Electronics help please

dirk

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Hi guys, I need some electronics help please, I’m a complete novice.

I’m converting an old 50cc quad bike into an electric quad bike so I can take the dog out for long walks. I’ve ordered one of those E-bike kits. 48v 2000w motor and 2000w 34amp controller.

I’m now looking at suitable batteries. I want to be able to do at least 4 - 6mph for a couple of hours over rough terrain. I’m going with the cheaper lead acid at this stage. If it works great, then I will invest in Lithium in the future.

I understand that volts x Ah = power (watts)

I’ve seen some lead acid batteries 12v x 55ah I think this equates to roughly 660 watt

I will connect 4 in series to give me the 48v.

48v X 55ah = 2640w

The bit I am confused with is the C rating. These batteries have a C20 rate.

I think the maths for working out the hourly draw of amps is 55/20 which gives 2.75 amps per hour for 20 hours. Does this mean 4 connected in series can draw 10.5 amps for 20hours and 40amps for 5hours, or have a I got the maths completely wrong?

I was also wondering what the average amp draw the bike would consume as flat out I assume would be 34amps as that’s the capacity of the controller?

Any recommendation for batteries would be great please. The ones I have been looking at getting is 4 12v x 55ah which weigh a whopping 150Ibs and cost £340 The weight will add considerably to how much distance I will get out of the quad bike I'm sure. I want at least 2 hours, if possible, per charge.

Thanks in advance of any suggestions,
 

Fireblade929

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I recently used these chaps for a new car battery, great service & price highly recommended, they do a load of different batteries for different uses from own brand to high end, were also happy to give advice over the phone when I placed my order.
 

stikflote

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@dirk. instead of using 4 batteries get yourself a mobility scooter
they easily do 4-mile mph up to 8 mph,i have one that does 4mph to 6 mph
get one with big pneumatic up wheels
 

TrickyD

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With a quad bikes propensity to flip and the almost immediate power delivery of an electric motor, I see trouble ahead. I would be inclined to go with @stikflote idea of a mobility scooter.
 

dirk

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I had considered a mobility scooter in depth but an all-terrain scooter that will go on the beach costs the best part of £7,500. So you can see why I'm going for a custom made quad bike that will drive up ramps into the back of the car, mobility scooters are too high to fit. unless you lower the tiller and remove the seat. The motor I've ordered are 3 speed so no flying off the starting grid unless I want to :D . Thanks Total I'll give Markeywhizz a PM.
 

Markywhizz

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Hi Dirk. Sounds an interesting project. The important calculations are as follows:

A 34A controller will deliver 34A flat out so the maximum power will be 34 x 48 = 1632W. A good safe limit for a 2000W motor.

To calculate how long it will run for: Four 55Ah 12V batteries have a capacity of 55Ah at 48V if you connect them in series. It will be possible to run flat out (1632W , 34A) for 55/34 hours. Approximately 1h 37m. That is flat out though so you should easily get well over 2 hours running in normal use.

Sounds like you are on the right track to me.
 

dirk

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Hi Mark, That's brilliant, Thank you.

The only thing I still don't understand is how the C20 rate comes into the equation?

Yes it will be a great Winter project (y)
 
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