ninefives

One thing on the reserve idea I didn't think about! The buzzer can't be turned off without disconnecting from the balance lead which would be a PintheA out at a trial - Guess just make them muffled enough and get the charger on quick - still work in progress here or set them at the vary lowest voltage as purely a last minute reminder. As mentioned in previous posts - I do have a voltage and ma used display that sits on top of the batts so have a fair idea of how much left already, my alarms will be set as a last ditch reminder when they arrive.

Heymak, Re chargers - mikedufty makes a good point as you are running at 6S voltage, all the batts are in parallel, so 1 charger that does 6S could do - just would take 2x as long to charge 2 batts. For my 36v I have to use 2 banks of 5S (2x18v so 36v) so I have to charge them separately. My guess would be that with the Accucell charger I use would charge 2x5000 in about 2-3 hours from 30% left, but a bigger power supply and charger or 2 chargers = faster time. For me I charge at home at the end of the day so it doesn't matter, but you could charge over lunch with the right setup. His comment on small stages is right on - the only downside is shipping costs, there is a minimum shipping charge - when you are in the ordering page at HK it shows the weight remaining for the shipping cost shown - you keep buying little bits to fill up the shipment weight! I made up a spade to XT60 lead so the original connectors are still on the bike, as per comment above, I can swap in the SLAs if I need to (probably when I sell the bike!) See Froggers photo for the low voltage alarms setup - these are made for RC model kits so the alarms are designed to sound from inside the helicopter 100ft up. I couldn't find a handlebar mounted voltage display/alarm that would survive a trials environment. I think that the alarm should be loud enough even covered in the battery box that we get the message. Get ones you can set the voltage, that way you could build in a "reserve" by setting the voltage to say 22v to have enough to get back to the van - trial and error on that I'm afraid!!

Hi, 1st - You want 24v - each LiPo cell gives 4.2v fully charged 3.6v lowest working voltage. So 24/4.2 = 5.7 so 6 gives 25.2v and when depleted to 3.6v you get 21.6v - that will work - so you need to use either 6S1P (6 cells in series giving 25-21v) - you could use 2 sets of 3S1P joined in series - same thing. 2nd - you need the capacity AH to keep the OSET running for long enough - your current setup is 14AH. Each 6S1P or 3S1P battery comes in many different capacities - eg 5000ma or 8000ma. 2 x 5000ma in parallel = 10AH logically 3 x 5000 will give you 15AH but you cannot fully deplete these suckers so you need to build 20AH giving 14AH usable (leaves 30%). If you pockets are deep enough you can add another bank so would run twice as long. I recommend stick with 4 batts to begin with. 3rd - Each battery is rated in C eg 15C 25C etc - this is to do with the battery's ability to take load either discharge or charge, OSETs are gentle in this regard compared to some RC model use so I was advised earlier in this thread 15C is fine - the higher the C the more expensive the battery. 4th - Look at the sizing so that after being protected the batteries fit in the battery compartment well protected and tidy Hobby King (Hong Kong) website gives the dimensions so tape measure and paper and do the sums how to fit them in - that may be when you decide between 3S1P and 6S1P and also whether 5000 or 8000ah (the 8000 will be bigger (longer I think). Lots of flexibility here 5th - You need the connectors to connect the batteries in parallel 6S1P or parallel and series if 3S1P 6th - Chargers - I'm happy with my chargers - see my earlier shopping list - 3 would mean that you can charge each battery at the same time - less faffing about but 1 would suffice. Don't forget a 12v - 18V power supply - computer power didn't work they are 18.5v so outside charger input tolerance. I use a battery connected to a charger and also an AC to 12V converter with car plug (order the car plug power lead at the same time as the charger - they come with croc clips) 7th - I'm on the fence on changing the connectors, its a PintheA but once done pretty solid 1 way setup - ie can't accidently mix polarity, although not sure its that easy to do with the connectors they come with - Frogger didn't change and he has worked with LiPos before. I think thats it - but its late and check everything I suggest. And remember the health warning. Have fun

No heat - mine are fully sealed - I had the same conversation way back much earlier in the thread. I think that if you fast charge (ie 10 mins a battery!!) them they may warm but I trickle charge over several hours.

