more traction. Outside diamter of the tire is 20.5". This made it a heck of a deal to get on the hub motor but it worked. I had to use a 10" tube in order to get a TR87 valve stem (90 degree) because the rim is barely bigger than the hub so no air chuck is going in there. The tube required tire irons to install! I took 1.5" out of the preload spacers on the forks by replacing them with some heavy duty 3/4" PVC pipe. I replaced the fork oil with 3.5 weight stuff (the lightest I could find). This has the forks working ok but still not perfect. These mini forks don't have brass bushings to let them run smooth so the rear suspension tends to give a lot better action than the front but for now we are calling it ok. I built the battery box from 1/8" ABS plastic. It is absolutely amazing what you can do with plastic sheet and a heat gun (no, you cannot get away with your wife's hair dryer). I lined the inside of the box with blue foam from a pad made for laying on when you camp in a tent. I am thinking about a redesign that would use nomex (race care driver fire suit stuff) or some deconstructed Lipo safe bags to have some fire-proof-ness if things get sideways. I think the ABS is pretty darned impact resistance, but lipos are kind of scary! The current battery box is revision 3. Previous attempts included modifying a camper battery box, cutting open a new plastic gas can, and even one attempt based on a small trash can.

So far so good. We have maybe 12 hours of solid riding on it now. We are going through batteries a lot faster than I expected. I must have miscalculated something, somehwere. I ordered a couple more 5aH 6S lipos tonight. Right now I run it with 4 of those to get 12s2P for 50V 10 aH. I am going to try adding in some of my 3s1P batteries to run more like 63V 10 aH and see how that works. I will then have three "sets" of batteries. Today she burned through 3 full sets of 50V batteries. It was pretty cool as she rode her first air log, but dang, that is a lot of batteries for one day! Our next trials is in a week so we will see how the run time works. Just to be clear on the questions of range, it appears that we are getting maybe 30 minutes of riding (pure trials practice, no sitting) out of 12s2p 10 aH, but I stop the packs at maybe 60% of capacity because I am still a bit nervous about overdischarging and ruining a pack. I just got a Cycle Analyst (CA) which is a cool computer made just for e-bikes. I am still sorting through getting it calibrated right but that should give me some real data on run time and such. Mr. Sparks, your kid is a crazy awesome rider for his age! I will see if I can figure out how to PM you on here so we can email. You gotta ditch those SLA batteries! Carson will be even that much better with 8 pounds less on the bike! I had the new bike (Sparky) at that event but was having issues with the first motor I bought so she didn't ride it in the trials. We did have it kind of running. I wish I had known you were interested and I could have shown it to you. Let's see if I can link my newest video:

It is done and runs good. She loves it. It took a ton of work and learning but I love the end product. Let me see if I can embedd some youtube videos. The hub motor did work out good for balance as it puts the center of gravity quite a bit lower than a gas bike or a motor with chain. Reading the specs about the Oset 20", it looks awesome. I am still going to buy one of those as well. I wouldn't if it was a scaled up 16", but it is so much more than that. In the end her new bike (named Sparky) could end up being my "fun in the pits the night before the trials" sled. Then again, if she likes Sparky more than the 20" then I will inherit the 20 for the same kind of injury seeking. Most likely I will use what I have learned on Sparky to make something even cooler when she is ready for the next size up. We are running lipos at 12s2p to get 48V and 10 aH. I have it set to pull about 40A so she gets 2kW of power which is 60% more than what we ran the Oset at. I can go up to 3.2kW with the current setup so I have plenty of room to open it up for her as her skills increase. I ended up with a Vee Rubber 14" rear tire which is way softer than the old Cheng Shins that were the only option in the past. That tire combined with the more gradual controller give this bike tons of traction. I got to riding it today and it was a kick. I couldn't get myself off of it. Once my kid got on it she wouldn't quit until it got dark. I am the happiest guy in the world right now. After 10 weeks or so, lots of money, lots of problems, tons of learning, and some very frustrating nights it works awesome!

I think someone asked about this. I have run my daughter's early Oset (2008) 24V on 36V lipos for a year with no problems. We run 2 6S1P in series with 2 3S1P to get an effective 9S2P for 36V nominal and 10AH. No problems at all. Well, the problem is traction. When things are slick I run her at 6S to keep from spinning. I think her new bike will prevent the spinning...

Apparently posting a jpg is not allowed here. Click the link above to see pics of how she looks. During the test ride she pulled my fat ass a bit harder up my driveway hill than the 24V Oset running at 36V did. With the new controller I can run up to 48V at 80A which is WAY too much for her so I will have to limit it in software.

