Hi I am from Hampshire, been using the same mountain bike for over 25 years, thought I will give E bikes a try out, so bought an old model on eBay with lead acid batteries, hope I can get advice on the forum to change over to lithium, not sure if it will be easy but will wait and see.

Should be easy peasy to go lithium, just two wires from the battery to the controller and correct polarity. If poss a down tube fitting is best for C of G.

Show us a pic of the bike .

Hi Chris I'm new here too, that's some length of time too have the same bike !

Hello Chris

 

Gaz

Hi Chris I'm new here too, that's some length of time too have the same bike !

I bought a fusion mountain bike light weight tangent frame, first thing I done was put a shimarno sealed bottom bracket on the bike had no problems since, just looked after it served me well could still go on for many years to come, touch wood.

Should be easy peasy to go lithium, just two wires from the battery to the controller and correct polarity. If poss a down tube fitting is best for C of G.

Show us a pic of the bike .

Is it that easy like changing batteries in a torch. What I want to do is keep the old casing which fits the frame and change the 3 x lead acid batteries inside which are 12 volts 12amps each total 36 volts. What I would like to do is swap and wire up the Same way the 3 batteries with lithium equivalents obviously with a new charger but that I don't think is going to be straightforward, I read somewhere that lithium gives out a slightly higher voltage and the amps are more efficient than that of a lead acid battery, I don't want to burn out the controller bearing in mind the e bike I bought is about 2003 not like the lithium made bikes of today but could be the same technology. I think the way to go would be lifepo4. My e bike seems to be made to good standard apparently these bike were issued to some police forces around the country back then who adopted the e bike concept. The bike is just called eco bike, I will post a picture and pick brains on the forum for peace of mind just to be sure.

Hello Chris

 

Gaz

Hi Gaz

The eco bike, battery pack sits in the cross bar. A bit high up especially with heavy lead batteries but lighter lithium you can see why I want to change. The bike although it has a couple of rust marks on the chrome is hardly used as there is no wear on the tyre's. Any seen this type of bike or had one.

Generally yes that simple you wil have to let us know your controller amp rating and a pic.

Lifepo is heavy, li-on is lighter and the foreseeable future, no need for 3 batteries wired in series and the faff of 3 x charging. A nice 36v li-on with BMS encased in a premade fitted casing simply locks in to a cradle/docking fitment that simply bolts to the bikes frame in place of the bottle holder. You get rid of your heavy SLA's and clunky battery case for a lightweight compact battery.

The controller will only draw the amps it can handle /demand so any 36v li-on will be good, irrelevant of the ah. The bms has an amp rating to protect the cells.

Edited July 31, 20178 yr by Nealh

Hello Chris

 

Gaz

 

Hello Gaz

those older bikes can be quite power hungry, so it would be better to get a battery that can provide at least 25 amps continuous.

 

The battery and motor would be happy with 36v because the voltage of a lithium battery is approximately the same as a lead one. the controller regulates the power to the motor, so you can't overload the motor by using a different type of battery.

 

There's a lot of room in your battery case, so you have lots of options for filling it with lithium.

 

Personally, I wouldn't use LiFePO4. It's much heavier than other lithium types and generally has a lower power potential, so you need a bigger heavier battery to make up for its deficiencies.

 

The obvious question is how much you want to spend and whether you have the ability to construct your own battery?

Thanks for the info, I thought a conversion would be a bit of an issue, seems straightforward. So I will look for lithium ion, I see that you can get custom battery packs made to size so it can fit in my already existing battery pack, just need to find a recommended company that sells packs and chargers or if I were to make my own the parts. Would there be a difference in price with made up pack or home brew bearing in mind that the cost can mount up too with the extras and tooling to spot the tabs etc plus a bms. Anyone gone down this route from lead to lithium. I am sure it's a question e bike owners will need to find out when their battery life comes to an end and then find out the battery is worth more than they paid for the bike or the bike is now obsolete because the firm went bust or the model and battery is no longer made.

BGA Reworking will wire up a battery into your case for something like £250 to £350, depending on which cells and how many. You can buy a ready-made cell-pack from Aliexpress, that just needs the charger and power wires connecting to your case, but you need to be sure that the size fits in your case and it can give at least 20A continuous. 25A would be better without seeing your controller.

 

I think i remember someone doing the same as yours fairly recently with an Aliexpress cell-pack. He had to remove some unimportant internal webs from the case so that it would fit. Make sure that you pack out the cell-pack so that it can't move when the case is screwed together.

Thanks for your help, tried the bike out today with lead acid to see if everything functioned, worked ok would certainly help if the bike was 3 batteries lighter, trying to work out the range and how long the batteries will last on a run.

I managed to take the controller out of it's hidy hole I believe it's a 36volt 18amp controller according to its number. Are there better controllers that are suited to use lithium more efficiently. Would anyone know how this one compares to up to date one's. I may end up renewing the controller throttle and power display, the battery display shows 3 bars to tell me the battery life and when the power kicks in.