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[Jdub1970]

Hi

My son has a Kuberg Cross. Great little bike, tons of torque and great fun. Only thing that could make it better would be better batteries.

Lithium batteries would be much better.

Has any ever done a lithium conversation or know of one being done?

Cheers

[mrwilsn]

It uses a 36v battery just like the razor mx500.

http://electricmotorcycleforum.com/boards/index.php?topic=5353.0

Sent from my Nexus 6P using Tapatalk

[Jdub1970]

Hi

Thank you for that. Yes I know but I wondered if there was a lithium battery upgrade in the market for it or had anyone ever one it.

[Jdub1970]

Just read that post. Thank you for that good post

[Jdub1970]

Just read that post. Thank you for that good post

[JoelR]

Hi,

I found this post by googling "kuberg cross battery".  I've recently purchased 2 2015 Kuberg bikes, the Cross and Trial E and both are due for a battery replacement (individual SLA batteries range from 11.6v to 12.7v fully charged w/stock charger).

The Luna Cycles battery pack referenced in the Razor MX500 post doesn't appear to be available and I'm curious what others have done since this thread was last updated.

Thanks,

Joel

[MDW195]

Following as well.
I am about to just purchase a prebuilt 36V LiPo with BMS off of ebay, but like the idea of supporting Luna. especially since it would not be a case of reinventing the wheel.
If I get some time tomorrow, perhaps I can try to call them...But then I might be tempted into looking at the SurRon.

[acacia1731]

Keeping this alive in hopes that someone has found a compatible pack and is willing to share the details, or a battery expert is willing to give advice.

I'm not a battery expert, but here's what I've gathered so far:

• Stock batteries: 3x 12v SLA (NT12-12)
• Motor: 750w
• POWER: 3000 watts, 36 V
• CONTROLLER: PWM, 40 amp
• Rule: Battery should be rated for more current/amps than controller - motor and controller will draw what they need
• Peak power(3000W) = Voltage(36V) X Max Current(83A)

So, does this mean we need a BMS with a continuous discharge > 40A and max discharge > 83A?  If so, this seems to rule out most of the 36V packs that are readily available.

Any help much appreciated.

[acacia1731]

A few I’ve found that might work:

https://www.ebay.com/itm/303208792815  ($254- almost 6” wide, vs 4” Kuberg tray)
https://www.pingbattery.com/ (Traded emails, said he could build one that fits perfectly But didnt give a price - similar packs on website run around $450)
https://www.boost-bikes.co.uk/pages/oset-battery-kits  (Traded emails, said they have a design ready for kuberg for $513).  Found them per this article:  https://www.juniormoto.com/2019/01/23/switch-to-lithium-battery/?lang=en

Kuberg OEM:
https://store.kuberg.com/part/battery-trial-and-cross-li-on-36v/UN-0235. (767 Euro)

[MDW195]

Well, I had forgotten about this posting...and what do you know? I went and purchased a SurRon Black.
But I did order a LiPo battery for the Kuberg Cross. This is what I purchased.
"https://www.ebay.com/itm/293314294162"
Now, I know even less, but apparently enough to get into some trouble, but the good news is that nothing dangerous. This battery will shut down if you pull too much current, and it has done so multiple times. (It also does so when voltage is too low...which is a good thing).
In order to reset the BMS, I need to disconnect the battery leads (I am using XT60 connectors, lengthened just enough to be able to reach from the back without removing bodywork). Then we are back on the road.
The SLA batteries that came with the bike were "supposed" to be fairly new, but we would be lucky to get 5 miles out of them. So the LiPo's are great in that have seen 15 miles on the bike...but the power has to be reduced in order to avoid tripping the BMS.
The Cross also has other issues, such as no LED indicators on the throttle...but replacing the throttle requires replacing the entire wiring harness and controller as the bike is a 2015 and has early release parts on it, and I have not had much luck contacting Kuberg over the phone, but did get an estimate of $400 for the parts I assume that I need. It would be much easier to simply add a voltage indicator on the bike, but again, I am not sure what to look for.
My daughter is 9, so the bike is close to getting too small for her, but I LOVE the bike as it is so quiet. She loves it as well...we also have a CRF50 and she prefers that Kuberg every time...It is lighter, and no shifting...quiet, not kick starting, etc. At $700 I feel like I got a great deal, although I COULD nitpik the bike quite a bit as well. -Basically spares pricing is insane, and new bike pricing not much better.

