TaiLG Electric Bicycle Scooter 48 Volt 12 Ah 250 Watt

Alastor

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Joined
Apr 24, 2012
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394
Location
Greece
Hello everyone ,

I wanted a small electric bicycle scooter without having to issue papers insurance and all that for me and my girl so we can roam the city cheap.
The electric bicycle-scooter i took was the best in Greece at the moment but as always i want to improve some of its features.

DSC02472.JPG


The technical specifications of the bicycle is 250 watt rear hub drummed motor 20A controller 48 volt 12Ah Lead acid batteries.
The bicycle has a lot of tongue even with two peoples riding it but the controller gets really hot when i climb hills with a second person.I think that the controller gets hot because it is enclosures in the body of the bicycle and because the motor runs in 20A when i climb a hill.I was wondering if i can do something about that to improve its temp please let me know.

Also the bicycle has 60KM range with one person and 40-50 km with two persons.For now i am not thinking investing in a Lipo4 battery but i will do it in the future after the lead acid ones die.

So i derided to make a small project that will give an extra 10KM of charge when i need it.I was thinking to buy a small inverter 150 watt and take a 4s lipo pack's at 5Ah and use the inverter with the bicycle charger as an insurance in case i run out of battery.The only think i am not sure is if i can use this kind of setup while the bicycle is running because i don't want to discharge my lead acid batteries more than 50%.Do you think that is possible ?if it will help i can also provide you with the electric bicycles electronic schismatics.

Thanks in advance
Andreas
 

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are you sure it's 250W? Seems pretty low for a bike!
Most similar bikes are created with at least a 350w, some even 700W motor.
 
so what is the question?

is it rhetorical? as in you just want us to say it is ok to carry a lipo so you can charge up the SLA through a dcdc converter and charger.

this is all to keep the SLA alive and you think lifepo4 is too expensive and heavy?

where is your location? are you in greece and just bot this scooter so you could avoid paying taxes as you would if you bot a motor scooter?
 
One way to cool the controller,is to mount a sink on it, or if it is enclosed within a box, mount it on the chassis of the bike, or any METAL plating of the body.
If it's in a sealed compartment, at least the heat will be able to escape through the chassis.

You can also mount the controller outside on your bike, like done with the Xtreme XM-series bikes, you can see it on the rear wheel:
xm4000li-angle-left-red-250px.jpg


For extending range, so far the best I can think of is using your trunk space, and install more lead acid batteries in them.
There are a whole bunch of batteries for sale on Amazon and other sites.
The batteries that might be interesting to you are alarm system batteries.
They are lead acid, 12v based, you'll need to buy 4 of them, and put them in series.
You can find them from $18 to $25 easily per battery.
They are not very powerful, usually between 4 to 7 amps gets you the best price.
Before you do, make sure they will fit in your bike!
If you have a lot of money, you can find more powerful batteries.
You can also buy the LiPo4 battery, they're about $699, and open the compartment.
Inside you will find 4 sealed batteries.
You can take them out (they're very small) and fit them in your helmet compartment under the seat or perhaps with some body work, can find a place to stow them in.
 
dnmun said:
this is all to keep the SLA alive and you think lifepo4 is too expensive and heavy?

where is your location? are you in greece and just bot this scooter so you could avoid paying taxes as you would if you bot a motor scooter?


LoL what can i answer to you ..... i don't understand the meaning of your question and it seems irrelevant.Do i think lipos are heavy lol :p hahhaahaha no i don't .
You know what you didn't understand what i was trying to say because of my terrible English :p so i will try to explain my point of view to you the best way possible :p

I don't want to use a DC DC converter because of its limitations and by limitations i mean i cant use it for any other purpose but the inverter has many uses and if am right pure sine 150 watt continues are quite inexpensive at a 97% efficiency.
Also it might be handy in my solar setup as well.And to make it even clearer to you i was just wondering if its safe to charge the battery while the bicycle is moving.
 
ProDigit said:
are you sure it's 250W? Seems pretty low for a bike!
Most similar bikes are created with at least a 350w, some even 700W motor.

Its legal papers ratting the motor 250 watt :D so its free.
 
For the controller heat I would suggest a 48 volt computer fan. Mount it with a bit of gap between it and the case and maybe a switch if you just want to turn it on for hills.

As to using lipo to charge the sla that's not a very good way to extend range. You lose quite a bit of power inverting then charging like that. Cheapest option is to just carry your charger and hook it up while eating lunch.