The project is almost done. We rode it for the first time yesterday and then I blew the motor controller while trying to hook up a new throttle. I am going with a bigger, more fun controller which should be here in time to pack it up and head to the youth nationals in Colorado Wednesday. She will probably ride the 16" Oset for the nationals but maybe I can finish the new bike for the last day. I still am a giant fan of Oset. Check the link below for the place where I got a lot of advice and the "build log" I am working on. http://endless-sphere.com/forums/viewtopic.php?f=3&t=41746&p=610472#p610472 I kind of got distracted from making it work and ended up making it pretty. Lots of polished aluminum, custom graphis, and S3 hardware.

I know this thread might be a bit mis-categoriized, but I hope it doesn't get moved as this is the place to get to the audience I need. I started to build my daughter's 16" Oset up to a 20" about 6 months ago. Then I heard that Oset was coming out with the 20" so I decided to wait patiently for it. However, I just can't wait any more. She is getting too big and Oset doesn't have a firm date or price for the 20. I hate to do it as I am a huge fan of Oset, but my daughter is really getting into trials and this summer is the perfect opportunity for her to do a bunch of riding, but the 16 is now way too small and underpowered. So I need your help. I see a lot fo very smart people on these threads and a lot of people from the e-bike community helping out with their experiences. Any thoughts, suggestions, or ideas are greatly appreciated. The one project like this that I have seen worked out very well. It was basically upgrading the 16 with new forks, a 20" front wheel, lengthening the swingarm and stringing the rear hub to a 14" motorcycle rim. I was going to head this way, but have changed my mind. Since I want to add more power and she is now too tall even with the big neck I put on it I think I will build a new bike. This also lets me allow her to keep riding while I sort this out. The final argument for this aproach is that when all is done I should be able to recoup some of the money by selling her gently modified 16" Oset. I got my hands on a Gas Gas 50 Boy. In comparing them it has everything I want in general. It is a bigger frame, and has motorcycle rims of 14" rear and 16" front. For those who don't know, motorcycles measure wheels differently than bicycles. It works out that a 20" bicycle has tires that are about 20.5" diamter whereas both tires on the 50 are about 21" diameter. The GG has pretty nice suspension and geometry and enormous discs front and rear. I started out by weighing both bikes. I found that the 16 Oset with Lipos is 52.6 pounds but the GG 50 is 101.6 pounds dry! No wonder Oset took all the market share overnight. Putting my 60 pound kid on a hundred pound bike is close to putting me on a 400 pound bike. I really think the light weight of the Oset has been the key to her riding really coming on. Her newest trick is to take advantage of a dab by moving the front end. On the Oset she moves the front whereever she wants it. I had her try it on the 50 and she cannot even get the front wheel in the air with just muscle. So to make this work I need to shave some seriosu weight. I took out all the bits I won't need like engine, radiator, clutch, exhaust, air box etc and got it down to 67.2 pounds. I figure to run it at 60V so I will add back in maybe 7 pounds of batteries. This puts me at 75 pounds without a motor or controller yet, so still some work to do. For the motor I have been poking around the web a bit. She has the 24V motor but we run it at 36V. My meter says I am pulling 42 amps peak so that gives me about 1500 watts. The motor is rated for 600 watts. I am figuring that this means we are looking at 600 watts sustained and 1500 peak when trying to compare to other motors. Finding a motor is a bit of a challenge. You don't want your average industrial motor as wieght is no big deal to them. So I looked mostly in electric vehicle (EV) circles. I figured I wanted something with a nominal rating of maybe 1,000 watts to get a bit of a bump over the nominal 600 watts in her existing motor. Kelly makes one that would mount up pretty well and sells for about $200. However, I got very interested in the idea of a hub motor. Golden Motor makes a kit for converting a bicycle to electric called the Magic Pie 3. The motor and controller both live in the hub of the rear wheel. This keeps things pretty clean and keeps wiring to a minimum. It is rated for 1,000 watts at 48V and you can run it up to 60. You can run it all the way down to 24V which might be good for low traction situations (I currently run her at 36V normally but 24V when things are slippery). The controller has an optional USB cable to let me program some options. It even has regenerative braking although for trials I will probably disable that as the complication and risk are not worth it for trials. I think I can get the hub motor, controller, a 20" cast bicycle wheel, disk brake and throttle for about $600 US. Getting rid of the chain is pretty neat from the stand point of maintenance, safety, and efficiency. I am trying some of their forums to decide if the power will be enough. I am a bit concerned that the normal behavior has it kind of soft off the line. I think it might be focused on top speed rather than acceleration which is pretty much the opposite of what we want for trials. The other big concern is the weight. The whole thing is about 20 pounds. Having that much weight, that far back and being unsprung wieght could do some really odd things to the handling of the bike. Then again, it might make wheelies much easier, and having the weight all unsprung could be fabulous for traction. So the plan would be to strip some more weight off the 50, maybe get rid of those huge disks and such, maybe even replace the front suspension and wheel with some lighter bicycle stuff. Put the hub motor on with a 20" Maxxis Creepy Crawler bike trials tire, and give it a try. If things work, I think I can later swap the rear over to the 14" motorcycle tire so I can run the new Vee Rubber tire (which is a fair bit softer than the old Cheng Shin although still not near a real trials tire). The rear wheel thing will be tricky as bicycles use 36 spokes but motorcycle 14" uses 28, It will also be tricky since the hub motor is big so the spokes will be really short, but I think I can get it to lace up. I am starting with 67 pounds and adding 27 pounds of electronics, but I will be ditching the old rear wheel. Maybe in net I would land at 85 pounds or so. I think I need to find another 10 pounds or so to make it really work but I guess I can figure that out once the trickier bits are sorted. What do you think? Am I nuts to try a hub motor? Would i be smarter to just do the 20" conversion to her existing Oset and upgrade the motor a bit and maybe drop the pegs some to get her riding position more correct? Please help me out before I start placing orders and firing up the welder!

