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Yrocmoto

Oset 20 Lipo LifePO4 Pack

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Been reading the posts I can find about this and see that most are using RC packs in series, which I can do and have done with other electric bike projects.  But I'd rather have a pack with a BMS so the cells can be charged and balanced on the bike all at once.  What I'm having trouble with is the max volts that the Oset's controllers can handle.  Most Lipo or Lithium packs are well above 48v and most peak around 58v and that worries me.  All my other electric bike projects have been for 36v and I have sent over 48v to those without issue...but this Oset is a way more expensive bike and I don't want to blow any electronics.

Here's the pack I'm looking at, probably the LifePO4:

 

https://www.ebay.com/itm/48V-20AH-Lithium-Battery-Pack-Power-for-1000W-EBike-Scooter-with-5A-Charger-BMS/272702964037

or LifePO4

https://www.ebay.com/itm/48V-20Ah-LiFePO4-Battery-Pack-for-Rechargeable-1000W-EBike-Scooter-Charger-BMS/113149616816

These packs have AWESOME specs, a 5amp charger and good reviews.....

It's the 58.4v when fully charged that concerns me.

The lithium pack is 14s, where I've seen 13s packs used for these Oset bikes, but the LifePO4 pack is basically the same max voltage.  These are built for 48v electric bikes, but I'm still worried I'm missing something.

Any help is appreciated!

BTW, I have a 2013 Oset 20.0.  My daughter loves it, but we get stranded on trail rides every time at only 6-7 miles!!  I was expecting 10 min, and that's still crap...need more range, she's excited to ride!

Edited by Yrocmoto

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the voltage should be fine, but the power of these packs may not be suitable for the 20.0 if they are rated at 1kw (58v ) which is round 20A cont, but you do not know what the peak current is for the bike and how long or how high the current will the bms be allowed to over shoot I think the current setting for the standard 20.0 is around 40A ( but i know on the 20.0r it can be set upto around 120A ) but can peak much higher. the packs will be a good buy for a standard 250W/500W ebike but not sure about a off road bike like the 20.. 

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gwhy

Thanks for the reply.  My daughter is 8 and we have it on the lowest setting right now, I really don't think she's going to need crazy high amp draws. we have the regular 20.0 not the r, I think the 50A continuous with the 100A bursts should suffice.

Just to clarify though.   The pack should work fine and not cause any issues, it may just limit the Oset's potential, correct?  The BMS should limit what can be drawn....so if the bike wanted 120A, it would only get 100A but still function properly.  Correct me if I'm wrong here.

I have run into this before when I went to Lithium on a 36v bike.  I tried it with one lithium pack, which would only supply 20A, it worked fine, but wasn't 'peppy'  then I added 2 more packs, so 60A total and that woke it up....I guess I could get 2 of these packs and run them in parallel to double the draw limits to 100A continuous and 200A max....but I really don't think I"ll need it...

Edited by Yrocmoto
added info

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most bms's allow a peak much higher then they are rated for but only for a very short period i.e no more than 500ms  then shut down the battery if the current dont come down to (or below ) its cont current rating, 1000w bms on 14s would be around a cont of approx 20A. A bms dont limit the current it just shuts the battery down if the current is higher then the specs of the bms, its the controller that limits the current. I would borrow a lithium battery pack ( if you can ) and use a watt meter to see what the peak currents are when the bike is being used. yes you can p battery packs together to double the peak current and the cont current but you must be aware that both battery must be identical voltages before connecting. 

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most low output bms's have issues when the bike is pulling a heavy load for a longer period of time. this very rarely happens on a road bike but off road can be more of a problem, i do think a 8 year old new rider should not have any issues . on the flat current comes down very quicky once the bike is moving, it may become a problem if for example you try to give it a handful whilst pointing up a hill from a standing start. but if the contoller is set to limit the current @ appox 20~30 then at least the bike should keep moving and not trip the bms.

when you added a additional pack to your 36v bike it would have become more peppy because there would have been less voltage drop when accelerating, unless you also altered the current limit on the controller.

Edited by gwhy

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Okay, everything makes sense except for your calculation for this pack being only 20A continuous as the listing states 50A continuous.  Are you saying the 50A spec is likely wrong and that a 1Kw pack will only provide 20A?

Edited by Yrocmoto

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....and running packs in parallel. Wouldn't the BMS in each pack manage the voltage?  I'm actually running 4 in my 36v bike and just charge them with a single 36v (42v) charger, and I always assumed that if they got drained unevenly, that the BMS would cut off the charging when they reached 42v.  Although, I did make sure each pack was individually charged to 42v before connecting them in p in the bike.   They've been connected in p for over a year now and charged probably a hundred times....should I charge them individually every so often?  