A better option is to get lipo in the correct voltage to match the sla and parallel it. You will need to monitor the lipo to not over discharge but you would have to do that using it for charging also. You need separate monitor for the lipo as the voltage monitor built into the bike is worthless for pretty much any type of battery other then sla.

Gary
 
ProDigit said:
One way to cool the controller,is to mount a sink on it, or if it is enclosed within a box, mount it on the chassis of the bike, or any METAL plating of the body.
If it's in a sealed compartment, at least the heat will be able to escape through the chassis.

You can also mount the controller outside on your bike, like done with the Xtreme XM-series bikes, you can see it on the rear wheel:
For extending range, so far the best I can think of is using your trunk space, and install more lead acid batteries in them.
There are a whole bunch of batteries for sale on Amazon and other sites.
The batteries that might be interesting to you are alarm system batteries.
They are lead acid, 12v based, you'll need to buy 4 of them, and put them in series.
You can find them from $18 to $25 easily per battery.
They are not very powerful, usually between 4 to 7 amps gets you the best price.
Before you do, make sure they will fit in your bike!
If you have a lot of money, you can find more powerful batteries.
You can also buy the LiPo4 battery, they're about $699, and open the compartment.
Inside you will find 4 sealed batteries.
You can take them out (they're very small) and fit them in your helmet compartment under the seat or perhaps with some body work, can find a place to stow them in.

Thanks for the tip about the controller i will make sure to add some heat sinks and mount it on something metallic if its not already.
I don't agree with you the best lead acid batteries to use are the alarm system batteries because they are meant for stand by and not for heavy use that is required in my case .
If the batteries die i will probably replace them with deep cycle ones they cost a little more but they don't get damage so easy.

I just wanted to make a small portable emergency charge station (if that makes any sense) in case i run out of juice while i use the bike.If i can use this system when the bicycle runs so i can extend its range for about 5-10 km in case i need it i will be more than happy :)

The charger the bicycle uses is 59 v * 1.8 A = 130 watt and i was thinking taking the below parts

1 x Turnigy 5000mAh 4S 20C Lipo Pack 40 euros
1 x 150 watt inverter modified sine 30 euros
or
1 x 150 watt pure sine inverter 150 euros ( but in my case i think its best to take the cheap one and invest on a second lipo i will appreciate any feedback on that )

Also i was thinking to re-wiring all lights , alarm and horn to one of the lipos so i can get more juice from my sla batteries for the motor.The bicycle is a cheap one so i don't want to invest money on it just make some improvements that will give my some more range.
 
GrayKard said:
For the controller heat I would suggest a 48 volt computer fan. Mount it with a bit of gap between it and the case and maybe a switch if you just want to turn it on for hills.

As to using lipo to charge the sla that's not a very good way to extend range. You lose quite a bit of power inverting then charging like that. Cheapest option is to just carry your charger and hook it up while eating lunch.

A better option is to get lipo in the correct voltage to match the sla and parallel it. You will need to monitor the lipo to not over discharge but you would have to do that using it for charging also. You need separate monitor for the lipo as the voltage monitor built into the bike is worthless for pretty much any type of battery other then sla.

Gary

Nice idea with the fun there .

I made some calculations the battery bank of the bicycle has now is 48 v 12ah lets say that the bike is on 80% i get around 562 watt of juice from the sla's with 2 lipos including the losses from the inversion i will be able to charge the batteries a max of 120 watts 1/4 of the total battery.way better of any regeneration i know its about 15 km with an extra cost of 100 euros and thats the only reason i am tempted to try it :D and i make all this peculiar questions ;) .Getting a DC DC converter i could add 146 watts max or even with a pure sine inverter with a cost of 250 euros that i don't believe worth investing .
 
why not just buy another battery and put it in parallel with the SLA?

you are looking at 220 euro, so about $300 and for $434 you can buy a 48V16Ah lifepo4 pack from BMS battery with the headway cells.

or just use that battery and sell the SLA to recover some of the cost. if you get $130 for the 4 SLA then you would be even with the cost of going to the lipo hack.

then once the SLA has been removed, lower the LVC on the controller to about 32V to get the entire capacity of the lifepo4 pack.
 
Alastor said:
I don't agree with you the best lead acid batteries to use are the alarm system batteries because they are meant for stand by and not for heavy use that is required in my case .
The batteries will provide between 4,5 and 7amps in series. Your 250W motor, if it is really a 250W motor, only consumes 5.2A max; that is in the acceleration stage (and probably at the stage where you are driving at it's fastest).
Having these $25 batteries on board could extend you 5 to 10 miles easily.
But they only recharge 250 times.
If you want any better you'll have to dock some $$$'s!