Jonny - The best thing to do is have a conversation with folks in a helpful model shop about LiPo attention and maintenance. These guys really understand LiPos - that said - I think Frogger has some experience in that department - look back through the threads - his charge setup is awesome! LiPo safety has moved on with safe (and not expensive) chargers that have time/voltage/load/temp cutoffs. There is no doubt, there is the potential for fire that you do not get with Lead Acid, handling the batteries/charging etc is the responsibilty of an informed adult but it isn't nuclear bunker stuff. The biggest risk I see is grit or a stone getting into the battery case and puncturing a cell - that equals a fire - so protect them well. If you do run the battery down to below 20-30% you may not kill the battery but you are in the pain in the A place, you need to nurse them back up with some TLC (or get Froggers recover setup). The prognosis is fair that they will pull through, but there may be complications meaning replacement - best not to go there - hence the low voltage alarms. I understand the frustration on battery life, I love the bike - right size and simplicity for my kids (5 and 8) so bit the bullet and have spent about 300 quid on LiPos - but I now have 5 hours high voltage running (about 5x what I used to get) with the batts in a sealed metal case and it all weighs less than the 3 lead acids.

Just adding my 2c, unless there is some variance in the performance of individual OSET throttles they just take getting used to. The instant torque makes initial throttle control a challenge to new users. If new kids want to try the bike I put it on a stand and get them to practice getting the back wheel to start slowly, it can be made to move very slowly. Then put them on mud/slippy grass, that stops it standing on the rear tire. My kids (at the time 4 and 6) mastered the throttle in about an hour, I just kept giving praise for gentle starts. I have no concerns with my 5 year old starting and weaving around parked cars (even nice ones!). An upside of this need for control is that both of them can now ride bikes very well in slippery conditions. The absence of a clutch I see as a benefit - less controls to have to think about as they get started. There is also a arguement that riding Junior/Novice sections without using the clutch teaches smoothness, planning, anticipation.

Ah ha - you asked THE question!! You have had the very clear reply from someone very well informed in Mr Cleanorbust Its a motorbike and nobody in authority is going to care or put in the effort to accoommodate us. We must operate under the radar me thinks! Personally I have a piece of parkland nearby where kids have created a BMX track in the woods, we wonder over at walking pace, very respectful of folks and dogs and quietly go about our business. Houses overlook the area but any audience is always curious, not hostile. Yes Mr Plod could take a dim view, but a suitable apology, a promise not to return, (and if you are not in Warwickshire) a "I'm sorry I wasn't aware" with a big smile from your daughter should help. It took years for local authorities to acknowledge skate boards and BMX and create parks for them. The bike trials guys have to operate under the same conditions as us.

Hi Frogger - I moved this from the LiPo thread! I avoided welding to the bike - to much hassle removing the wiring. The bracket was fabricated from some rectangular tube sized to fit the shock top mount, one side cut away and lugs welded on that attach to the original shock mount with a bolt. The mount then rests against the frame snug under the seat. Fair bit of cutting and grinding to accomodate the shoulder of the shock. I haven't touched the front forks, they seem adequate for my boy, talk to a mountain bike shop, that's where I got the info for the rear.

Moved my response to the Rear Shock Thread

Hi Guys, My alarms are coming from HobbyKing - Voltage-Alarm/18588 Hobbyking 2-8S Cell Checker with Low Voltage Alarm = $3.46 I bought 2 as they are so cheap and I'll put one on a battery in each bank. That said with the amount of power I have stored, I hope that I have bought enough time that low voltage isn't an issue. gwhy - I don't want to stick anything extra electrical on the bars - it will get crunched. Re the rear shock, I got a new 6.5" Air RockShox for US$100(older model) www.pinkbike.com. Raised the top mount with a bracket from the old mount up under the seat to get the same ride height as the 5" OSET shock. Setting up the pressure - get a pump with the shock (seller gave me one free). We are at the lower end of the pressures for both compression and rebound.

Hi Frogger, Ossa and Oset, perfect setup. Same here Just "upped" the OSET battery capacity to 25AH (2.5 times standard OSET), I'm guesstimating that should give me a full days trial without worrying about hitting low voltage. Its a snug fit in the battery box. I've ordered an adjustable low voltage alarm from HK. Before I upped the capacity I did manage to discharge the LIPOs to below 3.6v which confused my charger into thinking they were 4S not 5S. Manual trickle/tickle on Nimh got them about 3.6 and back to 5S and back to LiPo charge, guess you know this! It occurred after about 2+ hours, my son suddenly noticed the power meter light on the throttle went from 3 to 1 seemed to miss 2, and we were at 35.8v. An aside - not for this thread but a couple of significant other upgrades is to put a mountain bike shock on the rear, 6" or 6.5" with a bit of welding made all the difference on rock steps and I raised the bars with a raised adjustable clamp.

