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Old 01-07-2022, 07:08 PM   #71
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One other thing on those power max converters. I get about 30 amp charge rate at 14.3 volts out of a 55 amp converter. Now that is plenty for me. But if I were to buy a new one I would get a more powerful one if I had a larger battery bank. Now no converter I know of actually charges at its limit rating.
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Old 01-08-2022, 12:05 AM   #72
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My Progressive Dynamics PD9260 is pretty close, I have measured it at 58-59 amps while charging.
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Old 01-08-2022, 01:35 AM   #73
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My PD 9000 series 60amp unit also hangs in at around 59 amps.
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Old 01-08-2022, 09:57 AM   #74
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Wow, quite a verbose thread. I especially love the part about our drop in batteries BMS only allowing between 10~90% charge/discharge. When we have seen documented testing getting the rated capacity from quite a few different brands of LiFePo4 batteries on Will's site. And after tear down he did not find any "extra" cells in them.



I started using Victron Controller "Presets" to change my solar charging between storage & traveling. Still fine tuning the voltages to find the sweet spot, which for me is 70-80% SOC while in storage. -Bill
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Old 01-08-2022, 10:23 AM   #75
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That's a very informative article, Don. Thanks...

But the last statement is still the question, for me.

"Do not charge to 100% SOC if you do not need it"

I don't think anyone in all these posts, actually answered the question 'how?" to limit charging to say, 80%, without just monitoring the SOC reading and using it as a 'guess'. With the tight voltages on charge profile, and variation in load and charging voltage during charging, I don't think we can do anything but guess.

And we still need to go to 100% once in a while, just to top balance cells and recalibrate the SOC indicator.

I appreciate everyone's participation. I think there were lots of valid points made, and knowledge shared. Thank you!!!
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Old 01-08-2022, 01:01 PM   #76
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I don't think anyone in all these posts, actually answered the question 'how?" to limit charging to say, 80%, without just monitoring the SOC reading and using it as a 'guess'. With the tight voltages on charge profile, and variation in load and charging voltage during charging, I don't think we can do anything but guess.
It was covered and you just reiterated the solution. Though SOC is anything but a guess if one synchronizes the SOC monitor occasionally. We are talking LiFePO4 here, not lead-acid (where SOC really is a rough guess).

I have to wonder how much advantage limiting Ah use provides. Like the 70F "recommendation." Is it worth doing? Where are the statistics? I think this is a Youtube pundit stirring the pot for his own benefit.

When I think about it, I'm amused that this even comes up. We switch to LiFePO4 at significant up front cost for the benefit it provides and then discuss forgoing significant amounts of that benefit to get, maybe, an extra year of life 10 or 15 years from now. To say nothing of more up front cost for the added capacity to accommodate a reduced Ah usage. Silly.
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Old 01-08-2022, 01:03 PM   #77
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In my case I use the charge wizard pendent on my Progressive Dynamics PD9260 to set the converter for "storage mode" which outputs 13.2VDC (actual measured output 13.26VDC) when I am not traveling in my coach. This works for me as I store my coach ready to use plugged into shore power in its shed with refrigerator running, etc. so there is always some parasitic draw on the DC system (refrigerator / air conditioner control boards, DC lighting that may be used, etc.), so even if I return from a trip with the batteries fully charged the circa 1-2 amp parasitic draw will pull them down to 50% ballpark range within a few days, and the converter in storage mode will hold it at 13.26VDC.


I personally don't care if 13.26VDC works out to 50% SOC or 75%SOC, the important thing is that it is greatly extending the battery life while the coach is in storage, Pre-covid we were using the coach about 75 days per year, so over 3/4 of the time it sits in storage.




p.s. the PD9260 automatically drops in the 13.2VDC storage mode after 3 days of battery inactivity


If I want it fully charged for a planned trip, all I need to do is press the charge wizard pendent button the day before the trip to take it out of storage mode, and put it back into either 14.4VDC bulk mode, or 13.4VDC float mode.
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Old 01-08-2022, 04:58 PM   #78
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I don't think anyone in all these posts, actually answered the question 'how?" to limit charging to say, 80%,

You battery manufacturer can tell you the voltage to charge your battery up to for 80% SOC According to my battery manufacturer 13.2v is 70% 13.3 is 90%. Mine are currently set to 13.25 as full charge while charging in the storage lot. 14.4 would bring it to 100% (13.6v) -Bill
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Old 01-09-2022, 01:42 AM   #79
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You battery manufacturer can tell you the voltage to charge your battery up to for 80% SOC According to my battery manufacturer 13.2v is 70% 13.3 is 90%. Mine are currently set to 13.25 as full charge while charging in the storage lot. 14.4 would bring it to 100% (13.6v) -Bill
Good suggestion. Great for storage. Though with typical LiFePO4 monthly self-discharge at less than 0.5%, IMHO floating in storage is only warranted if parasitic load is left on the battery. My Lifeblue is rated to have 0.2% per month self-discharge including the bluetooth load.

