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Author Topic: Lithium-ion battery  (Read 699 times)

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Offline Bundu

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Re: Lithium-ion battery
« Reply #20 on: July 30, 2019, 09:16:49 pm »
Traditional LiFe batteries cannot be reliably charged with a normal charger, hence the charging circuit built into the LiFe bike batteries (http://www.fastbikegear.co.nz/index.php?main_page=page&id=18&chapter=1). This will permit a bike to charge a LiFe battery with a circuit designed for a lead battery. And then obviously with a traditional charger you guys mention as well.

What charging circuit are you talking about? 
All I know off is the BMS (battery management system) that is included in some batteries and all that does is balance the voltage between cells inside the battery.

Do they now have something more advanced in the batteries?

Sorry, my bad, I misread that. I've got quite a bit of experience with RC batteries and the cell balancing is quite important. It'll be a bit strange for me if they don't have some type of circuit to regulate the charge rate in the charging cycle. And some kind of way to stop charging when the battery is full. These batteries don't take well to overcharging.
I'm not sure which batteries are used in these Li 12V setups, but I know that the 18650 batteries are very reliable, provided they are kept within their 3.0V and 4.2V range per cell
 

Offline 2StrokeDan

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Re: Lithium-ion battery
« Reply #21 on: July 30, 2019, 09:32:29 pm »
What happens if you depleted the battery to far while on a trip?

That is one of the disadvantages of Lithium.
But ask yourself when last have you depleted the battery on a vehicle.
It happens:
- On old vehicles such as leaving the lights on etc.
- When something is wrong with the vehicle and it struggles to start
- When the battery is at the end of it's life.

Thus don't install a lithium battery in old shit.

The lithium is less effort since you don't need to keep it on a trickle charger when not using the bike.
Happened to me twice that a lead acid battery failed during a trip.

So what do you do? You buy a new battery along the way or buy a small 12V alarm battery and run start the bike every time.

On new vehicles you can also leave lights on.
New vehicles have in fact more chance of electronic leakage than what you term "old shit".
L.ion batteries also reach the end of their lives.
 

Offline Sláinte Mhaith

Re: Lithium-ion battery
« Reply #22 on: July 31, 2019, 07:03:05 am »
Traditional LiFe batteries cannot be reliably charged with a normal charger, hence the charging circuit built into the LiFe bike batteries (http://www.fastbikegear.co.nz/index.php?main_page=page&id=18&chapter=1). This will permit a bike to charge a LiFe battery with a circuit designed for a lead battery. And then obviously with a traditional charger you guys mention as well.

What charging circuit are you talking about? 
All I know off is the BMS (battery management system) that is included in some batteries and all that does is balance the voltage between cells inside the battery.

Do they now have something more advanced in the batteries?

Sorry, my bad, I misread that. I've got quite a bit of experience with RC batteries and the cell balancing is quite important. It'll be a bit strange for me if they don't have some type of circuit to regulate the charge rate in the charging cycle. And some kind of way to stop charging when the battery is full. These batteries don't take well to overcharging.
I'm not sure which batteries are used in these Li 12V setups, but I know that the 18650 batteries are very reliable, provided they are kept within their 3.0V and 4.2V range per cell

The 18650 is a lithium ion battery is nominal 3.6 or 3.7V  (4 x 3.6V is too high for 12V application)
To make 12V batteries they use LiFePo4 which is nominal 3.2 or 3.3 V

I don't know about over charging circuits or if BMS also incorporate over charging circuits.  What I do know is that some of the vehicle application batteries don't even include BMS never mind anything fancy.

Yes these batteries gets killed with over charging. 
One of the reasons you should not use a modern battery charger on them as modern chargers can give high voltage pulses and other fancy stuff suitable to lead acid.
But does a vehicle voltage regulation not cover you in this regard?  It is regulated to stay below 14.4 or 14.7 or something?

Lithium can deal with a higher initial charge rate than lead acid can but then when soc goes up they need a constant voltage and the amps need to taper down.
Under correction but this is the way the older battery chargers worked.
 

Offline ultraflight

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Re: Lithium-ion battery
« Reply #23 on: August 05, 2019, 10:14:45 pm »
I changed to a Shorai brand LiFePo (Lithium Iron Phosphate) battery and never regretted it.
The reason why modern smart chargers cannot be used on these, is the desulphating feature “pulses” very high voltage which damages the LiFiPo type batteries. They can handle much higher charging current and are able to deliver much more CCA (Cold Cranking Amps) but should not be charged with more than 15 Volts. I have a calibrated digital voltmeter on my dash and the highest I have ever seen is 14.7V and that was with the revs into the red.