I would not go with a fan for cooling, as the fan consumes energy.
I would install LED lights to reduce the power draw when the lights are on.

I would also not buy a voltage convertor, it will most likely not run very efficient, and if you have standard 12V car battery, you will have around 400 cranking amps, but sustained amps for most car batteries are around 15-18A in your storage, extending it to 48V will mean the amps will reduce by a forth (to 4-5A).
In that case you will have even a lower rating, as your voltage convertor will also draw power to operate.
If you want your bike to run via a voltage convertor you'll need at least 2 x 12V batteries for cars, or one that has over 24A, which is roughly around $140-160.
Keep that in mind!
 
Alastor said:
GrayKard said:
For the controller heat I would suggest a 48 volt computer fan. Mount it with a bit of gap between it and the case and maybe a switch if you just want to turn it on for hills.

As to using lipo to charge the sla that's not a very good way to extend range. You lose quite a bit of power inverting then charging like that. Cheapest option is to just carry your charger and hook it up while eating lunch.

A better option is to get lipo in the correct voltage to match the sla and parallel it. You will need to monitor the lipo to not over discharge but you would have to do that using it for charging also. You need separate monitor for the lipo as the voltage monitor built into the bike is worthless for pretty much any type of battery other then sla.

Gary

Nice idea with the fun there .

I made some calculations the battery bank of the bicycle has now is 48 v 12ah lets say that the bike is on 80% i get around 562 watt of juice from the sla's with 2 lipos including the losses from the inversion i will be able to charge the batteries a max of 120 watts 1/4 of the total battery.way better of any regeneration i know its about 15 km with an extra cost of 100 euros and thats the only reason i am tempted to try it :D and i make all this peculiar questions ;) .Getting a DC DC converter i could add 146 watts max or even with a pure sine inverter with a cost of 250 euros that i don't believe worth investing .

What you could do is buy ANY 12V battery with the same current handling as your current battery., or buy 2 with half the current handling.
Say if your battery is 48V, 12A, get 2x6Ah (the 2x7Ah batteries I mentioned to you), put them in parallel with each other. Then put those batteries in series with your current battery. Your system will have 48V + 12V = 60V.
Then use a voltage convertor (take note, a digital one, that does DC to DC, not DC to AC!), to lower voltage back to 48V.
The benefit is that your amps increase from 12A to 15 amps. Theoretically you will extend your travel distance by 25%, but practically because of the loss of the voltage converter, and the weight of the batteries, you will more likely have only a 20% increase in travel distance.
for 45 miles you can do 55 miles.
65 miles, now you can run 80 miles! That's a lot!
 
dnmun said:
why not just buy another battery and put it in parallel with the SLA?

you are looking at 220 euro, so about $300 and for $434 you can buy a 48V16Ah lifepo4 pack from BMS battery with the headway cells.

or just use that battery and sell the SLA to recover some of the cost. if you get $130 for the 4 SLA then you would be even with the cost of going to the lipo hack.

then once the SLA has been removed, lower the LVC on the controller to about 32V to get the entire capacity of the lifepo4 pack.

I totally agree with you the best way to go is to get one big 48v 15 ah lipo4 pack .

Lower the dc on the controller sounds awesome how can i do that ? any suggestions ?

BMS site is awesome i used them in the past and i am very happy with there products and response time.
 
48V15Ah is kinda small for your scooter, but it is about the cheapest i have seen using the headway cells. the $434 was with the 30A BMS. but lifepo4 is the cheapest way to go for the long term and without the risks and short lifespan of the lipo. people like the lipo because it is so light and powerful but you can live with the weight of the headway cells since it is a scooter.

your controller will have a resistor divider bridge tied to the Vcc that is compared to a zener and when the Vcc drops below the Low Voltage Cutoff voltage then the controller is disabled.

to determine how to adjust it we will need to examine the input circuitry inside the controller. so if you go that way be prepared to open it up and examine how it works. it may be a controller we already know and maybe it can be reprogrammed like the other controllers that have been hacked here. but we may be able to figure it out from pictures you post up then.
 
ProDigit said:
Alastor said:
GrayKard said:
For the controller heat I would suggest a 48 volt computer fan. Mount it with a bit of gap between it and the case and maybe a switch if you just want to turn it on for hills.

