I'm replacing the two 12v deep-cycle batteries on my Mobility scooter but I want it to go fairly fast if possible? It has a Curtis 24v, 110a controller and a CM808-001C electric motor, I don't know how many Watts it's supposed to rate? I suspect it's around 600W. So what would be the best batteries to use? Sealed Lead Acid, Lithium, etc... It's only used to go to the shops within a 1-mile radius when I'm picking up something heavy or doing a big shop. I gave my 4x4 to my daughter and get around on a bike now to keep fit. 
It's the supply voltage that sets the amount of power an electric motor will deliver to a given load. Using bigger (and heavier) car batteries - of the same voltage as the existing scooter batteries - won't deliver any more power, unless the existing battery is so weak that it's voltage drops severely under load.
In more technical terms, a motor has a parameters called "motor constants", and one of them, the voltage constant, (Kv) tells you how many RPM the motor will spin at per volt applied. If the Kv is, say, 1000 rpm/volt, the motor will spin at nominally 1000 rpm if powered by a 1 volt source, 2000 rpm if fed 2 volts, and so on. Two different 12-volt batteries will both produce the same motor speed, even if one battery has bigger CCA or capacity than the other.
What bigger-capacity, same-voltage batteries will do is extend the scooter's range. But from your first post, it didn't sound as though range was currently a problem, so this may not benefit you at all.
Bumping up the battery voltage (not CCA or capacity) might deliver more power, but it might also burn out your motor and motor control electronics, so I wouldn't recommend it. Not unless you're willing to sacrifice motors, electronics, and money in the quest for more speed.
I don't know enough about mobility-scooter electronics to offer more than that; if there is some sort of onboard governor or speed limiter to deliberately restrict top speed (for safety reasons), there may be some opportunity of hacking or modifying that for more performance.
An Internet search will turn up an online article about a mobility scooter that is so fast and powerful that it does wheelies, after being "upgraded" to 60-volt batteries instead of 24 volts.
I doubt the motor or powertrain will last long with that level of abuse.-Gnobuddy
Geez, haven't we all? This crazy Coronavirus pandemic can take over every waking moment of your time if you give it half a chance....I've been distracted by this and that. lol
And you're very welcome. I wouldn't want you to waste your money on car batteries that don't give you what you want!
-Gnobuddy
Given the issues mentioned above by Gnobuddy tinkering with voltage could be a no go but If I was trying to get more speed I might be tempted to just fit larger diameter drive wheels, or modify the gear train (if there is one). If you go too far with that you would sacrifice low speed torque but you might get an impressive top speed.
Helmet and gloves advised.
Helmet and gloves advised.
So far I have replaced the 5K ohm throttle pot, the speed pot? I can't remember the ohms on that one? The 70 amp Curtis controller has been replaced with a new 110 amp Curtis controller, 2 new 36ah gel batteries and a new wiring harness for the batteries and the scooter still does only 3 kilometers an hour? I've stripped the motor and cleaned the rotor with a fiberglass pen and blown all the graphite dust out. The electric brake clicks in and out Ok when starting and stopping. This scooter is about 20 years old it is a Swan VFH120 but I can't find any manual or specs for it to see if it's got the wrong throttle pot or something? Has anyone heard of this model before?
As I said before - the speed will not change with bigger batteries of the same voltage as before.
However, if you put three of those 12V batteries in series for 36 volts total (instead of 24V), you'd immediately see about a 50% speed increase - 4.5 km/hr instead of 3 km/hr. However, you would also put an increased strain on any existing electronics and on the mechanical parts of the driveline, particularly the clutch, if there is one. Stuff might break - the only way to find out is to try it, and that tends to be an expensive way to engineer anything!
If you are determined to make the scooter faster, your only options are to either increase the battery voltage, change the mechanical gearing ratio in the drivetrain to make the wheels spin faster, or find a motor with a higher Kv (rpm per volt motor constant.)
