betarambo

It's hard to bevel that it has been 4 years since I started this thread. Thanks a ton to Gwhy for answering all the questions and taking care of everyone. I feel like I should contribute something so here is an update on the batteries I use these days. I played around a bit to find that the high voltage cutoff on the 20" is 60V (at least for 2014 and earlier controllers for sure). To take advantage of this I changed to a 14s1P setup for competitions. I get there by using the 8 aH Zippys with two 6 cell and one 2 cell in series. This lands at 59.5V hot off the charger. This lets us get through most of our local trials (Novice class) on one set. We do sometimes use two sets for our longer events. My daughter is 12 now so she monitors the aHs used and changes the batteries herself. I rig up all of my bikes with the bigger XT-90 connector but still use XT-60 on the batteries. This allows me to make different wiring harnesses for different setups. The normal harness does the 14s1p. I have one that does 14s2p for longer trail rides. I also have one that goes to spades for lead battery comparison testing and one that goes to rings for Earth-x's. I recognize that at peak output I am pulling more current than the XT-60 is rated for (when I run the 1P setup) but I have never had one even get hot since you never run over 60 amps for more than a second or so. While running 2p would mean never changing the batteries during competition I feel like changing them is worth it to shave about 6 pounds off the bike. I did a little weight reduction on her bike and got it down to about 60 pounds. I ditched things Ike the kickstand (Osets are like Montesas in that laying them on the ground is fine), ditched the ridiculously heavy key switch, and did some drilling and cutting to remove some of the way over-designed steel around the battery box. Mounting lipos has gotten simpler since the 2014 model introduced the inclusion panels. I put a piece of plastic in the battery tray to protect from poking objects through the holes in the skidplate. It turns out the black plastic pieces in the shipping box for the bike work great after some trimming. I then put the batteries in the tray parallel to the wheels. I used Velcro with sticky back and put four pieces permanently on the bikes through the slots in the sides of the tray. I then use two pieces of non-sticky backed velcro to connect across the top of the batteries. I had to add a notch to each exclusion panel to go around one of the pieces of velcro. I ended up ditching one of the factory pieces of velcro on on exclusion panel to make it faster to open and close it for battery swaps. I will try to get some pictures of that posted soon. I have not yet converted a 2015 but I suspect I will need to figure out a different velcro method. There is a 2015 20" Race sitting in the garage that may end up being my daughters new ride if I don't sell it out from under here again so I will let you know how that works out. Pic of holes drilled for weight and stylish looks.

Cool setup. FYI I started using the XT90 for the bike interface on the 20" since it can draw over 100 amps. I still use the XT60 for all the other connections.

Jeez Bob! Just because you couldn't handle the power doesn't mean this guy can't. Your plan sounds like a good one to me. The 20 is great fun for kids and adults. My 10 year old has one and so do I. You will not regret it. Things to consider: 1. The bike comes with a heavier rear spring just for adults. I never used it until I lengthened the swingarm to put a bigger wheel on. You will probably want to put some preload into the stock spring and add some air to the forks to avoid bottoming. 2. To get the geometry right you can put a different stem on it for you (although it is fine to ride without). It is a standard bicycle stem. You need one for 1 1/8" steerer tube, fat bars. Your local bicycle shop can hook you up or you can look on line. I used a trialtech stem, 35 degree 110 mm to get it similar to an adult sized gas trials bike in the relation between pegs and bars. 3. You are probably about right on the batteries. This bike has a low voltage cutoff (LVC) around 40V. Be careful with this until you get used to it. As you drain the batteries when they are getting close to done you will trip the LVC when pulling a lot of power like going up a hill. The bike will stop. You will not know what is going on. If you keep it at full throttle the batteries will rebound and after a couple of seconds the LVC will shut off and the bike will shoot out from under you. When the LVC hits just let off on the throttle and limp it home. 4. You might end up looking at some other batteries. There is a posting on here that has most of the directions. It turned from directions into a big discussion so it miht have more info than you really need. Let me know if you are interested and I will try to post a new one with just directions. You can shave 25 pounds off the bike, get longer run time and charge up in half an hour. Good luck, you will have a lot of fun with this thing!

Sounds like a motor problem to me too, but Juan is on the money. Check the cheap/easy things first. Always start with the throttle. The throttle has two connectors (assuming it is fairly modern). Find the three pin one and disconnect it. You didn't mention which size it is, but I think that most of them now have decent color coding. If you see red, black and something else then use a piece of wire or paperclip to short red to the other color (not black) while the bike is truned on and sitting safely on a stand where the spinnign wheel will cause no mayhem. It should spin like full throttle. If you color coding does not match my description then just go through them trying each combination. Make sure you do this on the bike side (controller) not the throttle side. If the wheel spins then you need a new throttle. On 12" and 16" bikes the next easy/cheap thing to check is the potentiometer that controls power. When these fail it can intermittently stop the bike. Find the wire for this and just disconnect it. A disconnected pot is the same as setting it to full throttle. I know it sounds like a motor problem but I have seen (and often been the guy doing it) many people replace motors and controllers when they just needed a throttle.

