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Charger Bike
#1
Hello,
  
  There's this bicycle in my garage... It's a "Charger".  It belonged to my late son.  After his second DUI, he needed something with no license requirements to make it up the hill to our house.
The bike dates from the mid 90's.   It was pretty hot stuff for the time, with a 24V motor mounted in the frame driving the rear wheel via a chain.  Said rear wheel has a 7-speed Shimano hub.  The front forks have shock absorbers.  The two 12V SLA ( lead acid ) batteries are in a plastic box, along with the control and charging electronics.  The bike had no throttle - it would help you when you pedaled.  

Said electronics are long dead.  I thought to resurrect it - bought & installed a pair of brand new SLA batteries.  Left them to charge overnight.  Came out the next morning, and the whole garage smelled like battery crap.  The batteries had swollen up like little balloons( sigh ).

So now I am embarked on a new project - to bring this bike up to date with a lithium ion battery pack.  I got a boatload of 18650 cells from batteryhookup, and a fancy charger/tester that tells their capacity in milliamp-hours.   A package of nickel strips.  A "k-weld" spot welder.  An old aircraft battery to power the k-weld.  Need a box for the battery ( on order from Amazon ), because although it does deliver the current, it's not as liquid-tight as it once was, and when you pull great gobs of current out of it, it *spits*.

I had gotten a cheap Chinese welder board - IIRC $25 including probes - but it didn't work reliably.  Basically, I would put approximately one zillion spots on each battery, and hope that enough of them "took" to have the strap stick on.  Reading about the kweld, I just had to have it.  Would have been cheaper to just buy a premade battery pack Smile
But now I'll be all set up for any battery projects that come around.

  The original electronics package is large and heavy - with 2 SLA batteries, the charging circuitry ( you open a little door and pull out the line cord ).  I think a pack of 18650's will be much lighter. 

   I don't know how much power the motor takes under load.  Am hoping a 7S5P pack will be adequate.  Or is it 5P7S?  I  bought a 20A BMS on Amazon.  We'll see how it does.
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#2
7s5p might not be enough do you know how many watts the bike motor was rated at?
Later floyd
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#3
Don't know the watts of the bike motor. Very little documentation on the Web. You search for "charger bicycle" and you get lots of hits for chargers for ebikes. I plan to put together a pack and see how it does. I can run the bike up the hill and measure the amps draw. If it doesn't make sense, I'll tear the pack apart and change it.

Besides just a raw pack, I also need some sort of controller. The bike has some sort of sensor to know how hard you're pedaling. Not sure I can figure that one out. I see there are controllers on amazon,ebay etc. But those use a twist grip.
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#4
What's the model number of the eBike? That might help narrow down the search results
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
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#5
The motor may have a hp rating or watt rating printed on the motor or maybe a part no.with the manufacturer could really help. Might not even say hp or watts.

Later floyd
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#6
Here's a web page about the bike: http://abc.eznettools.net/D300013/X300109/eBike1.html.

The motor is hidden in a plastic shroud.
Here's another web page:
https://abc.eznettools.net/D300013/X3001...rFAQS.html
Which has some info about the motor! They quote 375W of "shaft horsepower" and "up to 36 Amps" of peak power.
...Which means I need a bigger BMS. Sad

It seems that Electroportal still has a functional website - maybe they can sell me a new electronics box? But what's the fun in that? Honestly, I need
an electric bike like I need a hole in the head Smile. But it's a fun project.
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#7
yeah, I'd say go with an ESC that can do 40A. That way you aren't taxing it when you need full power. Besides, going with their electronics, you're limited to 20mph and "assist only" when going up hills. What fun is that? Tongue
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Certified 18650 Cell Reclamation Technician

Please come join in general chit-chat and randomness at Discord Chat (channels: general, 3d-printing, linux&coding, 18650, humor, ...)
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#8
OK, I slapped it together. Made a 29V 10 amp-hour pack from Pegatron modem batteries from batteryhookup. Balanced them with the tool on this website. Welded the tabs with the Kweld. A 24V brushed controller from Amazon. Also a twist grip throttle - one of those with the little voltage display. Chopped the connectors, soldered and shrink wrapped everything together, and hung it all on the bike with cable ties. This is all just to see if it works - I planned to mount everything properly once I proved the concept.

It successfully carried me up the hill. HOWEVER, I don't think it's going to work. Not really. Why?

.... The pedals are in lock step with the hub. When the motor moves the bike, it moves the pedals also - which is very disconcerting. I don't think it's going to be usable. Very disappointing. Sad
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#9
You need to have a bike overrunning clutch. This is what allows the wheel to turn w/o turning the pedals.

If you don't use the electric motor, does the pedals freespin? If so, I wonder if there's something that needs to be modified to make the motor allow the freespin
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Certified 18650 Cell Reclamation Technician

Please come join in general chit-chat and randomness at Discord Chat (channels: general, 3d-printing, linux&coding, 18650, humor, ...)
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#10
The motor has its own separate chain and sprocket. But I think the two sprockets - one for the motor, the other for the pedals - are essentially bolted together. I think there is an overrunning clutch ( built into the nexus7 hub ) between the sprockets and the wheel.

Something like this?

https://www.amazon.com/STARTER-CLUTCH-CA...B01MRB4LHN

If the dimensions were right, I could replace the sprocket at the pedals.
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