One important update for most people who are tackling this for the first time is that soldering is no longer required on the batteries. I found that HK now sells adapters to go from the lame red plastic covered connectors the batteries come with to XT60 so the connector conversion is now much simpler for people who don't solder every day. You still have to do the bike side, but that should be your only soldering. The 9S solution certainly is cleaner and more convenient (I use a 6S in series with a 3S). One counterpoint to that might be the money if a cell goes bad. If a cell goes bad on the 9S the whole battery is junk whereas using a couple of smaller batteries makes a bad cell less expensive. Then again, I am now up to 10 6S batteries and 8 3S and have not had a bad cell at all. I don't need this many batteries, but I bought some extra in preperation for the 20" bike so I could run 15S2P. Speaking of the 20" I officially gave up on waiting for it this weekend. Oset has been on radio silence about when it will actually release. While I can be patient, I can't stop my daughter from growing. She rode her first national a week ago, and this weekend she beat her first "grown up" in a trials. I just can't wait until maybe October or maybe later. This weekend, not only was the 16" getting way too small, but for the first time she didn't have enough power. So I started to build my own. I will start a thread on it and keep you posted. Then again, maybe someone at Oset with see this and decide that they need a pre-production bike in the states for testing!

Pete, I think you are talking about the standard SLA batteries that the Osets come with, not a LIPO conversion. In that case, the stock 24V charger uses 120 V at 1.2A which is about 150 VA. Assuming the 36V draws a bit more I would say you need maybe 400 VA (.4KVA) to charge both bikes at the same time, which is probably the smallest generator you could find. However, since you need like 8 hours to charge those SLAS this might be a pain. I know it sounds lame, but one option would be to buy an inverter to hook to your car battery. You would need to start the car every so often to keep its battery topped of but at least this way you could use the standard charger without having to get a generator. It is lame because you are going from DC on the car to AC at the inverter back to DC at the battery, but if you have an inverter laying around this would work. I did it this way back before I went to lipos. The better solution of course would be to convert to LIPO so that you could charge in half an hour from your car battery directly. Good luck!

I always charge mine individually. If you get it setup in a good way then they are pretty easy to pull out and disconnet. Your setup would be 9S1P when in the bike but you want to charge them individually as 3S1P packs. My normall load now is 2 6S1P 5 AH packs in paralell tied in series to 2 3S1P 5 AH packs to effectively give me 9S2P at 10AH. Even though this is 4 batteries, they fit nicely in the stock battery tray and they are straight forward enough to pull out and charge. It helps that I bought a 250W charger so that I can charge them at 10A (2C for a 5 AH pack) so they generally charge up in half an hour per pack.

Not much help, but here goes. All of the reading I have done and the specs I have seen generally say that Life is more expensive for less capacity. I think they are supposed to be a bit safer but as long as you are thoughtful when charging and mount them in the bike were they are physically protected, lipos don't really have much danger. That might be why you are having a hard time finding people who have tried them. Good luck, please let us know what you find out.

