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I know from past experience that I can install a lithium ion battery in my bike with no ill effects. I ran one like that for a couple of years.

My question is, “Why do I need a special charger for a lithium battery?”

As far as I know there is nothing special about the bikes charging system.

I believe it is a 3 phase alternator as most cars and motorcycles have been using this type for the last 20 years.

The bike comes with a lead acid battery so I doubt there is any special circuitry included for charging a lithium battery. If this is correct then why can’t I just use any normal battery charger to charge a lithium ion battery given that it has an output that is rectified and clipped to not produce a large DC frequency or a voltage above about 15 volts? I would imagine that most none el-cheapo ones sold in the last 10 years would fit this criteria. 

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It never occurred to me why until it was pointed out on another forum that a Li-ion and a LiFePO4 battery actually need a higher voltage to charge them.

The cell voltage of a Li ion is 3.7v so the battery needs 14.8v ( 3.7V x 4cells) and a LiFePO4 needs a 12.8v ( 3.2v x 4 cells) to charge. Most charging systems will give 12.8v over some of the range but 14.8 is pushing it.

Now it is possible to charge a 14.8v set using a switchmode circuit with a voltage regulator in the front end of the battery to allow the bikes 12-13.x or 14.x V circuit but I don't know if it is done.

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Posted (edited)

YEah, good question - it seems like a contradiction that the bike's charge system will keep the battery charged, but a standard battery charger won't work. 

 

Some of the newer Li Iron phosphate batteries have circuitry inside that self-balances the cells. I would choose one of these. They also let you use a not so smart charger (one w/o desolate and float modes). Otherwise, you'll need a charger the manufacturer specifies as it will have a proper plug that will charge all the cells equally.  

 

This article will help explain better  http://www.fastbikegear.co.nz/index.php?main_page=page&id=18&chapter=1

 

 

Edited by rick

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Posted (edited)

Yes, keeping the cells balanced is essential.  As well as never overcharging or discharging. You can use a standard charger on Li ion if it's the correct voltage, but you need a way to keep an eye on individual cell voltages.  the cell voltages will fluctuate over time, and you need a way to keep them balanced.  That's where the BMS comes in, or the battery specific chargers.  But the FZ-07 charging system isn't balancing any cells... it's just sending a voltage to the battery, same as any constant current charger.

 

In the electric bike world, lithium ion cells are 4.2V fully charged, the nominal voltage is 3.7V.  Studies have shown that battery life can be greatly extended if you don't overcharge or discharge.  You may get 500 cycles out of a battery if it's fully charged, but you can get 2000 cycles out of the same battery if you only charge it to 80-90% of capacity - assuming the battery is never over discharged.  For best life, you want the cells to operate between 4.1-3.7V.

 

I have a couple a electric bikes that I run with lipo and no BMS.  Lots of info on this site: http://endless-sphere.com/

Edited by Spanglo

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I wish I never tossed my Shorai battery that was charged with a normal charger.  It basically Explodes, so that is why, new charging systems will or may support and detect lithium most wont,

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9 hours ago, twf said:

Standard chargers have desulfation mode which kills lithium batteries. 

 

Was going to say this. Some manufacturers state that regular chargers can be used on their LiFePo  batteries if the desulfation mode can be turned off, but have read it is still not recommended because it doesn't balance the cells. I plan on getting the lithium battery charger so will pick one up soon.

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What's really comical is the description and caveats here. https://www.batterystuff.com/batteries/lithium-iron-batteries/sstz14s-fp.html

 

They can only ship Li batteries at 30% charge and recommend an Optimate Li-specific charger ( I own 3 Optimates and am a fan, but none are meant for Li batteries) even though Scorpion claims no special charger  (as long as there's no desolate mode - something std. Optimates have) is necessary due to the self-balancing electronics in the battery  

 

 

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One of the reasons I chose the Shorai Li-Fe-Po battery was due to the fact it has a special port (shown with the white cover in the indent between the posts)  that allows a pigtail to be installed. The pigtail can just be left installed and ran up under the pillion seat for easy access. 

