Electric bike extra speed (battery)

Hi. this is my first post

Anyways I'm not a great electrical person, but I know a couple of things. I have an electric bike which has 4 12V batteries and 20 Ah. Its a 500W ebike with a 48V motor. Now my question is, can I add another 12V battery, in series to give it extra power for speed?. I saw some people hook up the cables from the extra battery to the main power cables. The bike goes really slow and I want it to go faster. But this would mean it would have an impact on the motor. How can i make it faster and not really damage anything? Is this even possible? THanks

You may need a new controller, at least. Beyond that, wiring the pack in series, and assuming your motor can handle it and such. I am guessing you didn't make this bike yourself, perhaps you can contact the manufacturer for information that you are asking for.
What sort of setup do you have? Is it a mid drive, geared, or direct drive? When you say slow, what speed is slow? 48v setups usually carry a person plenty fast enough, is top speed really what you are after? If you have a direct drive hub, you may be able to get a different winding a change nothing else, resulting in higher top speed.

its an electric scooter, so im not sure how its set up. Its not geared. it goes 32 km/h. how do i know if i have a direct drive hub?

Flaperjacker said:

its an electric scooter, so im not sure how its set up. Its not geared. it goes 32 km/h. how do i know if i have a direct drive hub?

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Perhaps you can contact the manufacturer for information that you are asking for.

A 48 v controller would likely have 63v capacitors inside. At a guess 5 fully charged sla would be too much and damage these components. You`ll need to check this yourself.

Voltage is the way to go for more speed so you may want to look at a new controller.

5 batteries would be at least 5 x 13.8V = 69V when charged

OH really? I don't really want to risk it thought. I read online about a "shunt mod' which helps with the one battery and hooks it up to the motor. I'm not willing to change the controller or motor or anything like that. Im not looking to go like 60, just a bit over 40 to be able to keep up with cars and stuff. The controller on my scooter already allows the speed to go over 32.Right now it goes as much as the batteries can do at this moment, which is 40km,

The shunt mod would give you more wattage. This will get you more quick take offs, and increase speed when climbing steep hills. But it won't do a lot to make the scoot faster. At most, one or two mph more, if any. Since you are using lead, there is also a good chance that more wattage will cause them to sag under load more, and even wear out faster. If they sag enough, your voltage could even be less, and the result no faster at all.

More voltage is the key to speed. But your controller can't tolerate it. Chances are, your motor can tolerate up to 72v, if you buy a new controller.
But as you increase voltage or wattage, you do heat the motor faster. So don't plan on riding for hours at your new higher speed.

It's a good plan to add a thermometer inside the motor if you plan on hot rodding your scoot. Using a remote sensor, a wire leads out the axle to a readout on your handlebars.

Hi,

I experimented with adding an extra 12v of the same ah battery wired in series to an electric EGO scoota. The problem was that the stock controller had a high voltage cut off at 65v, 5 fully charged batteries came in at 67v. 2v had to burnt of before the controller would work. Leaving the lights on for 5 or so minutes to use a couple of volts up would let the controller operate again.

The extra volts does give more RPM and better performance, but also the controllers low voltage cut off is affected as is the battery monitor with the extra 12v showing a false full. You will also need a 60v charger.

These problems can all be worked around, the 5th battery wasn't really practical for what I wanted so I then experimented with fitting a relay wired into one of the unused handle bar switches (2nd horn switch/starter switch).

Basically a relay kicked in the 5th battery whilst the switch was pressed, a boost switch. The bike then had the extra performance all the time the switch was pressed. When released it was back to the stock 48v with everything else working as should and no high/low voltage cut off issues. The battery gauge obviously showed a false full during the pressed switch.

This boost battery had to be charged seperatly with a 12v charger.


Check out the blog link below for someone who has done a lot with scooters.

http://zenid10.wordpress.com/

I like that boost switch idea. Gets around that higher voltage than the controller likes problem nicely. Another one that helps a tiny bit, is to add a 6v battery rather than a 12v.

One thing hasn't been mentioned. Many controllers have a speed limiting loop. This will be a single wire coming out of the controller, connecting at a plug to another single wire, and coming back in. Such loops can be used to turn on and off various functions, like electronic regen braking, or perhaps cruise control.