The new generation has three controls, two dials and one switch. Switch: 0=70% of normal top speed, 1=100% of top speed (20 MPH I think) Right dial: This is the same as the one the first generation had. It controls throttle response. It is like an electronic version of switching between white throttle tube or black. It controls how twitchy the throttle is. Another way to say it is that it controls how quickly the controller ramps in power when the throttle is twisted. Left Dial: This is the new one. It is intended to be a max power control. It is similar to the pot on the smaller Osets but appears to be more subtle. For instance, you cannot stop the bike from working by turnign it all the way down. I think this one is probably handled in software while the smaller bikes do it in hardware. How to tell if both your switches are working: Get your gear on (helmet and boots). Turn both dials all the way clockwise (top of dial to the right). Point the bike in a safe direction. Get ready to bail off the back and/or put both feet down. Give it full throttle. If your eyes do not end up as big as teacups then something is not quite right with your bike. It may not be these controls. You could have bad batteries, a bad charger, or even a dragging brake. When people test ride them I turn both dials all the way down (counter clockwise). Then, if they want some more I gradually increase them. For my daughter I use about 1/3 - 1/2 on both. For me I turn the left one to 100% and the right one to 85%. Your bike should have a sticker on the "gas tank" right below the rubber bung that covers the controls that explains this. It is also in the manual. Good luck!

Doing some battery testing today I learned more about how it reacts with SLA's. The bike will cut out if the voltage goes below 37 volts. This can happen pretty quickly after a full charge if you try to accelerate up a big hill with a heavy rider (like me). It happens less quickly with lithium for two reasons. First is that lithium can have a higher charged voltage depending on which chemistry you use. LiFePo4 which are found in most lead battery replacements use four cells to emulate SLA so they end up 55.6v for the whole pack hot off the charger (52.2V for SLA).The second reason (and the main one) is that lithium doesn't have near the voltage sag so even when a pack runs low it still doesn't trip the LVC as easy. In my experiments today I ran all three battery types that I have through a circuit in my neighborhood that includes some trails, some road, and a bit of motocross track. I noted the readings from my meter when I first hit LVC and also when I felt the batteries were totally done. On the Lipos I never hit LVC as I don't want to run them that low so I stopped when cells were around 3.8v each. All battery packs were almost new (less than 10 cycles). Stock Oset SLA: 1.6 aH first LVC / 3.8 aH when dead 69/160 watt hours less than one lap EarthX 24 aH equivilant LiFePo4: 6.5 aH 305 watt hours 3 laps + Lipo (Zippy Flightmax 8000 maH 6s1p X4 wired as 12s2p for 16 aH): 6.2 aH 277 watt hours This probably isn't much help to you, but the bottom line is that the best way to avoid the LVC is to get some sort of lithium battery so that you don't get the voltage sag until the batteries are closer to dead. It is not a cheap solution but you do get the beneift of faster charge times and shaving over 20 pounds too. There are quite a few options out there now that are less complex than the RC Lipo route if you are willing to spend a bit more.

Yes, I can drop ship them to you. Contact me off-forum if you are interested. I will need your address to calculate shipping so that you can see if it is worth it. Email me at lance@sparkybikes.com if you want to look into it.

EarthX replied after hours on a holiday and said they will overnight me a replacement battery. Very cool.

Gwhy, your thought about lvc on the controller helped me find the issue. Thanks once again for your brilliance! Long story short, one of the 12V batteries I was running is a dud. Today the bike started cutting out on me after only using 2.5 aH from a 24 aH pack. I got it home, after a bit of a walk, and put it on the stand. I found that the controller will not spin the wheel if voltage is below 40v when first turned on or if it sags below 37v while the wheel is spinning. Wondering how the heck I could be that low I found that I had 3 batteries at 13.1v and one at 0v. I am playing around now seeing if the battery is savable. I suspect I will need to get one warranteed. That explains the odd cutout and also why I wasn't getting anywhere near the life out of my new batteris as I expected.

I will check and see if they will drop ship to you.

Cool, thanks for the info. I hadn't thought about a lvc on the controller. As the Earthx's runout I have seen the BMS cutout on me. Simple enough to check as I can run 9 or 10s lipos to see where the controller cuts out. There must be some sort of logic about wheel speed as they have the max speed switch that lets you drop top speed to 70%. Even at 100% it is clear that the controller is limiting power based on RPM as once you reach top speed the power drops. You can even see it on the voltage readout on the throttle as the batteries bounce back up at top speed. But I get your point, it is motor RPM and not speed so it is not likely related. Still, I don't think the lvc is the issue as the batteries were about halfway charged at the time. Then again, it was such a big burst that maybe the batteries really sagged. One way or another, it will be easy to figure out where the lvc is on the controller and on the batteries. Too bad I can't ride it right now as p[aint is drying...