Short answer is yes. With LIPO you get: Reduced weight for the bikes standard 10AH power(Lead Acid 10kg, LiPo 3.5kg - allowing for residual voltage requirement) Reduced size (You can fit 25AH of LiPo in the space as 10AH Lead Acid.) 25AH gives double the time/distance 20 or 30 minutes charge with the right charger/power Less of a fall off in performance as the volts drop Longer overall life of the battery (in years) Downsides $$ for the batts and equipment. More attention needed If your kid just wants to blast around for hours and noise is not an issue go gas/petrol.

Again, thanks to everyone for the technical advice and the common sense. I'm going to build a 10ah "cassette". That way, I can in the future build another to either swap or piggy back with a couple of parallel leads to get the 20ah distance. So my shopping list currently looks like: Hobby King 4 x 5000ma 5S1P 15C Zippy - (2.8kg) $160 (ordered a spare, as DOA likely) 1 x Nylon XT60 Connectors Male/Female (5 pairs) $3.19 - 4 x Female replace the ones on the batteries - 1 x Male replace the OSET power connector - 1 x Male and 1 x Female for the power meter 2 x XT60 Harness for 2 Packs in Parallel $4 1 x XT60 Harness for 2 Packs in Serial $2 Pack of 3/16th (4mm) shrink tubing 1 x Parallel Balance charging Board for 6 packs 2~6S (XT60) $9 (not sure this needed yet) 2 x Turnigy Accucel-6 50W 6A Balancer/Charger w/ accessories $46 2 x Lithium Polymer Charge Pack 25x33cm JUMBO Sack $5.46 1 x Turnigy 130A Watt Meter and Power Analyzer $24 - On backorder so bought an Eflight Power Meter rated at 120A from my local RC store ($50). This is essential equipment. Note that HobbyKing doesn't send manuals, web search them. My miscellaneous shopping list is: Battery Case (cassette)- used Lock n Lock Food Savers 800ml/27oz Laptop power supplies for the chargers - This hasn't worked for me they produce 19v, the chargers accept 10v-18v - use a 12v battery hooked up to a charger. 3mm padding (between and around batteries) - Wrapped the batteries in rubber antislip matting. Zip ties (hold the batteries together) Not required in the food savers. Grommets to seal around the parallel cables exiting the case - used silicon sealant Strapping to hold the cassette in the tray - essential - used the old battery bag - not ideal. Follow-up notes: Awesome upgrade - some important considerations around LiPo safety. If you are considering this upgrade, then read this extremely important information http://www.rcgroups.com/forums/showthread.php?t=209187 Stuff arrived in about 10 days. I ordered 5 batteries just in case, and one arrived with a cell out!. Soldering on the XT60 connectors is challenging to begin with, I had to upgrade to a 100watt soldering iron, a gizmo to provide an extra pair of hands, used old style lead based solder. Use the Allen Key heat sink or the plastic melts. Excellent how to video here http://www.youtube.com/watch?v=3Yj-DHxKS6c. I cut a 3/16th x 3/4in slot in the side of the food savers to allow the cables to exit. Work out where by dry fitting the food savers "cassette" to the battery box on the bike. Each cassette holds 2 batteries wrapped in the rubber matting very neatly with the XT60 connector just on the outside. The cassette fits across the bike battery case very snug! I fitted the power meter into another Lock n Lock 180ml/6oz. Fit the power connectors to the bike into another small Lock n Lock to waterproof. Findings: The RC world rates batteries at their minumum voltage, so my 5S1P batteries are rated at 18.5v but when fully charged actually have 21v - so I have ended up with 42v when fully charged - bike speed is up noticeably but motor does not get warm. DO NOT allow these batteries to fully discharge, a safe minimum seems to be 37.9v (30% life remaining) go beyond that and you could destroy the battery. This is where the power meter comes in, mine shows voltage and mA used. For my 10Ah setup I stop at just before 7000ma used. Currently the bike seems to consume 90ma per minute so a working range of 75 minutes. There is no significant loss of power down to that threshold. (Update - blasting around for 30 minutes flat out used average 125ma per minute so range to 30% remaining 55 minutes and to 20% remaining absolute lowest 63 minutes). Trials playing in the yard 50 to 80ma per minute. Always disconnect the batteries from the bike and power meter so there is no drain while in storage. Charging - This is where the move from the super safe lead acid to LiPo gets serious. These batteries can be dangerous - if you haven't read the link on safety, read it now. It seems that there are 2 main dangers: Charging at the wrong voltage and physical damage. The charger I have checks the battery, reads the number of cells and says what it finds, then asks for confirmation. I also charge them in a clear space on concrete in a Lithium Polymer Charge Sack and check them regularly and disconnect as soon as they are charged. (BTW LiPos like to be stored partially, not fully charged so the RC folks tend to charge them on the way to their event). Physical damage - these batteries are not well protected, at one end you can see the individual LiPo cells with a soft foil like material, a nick in this and you will get a fire - but not immediately, just after you have stored the bike in the truck/car and gone off for "refreshment". Hence my wrapping them and putting them in a cassette. Look at your current SLAs and see the wear marks on the sides where they bounce around in the battery case. Using my 2 small chargers seems to take 150 minutes to charge the 4 batteries from 40%. I could buy 2 more chargers and halve the time. 555555555