As to using lipo to charge the sla that's not a very good way to extend range. You lose quite a bit of power inverting then charging like that. Cheapest option is to just carry your charger and hook it up while eating lunch.

A better option is to get lipo in the correct voltage to match the sla and parallel it. You will need to monitor the lipo to not over discharge but you would have to do that using it for charging also. You need separate monitor for the lipo as the voltage monitor built into the bike is worthless for pretty much any type of battery other then sla.

Gary

Nice idea with the fun there .

I made some calculations the battery bank of the bicycle has now is 48 v 12ah lets say that the bike is on 80% i get around 562 watt of juice from the sla's with 2 lipos including the losses from the inversion i will be able to charge the batteries a max of 120 watts 1/4 of the total battery.way better of any regeneration i know its about 15 km with an extra cost of 100 euros and thats the only reason i am tempted to try it :D and i make all this peculiar questions ;) .Getting a DC DC converter i could add 146 watts max or even with a pure sine inverter with a cost of 250 euros that i don't believe worth investing .

What you could do is buy ANY 12V battery with the same current handling as your current battery., or buy 2 with half the current handling.
Say if your battery is 48V, 12A, get 2x6Ah (the 2x7Ah batteries I mentioned to you), put them in parallel with each other. Then put those batteries in series with your current battery. Your system will have 48V + 12V = 60V.
Then use a voltage convertor (take note, a digital one, that does DC to DC, not DC to AC!), to lower voltage back to 48V.
The benefit is that your amps increase from 12A to 15 amps. Theoretically you will extend your travel distance by 25%, but practically because of the loss of the voltage converter, and the weight of the batteries, you will more likely have only a 20% increase in travel distance.
for 45 miles you can do 55 miles.
65 miles, now you can run 80 miles! That's a lot!

Your suggestion sounds better than the original approach i did.The only think i am concerned about is the freaking weight because my motor is small.The sla's i use now are weighting more than the half total of the bicycle !

Your idea putted me into another approach ...I guess weight wise it should be better to take 3 x 6s 4ah lipos connected in series to get to the 60 volt dc controllers limit and use em when i run out of juice 200 pure watts aprox 5amps to my total range at an additional weight of 1.5 kilos only.And the load for the batteries should be a piece of cake with there 100 amp continues max discharge that they can handle.What do you think ? is it worth the investment ? 180 euros aprox the range should be aprox 25-30 km's .

Also changing everything to LED lights sounds nice and i will change that when the first globes start to decay :D.

To be on the safe side i think measuring the total amps from the battery to the motor in full load will also be a nice idea so i can be sure that the motor is consuming the wattage we calculate or else the bigger better lipo is the only way.

One last think do you think that its possible for the bicycle to run the same with a 48v 10 ah lipo pack that i can probably find around 300 euros in our market and weight about 4,5 kilos ??i am only considering that because i will make the bicycle lighter about 21 kilos.

Sorry for the tons of questions i am newbie with the e-viecle thing and trying to consider all possible options.
 
dnmun said:
48V15Ah is kinda small for your scooter, but it is about the cheapest i have seen using the headway cells. the $434 was with the 30A BMS. but lifepo4 is the cheapest way to go for the long term and without the risks and short lifespan of the lipo. people like the lipo because it is so light and powerful but you can live with the weight of the headway cells since it is a scooter.

your controller will have a resistor divider bridge tied to the Vcc that is compared to a zener and when the Vcc drops below the Low Voltage Cutoff voltage then the controller is disabled.

to determine how to adjust it we will need to examine the input circuitry inside the controller. so if you go that way be prepared to open it up and examine how it works. it may be a controller we already know and maybe it can be reprogrammed like the other controllers that have been hacked here. but we may be able to figure it out from pictures you post up then.

I want to believe that its not the cheapest one and its reprogrammable because i don't want to open it up just yet in order to keep the 2 years warranty they gave me :D (or at least having a new controller next to me ;) )
I think i got your point i saw a similar post with details about that bridge in a shunt mode article.To tell you the truth if the controller is rubbish i will probably upgrade it because its the weakest link getting hot easy with some extra load on the bike , that's why i try to think weight wise as well.
 