So, now for the help I need from you... I foudn an issue today where I think the controller decided to protect itself and went into some safe mode. What happened: I was trying a big stack of logs. As I lifted the fornt the lame rear tire spun in the sand. I panic gassed it and caught traction. I easeentially did a splatter minues the un-weighting. This caused the rear wheel to fly right into the log face at max power. Luckily the wheel held up just fine despite the lound "bang" when it hit. I pulled the bike down and went to ride off put the throttle made the bike try to move but not actually go. The lights on the throttle showed good voltage so it was not the BMS in the batteries. I could feel it pushing forward about one pole of the motor when I gave it throttle. I figured the wheel or chain was jammed somehow but it rolled fine when pushed. I shut it off and turned it back on and the problem went away. A minute later my buddy was trying the bike and it did it to him under very low load. I shut it off and turned it on and everything was good again. It has not shown this problem again. Theory: I noticed on my wattmeter that I am pulling almost 140 amps rather than the 100 amp limit I used to see with 20" wheels. I have checked my watt meter somewhat and I beleive it even though it is a cheapo. I may need to put my beter meter on and confirm this. I am wondering if by gearing the bike up by about 30% with this wheel I have confused the firmware in the controller. Perhaps the firmware uses speed in its calculation somehow and now that this is off, the control is off. I checked the controller after my ride. It is pretty hot but not at a level where most controllers would be freaking out. I forgot to check the motor temp. Without looking too closely I don't see any extra wires coming from the motor so I don't think the motor has a temeprature sensor going to the controller. I suppose it could have somethign internal but I doubt it. So I think that either I am pulling too much current and the controller goes into safe mode or I am overheating the controller and causing the same thing. Then again maybe it is not a safe mode but a true temperature failure somewhere along the way. I live in the high desert. It was probably around 90 degrees F when I was doing this. Questions: 1. Does anyone have any details on this controller? 2. Does it have any safe modes? 3. Does it use wheel speed for feedback? 4. Does this motor have anything "smart" in it? 5. Any other theories? Moving forward: It ocurrs to me that Oset gave me a handy way to test my wheel size theory. The speed limit switch is supposed to limit top speed to 70% which should be close to limiting it to max speed of a 20" bike. I might as well check the math here. If top speed with the switch at 1 was 20 mph on a 20" wheel then it should now be 26"/20"X20 mph = 26 mph. Changing the switch to 0 give 70% X 26 MPH = 18.2 MPH. So that means that flipping that switch will limit my speed down below stock. I guess I will try it and maybe rule that issue out. Of course the only way I made it happen was in a panic near crash so I am not sure how to repeat it!

I got the bike built and it is working pretty well. To make this work I: 1. Stretched the swingarm 3". 2. Bought the beefiest 36 spoke 26" bicycle wheel I could find. 3. Laced the wheel to the stock Oset rear hub in a 4-cross pattern using DT Swiss butted spokes (13 ga. at the end like stock, 14 ga in the middle). 4. Added 6" to the chain. 5. Bought a standard front wheel for downhill bikes (26" for 20mm through axle). 6. Put in 4 EarthX LifePo4 12V 24 aH batteries and made vacuum molded custom plastic shells for them. 7. Added a Trial Tech stem with 110mm length and 35 degree rise. 8. Flattened the downtubes a bit on the front with a torch and hammer to make clearance for the front under compression. Hoping that I am right that these downtubes are overkill considering the reduced loading here with no engine and only ten pounds of batteries. 9. Cut away most of the front most of two plates in front of the battery. Same as above. 10. Changed over to 1,000 lbs per inch rear spring that comes with the bike and added some preload. 11. Pumped 60 psi into the front forks. 12. Installed a HobbyKing watt meter. It ended up 75.8 lbs. in weight so about half of my Beta. All the dimensions are pretty similar to my Beta. The 26" wheels are a little bigger, the skidplate and pegs are about half an inch higher. The only major difference in gemoetry is in the steering head area of the frame. The Beta puts the steering head a lot further forward, like 5". I am still waiting until Tuesday for my good rear tire which is supposed to be 2.7" wide. Right now I am running something I had laying around which is a cheap standard mountian bike tire. This is my biggest issue so far. As it sits now I am able to ride Intermediate to Sportsman sized obstacle (about class 4-5 of 9 locally). I think the new rear tire will be worth about one class.

In New Mexico they sell pretty quickly. $800 for a good used 16" is about right. Normally I have people looking for them and can't find them. Often they are "claimed" before the kid even grows out of it. I would list them on the local trials club sites around your area and give it some time.

For my money the 20" Oset is a ton of fun for adults. I just got my own as my daughter was getting mad that I always ride hers. I am about 230 lbs and it has plenty of hit for me. By next week I should be done bumping it up to 26" wheels so I can try some bigger ledges. We'll see how that works out...