betarambo Posted January 11, 2013 Report Share Posted January 11, 2013 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! Quote Link to comment Share on other sites More sharing options...
gwhy Posted January 11, 2013 Report Share Posted January 11, 2013 Yes I know someone who runs lipo on the 20" oset as a 48v sla replacement. I cant answer the controller question directly but if you open it up and have a look at the big capacitors max voltage this will give you a idea if it will handle the voltage. i.e if they are marked with 63v then I would not take the chance You need to hope that they are marked as 85v or 100v also if you have the controller open have a look at the part number on the fets ( 3 pin devices , there should be at least 2 side by side but I expect it will be more like 6 ) , this will enable to find out the max curret and max voltage that they will work at. Quote Link to comment Share on other sites More sharing options...
betarambo Posted January 11, 2013 Author Report Share Posted January 11, 2013 Thanks gwhy. I will check it out. Do you know the details of what cell configuration the "someone who runs lipo on a 20"" runs? Are we talking the standard HobbyKing flightmax lipos or something more like the drop in replacements with built in BMS? By the way us Yanks are kind of jealous of you Brits since I have had my first 20" for like a week while you guys have had them for months! Quote Link to comment Share on other sites More sharing options...
gwhy Posted January 11, 2013 Report Share Posted January 11, 2013 Thanks gwhy. I will check it out. Do you know the details of what cell configuration the "someone who runs lipo on a 20"" runs? Are we talking the standard HobbyKing flightmax lipos or something more like the drop in replacements with built in BMS? By the way us Yanks are kind of jealous of you Brits since I have had my first 20" for like a week while you guys have had them for months! At the moment they are running 12s2p HK turnigys (5000mah) 44.4v 10Ah. Dont be jealous all good things come to those who wait ( you may not have to wait so long for the next major upgrade from oset ) Quote Link to comment Share on other sites More sharing options...
betarambo Posted January 11, 2013 Author Report Share Posted January 11, 2013 Thanks for the info. If they are getting by with 12s2p then I think I will give it a try and see how it works. While I am at it I think I might pull the Cycle Analyst off of Sparky and put it on the 20" so I can get some data. If that works ok then I would probably run 12s3p to get enough range for a trials (15aH). since there should be plenty of room for 6 packs. Quote Link to comment Share on other sites More sharing options...
frogger Posted January 11, 2013 Report Share Posted January 11, 2013 (edited) We have been running 48v lipo on our 20 since it came out. Works awesome, checkout my battery build: http://www.ktmforum.co.uk/off-road-enduro/140584-oset-20-a.html My boy gets around 3hrs full power. Edited January 11, 2013 by frogger Quote Link to comment Share on other sites More sharing options...
betarambo Posted January 11, 2013 Author Report Share Posted January 11, 2013 (edited) Thanks! From what I read there (aside from all the electric bike versus gas bike garbage) it looks like two of you are running 12s2p and having good results. I will try this out first before messing with 15s2p. I still think I will need to go up from 12s in order to use the full charge of the battery, but perhaps I am thinking of some artifact of the old 24v controller that the new 48v one will not show when voltage drops below nominal. Have you done any measurements to see how many aH you have pulled out of them when your kid reports it is slowing down? Curse all you Brits talking about the decision of if you should hide the 20" until Christmas! Those of us in the colonies got ours a couple weeks AFTER Christmas! I enjoyed reading about the adults who are riding them. I do think that it has everything you need. My local club has 9 classes and I normally ride #7. I think with no modifications I could win #4 on it. With some mods to let me stand up a bit more straight I think I could get to #5 or #6. I am seriously considering getting one for myself. Edited January 11, 2013 by betarambo Quote Link to comment Share on other sites More sharing options...
frogger Posted January 11, 2013 Report Share Posted January 11, 2013 We had one of the very first batch of the generally available 20's that came in and gave it to my boy straight away. It was meant to be his birthday present in May but they were a little delayed. We used the same packs that we previously used on our Oset 16 36v and just added 2 packs and made it 48v. As long as we have had it he has never reached the bottom of the packs so have never complained of it slowing down with the lipo's and the low voltage alarms have started flashing but not screamed. I haven't actually checked how much milliamps go back in when we charge them but the lowest my chargers have ever reported them was 9% after about 3hrs and 20mins of riding. My boy is quite experienced and rides it like he stole it! I don't really have any desire to ride it as an adult as I have a Gas Gas 300 that I ride and so ours is setup 100% for him with soft suspension and tyre pressures. Quote Link to comment Share on other sites More sharing options...
will barley Posted January 13, 2016 Report Share Posted January 13, 2016 gwhy, and the rest - can you explain the sluggishness that betarambo saw: 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. Is this a characteristic of the particular motor in the 24V OSET - i.e. the motor does not respond well to voltage < 22.2V, not enough torque at that voltage? Or is it the controller, or something else? Impossible to say without looking at spec sheets? Quote Link to comment Share on other sites More sharing options...
gwhy Posted January 14, 2016 Report Share Posted January 14, 2016 without knowing the battery that BR was running its very hard to say, he may of had a weak cell group in his pack or a connector that was getting hot and becoming high resistance. In theory there should be no difference at the very minimum ( but there should be a increase in performance ) 24v sla fully charged is around 26v and a fully charged 6s lipo is around 25.2v so not that much difference in voltages and both battery chemistries will reduce in voltage as they become discharged, the sla will run down much quicker than the lipo.. so to answer your question is: I would need more information about the pack that BR was using.. once a sla gets down to around 10.5v ( 21v for a 24v setup ) its classed as flat which is going to be around the same voltage as a lipo ( if being on the safe side not running a bms or lv alarms ) but a cell level flat lipo is 3.2v per cell i.e 19.2v .. a weak cell in a pack will make the whole pack sluggish once it get to around 80% SOC ( state of charge ) there are ways to test for weak cells. The controller and motor do not really care where the voltage and amps come from so this should not effect the over all performance Quote Link to comment Share on other sites More sharing options...
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