Thanks for the info guys. I'm building a simple diagram and shopping list based on 5S 10 and 20ah solutions - I get the relative simplicity of that config!, but a couple more questions: I plan to end up with 2 x 18.5v 20ah connectors outside the battery case each connected to 4 5S batteries in parallel. Serial connector then gives me 37v and 20ah - fantastic!! For charging, I remove the serial connector (I'll make the serial to the bike connection permanent to prevent mistakes). So I have 2 banks of 18.5v cells (20ah) to charge (each one 4 5S batts). Its at the point my brain breaks (again). Which charger should I use? I'm confused by the assortment available at Hobby King. I'm not looking for the most economic if that compromises the life of the batteries or safety. Input AC, a charge time of under 2 hours ideally. Recommendations? Every 5 charges or so I can undo the case and plug the individual battery balance plugs and power plugs into a "Parallel Balance charging Board for 6 packs 2~6S (XT60)". What other monitoring equipment is really essential? I remember some previous dialogue that suggested that the bike isn't going to move much before we get to the 20% lowest safe remaining charge. Is that knowledge enough?

First - thanks to all who have contributed so far on this thread, so much information, actually that is my problem - I'm confused by all the variations and am really looking for help to define a sensible repeatable setup (for 36V Osets) that folks like me can easily understand, shop and put together. I'm more mechanical than electrical so please be tolerant of any stupid assumptions I make. We have a 2010 36V Oset and the main issue I want to overcome is range, I really need about double the life I currently get from the SLA's with probably 30 charges on them (properly charged initially and seem to be holding close to original range). I can then have my son come with me on the trial loop without concern for getting back.. I'm happy to convert to Lipos. From what I have read: Batteries: To convert to LiPo and to give the existing range - 6 x 3S1P15C 5000ma (3 batts in series giving 33V) and the 2 banks in parallel giving me 10ah. I could replace 2 x 3S with a one 6S (this reduces the connectors but (I think) may complicate charging (more later). To increase the range I could add further banks of 3x3S1P 5000ma. Each 5ah layer would be 150x143x23 mm and cost about US$75 from HobbyKing, the weight saving is huge - standard OSET batts setup is 10ah weight 9.1kg, LiPo is 2.7kg per 10ah. Question - Is there a heat issue with stacking the batts, as each layer of 3 batt in series would fit nicely in a hard sealed case in the OSET battery compartment and they would be 3 or even 4 layers deep (20ah!) and assuming a continuous but variable use. Setup - Discharge (riding) I would replace the batt connectors with XT60 and use the series connectors on each layer (33v and 5000ma) and parallel connectors to connect the layers to get to 10, 15 or 20AH capacity. I would then need to change the current bike power connector to XT60 and disappear into the sunset, but..... charging. Setup - Charging I don't want to have to remove or disconnect the batteries to charge them. I understand the fire issue but am prepared to buy a charger that manages voltage/current/shutoff - which I assume should reduce this risk considerably. So - I have 6, 9 or maybe 12 3S1P batteries all connected in a sealed box and ending in one XT60 connector carrying 33V. Each battery has a +ive -ive and a balance plug for use when charging. This leads me to believe the only way to charge these batteries will be with a separate charging circuit as I haven't seen a 33v charger and I haven't connected the balance plugs to anything yet. Hobby King have a Parallel Charging board ($8.99) "Our very own in-house designed and built parallel charge board! Now you can charge SIX (2~6S) lipo packs with same capacity & cell count simultaneously with this parallel charging board. That means you can charge 6 3S 2200mAh or more at the same time with a standard charger!" (The same cell count was what made my decision about using all 3S rather than a mix of 3S and 6S). Question - Can I branch the discharge circuit from each battery to create individual charging circuits that would terminate with XT60s (with it's associated balance plug) on the case cover, leads would then connect to the external parallel charging board and the charger? Or is there a simpler way to do this? Question - Having got to the point where I have the ability to charge the batteries (my assumption), what charger would be recommended, assuming that it would need to charge 9 or 12 3S1P 15Cs through 2 parallel charging boards. I should add that I'm not planning on charging in the field but back home unless it is fairly simple and I don't have to rewire my minivan to make this happen in the field. I hope that through all this, with your help I can maybe get to a diagram, shopping list and instructions on how to easily improve the performance of these excellent bikes. Thanks in anticipation !

