Oset Batteries Lithium (LiPo) Conversion Directions

[heymak]

Hi everyone, I have posted here before but ony just taken the plunge,

my kids have a 16-24v 2011 oset, 2 x 12v 14ah 20hr SLA batteries

my order arrived yesterday,all looks good

4X ZIPPY Flightmax 5000mAh 6S1P 20C

1 x TURNIGY MEGA 400W V2 Lithium Polymer Battery Charger (Version 2)

various leads plugs and connectors,and volt cell checker

I have balance charged all 4 batteries,all cells 4.2v ,but not connected up before some final advice,

What will be the best way to get the max run time from the 4X 6S1P

connect a bank of 3 or all 4 in parallel

just use 1 bank 2 in paralell then swap to next 2 when at 3.7v

or 2 banks of 2 in series, linked in paralell

or just 1 bank of 2 in series

just want to get the best set up before we go out on sunday,

all can be fitted in to bike protected and dry no problem,

thanks guys

[gwhy]

Any configuration where you series the battery's will increase the voltage into the controller/bike 2 in series will end up 44.4v ( 50v hot) so to keep the 24v you will only be paralleling them . I would parallel 2 battery's at a time this will give you 10ah ( so it will give you 2 x 22.2v 10ah battery's ) , by using the battery's this way should one of your cells within the battery fail in anyway it will not kill the whole 4 packs in one hit. Run time will be the same just means you have to swap out one pack when its flat and replace it with a fresh one.

[heymak]

Hi gwhy thanks for the advice ,need to hook them up and will be ready to go,

Thanks

[zip]

Hi Guys,

I am new to the forum and the world of electric bikes.

My son has a 36v Oset and as others have poor battery life.

I have been reading this post with great interest but do not personally feel confident to take on this task.

Whilst looking on ebay for a 12.5 for my youngest I came across this

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=130860920695&ssPageName=ADME:X:eRTM:GB:1123

I have spoke to the guy and he will make up the batteries to two different specs.

He says he has 42v on his sons 12.5 24v bike and it's running fast a reliable.

He has offered me the same 42v or 50.4v.

He has built in cut off circuit boards to protect the batteries and a one charger system for the battery pack.

I will copy and paste his specs.

My question is do you think that these will be ok and or should I go for the 42v or 50.4v

Thanks in advance Richard.

Thanks for the interest, my son also has a Oset, a 24v 12.5 and I built a 42v lithium ion battery pack for it, it flies, and ive had no problems with it whatsoever, these wee bikes can handle a fair bit of voltage.

I would suggest a 10s (10 cells in series) pack - 42v peak, 37v nominal and 30v cutoff for your 36v or if you want I could build you a 12s pack 50.4v peak 44.4v nominal and 36v cutoff?

To build a 10s pack with approximately 20ah capacity you are talking £250 plus postage, I know this sounds a lot of money and it is! but this lithium ion battery will provide more power than the SLA batteries and last twice as long with a flatter power curve too. This price includes a charger and also an extra pair of HXT battery terminals to solder to the battery leads on the bike. The battery will have two leads with HXT connectors on them, one to connect to the bike and a lighter gauge lead for charging, with a matching connector on the charger lead.

Next reply

As I said, my sons Oset has a 42v pack even though its 24v standard with no problems whatsoever. A 42v peak battery pack is as close as you will get to 36v as the nominal voltage is 37v.

A lithium battery cell has a fully charged voltage of 4.2v and as it drains a built in circuit board stops the cells going any lower than 3.0v, this is the cutoff voltage. The nominal voltage is in the middle and is 3.6/3.7v.

The battery pack has one charge lead which will charge the whole pack at once and the built in circuit board (BMS) controls the charging of each group of cells within the pack ensuring they are not overcharged, undercharged and prides short circuit protection also. Hope this helps.

[gwhy]

Hi Richard,

Yes these batterys will be fine for the smaller oset at upto 44.4v But remember that if using twice the standard voltage that the bike will have a 2x top speed , One thing I would check is the peak current that this guys batterys can deliver, the one in the link that you posted looks like it can only deliver 25A ( and this is a 15ah battery ) so he is suggesting a 20ah 37v will this be the same max current delivery ?. These batterys will be no good for the 20" oset or if you wanted to start upping the power of the 12.5 or 16 . Also it sounds like he is just using the built in protection on the cells them self and not a proper bms external board that manages the full pack ( I could be wrong and it will be worth asking the guy ) If he is using just the individual built in cell cutout this do not always reset itself if over current occurs and there fore will render the battery useless. If it has a full BMS system and you are not intrested in upping the power ( in the future ) of your bikes then they seem to be a reasonable turnkey solution but at 2x the price of a lipo setup.

[zip]

Hi Richard,

Yes these batterys will be fine for the smaller oset at upto 44.4v But remember that if using twice the standard voltage that the bike will have a 2x top speed , One thing I would check is the peak current that this guys batterys can deliver, the one in the link that you posted looks like it can only deliver 25A ( and this is a 15ah battery ) so he is suggesting a 20ah 37v will this be the same max current delivery ?. These batterys will be no good for the 20" oset or if you wanted to start upping the power of the 12.5 or 16 . Also it sounds like he is just using the built in protection on the cells them self and not a proper bms external board that manages the full pack ( I could be wrong and it will be worth asking the guy ) If he is using just the individual built in cell cutout this do not always reset itself if over current occurs and there fore will render the battery useless. If it has a full BMS system and you are not intrested in upping the power ( in the future ) of your bikes then they seem to be a reasonable turnkey solution but at 2x the price of a lipo setup.

Thanks for your reply.

This is the next reply I have received about the kit.