For the OP's case of regular cycling when camping, using voltage to get to only 75% is impracticable. The problem is that bringing the SOC up 20 or 30% would take days with the voltage set at the idle voltage corresponding to 75% SOC.
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Old 01-09-2022, 08:12 AM   #80
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It was covered and you just reiterated the solution. Though SOC is anything but a guess if one synchronizes the SOC monitor occasionally. We are talking LiFePO4 here, not lead-acid (where SOC really is a rough guess).

I have to wonder how much advantage limiting Ah use provides. Like the 70F "recommendation." Is it worth doing? Where are the statistics? I think this is a Youtube pundit stirring the pot for his own benefit.

When I think about it, I'm amused that this even comes up. We switch to LiFePO4 at significant up front cost for the benefit it provides and then discuss forgoing significant amounts of that benefit to get, maybe, an extra year of life 10 or 15 years from now. To say nothing of more up front cost for the added capacity to accommodate a reduced Ah usage. Silly.
1. I'm not going to sit here monitoring my SOC, to turn off my charge controller daily when it gets to my target SOC.

2. I'm NOT a youtube pundit stirring the pot. For my own benefit? Silly.
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Old 01-09-2022, 08:29 AM   #81
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I feel there is no reason you should, though I feel lowering the float voltage while in storage does make sense, particularly if you have a parasitic load to drain the batteries down.
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Old 01-09-2022, 11:04 AM   #82
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That's a very informative article, Don. Thanks...

But the last statement is still the question, for me.

"Do not charge to 100% SOC if you do not need it"

I don't think anyone in all these posts, actually answered the question 'how?" to limit charging to say, 80%, without just monitoring the SOC reading and using it as a 'guess'. With the tight voltages on charge profile, and variation in load and charging voltage during charging, I don't think we can do anything but guess.

And we still need to go to 100% once in a while, just to top balance cells and recalibrate the SOC indicator.

I appreciate everyone's participation. I think there were lots of valid points made, and knowledge shared. Thank you!!!
It was answered... 'if' you have a programmable charger for voltage. If you have a one size fit all programmed charger then no without nursemaiding the batteries.

So many "Johnny come lately" over thinking lfp batteries, charging, SOC just for longevity instead of use.

Probably easier for many weekend worriors just the get cheap dead lead batteries every 2-4 years. Rinse and repeat.
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Old 01-09-2022, 07:41 PM   #83
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1. I'm not going to sit here monitoring my SOC, to turn off my charge controller daily when it gets to my target SOC.
Exactly. That was my point. Maybe it didn't come through. This was covered earlier. I was mostly just reiterating.

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2. I'm NOT a youtube pundit stirring the pot. For my own benefit? Silly.
I'm not sure where this comes from. I thought it was clear I was talking about Will Prowse. I.e., the OP's source for the 25-75% recommendation.

I apologize for the confusion.
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Old 01-10-2022, 10:47 AM   #84
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Quote:
Originally Posted by Itinerant1 View Post
It was answered... 'if' you have a programmable charger for voltage. If you have a one size fit all programmed charger then no without nursemaiding the batteries.

So many "Johnny come lately" over thinking lfp batteries, charging, SOC just for longevity instead of use.

Probably easier for many weekend worriors just the get cheap dead lead batteries every 2-4 years. Rinse and repeat.
The ironic part of that is that most RVers are incapable of managing their legacy lead acid batteries properly resulting in premature death. I ran 2x6vs in my last trailer for 11 years by taking care of them.

I'd say most of the LiFePO4 FUD out there is a carry-over from other Lion battery types (in phones and EVs) (don't use all the capacity!) combined with "better safe than sorry" advice from companies that sell shiny new LiFePO4 chargers/converters etc.
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