18S of lipo is 80V and your controller will not take that.

you have a scooter, not a bike.

the only reason the SLA is in your scooter is because they are cheaper to make in china and to offer a finished scooter for the minimum price. lifepo4 will last for almost 10 times as many charge cycles as SLA and have a flat voltage during discharge instead of losing all their voltage to the peukert effect.

if you use lipo then you have to have the lipo protection from methods or other sources, so the cost needs to include that as well as the balancing chargers. then you still have the shorter lifespan of the lipo too.

that is why lifepo4 is cheaper for your situation over the lifetime of the scooter.

there is no evidence your controller is rubbish, it is normal for them to get hot. if you wanna keep it cool you have to upgrade the mosfets. not a fan.
 
dnmun said:
18S of lipo is 80V and your controller will not take that.

you have a scooter, not a bike.

the only reason the SLA is in your scooter is because they are cheaper to make in china and to offer a finished scooter for the minimum price. lifepo4 will last for almost 10 times as many charge cycles as SLA and have a flat voltage during discharge instead of losing all their voltage to the peukert effect.

if you use lipo then you have to have the lipo protection from methods or other sources, so the cost needs to include that as well as the balancing chargers. then you still have the shorter lifespan of the lipo too.

that is why lifepo4 is cheaper for your situation over the lifetime of the scooter.

there is no evidence your controller is rubbish, it is normal for them to get hot. if you wanna keep it cool you have to upgrade the mosfets. not a fan.

Yes i agree with you its all about the freaking money :D Lucky me i already have a nice balanced lipo charger that i can use if some small lipos get there way to me hands :wink: .
I think the best is to wait and buy a nice 15ah or even 20ah lipo4 pack with a 30A bsm the time my sla's die on me. 450 euros for the 48v 15 ah is kinda affordable after all.
 
dnmun said:
there is no evidence your controller is rubbish, it is normal for them to get hot. if you wanna keep it cool you have to upgrade the mosfets. not a fan.

One day i was ridding with a friend did some pedaling to climb some hills and on my way back home i felt the heat under the seat spot so hot that i stopped to chk it out the motor was not burning but it was ok to touch but the controller was like hellfire and that's concerning me because summer is closing in :)
 
Well, first lets get one thing straight. You say you have a 48v controller of 20 amps. Watts is amps x volts. So you have about a 1000w scooter, with a handy sticker to make it cheap at the licence place.

Second, you do need to improve the ventilation to your controller somehow. A small fan run on a 3s lipo pack would help, as well as some kind of way to scoop wind and direct it to your controller. Your controller is likely getting no ventilation at all now, and will run cool enough if it gets some breeze. So it's not so much a fan it needs, but just to have some wind reach it when you ride. You'd think engineers who design these things would have some commonsense, but they don't sometimes.

One thing you should know about controllers is that they make less heat when you ride wide open throttle. Half throttle makes the controller work harder, to shorten the pulse of the power, which makes some heat in the fets. So when possible, do more riding full throttle, then coast. It will help some with the hot controller.

As for the bike on hills. Well, just because they put a cool looking seat for a passenger on the thing to make it sell does not mean it was designed with climing a hill with two passengers on it. No real solution to that, 1000w is enough to get 180 pounds up a hill fine, But if you both combined weigh 300, better stick to the less steep hills as much as possible. A second scooter is the real solution. It's ok though on flat ground and mild hills to carry your girl. Just avoid really steep hills. It's very important not to overload the bike up steep hills. If it can't climb the hill at 20-25 kph, you are going to be heating up the motor real bad as well as the controller. A very short steep hill can be ok, just avoid long steep ones.

On to the batttery. Install a set of new connectors between the battery and the controller that you can get to easily. When you have discharged your lead battery as much as you want to, you can then disconnect the lead and connect some RC lipo. No need to use the inverter and charger.

Two 6s 5ah packs will do for a small range extender. 4 packs makes a nice battery with a bit more range. Connect the packs in series to have a 12s pack. If you have 4 packs, paralell connect two packs to make 6s 10 ah, then do the series connection.

12s RC lipo will charge to 50v, and finish at 44v. You will need a voltmeter added to the bike to be sure you don't go below 44v. Your scoot will run fine with 12s lipo. For a bit more pep, your controller can handle up to a maximum of 14s lipo. That's about 59v fully charged.

Another option would be a lifepo4 battery. A 48v lifepo4 battery of 48v 20 ah would be a perfect replacement for your lead. It would extend your range a lot further than you get from the lead now. One thing about short range though, you have to stop before things fry. With lots of range, you can ride till things melt.

