Oset Batteries Lithium (LiPo) Conversion Directions

[gwhy]

try this..

 

i have not shown the balance taps as it will start to get messy and will look even more complicated than it really is.

[bowser]

thanks heaps, much appreciated

[wacksotn]

Thanks to the originator of this forum Series! I have just converted my Kids 24V  OSET 16  to LiPo with great success.

I definately encourage the undecided to "take the plunge" it really makes the little Bike.   

 

In the end I went for a 7S 2P (two 5800mAH 7S Batteries paralleled)  configuration.  Last waay longer than the factory lead-acids....

 

For safety reasons (charging well away from the petrol tanks of diverse MX Bikes!) and because I have two sets and so swap anyway I remove the batteries to charge.

 

The 7S configuration was chosen to give the Bike a little more top-end grunt (both my kids ride MX too so they lap up the power).  The end-result is hard to measure objectively but according to the kids it worked.  "Much better Daddy!".   7S  cells also seemed to me likely to be a better match to tvoltages I measured at which the throttle indicator leds were "counting down". 

 

As it is telling the kids "Once you see only 1 red dot its  time to swap, low battery dot means - swap NOW" is giving nice conservative battery cell voltages around 3.2 with the battery drained to around 10-20% rated capacity according to the charger.   Just to be safe  I've put those cheap little LiPo "beeper" monitors you can get on ebay on the balance cables to watch  for individual cells dropping too far.  So far (20ish charge cycles)... not a peep!

 

There was one self-inflicted negative I like to share though.  One of my shiny new batteries had a bad cell.   My charger started warning me about it from the from the 2nd charge onwards  - warning messages and needing several retriesto get started charging.  Unfortunately,  I  assumed I'd  discharged too deeply overall and didn't check the error code in the manual.  Needless to say the battery gave up the ghost completely 3rd or 4th charge.  Alas, by that time the 30day warranty had expired.... Doh!    Lesson:  if your charger starts grumbling with a new battery - trust it, discharge for  shipping, and send the damn thing back right away.

 

Edited August 21, 2015 by wacksotn

[bowser]

well I decided on a charger, ordered 2 of these today (free shipping deal) 

 

http://www.hobbyking.com/hobbyking/store/__53601__HobbyKing_8482_X200_AC_DC_Touch_Screen_Smart_Battery_Charger_10A_6S_US_Plug_.html

 

the built in power supply sold me, will allow a quicker charge time for the 6 batteries than the single 10s charger and simplify without needing a separate power supply.

Plan to split the batteries into 2 separate banks of 3P and charge them in a fireproof bag

[scottwitting]

Similar to wackston above, after making good use of the valuable info in this thread, I've successfully converted a 36v 16" to LiPo's (two 5s in series in various capacities). All very positive, the weight saving and the ability for LiPo's to maintain voltage even at high current draw really transforms the bike.

 

My one remaining issue/fear is running the batteries too low. 37v corresponds to loosing the first throttle indicator light, so I've tried my best to train our 4 year old (& Mummy) to stop riding at that. However, sometimes he gets carried away chasing other kids around, I'm absent riding the adult trial and Mum is off the ball. A couple of times I've had batteries down as low as 13v (5s) but luckily seemed to have recovered them ok with no lasting effects. I've just got some of the 'beepers' that wackston mentions so will see how they go.

 

However, ideally, and this is my question, does anybody (gwhy!) know if it is possible to get a device that you can connect in line which measures voltage and ramps down current between two levels (say 37 and 36v in my case)? Hopefully this would give the feel of SLA's dying and leave it impossible for said child to run the voltage below 36v.  

 

I guess you may be able to get low voltage cut offs, i.e. get to specified voltage and cut power off completely. However, I'd not be comfortable with this as it's most likely to happen whilst drawing max current when part way up a hill, having dangerous consequences for the rider!

 

If something is available it needs to be reasonably simple as my background is mechanical, not electrical!

 

Cheers

 

Scott

[gwhy]

Hi Scott,

  As far as i know there is no such device off the shelf, the nearest thing would be a CA ( cycle analyst ) but it is expensive and has a lot more functions that you will prob ever use ( but it will also act as a throttle interface to make custom throttle ramps and mods ) , but I dont think in reduces power at lv , its more of a cut off ( may be worth sending grintect a email to ask exacly how the lv cutout works ).  Sometime this week I will play around with 2 of the very cheap lipo alarms to see if they can be put in series to cover the 36 or 48v and still emitted the very loud alarm when these threshholds are exceeded .. ( as the alarms are quite loud this should be enough incentive to stop riding :-) ). 

