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Converting to Lithium Battery


XO71
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Hello all,


Just a general question, has anyone had success in converting their bike to using a lithium battery? Do you just need a new regulator, or is it more complex? I suspect the latter, but any experiences people are happy to share would be gratefully received.


Many thanks,


Mark

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A mate put one on an old Suzuki gsx1100efe with standard charging system. It burst into flames. Check what max charging current and voltage should be, monitor it and make battery easy to remove.

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My owners manual doesn't beat around the bush. it says that the battery must be removed from the bike for charging.


Fortunately its very easy to get at.


Given that you really need a charger specifically for the battery.. ie one that balances each cell (sub battery?) as it charges.. im not entirely sure that an ordinary charging system that you have in most if not all bikes is suitable. its something to check before you buy.


My bike came with one of these.. but Ive yet to have a look at it. it weighs 3lb. 8-)

 

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my understanding is that it depends on your charging system and the battery.


A lithium cell, of which multiple are put in series to make up to the correct voltage. An empty cell is about 3.2v, a full cell is about 4.2v, so they say the normal voltage is 3.7. I've made up a lithium battery pack from old laptop cells and used 3 in series, so that is 12.6v full and about 9v empty, that's fine for what I use it for, which is just charging phones/tablets ect when I'm away in our caravan. For a bike I suspect they do 4 in series, giving a full voltage of 16.8, a nominal voltage of 14.8, and an empty voltage of 12.8. So if your charging system has it's highest voltage at 14v, you're not getting to the nominal voltage nevermind to it being full.


Then there is the issue of balancing. As I said it maybe either a 3 or 4 cell pack that makes up the whole battery. They should all stay about the same voltage as they are charged and discharged, but they sometimes drift a little. You might have one cell at 3.6v, one at 3.7v and one at 3.75v. Now that's fine until you come to stick it on a charger. If its a dumb charger, it just tries to get the battery upto it's full voltage, if one of the cells is a bit low it doesn't know that and keeps putting power into the whole thing, which can lead to the cell that is the highest voltage going over the 4.2v maximum, which can be dangerous. That is where smart chargers or battery management systems come in. They have connectors between each cell and across the whole battery, so they can tell what voltage each cell is at and restrict or apply extra voltage to the cells that require it.


Admittedly this is all for lithium ion batteries. The tech used in motorcycle battery is LiFePO4 which is slightly different in regards to charge rates and voltages, but the same principle applies.


This seems like a good read

http://www.fastbikegear.co.nz/index.php?main_page=page&id=18&chapter=1

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Thank you all for the information. Lithium batteries certainly seem to be the way forward. I imagine newer bikes will increasingly tend to be manufactured with lithium ions in mind.

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Thank you, Pbassred. I understand Lithium cells cannot be charged in the same way as a lead acid cell, I was just wondering if there are modifications you can make to allow you to fit a lithium battery to your bike. Surely it must be a pain in the rear end removing the battery to charge after every ride. And what if you do a lot of starting and stopping, or use your lights a lot?

Edited by XO71
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The battery is only used to start the bike. The power to run it comes from the alternator. Why would you want a lithium battery anyway? what does it provide over a normal battery especially when you consider the cost and potential danger of Lithium.

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The battery is only used to start the bike. The power to run it comes from the alternator. Why would you want a lithium battery anyway? what does it provide over a normal battery especially when you consider the cost and potential danger of Lithium.

 

It may not be possible or practical - just now. But it soon will be. And for a reasonable price. And the benefits are huge.


My bike has one.. I knew that before I bought it and didn't think twice. Obviously the price of a replacement is high right now, but as its not going to be replaced until around the year 2028 - thats not something Im going to worry about. The benefits for me are.. I should never need to buy a charger. because it recharges in minutes, replacing the charge used to crank the engine takes minutes of riding, It weighs next to nothing. it can be placed in any position. it doesn't lose power from standing.. so, if i were to stop riding the bike now and not use it until April? or July? No appreciable effect.


I can remember a time when a mobile phone had a lead/acid car battery in it as power source. but demand drove technology. as phones became smaller everyone wanted one and lithium was the way to go. in the early days there were accidents. but who thinks about the danger of the lithium battery in their back pocket now? if you go out and forget to pick up your mobile do you spend any time worrying about your house burning down? probably not.


Likewise.. a lithium battery in a vehicle is safe. perfectly safe so long as its from a reputable manufacturer and was built with safety uppermost - as they must be. And that is the way things will go, before long vehicle lithium batteries will be very cheap and most all vehicles will have them - it will be 'normal'. its just a matter of building the charging/management system into the battery so it can be charged by a normal vehicle charger. And thats the next step.


My bike is parked just a foot or two from my house. it has a lithium battery just inches from a tank full of petrol. I'm only thinking about that now. I'll be off to work in an hour and not back until 10 tonight. I wont waste a moment of my day worrying about the battery, the bike or my house. just as you never think for a moment about the phone on your bedside table, with its own lithium battery, when you go to sleep.


when you ask.. why lithium. ask yourself, why does a mobile phone not run on ordinary AA batteries. or even a full size lead acid battery. as they did in the 1980s.

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But a mobile phone uses the power from the battery all the time. A car/bike only uses battery to start. An alarm or light left on will drain any battery so I still don’t see what lithium has over lead acid apart from some weight saving. Is that really sufficient to be worth the extra cost/complications of lithium?

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But a mobile phone uses the power from the battery all the time. A car/bike only uses battery to start. An alarm or light left on will drain any battery so I still don’t see what lithium has over lead acid apart from some weight saving. Is that really sufficient to be worth the extra cost/complications of lithium?

 

No a motorcycle uses power from the battery in normal everyday use as it requires a stable source of power ..

The charging system replenishes the power in the battery


If you used all electrical items at once on a motorcycle

ie full beams , hazards, brake lights illuminated ,heated grips , ABS system activating , Horn ...The alternator would struggle to provide a stable source for the Ignition and fuel injection sysyems .


Even without doing the above if you started the bike and isolated the battery from the system yes the bike would run but as soon as you push the limits the FI and Ign will start to struggle .

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I've used lithium batteries in model aircraft for years - in which application the cells operate with none of the usual safety designs incorporated into most lithium uses. They do that in order to extract the performance needed for flight and they are brilliant. The two main issues are charging and accident damage. A damaged battery can sit there for a long time whilst heat builds up - then they explode. I've known guys crash a model, stick it in the car and fly a spare model for a couple of hours, then their car suddenly catches fire.


But in normal use they are light years ahead of lead acid technology.


However, I wouldn't retrofit one to a bike designed for a lead acid battery. There's little to be gained as a good lead acid coupled with a decent charger will last you for years. I'm sure at some stage I'll buy a bike fitted with a lithium battery but until then I'll stick with lead acids.

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