Help With Replacement of Batteries for Project

You just have to make sure the batteries are arranged to provide the proper voltage...Do you know the motor voltage? I think it is 48v....The reduced AH will not last as long, but the decrease(?) in weight will increase the performance, in the end the gearing will tell the tale, maybe...

yes the batteries add up to the same voltage (48V)when connected in series,and yes the motor voltage is 48V.

my initial battery pack weighed 160 Kg,this one weighs just 60Kg,the motor has 3000 RPM so i will be using 3:1 gear ratio for the sprockets. expecting to get good speed and power out of it :)

and yes if voltage is the only factor that needs to be taken care of,then i am good to go i guess,but i was just worried whether the controller programmed to take current from 6V 150Ah batteries might not be healthy for the batteries in the long run....

the battery data sheet says a lil over 10 mins at the rate of 100Amps....the golf cart motor is rated at 3Kw power...i cant measure the current directly as i am still waiting on the parts to arrive...

That should be fine then, even if you overload the 3kW motor during normal operation the motor should fail due to overcurrent before the 42Ah batteries do.

Thankyou for your reply.... really helped clearing my doubt... :)

Unless you have a particular reason for the 42Ah SLA batteries, you could consider "U-1" 32 amp hour batteries. They are less expensive and very commonly available. The "AGM" type (absorbed glass mat) has low internal resistance. It responds very well to high charge/discharge rates. They are defined as a dry battery and FAA allows air shipment. AGM U-1 batteries are the standard for small wheel chairs. AGM batteries are very sensitive to over voltage when charging. A modern wheelchair uses two 12 volt batteries to make"24 VDC". A wheelchair charger or scooter charger that absolutely limits the charger voltage to 28.8 volts (or somewhat less) is needed. No trickle chargers. The most common charger used for wheelchairs is from Soneil. They have several US EV distributers

You could look for scrap motors from scrap wheelchairs. They should be direct drive gearmotors and run at 24 VDC. The angle drive gearmotors are not as mechanically efficient, but they might be easier to mount.

The wig-wag and controller from a scrap scooter will work with them.

If you are moderate in weight and using a multi sprocket rear wheel, you could probably get enough speed and range with the wheelchair parts.

I have always thought that with a choice of gears that a controller might not be necessary. Perhaps a 50 Amp microswitch and a large capacitor would give you a soft enough start to prevent over torquing the chain and gear set. Then you have no efficiency loss due to a pwm controller.

The AGM and charger advice is solid.
The rest is blue skying as I have only built wheelchairs and scooters, not bikes.

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A nice informative answer. Welcome to the insanity, and enjoy the ride.

good one bob..

What speed and range were you expecting?

i am hoping to get a range of 30Kms.... speed close to 100Km/Hr... :)

i am not very good in electronic calculations,hope my calculations are correct...

I built a similar E-moto in 1981 in Key West, using a 3 hp motor from a small golf cart, and two 105 AH deep cycle trolling motor batteries, mounted as quick-detach saddle bags. Charged them out on my offshore boat with twin 50 watt solar panels. It accelerated nicely to about 50 mph using a series parallel 12v and 24 direct connection. Key West is only four miles long, and I never ran out of charge during a day of chasing around. It was built on a 175 cc single Honda dirt bike. Sold it for way more than I put into it. Not glad to see it go. It was a happy combination of speed and economy.

good to hear about your build,i bet you had fun making it...

i am using a 150cc donor bike,hopefully with a 48V battery pack i get a lil more speed.. :)

with the fuel cost goin up like crazy,this should give me lil relief :)

with eight(8) 6V, 150Ah batteries, that's 1200 total Ah. with four(4) 12V, 42Ah, that's

only 168Ah. those four 12V batteries will become discharged very quickly and the EV will not travel long and far.

four 12 v, but what AH?