Newbie with a Rad2Go E36 project...

[milesinfront]

Hello everyone! So it seems my inexplicable interest in EV's has now reached the point where I'm joining this forum...

Some years ago I bought a 2nd hand Rad2Go E36. (36v 800w) I must admit is was a knee-jerk reaction to seeing Al Gore's little movie. Anyways, I was seriously blown away by the performance. (massive torque and 42km/h on flat ground) I began regularly using the scooter for my daily bank and lunch runs but quickly found the range limit and short useful life span of the 12ah Panasonic SLA's. Decent capacity Lithium's (20ah) were, and still are, too expensive for my budget, so my enthusiasm for responsible usage of the scooter has dwindled. Now I mainly just use it for a bit of a laugh and a few wheelies every now and again...

But I still love the E36, and want to make it even faster! A while back I sourced a 48v controller from Ebay, and am considering going down this path. I'll need some new SLA's obviously (down to 9ah so they fit) and a pair of 24v chargers. (quality 48v chargers seem to be rare and expen$ive) I'm probably looking at a $300 exercise.

More recently my interest sparked up when I noticed the falling price of RC lipo's, BL motors & controllers. I'd seriously consider a stack of 7.2v nimh RC packs also, but haven't found a convenient charging solution... Further reading has shown the RC motors and controllers aren't as easy as first appears.

So I'm looking for some ideas/advice as to some big bang-4-buck options!

I would prefer 1 of 2 outcomes:-

1) A short range land missile! 5 mins of crazy front wheel lifting madness would be kewl... (60km/h please?)

or

2) Increasing the full throttle range to 20kms+ (current is ~6 or 7 with fresh SLA's) without any loss in current performance.

Today I installed my Cycle Analyst from ebikes.ca. I was surprised by the numbers! 110amps Max. Does that sound right? (external 200amp shunt) On the way to top speed the amps drop to around 40! My current SLA's are nearly toast, and only notched up 1.3a/h (hard ride) before quitting. But if the poor little guys are pumping out 110 amps it's no wonder!

[milesinfront]

I don't like sitting still for too long...

I've just ordered 2 of these:- http://www.hobbyking.com/hobbyking/stor ... duct=19894 Cheep cheep!

After reading on this site how SLA's drastically drop capacity under high discharge rates I'm assuming that 8ah of 30c Lipo power may likely outrange the 12ah SLA's...

I have a Swallow2 charger which I'll use initally to see how the experiment goes. If successful I'll upgrade to a balance charger and charge in parrallel...

[vanilla ice]

Should be good with three of those packs in series. That would at least get you to goal 1.

[SamTexas]

After reading on this site how SLA's drastically drop capacity under high discharge rates I'm assuming that 8ah of 30c Lipo power may likely outrange the 12ah SLA's...

Definitely (assuming the same voltage). At the same riding speed, your range will increase significantly (25% or more).

[milesinfront]

Should be good with three of those packs in series. That would at least get you to goal 1.

What would be my controller options?

[milesinfront]

Had my first taste of LIPO power yesterday... Wow! The old Rad2Go has a new lease on life. As well as swapping from Pb to LiPo I also beefed up some of the battery wiring, and upgraded the connectors. With the extra voltage available and considerably less weight, keeping the front wheel on the ground is a full time job!

I took just over 4ah out of the 8ah pack. The first 1ah was with the granny switch on. This limits the throttle to about 25%. Max amps are about 35 and max speed is a useful 30+km/h @ ~ 21amps. I went back to the pits and checked everything out, making sure nothing was getting hot... All okay!

The next 1ah was with full power available. Now we're having fun! Was easy on throttle application and didn't stay WOT for too long at a time. Another return to the pits and I was surprised to find nothing hot under the hood!

So now it was all go go go! Lots of hard acceleration from low speed (wheelies) treating the throttle like a switch! Was great fun! Got up to 46km/h on flat ground. (~3km/h better than Pb) On my final pit-stop I found that even with the abuse I had just dished out, the LiPo's were only lukewarm to touch. Everything else was happy, except I nearly burnt myself on the speed controller!

[sk8norcal]

looks good !
seems like a solid frame,

i read those are non-pneumatic tires,
switching those out should give u a better ride.

another modded e36,
http://www.angelfire.com/ca4/renewables/E36page.html

[milesinfront]

The ride of the solid tyres is actually VERY nice. They are normal tyres with a foam fill. I'd say pneumatic tyres with lots of air would be quite a fit firmer, but definitely faster with much reduced rolling resistance... (These tyres get quite hot)

Thanks for the link! I read that one many years ago, and still use it for reference...

The frame is almost overkill is some areas, but there's a weak point at the head-tube which has cracked. I will get around to brassing it one day.

[milesinfront]

After only 2 recharges, and never using more than 40% of C I've discovered one of my Zippys has a bad cell... It won't charge over 3.92v, while the others will happily go to 4.2v. I'll try returning it to Hobbyking...

Out of interest, does anyone know more specifically what would cause a 'weak' cell?

[parabellum]

Out of interest, does anyone know more specifically what would cause a 'weak' cell?

Fire. if it is less capacity then the rest, you can easily reverse charge it in application. It will at least severely damage the cell, but more likely overheat and catch fire, starting sort of chain reaction incinerating rest of the cells. How are you charging lour Lipos now?

[milesinfront]

I was meaning what manufacturing fault would cause the cell to not charge over 3.9v...

[parabellum]

Sorry, have not had this problem, I have seen cells self discharging over time. What are you using to charge your packs. Is the cell 4.2 on charger and goes down to 3.9V when of the charger?

[milesinfront]

Have started a build thread:- viewtopic.php?f=35&t=37582&p=548175#p548175