How do you know when to stop? Lots of us use inexpensive thermometers to know. With a remote sensor, you put the sensor on the motor axle, or the controller, and the display on the thermometer will tell you when you are getting hotter and hotter, or if you are just warm, but stabilzed at that temperature.
 
dogman said:
Well, first lets get one thing straight. You say you have a 48v controller of 20 amps. Watts is amps x volts. So you have about a 1000w scooter, with a handy sticker to make it cheap at the licence place.

Second, you do need to improve the ventilation to your controller somehow. A small fan run on a 3s lipo pack would help, as well as some kind of way to scoop wind and direct it to your controller. Your controller is likely getting no ventilation at all now, and will run cool enough if it gets some breeze. So it's not so much a fan it needs, but just to have some wind reach it when you ride. You'd think engineers who design these things would have some commonsense, but they don't sometimes.

One thing you should know about controllers is that they make less heat when you ride wide open throttle. Half throttle makes the controller work harder, to shorten the pulse of the power, which makes some heat in the fets. So when possible, do more riding full throttle, then coast. It will help some with the hot controller.

As for the bike on hills. Well, just because they put a cool looking seat for a passenger on the thing to make it sell does not mean it was designed with climing a hill with two passengers on it. No real solution to that, 1000w is enough to get 180 pounds up a hill fine, But if you both combined weigh 300, better stick to the less steep hills as much as possible. A second scooter is the real solution. It's ok though on flat ground and mild hills to carry your girl. Just avoid really steep hills. It's very important not to overload the bike up steep hills. If it can't climb the hill at 20-25 kph, you are going to be heating up the motor real bad as well as the controller. A very short steep hill can be ok, just avoid long steep ones.

On to the batttery. Install a set of new connectors between the battery and the controller that you can get to easily. When you have discharged your lead battery as much as you want to, you can then disconnect the lead and connect some RC lipo. No need to use the inverter and charger.

Two 6s 5ah packs will do for a small range extender. 4 packs makes a nice battery with a bit more range. Connect the packs in series to have a 12s pack. If you have 4 packs, paralell connect two packs to make 6s 10 ah, then do the series connection.

12s RC lipo will charge to 50v, and finish at 44v. You will need a voltmeter added to the bike to be sure you don't go below 44v. Your scoot will run fine with 12s lipo. For a bit more pep, your controller can handle up to a maximum of 14s lipo. That's about 59v fully charged.

Another option would be a lifepo4 battery. A 48v lifepo4 battery of 48v 20 ah would be a perfect replacement for your lead. It would extend your range a lot further than you get from the lead now. One thing about short range though, you have to stop before things fry. With lots of range, you can ride till things melt.

How do you know when to stop? Lots of us use inexpensive thermometers to know. With a remote sensor, you put the sensor on the motor axle, or the controller, and the display on the thermometer will tell you when you are getting hotter and hotter, or if you are just warm, but stabilzed at that temperature.


I called the dude that imports this model and he told me that he was referring to the circuit safe that is 20A Jesus ....The controller continues can handle 48 * 5 amps and burst some times 7 amps for a few seconds.so its not even close to 1000 watt but it is indeed 250 watt with a pick of 350 watts of a few seconds.I will make sure to make some sort of ventilation with a cheap rechargeable battery for now and probably install the cheap thermometer as well .

Thanks for your time
 
In all honesty, nothing beats the LiPo4 batteries at this moment!
If your bike is truly 250W like you say, it uses I=P/U=250/48=5.21A. If you want to use the battery pack independently, You must select batteries more powerful than 5.02A!!! 4.5A is not good enough!. If you want to use them in combination with the internal battery, any type of 12V battery could do.

The cheapest battery from BMSBattery will be more than enough!

The issue is the following:
Put in those 2 extra lead acid batteries from amazon, with convertor, and your bike will drive only marginally longer (20% max).

put in 4 acid batteries, 7A in series, and connect that in parallel with your current 48V20A battery and your range increase will be ~35% (minus the weight would be around 30% increase).
Your theoretical mileage per charge would be:
45km to almost 60km
60 km to almost 80 km.

You will have between 15-20km increased range max, but these batteries only last 250 cycles, remember that.
4 of these batteries weigh 25LBS, or 12kg.

@$25 per battery for a 7A battery,that's $100 total, they are large, and pretty heavy. They have a max charge cycle of 250 cycles, so in the long run, you're going to be spending the most money on these. In the short run these are your best option though (say,it's a good option for using the bike one year or less).