[MDW195]

acacia1731 -you are a wealth of knowledge. you found articles that I never found, and it was not because I wasn't looking either. But you did find the Kuberg site and now you know why I went my own route. That is almost a grand for a 12AH battery!
The article in juniormoto.com also did not mention what the battery rating was, only stating 5x the battery life? And what i found interesting is that they also has the bike's power turned down as well. But they appeared to be half the price of Kuberg!
I still cannot get over Kuberg pricing. The bikes, as new, are expensive for what they are, and spares seem equally pricey. Hence, why I am really taking a liking to the SurRon. PLUS the SurRon has off the shelf parts for chains, suspension, etc. Plus no bodywork...

[JoelR]

@MDW195 - The battery pack you ordered has some concerning and inconsistent specs:
Regarding the cell configuration, in some place it indicates 10s7p, in others it's 10s8p. 
The weight at 8.4lb suggests it's 10s8P.
The dimensions seem like they won't fit into the Kuberg's frame.  I found a 10s6p will fit but only with the cells staggered.  Using pre-built cell holders, my 10s6p was too wide.
The peak discharge current is 30A and the *Continuous Charge/Discharge* is higher at 50A.  I'm guessing they got these two mixed up.
If true, 30A seems too low for a bike with a 40A controller. 

The pack I intend to build has these specs:

PANASONIC/SANYO NCR18650GA

Cell Specs:
====================
mAh:   3500
Discharge:   10A
Charge (normal):   1.675
Charge (fast)   ??
Cell weight:   48.0

Pack Specs
====================
Configuration: 10s6p
Pack Capacity (Ah):   21.0
Pack discharge (A):   60
Pack charge (normal): ??   
Pack charge (fast):   ??
Pack charge (not clear if fast or slow):   10.05 ??
Pack weight (g)   2880
Pack weight (lb)   6.34
cell cost (ea)   $4.60 (but I found nearly new salvaged cells for $3.10ea)
cell cost (pack)   $276.00

BMS: https://www.ebay.com/itm/10S-36V-15A-60A-Li-ion-Lipo-Lithium-Battery-Protection-Board-BMS-Balance-ebike/322539980221
(waterproof 60A version)

Charger:  https://lunacycle.com/luna-charger-36v-advanced-210w-ebike-charger/

I was planning to build the pack with a friend that has a spot welder but got too busy and now the COVID-19 issue is discouraging us from meeting up to do so.  I might just borrow his welder and see if I can built it myself.  The old, tired lead-acid cells are becoming a real pain and limit our riding a lot.

[JoelR]

A few I’ve found that might work:

https://www.ebay.com/itm/303208792815  ($254- almost 6” wide, vs 4” Kuberg tray)
https://www.pingbattery.com/ (Traded emails, said he could build one that fits perfectly But didnt give a price - similar packs on website run around $450)
https://www.boost-bikes.co.uk/pages/oset-battery-kits  (Traded emails, said they have a design ready for kuberg for $513).  Found them per this article:  https://www.juniormoto.com/2019/01/23/switch-to-lithium-battery/?lang=en

Notice the weight of the pack in the first link (26lbs).  The 3 SLAs in the Kuberg weigh about 28.8lbs.  A 10s6p 20Ah lithium ion battery with BMS weighs about 7lbs. My son's Kuberg Cross E has a 10s4p 13.6Ah that weighs under 5lbs which totally transforms how the bike feels to ride and handle.

If hadn't already purchased everything for my daughter's bike, the $513 pack at Boost Bikes seems like a really good deal (I've logged WAY too much time researching by DIY solution but have enjoyed the learning process.)

[acacia1731]

I stumbled across this bike when searching for batteries, and it spurred a couple questions:

MotoTec 36v Pro Kids Electric Dirt Bike 1000w Lithium
https://www.walmart.com/ip/MotoTec-36v-Pro-Kids-Electric-Dirt-Bike-1000w-Lithium-Green/184498868

Q1 - Would the 10Ah lithium battery for this Mototec bike work with a Kuberg Cross?  If it's 36V, and has a 1000W motor and up to 35A controller, then it seems like it would provide all the power that the Kuberg needs?  That said, I can't find a battery for this 2020 model yet, but if the whole bike is $700, the battery must be pretty cheap.  It would reduce significant weight from a Kuberg, and maybe could buy multiples.

Q2 - Is this bike as good as the Kuberg Cross, at 1/3 the price?  It's Chinese, vs Czech, but I don't see many things to criticize that I couldn't also say about the Kuberg.

[JoelR]

The Mototec's best feature is its looks.  My friend and fellow Sur Ron owner bought one for his daughter.  It has no front suspension, just lookalike suspension forks.  Its battery is indeed lithium but doesn't have enough capacity to be practical.  On a ride with 1 Kuberg Cross on old, tired SLAs, 1 Kuberg Trial E on a 13.6Ah eBay lithium ion pack and 1 Mototec, the Mototec died first.  My friend hauled the little Mototec out of the woods ON his Sur Ron.  Not recommended but he pulled it off!