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Old 02-21-2013, 05:09 AM   #292
Bli55
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Joined: Mar 2012
Location: Казань
Oddometer: 343
JoelWisman, oh how I missed your experiments!!
Just last night I studied the whole thread and remember wishing you would carry on with the envistigation, because there's so much more...

I mean, not only the aspects of your testing such as cold performance, chargers etc, but the LiFePO4 field itself is developing rapidly, with new names and products appearing.

I'd really appreciate if you could clarify a few points...

Quote:
Originally Posted by JoelWisman View Post
What I am seeing with the two Shorai LFX18s I have experimented with is that 14 volts and below will eventually fall out of balance, though how long it will take I don't know. 14.1 volts is marginal. 14.2 volts and above looks like it will be ok to me.
Imagine I have a bike with iron phosphate and a voltmeter.
Riding along, would probably see ~14.2-14.6 V
Imagine then some eqipment gets switched on - lights, heated gear etc...
Voltage might drop to ~13.0-13.5 on the voltmeter...
Does that mean - battery is discharging as the alternator is not able to support the consumers.
- battery is not discharging, as the alternator output is sufficient, but WILL get out of balance due to lack of current passing through it?

In other words, what minimum voltage would you suggest needs to be maintained (by regulating additional power consumption) in the system when riding as to ensure the cells are charged AND balanced?


Quote:
Originally Posted by JoelWisman View Post
Towpro, You hit the nail on the head. LiFePo4 needs to internally heat to provide full cranking amps, and not just when cold. Even warm LiFePo4, batteries that will start your bike fine have a large voltage drop for the first few seconds. Enough so, that even on a warm day, the the battery recommended for some bikes by some manufactures will be damaging bikes starting systems over time IMO.
Why would the starter get damaged operating at lower than optimal speed/voltage?
Or is this only applicable to certain types of starter engagement?

Quote:
Originally Posted by JoelWisman View Post
You don't need a special charger for LiFePO4 batteries, you just need to be sure not to charge them beyond 14.7 volts.

With a manual charger, sit with it and manually stop charging when you hit 14.7 volts.
I have a charger with one knob controlling the current (0 -10A), but obviously is i set it to, say, 1A, and connect to a poorly charged battery, it will only need a small overvoltage to maintain that amp.
As the battery gets charged, my charger ups the voltage to maintain this set current, until it reaches 15V.

Do you know if this is a what you call manual charger and if its suitable, or do I need to search for one with a set max. charging voltage of 14. what ????

Thanks for your time on this topic!!

Bli55 screwed with this post 02-21-2013 at 05:15 AM
Bli55 is offline   Reply With Quote