Second option is to put in the cheapest 10A Li ion batteries, @$233, and your mileage will increase by 20%, and puts you in the +10KM you wanted, but if you ask me is not the best option.
45 km to 55 km
60 km to 70 km
They are lightweight @ only 2.8kg!, powerful, and when using them in parallel with your current battery they will provide more amps and slightly higher voltage to your engine, resulting in more torq, tiny bit faster driving, and longer mileage.
Though if I where you, I'd replace the engine to a more powerful one. 250W engines are used to propel pedal (manual)bikes, not scooters.
When you do this li-ion mod, make sure the controller and engine stay cool!
Li or Li-ion batteries last you for 800 charges, that's over 3x longer than the lead Acid batteries, and usually have less issues too;
They are a better alternative, something you will benefit from financially if you ride your bike daily, for 2 to 3 years.

On BMS battery they don't sell LiMn batteries, but they are known to have 1000+ recharge cycles. Good for upto 4 years of daily use or 5,5 years of ordinary use.

Your last option, is most beneficial in the long run IF:
1- your bike does not get stolen,
2- Your bike does not get into an accident
3- You are not going to sell it, but keep driving it regularly:
4- Your bike does not overcharge (as this can cause fire, or damage the bike) or run dry empty for months (as this impairs the batteries).

In other words, if you will use it daily, and take care for it, the more expensive LiPo4 (or LiFePo4) batteries should pay you back your money over time!. They are rated 2000-4000 recharge cycles max. The cheapest one from the store will increase your mileage the same as the Li ion ones, by 20% (the 10A, $278.10 one). You will be paying only $45 more than Li-Ion batteries, but they last you more than twice as long, anywhere north of 5 years.
No one has experienced it yet, as these are quite new, (literally I've only heard of it for the first time this year, the newest production samples should be about a year out on the market, but according to the specs they should last almost 7 years.
In the long run these are the best solution!

Actually, not,
your best solution would be to buy the most expensive battery, as it will increase your current range by a 100%!
That means, if you buy the $530.10 battery, and connect it in parallel, (you will also need to buy a more expensive charger); your mileage would be:
from 45km to 90km
From 60km to 120km. (an increase between 45 and 60miles per charge)

The MBS Batteries should fit in your helmet compartment. Measure it, and verify with BMS (battery sizes are on their site) here: http://www.bmsbattery.com/56-48v?orderby=price&orderway=asc

I help you in all of this, because I have bought an Xtreme BX-700Li and am currently in the process of researching extending my range too. That's why I can help you in all of this, and share my finding! Whatever you choice you end up taking, please let the community know,so we can learn from your experiences!
Save this site in your bookmarks in case of something happening (like battery breakdown or so), so you can tell us about your experiences!

Don't be affraid to buy a battery with a too high amp rating. The higher the amps, the longer your mileage. They should almost be linear, meaning, a 10A battery has half the mileage as a similar battery with 20Ah rating.
And like mentioned, your 250W engine needs at least a 5.2A (that is a 7a) battery (because there are no 5.2A batteries on the market. There are 6A batteries on the market, but the problem with these is that when the voltage drops below a point still ok for the battery, your controller will shut down,and your mileage will be very low. So it's better to get at least 7a batteries, unless you plan on using them alongside the other battery, to re-inforce the amps.
 
You guys are awesome trillions of thanks ; )

When i start making the modifications i will make sure to come back and post everything but it will take me some time since i just took the bicycle and i don't really have a money to invest at the moment.
I use BMS site for spare parts for my other bicycle and i am very pleased with there products-value they sell staff way cheaper than they do here in Greece...you see our market is tiny at the moment not many people use electric bicycles so a few shops monopolize all the market.I hope to get the first battery from two months from now to extend its range and meanwhile i will install a cheap thermometer and some kind of small heat sinks or remount the controller if possible from wiring to a better location to prevent if from overheating and i will come back with pictures and test results as soon as i manage to play with it.

In my opinion this small scooter-bicycle has its potentials and with little extra work from my part it can solve my small - mid range trips around the city even get me to the sea only 25 km from my house luckily the road is flat with almost no hills in between.

By placing the battery in to the helm compartment the controller will have a lot of air flow because the battery enclosure witch is a 20 kilo giant gets almost all space under the seat.
They say that it gets 60km range with the 12ah AGM battery's it has but i really don't want to go over 35 km per charge to double the cycles from 400 to 800 till i save the money for the new batteries , 250 cycles for the simple lead acid batteries AGM weight a little more 4.8 kilos per piece but they have reenforced cell plates for deeper discharge without damaging the battery cells that's why my battery enclosure is 20 freaking kilos :( With that care the batteries might make a lot of kilometers.I don't want to use the bicycle every day so the batteries will not be stressed hahaha.