Wow, I am even dumber than I thought. After further digging I found that the root problem was actually a bad solder joint on the watt meter I was using. I had bought a $25 watt meter from HobbyKing so that I could monitor how many AHs she had used. I got to using it so often that I cable tied it to the frame. Since the meter had no mounting provisions I just tied the cable ties around the wires. One of my batteries has a shorter cable than the others and last weekend I kind of tugged on the wires to make it work. Apparently when she wrecked it put just enough force to finally disconnect this wire. When I got the meter opened it barely had any solder on it at all so I fixed it and hit all the other joints to avoid this in the future. If I had just routed around the meter in the first place I would have nailed it. I then would have avoided mistakenly reconnecting the pot and probably didn't need a throttle. Then again, the throttle was pretty beat and full of plastic dust so it probably didn't hurt to replace it. Anyway, I just had to share my goof in case it helps someone else in the future. Since the new 20" wont be here for a while I ordered up some more toys for the existing one tonight. It makes me wonder. Who are these bikes really for anyway? We like to say they are for the kids and my daughter certianly loves her bike. But then again, I get to spend money on tweeks and upgrades and tools and claim it is for my kid. I may be having more fun than she is, but I get points from the wife for my time in the garage "trying to make sure the kiddo will have fun next weekend". I think maybe these little bikes might be my favorite hobby. Don't let the wife know or she might make me use my own money!

I heard some rumours from OSET Us today. He didn't say it was secret so I will throw it out there. Hope I don't make anyone mad. The 20" is likely to be 48V using sealed lead acid batteries. They are making sure they get everything just right so it is delayed a bit. I imagine it will get to the UK first, but they say it will hit the US in late summer or early fall. Yay for 48V! Not yay for SLA batteries but I guess I can just convert that one to lipo too. Not yay for the delay but I guess it is better to get it right and late than to get it early and wrong.

Thanks for the tips. I found the problem. I called Oset for tech support and it took 5 minutes. The trick is that sometimes in troubleshooting you need a second set of eyes to check your assumptions. The original problem was indeed the throttle. While I was troubleshooting it on the trail I was in a rush. As I was digging through the wiring I found a disconnected set of connectors. Without thinking much about it I reconnceted them to see if it helped. It turns out that what I did was reconnect my bad pot that I had unhooked a couple of years back. So when I got the new throttle even though it was all happy, the bad pot was screwing me up. So I disconnected it and everything was happy. The bottom line is that I was being an idiot! Kudos to Oset: 1. I ordered the throttle online Sunday night. I took the only shipping option available which was ground. On Monday they revised my invoice, dropping the shipping charge down a few bucks. Tuesday afternoon the throttle was at my house from Fed-Ex in a UPS box. 2. I called their phone number on the invoice and they were happy to help and got me going in 5 minutes. While I was on the phone I got some rumours about the 20". He didn't tell me it was secret so I hope I don't make anyone mad by posting it. 1. It will probably be 48V with sealed lead acid batteries. This gives me the greenlight to order up more 6S1P Lipo packs since I can run those in a 2S2P configuration to get 48V and 10AH. 2. It will probqably hit the US in late summer or early fall. This is a bummer, but he said they are trying to make sure everything is just right on it so I guess it is what it is.

Man, the mecatechno sure looks like a copy of the Oset. I would tend to be pretty loyal to Oset. They broke the old paridigm and gave us a much better way to get our kids into riding. Ian's idea sure made things bloom around our club. At one point we went from two kids to like 8, all of them on Osets. Competition is always healthy, but in this case Ian's innovation was such a game changer that I have a strong feeling of loyalty. In practicle terms their quality and support have always been top notch so I would be nervous about the unknown. (no disrepect to Sandiford intended)

I did some upgrades to my daughter's 16". Hanging out in the garage with my buddy lead us to having a pint or two. Next thing you know we felt obligated to "test" the upgrades. It pulled us up and down the little skate ramp in the driveway, allowed some basic hopping and even tolerated a couple of deer hops. The front brake was even strong enough to support some nose wheelies. I was amazed that we didn't at least snap a footpeg off. I try to avoid riding it as I don't want to face the look she would give me if I broke it, but for what its worth, it held up fine that day. I am a pretty heavy guy so I probably exceeded their design spec by about 4X! Yous said you weigh 175 lbs, so put my daughter on your back and you are close to my wieght.

Very handy. Thank you for posting it!