Have enjoyed reading all the opinion, very entertaining. I'm now in a panic over my clutch as it seems OK to me, I came from a Sherco which must have had a faulty clutch as I don't see a lot of difference, obviously avoided a problem by buying the OSSA. Finding neutral, umm yes when stationary definitely had a challenge with that early on, easy if the bike was moving. Now its a non issue as I leave and start the bike in gear, waiting I just switch the bike off, that also stops the eyes of those behind from watering in the exhaust fumes. Most noticable +ives: Lighter More power and tractable Fantastic rear suspension -ives Hard starting initially - fixed with the new ignition map from Ossa Needing to get a little hole drilled in the transmission housing - not done yet as works ok. There is a 2012 model.

Key component - get the latest map loaded from the dealer (12 I think) - this addresses the hard start, and speeds up the tickover a touch. No throttle Neutral from cold Wear Boots Kick from the very top like you mean it It gasps a little for the first few seconds I now can't blame the bike when I stall in sections and it starts in gear first kick easily when warm.

I find these forums a great source of valuable information, and wanted to add with my review of the first 6 months of my OSET knowledge. I have a girl (5yo) and a boy (8yo). They both started riding the OSET at 4 and 7. I struggled a little with the price but with apparent good resale value and good reviews I overcame this. I bought a new 36V in Mar this year. I live in town, a quiet street with a back yard. Had I bought a 2T gas motor this story would have lasted about a day, but the whirr of the tires is the only sound so no neighbour issues. Getting my kids started with a twist grip and huge torque was a major challenge, it will dump every kid on their behind and try to attack the nearest tree if not approached with some thought and training. OSET suggest (and are absolutely right) putting the bike on a box and letting the kid practice throttle control, we did this in the house the day it arrived. No move forward until they could control the backwheel speed as you direct. Stage 2 - I adjusted the overall speed control with a screwdriver. Its not very sophisticated, seems to go from zero to full power in about 5 degrees so quite a challenge if you want to continually adjust. I set it on crawl to begin, but that doesn't control the torque (but it did give me a chance to catch my kid and lift them off before hitting the bushes). Stage 3 - I found some open space with poor traction as grabbing a handful of throttle results in stationary wheelspin not a launch into space (have I mentioned the torque). I made them practice pulling away without wheelspin, until I was happy they had got the throttle control. I cranked up the speed to full after a couple of sessions and when they could clearly start smoothly. (BTW The throttles are pretty good - these bikes can crawl along). My 5 year old just loves blasting up and down the street, and we get to a short grass field where I struggle to keep up on my bike as we weave between those conical fir trees (a softer ending). That said, we have had very few "incidents" but I do supervise them all the time. My 8 year old is "trials" focussed. He has started pulling some serious wheelies and competed in a local "veteran" trial. The sections included small logs, rocks and hill climbs, the climbing ability was quite remarkable. There is still a lot of potential yet to discover, in both him and the bike. What I appreciated at the event was that I didn't need to start or restart the bike, get on switch on, go. I would like to improve (we are competitive right), 1. The batteries with Lipo conversion (for weight and duration) although the cost again is making me struggle. 2. The rear suspension. The front I feel is fine, but the stock spring on softest setting still rides too hard for his 50lbs. 3. Handlebar position - perfect for the 5 year old, but low for the 8 year old. All these have answers in the threads on this forum, I just need to get to them! Lesson - Batteries - I was very diligent with the charging instructions on the first set of batts. They have now had many cycles and are useful for about 90 minutes, then power drops. A second set were not fully charged before I first used them - they quickly go to useless after about 20 minutes - read the instructions. I think that next year we will progress to an 80 for the older guy, but the OSET has proved to be so valuable in giving them seat time for confidence and skills on our street and in our backyard, and "man enough" to compete. I hope this helps anyone looking for information, the more kids we get into trials, the better for our sport!

I realize this topic has cooled but wanted to add my 2cents for researching folks. Have had an oset in the family this year. Both my 4 and 8 year olds love it as do the neighbors. The kids blast up and down the street, over curbs and logs and ramps and around the back yard after school and weekends. They say seat time is crucial and the oset makes it easy. The 8 year old has done his first trial (a vintage event) rode all the sections huge moral boost and I don't have to keep starting the bike for him. Of course he has his sights set on a bike like dads now hence my coming to this thread.

I have USD forks its just the wheels are now on top of the bike. A reliable source tells me that the radical dev of the Ossa meant a staged release of new tech by the factory and the USD got pushed back - no release date yet.