But the other very common use is to limit speed. Say the bike goes 25 mph normally, plug in the loop, and now the bike won't go faster than 15 mph. In some countries, the loop is used to limit speed where the laws there are more restrictive.

Look for such a loop of wire on your controller. If you find one, unplug it, and see what happens. Maybe you get lucky, and suddenly have 10 mph more.

Other bikes come with 2 speed or three speed switch. Most likely you'd know if you had that though.

Hi!. I am getting my new emmo x series today. I allready saw a video online of somone putting another battery on it and doing a shunt mod.

http://www.youtube.com/watch?v=PfmujyQMpoA


Would i need a 60V charger to do this? What about the lights an all that. I really want to to faster just by a bit. cars around here go about 45. My scooter would only go around 40-42. So it would just ab a tiny increase so i dont slow down traffic.

Hi Flapperjack, congrats on the new bike, Let us know what you understood/still need help understanding from the posts above.

Adding 25% more voltage will get you 25% more speed. A shunt mod will give better take off but cause more heat in the motor, and make the SLA battery drain faster (and the volts to sag more).

You don't NEED a 60V charger, you could charge the 5th battery separately with a 12V charger, but a 60V charger would be neater, and maybe for an electrical beginner, easier to install.

The controller may take 60V or it may blow. You need to check internal components for their voltage rating, or ask the manufacturer or someone else who has experience with exactly the same bike.

I think the stock battery gauge will be useless at 60V. The stock controller low voltage cut off (LVC) will be useless at 60V so you'll need a way to monitor voltage so you don't run the battery flat.

I'd guess a quality bike may use a separate DC-DC converter for the lights, horn, signals? A cheap chinese scooter might skip this and use 12V high from controller for brake, and a 48 V globe for headlight?

Hi. This bike accelerates way faster than my old one. it looks good and is extremely comfy. however the top speed is lower. i barely get over 36km, when compared to my other one it went 40km. This one inst limited, down hill i got it to go 50. How should i add the new battery. I really like the switch idea, however i have no idea how i would wire it up. Can somone explain how i should wire the new battery?

To add one more 12v battery, connect the negative terminal to the positive terminal of the existing battery. The positive terminal of the added battery is now the positive end of the entire battery.

Or on the other end, the + of the new battery to the - end of the old. Then the new battery is the new - end of the entire battery.

Just make sure you don't do both "for good measure" - connect the pos terminal of the new battery to the neg terminal of the existing chain and the neg of the new battery to the pos of the existing chain, or else that bike is going to go vertical (while the batteries go vertical, horizontal, and every which way at once).

Cameron

Well, I am going to try to find the speed limit wire on my Jetson electric bike which firmly won't go above 20mph and see if I can disconnect it and be able to get it up to 25mph. It would only be 5mph but that would make a huge difference at this point since 20mph is extremely slow...If I do find the wire, I will take some pictures and post it here.

BTW, if anyone has found the speed limit wire/plug on the Jetson electric scooter/bike, please do let me know.

Flaperjacker said:

Hi. this is my first post

Anyways I'm not a great electrical person, but I know a couple of things. I have an electric bike which has 4 12V batteries and 20 Ah. Its a 500W ebike with a 48V motor. Now my question is, can I add another 12V battery, in series to give it extra power for speed?. I saw some people hook up the cables from the extra battery to the main power cables. The bike goes really slow and I want it to go faster. But this would mean it would have an impact on the motor. How can i make it faster and not really damage anything? Is this even possible? THanks

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I have a 48v 40ah lifepo4 with an infineon 18fet irfb4110 with a 48v 1000watt hub. I'm wondering if I can hook up a 12v 40ah (56cells @ 3.2v 3000mah @ 4 series 14 parallel) in series with my 48v 40ah lifepo4, by connecting the negative on the bms to the positive of the 12v setup and the 12v positive to the controller. Do u think that would work out ok to give me 60v 40ah relaibly?

Seems to me if the "secret wire " ---to allow some 10MPH speed increase---really existed it would already be exposed! Sounds like "pie in the sky".