So if I understand you correctly, the fires probably happened from charging a battery with a bad cell that was below the low voltage limit. In that case I would think that balance charging them one at a time every time would catch it as most of the chargers check for that sort of thing when you start a balance charge. For that matter just throwing one of those little meters on the balance port before charging to check for a bad cell would catch it. I guess I am not really sold on needing the low vaoltage alarm. This is particularly true since my daughter has gotten so into it that she claims she can feel the performance hit at 40% of capacity and wants new batteries! So a couple of wrecks in the sand and the bike quit running on us this weekend. Having replaced a throttle once before I figured it was this. Trying to remember what Oset tech support had told me back then, I tried shorting some of the hall effect wires in different combinations. Nothing made the wheel spin so I figured I had a bigger problem. Once I got home I did some more troubleshooting. Finding nothing I went back to the hall wires. I found that shorting the two outside pins would spin the wheel at full power for a second. So I decided it must be the throttle. I ordered one up, but this week is spring break and she is anxious to ride. I went over to a buddy's house and borrowed a throttle off his for sale Oset. Both ae 24V although mine is 16" and his is 12.5". I had to swap the connector as his bike was the 5 pin connector and mine is the two connector setup with one 3 pin and one 2 pin for the indicator lights. Hooked it up and I got nothing. So I pulled the pins back out and tried every combination of the 3 wires with no result. I went back to the shorting trick and got it to spin. The throttle worked on his bike at his house. So I am stuck now. Any thoughts? My bike and his are both several years old, maybe like 2008 or so but his throttle is about a year old. I may end up waiting for the new throttle from Oset and hope that that does it. Maybe the wiring guide it ships with will help. I sure hate to have her miss riding on spring break! While searching the web for ideas, I tripped across this cool sounding product. It is a box you put between the throttle and the motor controller. They have one specifically for the Oset. It claims to change the control algorithm from RPM control to torque control which would in theory make throttle response more similar to a gas bike. I am not sure about how well it might work given that it only connects to the hall sensor wires. I would think that you would need some feedback from the controller like RPM, but I must be missing something. I also has some dip switches to set different characteristics. For the price ($180 US, 130 EU) it is probably better to try the Kelly controller that Ian wrote about a few years back. http://www.automotive.picoamps.de/en/products_more_en.htm#dmm Any thoughts from anyone who has tried this (or not) would be appreciated. Waiting for her new 20"...

Wow. I started this topic just as a way to document all the cool tips Rick Keffer gave me when I started out to make Hannah's bike work better. I tis now 7 pages! Thanks everyone for all of your awesome tips. These days I have 6 batteries in the 6S1P 5 AH configuration plus two 3s1P that I put in series to run her 24V bike at 36V. I normally run two fo the 24V 5 AH batteries in parallel at a time. Three might make more sense, but I like keeping the wieght down. She has ridden Beginner (the lowest adult class) three times now and the bike has worked grat. We change the batteries out after each loop since we run three loops and we have three pairs of batteries. We don't run the 36V setup for competition as traction becomes challening. I charge them one at a time at 10A (2C) and laways balance charge them. At the event I run them off the 12V system in my camper and at home I run it off a 25A Radio Shack power supply I "borrowed" from work. I also use a Hobby King current meter combo thingee for like $25 that lets me monitor pretty much everything I could want. We are on the waiting list for the new 20" Oset. I am really anxious to find out what the electrical configuration of it is. I heard a very vague and unreliable rumor that it is 48V. I also suspect (with no real information) that maybe they made the leap to lipo. I am curious about the low voltage warning you guys are all talking about. I get that it makes sense in the RC world. For the Oset world I think it doesn't make sense. I was told when I started on the lipo path that an Oset will not even move when the voltage gets that low. I later confirmed this. In fact, my daughter is so performance oriented now that she askes me for new batteries after she uses 4 AH of the 10 AH setup she runs (40%). I think she is so into it that she can detect the first small drop off in voltage. Anyway, I am wondering if anyone is using a low votlage alarm because they actually burned a battery on an Oset or if people are using them because their experience int he RC world makes them want one. Also, I feel obligated to poitn out that when people ask for a shoppign list, it is on the first page of this post. That is why I made it! Lovign the Oset lipo world!

