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Old 07-20-2012, 04:26 AM
evnz evnz is offline
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Default Lifepo4 what type of charger do i get

I am looking at getting lithium batteries and was told they use a diferant charger than lead acid can anyone please tell me what type to get please
Thanks owen
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Old 07-20-2012, 07:06 AM
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Default Re: Lifepo4 what type of charger do i get

A typical LiFePo4 charger is CC, CV. That means it charges at a constant current until it reaches a specific voltage, then holds that voltage until the current drops to a certain level, completing the charge.

The primary differences to lead charging is that lead will take less amps, and often terminates with a very high voltage gassing phase.
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Old 07-22-2012, 12:49 AM
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Default Re: Lifepo4 what type of charger do i get

So i looked for a charger and there is one at 48v 10amps and one at 48v 30amps what do you recomend
http://www.evworks.com.au/index.php?product=151

http://www.evworks.com.au/index.php?...t=CHG-KP4830KL

By the way i am 144v in 3packs
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Old 07-22-2012, 07:38 AM
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Default Re: Lifepo4 what type of charger do i get

I wouldn't recommend charging at less than pack voltage for lithium. Some have done it, but I would expect imbalancing to be caused by one charger being a bit more efficient than the others.

As for AMPs what size batteries are you using?
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Old 07-22-2012, 08:07 AM
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Default Re: Lifepo4 what type of charger do i get

Do you have a car yet? What motor and what controller are you using? I will assume that all three packs are connected as a single string of lithium batteries for a 144 volt system. Being that I'd go with a 144 volt charger that can pump out a reasonable amount of amps for charging. The Elcon is a good choice. Others use different ones but the Elcon is pretty specific for each pack size so if you do get one you will only be able to charge your 144 volt pack. If you later decide to upgrade then you will have to get a different charger. But 144 volts is good.

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Old 07-22-2012, 11:39 AM
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Default Re: Lifepo4 what type of charger do i get

Manzanita Micro PFC-20 charger is my choice. You can charge anything from a single 12 volt battery up to about a 400 volt Lithium pack. They are kinda pricey, but you don't need to buy another one if you change pack voltage.
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Old 07-22-2012, 03:20 PM
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Default Re: Lifepo4 what type of charger do i get

Quote:
Originally Posted by evnz View Post
I am looking at getting lithium batteries and was told they use a [different] charger than lead acid
Actually a CCCV charger is ideal for both lead acid and for Li-ion.

That's because the intelligence to charge your Li-ion battery resides within your BMS, not within your charger. The BMS will ensure that the charger stops before ANY individual cell is overcharged. Then, after the BMS has balanced the pack a bit, it will allow the charger to come back on, and charge the battery a bit further. At the last cycle, the battery will be top balanced, and the charger will then be able to go to the CV (Constant Voltage) mode, and finish charging the battery. For a detailed discussion of how that works, see this video.

Ironically, chargers with a "Li-ion profile" are not as good as a plain old CCCV charger. because A) they give you the wrong impression that they will protect your battery during charging (they don't), and B) they may stop before the battery is full, even if the BMS says it's OK to charge some more.

So:
1) Select a good BMS
2) Get a plain old CCCV charger
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Old 07-22-2012, 08:03 PM
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Default Re: Lifepo4 what type of charger do i get

Quote:
Originally Posted by Ziggythewiz View Post
I wouldn't recommend charging at less than pack voltage for lithium. Some have done it, but I would expect imbalancing to be caused by one charger being a bit more efficient than the others.

As for AMPs what size batteries are you using?
100amp hour and around here they say 60vdc is high voltage and we need to drop the volts to that or less in 2 min without tools my idea was to have the pack split with contactors into 48v packs and charge as 48volts but if i will have problems i can do as 144v pack i will just leave the contactors conected
Thanks
Owen
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