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LiFePO4 charging voltage

Ampster, my existing charger will do 42.5v absorb but after a time the charger goes into an automatic EQ cycle and goes to almost 50 volts. I am not sure I can adjust this charger for a fixed voltage without the EQ cycle. Question, can the Orion BMS let me know if a cell high voltage limit has been reached?
 
Its not a real good idea to let the protection device handle the charging voltage. The normal way is:
- control the charging voltage independendly by an charging controller
- protect the battery with the BMS
So you have a redundancy.
There are not so many things that could harm the battery to overheat and a fire. But overcharge is the best way to do it.
 
Its not a real good idea to let the protection device handle the charging voltage. The normal way is:
- control the charging voltage independendly by an charging controller
I agree, but in this case it is an AC powered charger and not a charge controller. Also in this case the charger cannot be set and goes into high viltage Equalization mode at the end if charging. The OP is considering a new charger that can be programmed for his golf cart.

It is normal in an EV for the AC powered cherger to be in communication with the BMS. There are several advantages to that arrangement in an EV or golf cart.
 
I've decided to only charge my LiFePO4 batteries to 3.4v per cell. (Following 80/20 rule)
Does that mean I set my CC/CV Power Supply to 13.60v for charging?

Also, for storage of a single, 4S LiFePO4 pack what is the ideal voltage?

Thanks
 
I've decided to only charge my LiFePO4 batteries to 3.4v per cell. (Following 80/20 rule)
Does that mean I set my CC/CV Power Supply to 13.60v for charging?

Also, for storage of a single, 4S LiFePO4 pack what is the ideal voltage?

Thanks
That's the voltage I have been testing with an 18 and 40 amp supply, and it works well.
Storage is 20 to 50% full, not necessarily a voltage.
 
The Orion has an add-on indicator that will show SOC but it seems that there are a few variables to set to make it accurate. Some of the settings I do not understand are "Derate CCL for temperature" and "State of charge drift points". I would assume that these adjustments are there for accuracy but if I use the 20-80 methodology, if I'm off by say 5%, is that going to be a problem. Are there some generic settings for these?
 
Are there some generic settings for these?
I leave them on defaults. The most important thing is to enter the capacity as you want to see it. Since I charge to about 90% I have entered a lower value for pack size by that 10 %. My pack resets almost every day so drift is not an issue. The important information from the PC program is the consumption in Ahrs measured by the accurate Ammeter and compare that to what it took to charge it back. As I may have mentioned earlier Amphour consumption is an important piece of data in a motive application like a golf cart or EV. One version of that SOC meter offers a slot so you can record data if that is an interest. It does not display Amphour consumption but the other guages can. There are several options for display.
 
I do not need the data logging feature but the "fuel gauge" type display would be useful. My use usually would be drive the cart around for a day then charge it. With the FLA batteries I have now I never go to the 50% SOC point anyway. Which gauge are you referring to that will display amp-hours?
 
I leave them on defaults. The most important thing is to enter the capacity as you want to see it. Since I charge to about 90% I have entered a lower value for pack size by that 10 %. My pack resets almost every day so drift is not an issue. The important information from the PC program is the consumption in Ahrs measured by the accurate Ammeter and compare that to what it took to charge it back. As I may have mentioned earlier Amphour consumption is an important piece of data in a motive application like a golf cart or EV. One version of that SOC meter offers a slot so you can record data if that is an interest. It does not display Amphour consumption but the other guages can. There are several options for display.

Yes, on DIY batteries.

I have a ready made 100Ah LiFePO4 arriving next week. I'll need that info when my Lischen cells arrive.
But on this Rebel battery, I'm not changing any settings on this one.
Just trying to make sure I know how to safely and properly charge it.
 
Which gauge are you referring to that will display amp-hours?
I don't know the particulars of every one. The most configurable is the most expensive. For your purposes the simple SOC one offered by Orion might be the most cost effective even thoughbit does not display the Amphours.
 
But on this Rebel battery, I'm not changing any settings on this one.
Just trying to make sure I know how to safely and properly charge it.
My comment to krell was specific to the Orion BMS defaults for drift. The charging settings for your batteries should be specific to them. Presumably Rebel publishes some info you can use for starters. My only suggestion is if it is truly LFP charge it to 3.4 volts per cell.
 
OK Ampster, I get it. Drift would be used when you don't fully charge the battery on a regular basis.
As I may have mentioned earlier Amphour consumption is an important piece of data in a motive application like a golf cart or EV
A SOC meter will do the same thing, right?
 
OK Ampster, I get it. Drift would be used when you don't fully charge the battery on a regular basis.

A SOC meter will do the same thing, right?
Yes the meter just does the math and displays it in percentage bars if I remember correctly. I haven't used mine recently because I have the Wifi display that works from my couch.
 
Great. I am slowly figuring out these batteries. One more thing, if I use the 20-80 parameters, would I do a top balance at 80% or the whole 100%?
 
One more thing, if I use the 20-80 parameters, would I do a top balance at 80% or the whole 100%?
What exactly are the 20-80 parameters? I hear a lot of folks saying they are going to stay with here yet charge to 14v every day (and that's in the 99% of SoC range).
Using only the middle 60% of your battery seems overly conservative. LiFePO4 batteries are hearty and cycle thousands of times so just staying above 11v and below 14v is very safe. I find that anything over 13.8v is overly taxing on the batteries for just a couple of percents of SoC. And at high SoC is where folks usually make the mistakes that kill batteries.

A good top balance as Ampster has shown will go a long way on keeping your cells behaving. Conservative charging is another import aspect of having a manageable battery (not requiring intervention of BMS or balancing).
 
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