For the guy who asked for directions to do the conversion, check the beggining of this thread. It should have everything you need, at least that was my intent. To Frogger, your bundled packs look like a great idea. I think you might want to revisit that final connectors. It is my understadning that if you short those batteries for even a split second they are garbage so a connector that makes this impossible is worth it. It looks like it would be pretty hard to do with your setup, but in the heat of battle at an event or bouncing around in your tool box it might happen. I have had good luck with the XT60 connectors. So I got back on the project this weekend and started diving into converting it to be bigger. My daughter is getting too tall for it. I ordered the new forks yesterday which are for a 20" mountain bike and started working on figuring out the wheels. While doing some research I foudn that Oset plans to release a 20" bike this spring. The pictures look really sweet. I think it has a lot of advantages over converting my 16" to a 20" like geometry and footpeg location. The geometry on this thing looks idnetical to a full size trials bike. So I scrapped my project to make her bike bigger and plan to pre-order one of these new ones. You can check out the pics here: http://www.trialsuk.co.uk/products/oset-20-electric-trials-bike It doesn't say what voltage it would be. I assume at least 36V but maybe for a bike this size they will go to 48V. If they don't I'll bet I probably can. We'll see...

So I kind of started this thread and then walked away. Sorry about that. I have been watching the thread but life sort of took me away a bit. First I got distracted building the tallest Subaru WRX in the US (think combining redneck with rice rocket) and then my wife had some health issues. We are now 104 days into her hospital stay, 9 days after her bone marow transplant and maybe two months away from going back to our side of the country. I was very happy to see that a couple of people who know more about this than I do jumped in here and provided some really good advice. It looks like quite a few people have made the leap. I thought I would update with you with what I have done and maybe answer some of the quesstions. Charging: If you are new to this I recomend experimenting a bit. You don't really know how into it your kid or you are going to stay. I would buy a single cheap charger that charges your batteries one at a time. Even the cheap ones are plenty safe. After that you will get to know things more and feel more confident in specing out a charger or chargers that make sense to you. You do indeed need some sort of DC source. I use the battery system on my camper since in my case it is either at home or at the trials with me. I installed a charging outlet on some 10 guage wire so that I can set the batteries and charger on a stand away from the camper just in case I have a "thermal event". I have three 12V gell cells in paralell in the camper that get charged by a 75 amp converter. When I am home the camper is plugged in so I get plenty of juice. Even when I am camping I sometimes charge all four 6S1P packs without plugging in or running the generator, but I bet it pulls a significant charge out of my house batteries. For the simplest case I think charging of of you car or van is fine but I would either have the engine running or make sure I have someone around to jumpstart me until I get the feel for it. I would start with this as it is cheapest and simplest until you get your feet wet and get a feel for what you really need. Make sure to be careful when hooking up to the car battery. Just like a jumpstart, a spark near the battery can potentially lead to an "energetic themal event" in your face. I hook the positice up first and the n hook the ground somewhere away from the battery. If you want to charge at home from AC you will need a converter. The idea of using an old laptop supply is a good cheap one, but keep in mind that these won't put out a ton of current so they are not perfect for fast charges. However, if you are only charging at home you are probably not in a big hurry. I got my fire proof bags a while back. I use on to charge, one to store, and one in the bike. It is certainly overkill, but for the price a little piece of mind is cool. 36V in a 24V motor: I think I posted this before, but in general it makes the bike way fast but very poor on traction. We pretty much don't use it this way anymore. A coutionary thought: These bikes are dangerous in a different way. They are fun for adults to ride and they tend to handle it. I bought a TY80 a few years a go with some buddies and we started having a TY80 championship the day before each event. This gave us the idea to start riding the osets a bit. The other day one of my buddies who shall remain nameless went to do a wheelie on a 36V bike and looped it. It happened too fast to react and he broke his tailbone. So it is probably best to leave these little wonders to the age group they are designed for or at least know what you are signing up for! My duaghter won her first junior championship this year so we are going to start trying the adult beginner class soon with 3 full loops and 8-9 sections. I should get some better run time results for you soon. I also put in one of the watt meters which works pretty slick. In summary, my key recomendation is to start with lipos slow. Buy the minimum, put it in and use it. After that you will start to understand better and then you can get fancy with containers, battery packs, multichargers, and charging in the bike.

I don't montior the cells while riding. With the Oset the bike pretty much stops moving before they get too low. Just tell your kid to let off the throttle when it stops moving and you are fine. You can get some monitors that show all 6 cells at once. I bought one from Hobby King for like $5 but I only use it in the garage. I got the 12V batteries the other day to try the 36V setup but haven't tried it out yet. I did at least make the series cable I need for it and swap the connectors on the batteries. We have a trials this weekend so maybe I can try it there. I have gotten distracted lately modifying my WRX for serious off road abuse, but that's another story for an entirely different forum...