111 replies to this topic

[frogger]

Packs arrived, just need to bunch them, package them, waterproof them (to some degree) and then go for a ride.

[frogger]

Working very well indeed. Not weighed the packs yet but they are significantly lighter than the stock batteries. Hope to get the first run on them this weekend.

Packs have been put together in 3's, hard plastic covering, taped, bubble wrapped, taped, taped again.

[idk786]

please pardon my ignorance i am totally new to electric bikes and i just plug in & charge my kid's bike till the light goes green and he rides. He gets about 45 minutes riding flat out on a set of batteries and I bought a second set to change when the first one is flat. Now he says he's just getting warmed up when his second set is almost out (he's 6). Was about to invest in a petrol bike when i came across this, how much longer can i get on 36V lipo upgrade? is there someone who could guide me on what i need to get? from what i understand after reading all these posts the main advantage is weight reduction and increased pwer but will i get more riding time also?

[mikedufty]

I converted a 24V using 2x5000mAH zippy flightmax, so nominally about the same capacity as the original lead batteries.
I haven't measured hours, but have a speedo showing distance. On the Pb batteries it was getting very slow after about 6km. With LiPo the furthest I've had it go is 12.5km, that took 6700mAh to recharge had 3.7 volts per cell, so 0.5 v to spare and possibly close to a third capacity left, was still going much stronger than the lead batteries after 6km.
Seems like a very significant improvement to me. There is room to get double the batteries in too if I needed to, as they are so much smaller than the Pb batteries.

May vary depending on how you use the bike and the condition of your lead acid batteries. Talking to electric car builders a big advantage of lithiums is they age much better than lead acid, cost more up front but save money in the long run.

[NineFives]

idk786, on 02 February 2012 - 08:32 AM, said:

please pardon my ignorance i am totally new to electric bikes and i just plug in & charge my kid's bike till the light goes green and he rides. He gets about 45 minutes riding flat out on a set of batteries and I bought a second set to change when the first one is flat. Now he says he's just getting warmed up when his second set is almost out (he's 6). Was about to invest in a petrol bike when i came across this, how much longer can i get on 36V lipo upgrade? is there someone who could guide me on what i need to get? from what i understand after reading all these posts the main advantage is weight reduction and increased pwer but will i get more riding time also?

Short answer is yes. With LIPO you get:

• Reduced weight for the bikes standard 10AH power(Lead Acid 10kg, LiPo 3.5kg - allowing for residual voltage requirement)
  
• Reduced size (You can fit 25AH of LiPo in the space as 10AH Lead Acid.)
  
• 25AH gives double the time/distance
  
• 20 or 30 minutes charge with the right charger/power
  
• Less of a fall off in performance as the volts drop
  
• Longer overall life of the battery (in years)

Downsides

• $$ for the batts and equipment.
  
• More attention needed

If your kid just wants to blast around for hours and noise is not an issue go gas/petrol.

Edited by NineFives, 04 February 2012 - 01:48 PM.

[betarambo]

For the guy who asked for directions to do the conversion, check the beggining of this thread. It should have everything you need, at least that was my intent.

To Frogger, your bundled packs look like a great idea. I think you might want to revisit that final connectors. It is my understadning that if you short those batteries for even a split second they are garbage so a connector that makes this impossible is worth it. It looks like it would be pretty hard to do with your setup, but in the heat of battle at an event or bouncing around in your tool box it might happen. I have had good luck with the XT60 connectors.

So I got back on the project this weekend and started diving into converting it to be bigger. My daughter is getting too tall for it. I ordered the new forks yesterday which are for a 20" mountain bike and started working on figuring out the wheels.

While doing some research I foudn that Oset plans to release a 20" bike this spring. The pictures look really sweet. I think it has a lot of advantages over converting my 16" to a 20" like geometry and footpeg location. The geometry on this thing looks idnetical to a full size trials bike. So I scrapped my project to make her bike bigger and plan to pre-order one of these new ones. You can check out the pics here:
http://www.trialsuk....ric-trials-bike

It doesn't say what voltage it would be. I assume at least 36V but maybe for a bike this size they will go to 48V. If they don't I'll bet I probably can. We'll see...

[frogger]

betarambo, on 05 February 2012 - 08:17 PM, said:

To Frogger, your bundled packs look like a great idea. I think you might want to revisit that final connectors. It is my understadning that if you short those batteries for even a split second they are garbage so a connector that makes this impossible is worth it. It looks like it would be pretty hard to do with your setup, but in the heat of battle at an event or bouncing around in your tool box it might happen. I have had good luck with the XT60 connectors.

I am analy retentive about my packs and so I have plastic caps for my connectors. I stuck with the 5.5mm gold connectors because I could't be bothered resoldering tons of connectors.

From working with lipo batteries for many years I know that a quick touch of the poles does not immediately destroy and render the packs useless. Sure, it's something you completely want to avoid for many reasons (not least of which is fire!) but I have had it happen on the odd occasion with my RC race packs over the years (before I started using Dean's connectors) and never noticed a loss in performance or pack life just yet. No need to throw $350 worth of batteries in the bin when you accidentally touch the poles for a micro second. Or if you feel compelled to, send them to me instead.

Edited by frogger, 07 February 2012 - 04:06 PM.

[frogger]

We rode yesterday with the new lipo batteries in the Oset 36 for the very first time. It was very cold outside with tons of snow everywhere. He rode for exactly 90mins on full power and I thought I would switch to the stock battery for no other reason than to be safe with the lipo's. Got home, put them on the charger and they still had 54% left in them! I recon in grippy conditions he should get a minimum of 2.5hrs runtime out of the packs.