Thanks again for all the help i will be in touch
 
Please do note, that you do not get the mileage increase by removing your old battery.
The calculations are made when you use your stock battery, together with these batteries.

In fact, if what you say is true, and the battery in your bike is only 12A, not 20A Like I had assumed, you will gain a lot more miles per charge adding a second battery!
What you basically need to do is wire the extra battery pack (4 x 12V batteries which are connected in series), in parallel with your stock battery.
If possible, use high power diodes on the anode (+ terminal).

Recalculated for a 12A battery, your mileage increase will be:

Internal battery + 4 Lead acid batteries @ 4.5A: + 130%
45 becomes 60 km per charge
60 becomes 80 km per charge
(15-20 km increase max)

Internal battery + 4 Lead acid batteries @ 7A: + 155-160%
45 becomes 70 km per charge
60 becomes 90 km per charge
(25-30 km increase max)

Internal battery + Li Ion or LiPo4 battery @ 10A: + 180%
45 becomes 80 km per charge
60 becomes 100-105 km per charge
35-45 km increase max.

Internal battery + LiPo4 battery @ 20A: + 260%!!!
45 becomes 115 km per charge
60 becomes 150 km per charge
70-90km max increase!

The above calculations are pure mathematical, under best conditions, meaning that all the energy from the secondary battery will be redirected towards the motor; and not towards the lights, horn, blinkers, breaklights, dashboard etc.
They also have a minimal mathematical compensation for the extra weight. Do know extra weight takes extra power, especially when the tires get flatter,and consumes more battery when accelerating.
In practice though you can take off perhaps 5 miles from the max km per charge increase you get; to get a more realistic outcome.

You can further increase mileage, by making sure your tires are inflated to a right pressure. you can also gain mileage by creating the bike's body more aerodynamic, taping off small holes and vents not used for cooling the interior.
By changing the lightbulbs to leds, or not using the lights at all; by lowering the bike (lower over the floor means less wind resistance), by bending forward while driving, by removing widshield, baskets, and mirrors if legally allowed, and by wearing tight clothes like jeans or leather jackets; and never wear loose scarfs or clothes on a bike, especially not if they could end up in the wheels.
Making sure that the battery compartment(s) are kept warm, meaning no freezing temps. If it is cold in the garage, plug in to charge your battery 30 minutes to an hour before departing, that way it can warm up. A warm (but not hot) battery performs at it's best between 20 and 40 degrees C.

If you ask me,
A bike like yours isn't meant for too heavy weight, and if you don't care about a +100 km driving distance (which, if you don't use it daily will just cost you more money to maintain these large batteries), I would recommend being satisfied with the cheaper Li-ion battery. Seeing that your bike will most likely run 2 years problem free,after which you will have to change the internal batteries, you might as well buy a regular Li battery, as your bike is made to last between 4 to 6 years. After that it probably will need some fixing, but you won't expect more than 8-10 years from it.
For that reason I'd recommend you to either go with a regular Li-Ion battery (without lead acid batteries). the 15 amps one, for $330 (and get anywhere between +10-15km extra range of what you currently have).
Use the cheapest ion battery (10A) together with your current batteries, you'd have about 180% of range added to your current range for $230.
The Li batteries (Li-ion or LiPo4/LiFePo4) are really lightweight, weigh less than a bookbag or a bottle of water. Lead acid batteries are different.
Or use the cheapest Lead acid batteries there are, the 7amps perform the best but if they don't fit in the helmet compartment, the 4,5 (or 5)A versions will most likely do (look around on amazon, where you can find these small cubes with 5A instead of 4,5)!
 
Thanks for the information mate :)

I went out today to choose what type of battery to pick for the computer fun .I took some rechargeable Nimi AA's that i can drain without having alarms or other protection , cut off circuits to insure there well being because a lipo might be tricky if over drained without protection.As crazy as it sounds protection cut off circuits for lipos are quite RARE here in Greece hehehehe.

I also manage to locate the controller i added one small heat sink from an old cpu and i mange to fit a large computer fan with a nice dimmer to control its spin.Now i am at the state of charging the batteries up to see if i can run it on my small 4XAA's pack and solve the heating issues.

Already with the extra heat sink the controller is quite cooler in touch and after 10 kilometers of travel the motor was also cooler.I will come back tomorrow with some pictures of the installation after i double check everything :)
 
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