 

The brand specific charger , plugged in to the pigtail, can do the type of cell leveling maintenance/charging that a regular Neg/Pos post charger just isn't capable of due to the fact they can't control the individual cells like the Shorai charger. The charger also has a "storage" function button that allows for setting the cells to an 80% charge that is best for long term storage of the battery. Evan at 80% charge that is still plenty of power to start the bike so you can still just unplug it and go when the mood/weather strikes.

 

For the kind of $$ these batteries cost I felt it was worth it to get a charger that can properly balance the cells. I learned the importance of cell balancing for the longevity of Li-Po batteries when I got into R/C Helicopters.

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Posted (edited)

With a big investment in quality float chargers and the price difference of the Li batteries, I'll likely just stay with AGM batteries 

Edited by rick

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I'm running the Deltran lithium in my DRZ and am using the Deltran charger with both,  lead acid/AGM and Lithium modes...this battery is around 3 yrs. old and sits a lot but to this point has been good. Supposedly the Detran has cell balancing technology built into the battery but I originally had the same thought that pegasus46 had...it's being charged by the motorcycles system and that's not lithium specific so what gives. After some reading though I first bought the Lithium JR. smart tender and then later the combo charger. I'll be putting a lithium in the -07 when this factory battery dies...the wt. savings is incredible!

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Posted (edited)

Had the Showa Lithium. Went back to standard. 2 reasons why...

#1 Cold starting sucks in the AM before work (30-50f) with lithium compared to lead acid, think it has to do with "cold battery" amperage or something.

Went back to standard no more cold start issues.

#2 Once the Lithium gets below a certain voltage its toast, you can still try to recharge on your special charger, but it wont hold the charge making you charge it every day or so. 

I run a lot of different kind of lithiums lipos, life4's with my RC planes and cars learned alot that way too. Some are better for high amperage (lipos) while some are better for longer constant voltage (life4's)...

For instance I use Lipos for my planes recievers/servo/engine battery, while I use Life4's for my transmiiter...

Anyways just my 3 cents....

 

Oh one more thing if you are going to go Lithium get a good charger.

I used this its been used by hobbiest and has one of the best reputations on the planet.

It charges all lithium types, lead acid (PB), NiCads, and Nmhd.

Comes with all cables you can plug in to wall, or use on car battery.

And its cheap too!

No need to spend over $50

https://www.ebay.com/i/181649828522?chn=ps

Edited by Kyuzo

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Posted (edited)
3 hours ago, Kyuzo said:

#1 Cold starting sucks in the AM before work (30-50f) with lithium compared to lead acid, think it has to do with "cold battery" amperage or something.

Went back to standard no more cold start issues.

Shorai so badly miscalgulated CCA on those batteries, I did the same thign and was a shorai dealer at one point, sold a freaking lot of them.  However I do believe they updated the web site, not 100% sure.  But if they have yet to do so find what is recommended then add mor CCA that will be the battery.  They told me it has to warm up, I said BULLSHIT they dont like to be challanged.  Worked right down the street from them in Santa Clara, so easy to speak direct.  100% agree and sold as kits the Shorai charger.  Great battery loved it accept on cold mornings

Edited by r1limited

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Posted (edited)

Yeah, I installed my lithium in Hawaii no issues. Took my bike with back to CA for a year. Be turning over the bike like 5 times in the morning eventually draining the battery and toasting it. Picked up lead acid 1st runover it starts, stayed that way for another year until my bike got trashed by thieves and I ended up giving it away and made some kid really happy! 

 

Enjoying my Fz07 though...  Muahahahha

 

 

 

 

 

MUAHAHAHHAHAHAHAHAHAHAHHAHAHA

Edited by Kyuzo

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