I have developed a device that can reduce the power @ lv as a 3 stage device .. 1: visulal display 2: reduction in power ( just like flat sla's ) 3: hardcut off

at which voltage can be set to what ever you want, the device also allow different throttle maps and modes, it has a built in watt meter, amp meter and voltmeter that also records max/min values. it also allow to set max speed and max/min power it also supports a temp gauge for motor, battery or controller. 

The bad news is It also works out quite expensive as they are hand made to order and they do not look like a off the shelf commercial product , so I dont tend to offer them for sell only to friends that know me and know what the device does and fully understands what its capable of. 

 

 

     

Edited August 23, 2015 by gwhy

[scottwitting]

Hi gwhy, thanks for the reply. Impressive device! Sounds ideal, with it having variable throttle maps and power/speed settings would it replace parts on the Oset (controller?) or could it just plug in-line and perform the soft cut off function? How much do you sell them for if you don't mind me asking?

 

I've been looking at some speed controllers on HK (like this http://www.hobbyking.com/hobbyking/store/__29665__Turnigy_dlux_80A_HV_Brushless_Speed_Controller_OPTO_UK_Warehouse_.html)

. Some seem to feature a programmable soft cut off function, but also do more than I require. They also have three output wires (for connection to a brushless motor) so I'm not sure how that would work with just the two wires on the Oset? They also have an input from a receiver which I guess sets the speed. I'm unsure what this would need to be fed with to see a permanent 'throttle fully open' signal, if that makes sense.

Edited August 23, 2015 by scottwitting

[gwhy]

The CA and my device works inline with the original controller so the controller is still required. The controllers on HK are all for brushless motors and will not work under any circumstances with a brushed motor.

 

Check your messages (PM sent)

[bowser]

Gwhy, do you still have the contact details for guy who makes throttle tamers for the 36V bikes?

[mikedufty]

I've got the cycle analyst on my push bike.  A bit expensive but a great device, very good for tracking your power use and battery condition.  As standard the low voltage cut off just shuts it down.  Generally you can limp along a bit as the voltage will rise again once it shuts down, but you wouldn't want it to cut out somewhere difficult.

 

There is quite a bit of scope for customisation with the throttle control etc, but I don't recall seeing anything that allows it to change automatically.  You can set up an external switch to change modes, which I guess could be hooked up to some kind of voltage sensor. 

 

As above, if you contact the manufacturer and ask they can probably give a better answer, also search endless sphere forum.

[gwhy]

Gwhy, do you still have the contact details for guy who makes throttle tamers for the 36V bikes?

 

 

Hi Bowser,

    The guys e-mail address is at the bottom of the instructions ( attached )

Throttle Tamer Instructions V1.0 (2).pdf

 

But I don't think he is making them but he may have some left from the last batch so worth asking.. 

 

they are not voltage specific as they just fit between the throttle plug and controller, just like the pico ( but cheaper ) .

 

edit:

  Just done searching around and found the throttle tamer are now on a website for sell and currently has 11 in stock.

 

http://www.greyborgusa.com/product/throttle-tamer/

Edited August 24, 2015 by gwhy

[bowser]

thanks, i emailed him and he said he didn't make them for Osets, I did order one from that site so will see if it turns up and if it can be made fit 

[gwhy]

there are a few things that need to be done to make it compatible with the oset controller but these are not major and very easy to carry out.. when you get it give me a shout and I can tell you what you need to do to make it work.. the throttle input and throttle output plug and sockets on the tamer are the opposite to the oset ( they may even be totally different depending on what throttle plug you have on the oset ) so these will need swapping ( just a bit of heat shrink and solder on the wires ) and a small resistor ( 10k ) needs to be added to the throttle output between the signal wire and the black wire ..  

[bowser]

no luck with the tamer, he didn't have any left in stock

[gwhy]

that's a shame... did he say he was going to get more ?..

 

other options are a cycle analyst , new controller, the pico device , these are off the shelf but come in quite expensive. There are other options but will involve making your own small electronic circuit up.