-Gnobuddy
I just want the scooter to go at its normal speed as in faster than the 3 kmh it's doing now? I've replaced just about everything so I'm going to replace all the electrical connections and see if that makes a difference?
Is that question that you answered yourself a joke or something? Anyway, a reasonable person would think it would go faster than 3 km and hour seeing as most mobility scooters go at around 8km to 12km an hour with the same Throttle, Batteries and Controller? I have updated this controller from 70Amps to 110Amps. Anyway, I'm replacing all of the Molex connectors because that's about the only thing left that I can think of that could deprive the motor of power.
Sigh.
Why so defensive ?
If you are unable to find information on this device, How can anyone speculate that a 20 year old device can perform the same as a new one ?
Let me try another way.
MAYBE, it's current speed, is all that it was designed to do.
I know my 24 year old car could NOT keep up with a new car with an engine half the size of mine.
Does that mean it's faulty ?
Times change.
Technology improves.
Why so defensive ?
If you are unable to find information on this device, How can anyone speculate that a 20 year old device can perform the same as a new one ?
Let me try another way.
MAYBE, it's current speed, is all that it was designed to do.
I know my 24 year old car could NOT keep up with a new car with an engine half the size of mine.
Does that mean it's faulty ?
Times change.
Technology improves.
I too suspect that 3 km/hr IS the normal speed for this scooter.
Times change, people get more impatient, attention spans drop, and every few years we want everything faster and with less effort than before. Perhaps, not so long ago, people with disabilities were happy to be able to travel at easy walking speed (3 kmph)?
Are the electrical connections getting hot now? If not, they are still good, and not slowing down the scooter. In that case, replacing them will cost you money, and won't change anything.
You can also use a voltmeter and measure the voltage drop across those connections. If there is little voltage drop, the connections are not slowing down the motor.
As an example, even if the connections dropped a rather large 1 volt, that is only 1 volt out of 24 volts from the battery, i.e. only about a 4% reduction in voltage. So if you could upgrade those connections to magic zero-loss connectors, your scooter would still only speed up by about 4%, going from 3 kmph to 3.1 kmph...barely noticeable, and not enough to make you happy, I suspect.
Looking at it as an engineering goal, what target speed would you like to achieve? That will tell you what engineering changes you would need to get there. For example, if your target is 6 kmph instead of 3 kmph, you have to somehow make the rear wheels turn at twice the speed that they do now, or make them twice as big as they are now.
I know nothing about mobility scooters, but I know something about motors and simple machines. From what I know, I can think of only three or four ways to make a scooter go faster:
1) Increase battery voltage.
2) Change sizes of drivetrain pulleys so the driven wheels spin faster.
3) Put bigger driven wheels on it.
4) Replace the motor with one with a higher Kv (rpm per volt motor constant.)
All of these options come with some risks of equipment damage, and some may be completely impractical. For example your existing control electronics may not be able to tolerate more voltage, your existing clutch may not tolerate more power, there may not be room for drive wheels that are twice as big, and so on.
As one more example, suppose you want to raise the top speed to 6 kmph instead of 3 kmph. You need to double the motor RPM. There is no doubt that the motor will turn twice as fast if you power it with 48 volts instead of 24 volts. But will the electronics survive? Will the clutch? Will the brakes be adequate? I don't know the answers to those questions.
Have you looked at any faster scooters to see if you can spot the engineering differences, i.e. how do those faster scooters get their increased speed? If the only change is a motor with a higher Kv, can you get a used motor out of one of those faster scooters, and do some shade-tree engineering to fit it into your scooter?
-Gnobuddy
If you're looking to replace your batteries again and looking to compare you battery choices, you can make this article from Dig My Ride as your reference guide. The article covers the different types of electric scooter batteries such as Lithium-Ion, Lead Acid, and Lithium Manganese batteries. They also have tips on how to get the most of your battery life. Hope this helps you, Cheers!
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