[NineFives]

Hi Frogger,

Ossa and Oset, perfect setup. Same here

Just "upped" the OSET battery capacity to 25AH (2.5 times standard OSET), I'm guesstimating that should give me a full days trial without worrying about hitting low voltage. Its a snug fit in the battery box.

I've ordered an adjustable low voltage alarm from HK.

Before I upped the capacity I did manage to discharge the LIPOs to below 3.6v which confused my charger into thinking they were 4S not 5S. Manual trickle/tickle on Nimh got them about 3.6 and back to 5S and back to LiPo charge, guess you know this!

It occurred after about 2+ hours, my son suddenly noticed the power meter light on the throttle went from 3 to 1 seemed to miss 2, and we were at 35.8v.

An aside - not for this thread but a couple of significant other upgrades is to put a mountain bike shock on the rear, 6" or 6.5" with a bit of welding made all the difference on rock steps and I raised the bars with a raised adjustable clamp.

[frogger]

Hey NineFives, yes, I am investigating low voltage cut offs right now because the packs are expensive and I don't want to kill them. My chargers charge through the balance leads and so at low voltage just go into restore mode which has brought other lipo's back from the dead before.

I've got some Magura hydraulic brakes which is going on the bike this week. Still need to find a suitable shock. A Fox airshock seems ideal.

[gwhy]

Re lipo monitor: I have been using a home made lipo monitor for about 6months now, and was just wondering if I were to make a bunch of them would anyone be interested if I was to start selling them ?. I dont know exactly what the final cost would be but I expect it to be around £15. It will just replace the original battery lights on the throttle to give a good indication of state of charge for the lipo's, it will be around the size of a matchbox and contain 2 leds to give 5 levels of battery condition.

[NineFives]

Hi Guys,

My alarms are coming from HobbyKing - Voltage-Alarm/18588 Hobbyking 2-8S Cell Checker with Low Voltage Alarm = $3.46

I bought 2 as they are so cheap and I'll put one on a battery in each bank. That said with the amount of power I have stored, I hope that I have bought enough time that low voltage isn't an issue.
gwhy - I don't want to stick anything extra electrical on the bars - it will get crunched.

Re the rear shock, I got a new 6.5" Air RockShox for US$100(older model) www.pinkbike.com. Raised the top mount with a bracket from the old mount up under the seat to get the same ride height as the 5" OSET shock.

Setting up the pressure - get a pump with the shock (seller gave me one free). We are at the lower end of the pressures for both compression and rebound.

[DAMMAD]

NineFives, on 23 February 2012 - 04:05 PM, said:

Hi Guys,

My alarms are coming from HobbyKing - Voltage-Alarm/18588 Hobbyking 2-8S Cell Checker with Low Voltage Alarm = $3.46

I bought 2 as they are so cheap and I'll put one on a battery in each bank. That said with the amount of power I have stored, I hope that I have bought enough time that low voltage isn't an issue.
gwhy - I don't want to stick anything extra electrical on the bars - it will get crunched.

Re the rear shock, I got a new 6.5" Air RockShox for US$100(older model) www.pinkbike.com. Raised the top mount with a bracket from the old mount up under the seat to get the same ride height as the 5" OSET shock.

Setting up the pressure - get a pump with the shock (seller gave me one free). We are at the lower end of the pressures for both compression and rebound.

I would be really keen to see a pic of the bracket you made to make the shock fit, this is something I have wanted to do for a while. Have you looked into replacing the fork with something better? Sorry to hijack this thread.

As for the Lipo's I really dont think you need an alarm on your lipo's I just carry a little hobbyking monitor with me and check them every now and then, you get a feel for how far you will get out of them pretty quickly. I have two of the latest 16's both running 10s lipo setups and I also have a 12.5 running a 7s setup, i've never had a problem with running them to low.

Edited by DAMMAD, 24 February 2012 - 07:22 AM.

[gwhy]

DAMMAD, on 24 February 2012 - 07:20 AM, said:

I would be really keen to see a pic of the bracket you made to make the shock fit, this is something I have wanted to do for a while. Have you looked into replacing the fork with something better? Sorry to hijack this thread.

As for the Lipo's I really dont think you need an alarm on your lipo's I just carry a little hobbyking monitor with me and check them every now and then, you get a feel for how far you will get out of them pretty quickly. I have two of the latest 16's both running 10s lipo setups and I also have a 12.5 running a 7s setup, i've never had a problem with running them to low.

The hk alarms are ok but connecting and disconnecting them over time to the balance tap plugs I think potentially can cause problems ( unless the balance plugs are re-enforced some how ) , I agree that if a your disciplined enough to check the voltage every now and again this is normally good enough but theres nothing like having a fuel gauge that is on all the time and can be seen all the time .

[frogger]

gwhy - I would be interested for sure. I think something small that sits either in the stem or on the front most part of the plastic (where a fuel tank normally is if that makes sense) would be great.

Dammad - I have also ordered a bunch of individual 3s HK low voltage alarms. My boy and his friend often go off by themselves and so the alarms will work very well letting him know when it's time to stop or return. Also, sometimes there is a lot going on and you just don't think to check. Alarms can only help in my case!

In June they will be releasing the 20inch version. Can't wait to see what they spec that bike at and look forward to some more tinkering.