The larger pack would cost £300 as there's a fair bit more work in getting a 12s pack into the Oset 36v. I recommend you go for the 10s pack where the throttle power gauge will work just fine, but what you might find is that it will stay on 4 bars for 80 -90 % of the battery capacity and then drop off quite rapidly. I can fit a gauge to the side of the actual battery pack as they are panel mounted pcb's if you wish, which is designed specifically for lithium packs, but to be honest it won't really be needed, the one on the throttle will do exactly the same job.

When the pack drains it will cut off immediately, but if the bike is turned off and on again it will go for another bit before stopping and so on with decreasing intervals of power, this protects the cells and is normal for all lithium powered devices.

A 10s pack will absolutely not do any harm to either speed controller or motor on a 36v Oset as it's as close as you can get with a lithium pack to SLA without sacrificing power due to lower voltage. I hope this helps and if you have any more questions I'd be more than happy to answer them as best I can.

So i need to ask if the if they are BMS protected.

The battery pack is different to the one listed. He said it would be 10s 42v pack.

Are Lithium batteries the same as Lippo batteries?

Does anybody know anyone who may build a set that would be key turn ready as I ideally want two sets. 1 for a 36v 16 and another for a 24v 12.5.

Thanks!!!

[gwhy]

yes you need to ask if they have a seperate BMS or is he using the built in protection on the individual cells as a BMS . The 10s 42v would be equivalent to the 3X 12v sla's (36v) . Im guessing he is using laptop cells in his batterys . Lipo are lithium Polymer and laptop batterys are lithium ion so they both are lithium batterys but the lithium ion claims to be a more stable chemistry than lipo. If you want more detailed info about using lipo or making your own lipo packs up then drop me a pm and I will try to point you in the right direction. If this guy is just using the built in protection on the individual cells then I would steer well clear, a battery pack of this size ( this many paralleled cells ) needs a proper BMS system for the whole pack, But if he is using a BMS to monitor the complete battery and your happy with the price then go for it .

Edited March 8, 2013 by gwhy

[awdrocks]

Richard,

I have a late model 12.5'', and the OSET controller didn't run on 36v. Test yours with an extra battery.

[zip]

Thanks so much guys.....

gwhy,

I have now spoken to him and the batteries are BMS protected and said he would never entertain building them with out.

I have gone ahead with the order now.

awdrocks,

I have a 16" 36v at present which this conversion is for. The guy who is building the batteries had a 42v set on his 12.5".

[8690q]

Hi,

I've been a lurker for a good while now. I own a Gas Gas 2001 280 txt and my boy has a year old Oset 16 36v.

He's found the limit of the batteries run time and power.

I use 2s and 3s lipos in my rc cars and have 2 chargers capable of charging upto 6s 5000mah.

I'm looking to change the Oset to lipo but want to keep the number of batteries down for simplicity.

I initially thought 2 5s packs would do but now I think of it they'd need to be 10000mah beasts to give the right voltage and amp hours.

I buy my rc batteries from these guys http://www.giantshark.co.uk/index.php Do they have what I need ?

Would 2 12s 5000mah lipos and right charger do ?

4 6s I could maybe handle but could the bike ?

Edited March 18, 2013 by 8690q

[gwhy]

You will need to get 4 x 5s 5000mAh lipos to make up a 10ah 37v ( 42v hot off the charger ) battery for the oset and you can use your exsiting 2 x chargers to charge these up and it would be quite stright forward. I guess you are in the uk if you buy from GiantShark but you may want to look at the prices of the zippy or turnigy cells on the hobbyking web site as they now have a uk warehouse which saves a lot!! of money and time for the delivery.

[gwhy]

Here is some pics on how to wire the batterys up to achive the different voltages and capacitys.

this diagram is another way to get the 36v ('ish) using 3s lipos.

using the 3s setup is more in the real ball park voltage for true 36v operation but this setup can get a bit tricky with re-charging using the 5s and 6s setups the charging and manual BMS becomes a little easier to manage.

Just a quick work of warning: always check that any battery is at the same voltage as another battery that you are about to connect it to in parallel, the series connection its not so critical. You don't need to un-parallel the battery's for charging but I would advise also paralleling the balance taps of the parrelleled batterys and balance charge at least 1 out of every 5 recharges at least until you get a feel for how well the cells remain in balance.

Edited March 18, 2013 by gwhy

[8690q]

Excellent ! Thanks for the help and the wee diagram. So 2 6s would give me volts and mah.

Will the bike be okay with the fully charged lipos being closer to 50v ?

If done the 2 5s way will the power difference be noticeable over the sla batteries ?

I'm looking at the Hobbyking site the now and your right about the battery prices, perfect.

[8690q]

I meant to say that I'll be using a lipo voltage indicator much like the screen on the chargers to keep an eye on cell counts.

I'll be wanting to charge them off the bike so I can monitor them whilst charging.

[gwhy]

Excellent ! Thanks for the help and the wee diagram. So 2 6s would give me volts and mah.

Will the bike be okay with the fully charged lipos being closer to 50v ?

If done the 2 5s way will the power difference be noticeable over the sla batteries ?

I'm looking at the Hobbyking site the now and your right about the battery prices, perfect.

no 2 x 6s will give you 44.4v ( 48v) which is to much for the 36v oset, the 36v oset may be ok to run on 48v but it will have increased top speed and more power but the motor and controller may not survive for to long as they are not rated for 48v . if using 5s this will give you a off the charger voltage of around 42v so there will be a small increase in power and a small increase in speed over using sla's which will be around 39v off the charger. But dont forget that you will need 4x 5s lipos you will be parrelling 2x 5s then connecting 2 of these packs in series to make up the 36v. if you order lipos from the HK website dont forget to get them from the uk warehouse :-) it can work out a very expensive mistake.