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yes each bms looks after each pack, but the more packs you p the less voltage drop you get because the over all rating of the combined packs will now have a much higher c rating. the reason for being careful when connecting bms packs together is because if one pack is flat and the other fully charged the fully charged pack will dump massive current into the flat one and this can damage the bms's in both batterys.

 

the listing states its a 1000w battery @ 58v this will be the cont current of around 20A (1000/58= 17.5) .....  I have no idea why the description says is 50A cont (but it may well be ) but this do not add up .. 58v x 50A = 2900W ?

 

best guess is that the battery is only rated 1c discharge this will make it a 1000W battery, and the bms is over rated for the cells .  lots of sellers spec there batterys like this and it dont make it a bad battery ,  discharging at a higher C rating reduces the life of the advertised cycle life.. most of the time ( on the flat and at a steady speed the the discharge will only be around 1c) 

Edited by gwhy

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Just an update.

This is the pack I bought:

https://www.ebay.com/itm/Rechargeable-48V20Ah-LiFePO4-Battery-Pack-for-Ebike-Scooter-pedicabs-Charger/123191554222?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

It's AWESOME!!  Shape is almost exactly the same as the lead acid battery pack, probably an inch taller, but the canvas pouch fits over it and it just looks stock. I added a gauge that's velcro'd to the top velcro strap.  We haven't been able to run it out of juice yet!!  What a huge improvement.  Used 9.5ah yesterday and did about a 12 mile trail ride, the pack is still at 52v.  It's rated for 20ah, curious to see if I get that much out of it, but it's REALLY hard to run it down riding around the house (I always fully charge it for rides...)  Even though the stock lead acid batteries said they were 10ah, We were only getting about 6 miles or 30-45min....so 12 miles or about 2-3 hours so far is a huge improvement, even if we don't get 20ah.

As for max amp draw, I don't have any real definitive info.  I turned it all the way up and compared it back to back with my buddies 2015 20.0R and it 'feels' the same to me, definitely plenty for my daughter trail riding.  The increased voltage does speed it up a little, so I had to turn it all the way down, so if you need the lowest settings with the lead acid batteries, you will lose that with this upgrade as it won't dial down quite as low.  I also went up a slight paved hill and was able look down at the guage, and it was pulling 1785-1900w up the whole hill (maybe 100yards)  which is about 37-40amps, so I think that the rating of 50a continuous is probably correct (there was some question about this that gwhy brought up above).

Time is the real test, but the pack seems totally legit and for $300 (make an offer, he accepted my $300 offer) its a crazy good value.

 

20200303_185350.jpg

Edited by Yrocmoto

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Hello Yrocmoto,

Can you keep us updated regarding this battery upgrade please?

I just bought a new 20.0 2020 and not happy with 20min riding time of my 9year old kid.
Its mix between offroad and obstakels. Because of corona we cant ride with his KTM 65 for the time beeing ?

On the other hand I would be interested in knowing someone who bought a HK solution.
So recent shoppinglist would be great because most are bit older and for 24V or 36V.
But I assume doing 2 x 24V pack in series would give me 48V pack?

Thanks guys!

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It's a great pack for the price.  We aren't getting the rated 20ah, but way longer ride times than the stock SLA batteries.  We rode for 2-3 hours yesterday and never ran out of juice.  The 5A charger helps keep it charged between riding.

We've only fully drained it twice and got 14.96ah out of it the first time and 13.88 the second time.  The second time was over 4 days, so I don't know if there is any drop just sitting.  

The low voltage cutoff of the pack is 40v, but the Oset goes into limp mode around 46-47v, and doesn't run long after that until full shut-off.  I don't know if that's a problem with my Oset as I bought it used, but I would assume that also has something to do with not getting the full 20ah out of the pack.  Overall, it's worth $300.

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Hi,

Thanks for sharing this with us. Could you repost some more info re this battery pack and/or where to find it as the EBay link is down ?

Many thanks !

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Did a quick search and this looks like what I got, check the dimensions to make sure it will fit, I will double check mine when I get some time.  Mine is 48v 20AH LifePO4, but they come in a couple different dimensions.

Lifepo4 Pack

Also, we did a 22 mile ride in the desert, I thought we'd get stranded when I saw that we were at 11 miles and still needed to make it back, but it made it.  My meter said she consumed 15.85ah, but I've been reading that the meter I use may be inaccurate for the accumulated ah, but I've found it to work for us and seems pretty consistent.

Edited by Yrocmoto

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Hi just reading the posts seems like an interesting battery potential, has anyone actually ran the battery on full power and used it for splatting a wall or log,??? as i brought a similar battery a Panasonic 1200w 18000 ah it was a good quality battery and it worked ok pottering about on it, but if used by an adult splatting logs or  quick wheelys power climbing, it would cut out and you would have to switch the bike off and on again, cheers 

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