Aprilia Enjoy replacement battery pack

[EndlessDoge]

Hi, this is my first post.
I’m trying to resurrect an Aprilia Enjoy by building a replacement battery pack using 18650 cells.
After lurking around here and on Jobike, I designed this battery pack.
if anyone could check it I would be grateful



The original NIMH pack had a nominal voltage of 24V, the output of the original charger was 32v though so I think that my pack being at 28V when fully charged shouldn’t be a problem (28V because I’ll stop charging when cells reach 4v instead of 4.2).

The motor is rated for 245w (actually the manual says 250w but on the motor there’s a label that says 245w)so it should draw around 10A at 25,2v but according to what people posted on Jobike and also to what my dad measured at the time , if someone cuts the white wire on the controller the motor can draw 70/80A for short periods of time.
Could my pack withstand such load or would the nickel strips overheat?
--
The white wire is a “feature” of this ebike’s controller, it’s a wire that goes out from the controller and then goes back in.
When someone cuts it the bike isn’t limited to 24 kph anymore, it can reach 40 effortlessly and if the speed selector is set to 3 the motor works all the time, even when not pedaling, and maintains the last speed you were pedaling at
--

I’m planning to use 18650 spacers like these: https://www.aliexpress.com/item/32948548101.html, some insulator rings on the positive ends of the cells and heat shrinkable pvc on the outside.
Is this enough or should I add something else to protect and insulate the battery? I saw that some people on this forum used some kind of adhesive tape wrapped around the whole pack.
I also found on AliExpress protective cardboard that’s made to be sticked above the nickel strips (https://www.aliexpress.com/item/4000349196151.html), what would that be useful for if the pack already has pvc around it?

 

[Hillhater]

Hi,and welcome to the ES forums.
Many fellow Aprilia owners and Ex owners here.
I have had several and much admire the advanced design and engineering that is in those bikes...considering they were designed nearly 30 years ago !
If you have not seen it, there is a long thread dedicated to the Enjoy here...
https://endless-sphere.com/forums/viewtopic.php?f=28&t=18505&hilit=Aprilia
Your pack is very large ..capacity , weight, and physical size,..i doubt it will fit the standard battery compartment ?
Where do you plan to mount it ?
Why do you plan such a high capacity pack ?....20Ah will last longer than most care to ride (double the original pack), and would still fit in the original pack location.
Nothing wrong with your pack design so far, but what are you using as “bussbars” between the 15p groups ?
Also , do you intend to use a BMS ?.. the original pack did not have/need one..
I do not know why you believe the original Aprilia charger went o 32v, none of mine went beyond 28v, and i never saw more than 26v on a fully charged NiMh pack.? Maybe my packs we not so good ?
Anyway, you are lucky if your original controller is still working, or continues to work on a higher volt/amp rate for long. Spare are very rare and very expensive.I would recommend you plan to replace it..Most of us switched to a aftermarket brushed controller ( V cheap) and ran higher voltages (10s =40+ volts ) to keep the amp load o the brushes down a little.
However, i doubt you will find a replacement controller that will allow the Pedalec “Torque sensor” system of the original system , to remain working..again , most of us disconnected that also.
The source of most problems with DIY battery packs, are usually caused by poor build defects, bad connections, pinch shorts, poor selection / checks of cells. Etc.

 

[EndlessDoge]

Thank you for your reply, I planned to remove the original battery case and fit my cells in the battery compartment
Battery Case:

The compartment is really big, according to what i measured my pack should fit in there.

I planned to build a large pack as there’s a lot of room and I can get more cycles out of my cells by charging to a lower voltage and setting the over discharge protection in my bms to an higher voltage and still have a LOT of autonomy.
The weight shouldn't be an issue as the original pack would be even heavier in comparison.

Between the 15p groups I'm using copper wire soldered to the nickel strips.
I'll use this bluetooth "ANT bms":https://www.aliexpress.com/item/32997552090.html


I read that the output voltage on the charger was 32v on this Aprilia enjoy’s workshop manual that I found on jobike, maybe Aprilia messed up the values on the manual, I don’t know.

("Tensione di uscita" means output voltage)

My original controller is still working and I actually have spare ones as well, I also have a spare motor.

I thought that since the motor was rated for 24v stepping up the voltage too much could have damaged it but probably I’m wrong

 

[Hillhater]

You will find the battery compartment is narrower at the front.
I suggest you make a “dummy” pack from cardboard or wood to the exact dimensions of your design, for a test fitting incase you have to change the cell arrangement before you start assembly.
Great that you have spare controllers,..they are a cleaver design for their age.
On the thread i linked to, you can find pictures of my motor armature and commutator after 5 yrs or so of 40 v 30A, usage...it looked fine , so voltage didnt seem to be an issue, ..and it is the key to higher road speed.
Get all the spares you can find , the main issue i had was with the bottom bracket bevel drive gears which seem to wear rapidly with hard use.
New gear sets used to be available from Italy, but sources seem to have dried up..so a spare drive gearbox is a valuable asset. Maybe you can find some local contacts with access to old stock spares ?
I understand your comment about pack weight, but honestly, dropping a few kg from that pack made the bike ride so much nicer !