Lithium battery for my Nightster: Ion/Iron???

semmyroundel

semmyroundel

Club Member
Hi all, I recently purchased a JMT HJTX14AH-FP-SWIQ Lithium Ion battery (advised by supplier).
Straight out of the box, it turned over the bike, but a few days later, nothing.
So I bought a charger (Optimate Lithium LFP 4s 0.8A).
However, the battery states it's a Lithium Ion, 12v. and the charger says for LIFEPO4 12.8v and not for Lithium Ion.
The bike shop said it was one of the right chargers for the battery, but lithium ion cells are 3.7volts each and Lithium Iron Phosphate are 3.2volts.
Should I be concerned? The LIFEPO4 optimate charger will max out at 14.2-14.4v and 4 fully cahrged Li-Ion cells can take 16.8 v.
Anyone used this charger on a LI-Ion battery?
 
I have some experience with lithium batteries in RC cars so this may or may not be helpful.Lithium batteries are supplied with a storage charge and should always be charged fully before use.Another thing is,they really don't like being fully discharged.If the voltage drops below 3.7 volts per cell the charger may detect a faulty battery and not charge it.You do need a charger that is suited to the type of battery you are using as overcharging can result in fire.
 
Roach said:
I have some experience with lithium batteries in RC cars so this may or may not be helpful. Lithium batteries are supplied with a storage charge and should always be charged fully before use. Another thing is, they really don't like being fully discharged. If the voltage drops below 3.7 volts per cell the charger may detect a faulty battery and not charge it. You do need a charger that is suited to the type of battery you are using as overcharging can result in fire.
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Some lithium batteries have built-in overcharge/discharge protection.

i don't think Motobatt are the only manufacturer to do this, but see this page on their US website:

https://www.motobatt.us/information-lifepo4-lithium
 
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LiFePO4 is the technology used in bike batteries. They have a charge voltage of 3.6 volts per cell so in your battery there is 4 cells to give you 14.4 volts at full charge. About the same as a lead acid or AGM battery.

I would be very surprised if the company used the lithium cells that charge to 4.2 volts per cell.

Lithium ion is a generic name for all lithium batteries. You will also see lithium ion polymer mentioned.

I wouldn't be at all surprised to find it is a typo and they actually meant lithium iron and forgot the phosphate!

The lithium ion polymer cells that have a nominal voltage of 3.7 volts can be discharged to 3.2 to 3.3 volts safely.

The LiFePO4 cells can go lower on the discharge voltage but in both cases it is best to avoid taking more than 80% of there actual total capacity ever.
 
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Thanks guys, I too know about Lithium cells from RC planes and cars.
I personally aren't too bothered about the charger as the LIFEPO4 cells have a LOWER voltage than the LI-Ion (3.2v vs 3.7v per cell).
So in effect, it'll charge them at a lower terminal voltage which is a GOOD thing. I was more concerned with the way it charged, but I guess that's not much different.
As you'll know, fast charging, and charging to 100% any lithium battery will shorten the number of cycles that battery ultimately has. I do this on my mobile phone wherever possible, only charge to 90%.
In fact, one of my RC plane chargers does just that. When it gets to 90% a loud beep can be heard, indicating that's the optimal time to remove the charged battery.
I suppose I'm asking the wrong crowd
 
I too have spent many years flying RC helicopters. I have also used the A123 LiFe cells for receiver packs on nitro models.

The charging regime of constant current / constant voltage (CC/CV) is the same for all lithium batteries just a different cell voltage as you mention.

If it truly is a LiPo type cell with 3.7v nominal 4.2v fully charged you would be charging it less than 50% of full charge and that would almost certainly see its demise in fairly quick order.

As to the 90% thing in fact for LiPo with 4.2 volt full charge to get an increase in the number of cycles you can charge to 4.1v per cell. This is typical of cold weather charging.

Most cheap LiPo chargers do a bad job of balancing the cells or waiting until reaching the CV stage. Other charges bring the cells into balance at a much lower voltage making the process quicker in the final stages.

Not sure on the comment about us being the wrong crowd.

If you have a real concern it is the manufacturer you need to ask.
 
Hi. I've been using an JMT HJX 9-FP, a bit smaller than your 14 but same make and type for nearly 2 years now with no issues. I also use a Optimate 1 duo, the baby brother of your Optimate 4, again with no issues so i wouldn't be overly concerned.
These Lithium ion batteries tend to just stop cranking when the voltage drops below a certain level, unlike a lead acid battery that will start to struggle when the voltage starts to drop.

You didn't say whether you took the bike for a run after the initial start, it maybe just needs a good charge. It should have a test button with 3 LED's to give you a rough idea of how much charge is in it.

Can't ad much more that hasn't already been said. Mine is in a Microlight Aircraft not my bike but same thing.
Good luck with it.
 
Update: , As I understand it, the optimate 4 is supposed to keep the battery in good condition.
Here's what's weird, the following ALWAYS occurs:
I put ignition on and press start, it turns over once, maybe twice but that's it-it won't turn the engine over again.
I switch off the ignition, and then on again, this time it turns the engine over quick time, almost liket the internal resistance in the cells suddenly drops and it regains power.
Now that I don't understand.
 
Isn't there something about sometimes needing to "wake up" a lithium battery by, for example, leaving the lights on for a minute or two before hitting the starter?

EDIT: https://motorcyclepartswarehouse.co... sluggish in,battery before starting the bike.

Lithium batteries
Lithium batteries discharge quite slowly when not in use and may only require a charge every six months. They also charge quite quickly. Do not let a lithium battery discharge fully, as it will not be recoverable, though if it is a good quality one with a BMS (battery management system) this should not happen, and likewise it should not be possible to overcharge it. Lithium batteries get sluggish in the cold even when new – this is not a problem with the battery but a characteristic, and all you need to do is wake it up by leaving the ignition and lights on for a minute or two to ‘warm’ the battery before starting the bike.
 
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On my bike the ECM, BCM, Speedo, hand control modules and ABS ECU are always powered. This is a drain on any battery. It will be the same for any bike after 2014 with ABS brakes.

Any battery will discharge on my bike even a lithium. What that statement refers to is self discharge being lower than a lead acid AGM battery.

Lithium batteries perform best at warm temperatures but taking a cold battery and putting a load on it is actually bad for them. This "waking up" is using the chemical reaction of the lithium cells to cause them to self warm and is not overly good for them. The reality is and it is what the RC quad racing crowd do and that is to prewarm the battery disconnected from the model before use but that is pretty difficult with a bike in the middle of no where.
 
Thanks guys, that explains a lot.
Once this lithium is past its prime I think I'll go back to AGM, at least they're a bit more predictable.
 
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