charge controller settings for 10% to 90%

terry82517

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Apr 27, 2020
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I have a 12v 280 ah lifepo4 bank in my camper van that I'm looking at keeping in the range of 10% to 90% as I'm looking to get a long life from the cells.
I also won't be using them very often, maybe two weekends a month so don't want to keep them at 100% when they aren't being used.

Could someone please suggest the setting for the solar charge controller that I would need to achieve 10% to 90%?

Here are my current settings

Over Voltage Disconnect 14.7 V

Charging Limit Voltage 14.6 V

Over Voltage Reconnect 14.6 V

Equalize Charging Voltage shut off or 14.4 V

Boost Charging Voltage 14.6 V

Float Charging Voltage 13.6 V

Boost Reconnect 13.3 V

Low Voltage Reconnect 10

Under Voltage Warning Reconnect Voltage 11.5

Under Voltage Warning 11.5

Low Voltage Disconnect 11.0

Discharging Limit Voltage 10.5

Equalize Duration 0 or set as low as possible

Boost Duration 180 minutes

Any suggestions would be greatly appreciated.
 

Bubba1

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Feb 6, 2021
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I think that's what the BMS does at least for the low end. Now let's see what someone that knows what they are talking about fill us both in.
 

MisterSandals

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Based on these popular charts:

90% charge is about 13.5v. So knock down your 14.x charging to here.
I would set your float to .05v below where your battery settles in an hour (this prevents micro-cycling).

I would put low voltage warning around 12.8v (20%) and disconnect at 12.6 (10%).

See how this works with YOUR batteries and anxiety levels (this is conservative so should be stress free). If you need more out of your batteries while traveling, charge higher, like to 13.8v (my 95% for MY battery).

FWIW, when my RV sits in my driveway, I turn off charging (solar cutoff breaker) and let batteries sit around 13.2v. A couple days before a trip I will turn on charging to 13.8v so fully charged.
 

PaulAtreides

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90% charge is about 13.5v. So knock down your 14.x charging to here.
I would set your float to .05v below where your battery settles in an hour (this prevents micro-cycling).
Unless you have a battery like mine which sits at 13.3V at 100% . Cell voltages in BMS confirmed by DMM. 280Ah confirmed by capacity test. So 🤷‍♂️ lol
 

MisterSandals

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2 pole breaker? Or, single on the PV+?
Single. I just want to stop charging. Is there a compelling reason for double?
Unless you have a battery like mine which sits at 13.3V at 100% . Cell voltages in BMS confirmed by DMM. 280Ah confirmed by capacity test. So 🤷‍♂️ lol
I am with you 100% on this! My cells settle to 3.35v in just a couple minutes. I call this 100% everywhere I can!
(3.35 x 4 = 13.4v). I was "quoting" the values I saw on the chart. My values are lower and more conservative than most and those charts seems to have general acceptance.
 

PaulAtreides

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Single. I just want to stop charging. Is there a compelling reason for double?
Yes and no. Just curious what you do. Nate from Explorist.life suggests a 2 pole for each PV wire. Something about NEC. I have a single on mine too.

I am with you 100% on this! My cells settle to 3.35v in just a couple minutes. I call this 100% everywhere I can!
(3.35 x 4 = 13.4v). I was "quoting" the values I saw on the chart. My values are lower and more conservative than most and those charts seems to have general acceptance.
Yeah, totally understood. The chart is a good guideline. But I guess we all need to tailor everything to our individual cells.
 

terry82517

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Apr 27, 2020
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Based on these popular charts:

90% charge is about 13.5v. So knock down your 14.x charging to here.
I would set your float to .05v below where your battery settles in an hour (this prevents micro-cycling).

I would put low voltage warning around 12.8v (20%) and disconnect at 12.6 (10%).

See how this works with YOUR batteries and anxiety levels (this is conservative so should be stress free). If you need more out of your batteries while traveling, charge higher, like to 13.8v (my 95% for MY battery).

FWIW, when my RV sits in my driveway, I turn off charging (solar cutoff breaker) and let batteries sit around 13.2v. A couple days before a trip I will turn on charging to 13.8v so fully charged.
Thankyou very much. Very helpful.
Do the other settings matter? Ie boost charging/ boost reconnect? Do you know of a place where these terms are explained by any chance?
 

jnrhome

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Feb 2, 2021
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you can create multiple profiles in Epever via the software, and save them to your computer. More of a manual process, but totally works the same way.
 

terry82517

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Apr 27, 2020
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you can create multiple profiles in Epever via the software, and save them to your computer. More of a manual process, but totally works the same way.
Oh, can you save them to the charge controller do you know? As plugging the controller into my computer every time I want to change profile would be a pain.
 

RandyP

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Sep 21, 2019
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642
Based on these popular charts:

90% charge is about 13.5v. So knock down your 14.x charging to here.
I would set your float to .05v below where your battery settles in an hour (this prevents micro-cycling).

I would put low voltage warning around 12.8v (20%) and disconnect at 12.6 (10%).

See how this works with YOUR batteries and anxiety levels (this is conservative so should be stress free). If you need more out of your batteries while traveling, charge higher, like to 13.8v (my 95% for MY battery).

FWIW, when my RV sits in my driveway, I turn off charging (solar cutoff breaker) and let batteries sit around 13.2v. A couple days before a trip I will turn on charging to 13.8v so fully charged.
I was wanting to know more about micro-cycling. Could you talk more about that and perhaps even provide an example ?
 

MisterSandals

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I was wanting to know more about micro-cycling. Could you talk more about that and perhaps even provide an example ?
My cells settle to 3.35v in just a few minutes. If I set my charger to float at 3.4v, my SCC charges every hour or two to maintain 3.4v.

Its pretty easy to see where your battery settles after reaching "your charge setting". Remove all loads of course and it will settle to some level below where you charged it. For me, its repeatable for over 40 cells varying from 22ah to 206ah. Its uncanny.
For some folks theirs settle to 3.5v.

Find where YOUR batteries settle. If you set the float above this value, it will micro-cycle at the rate determined by how fast it settles and how fast it charges.

There's no magic to it. Its all a matter of the voltage you set your charger to float and what it takes for it to accomplish that task. I don't know exactly how bad this is but its definitely unnecessary thrashing with nothing to gain.
 

RandyP

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My cells settle to 3.35v in just a few minutes. If I set my charger to float at 3.4v, my SCC charges every hour or two to maintain 3.4v.

Its pretty easy to see where your battery settles after reaching "your charge setting". Remove all loads of course and it will settle to some level below where you charged it. For me, its repeatable for over 40 cells varying from 22ah to 206ah. Its uncanny.
For some folks theirs settle to 3.5v.

Find where YOUR batteries settle. If you set the float above this value, it will micro-cycle at the rate determined by how fast it settles and how fast it charges.

There's no magic to it. Its all a matter of the voltage you set your charger to float and what it takes for it to accomplish that task. I don't know exactly how bad this is but its definitely unnecessary thrashing with nothing to gain.
Thanks for the info. Did a search here for micro-cycle. Read all I found, including your replies to posts and others comments. Learned some. I would not set my system up to micro-cycle, but would set it up to max battery SOC at end of solar day. Operating in a narrow band between boost, float and re-boost settings. Definitely not 90% to 10% SOC. More like 85% to 75% SOC.
 

RandyP

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Sep 21, 2019
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642
It will be a compromise. Need to stay within battery manufacturers charging specs. Need to use features of Victron Smart MPP charger and Magnum MSH1230M inverter. So my plan is to use these settings:
RandyP said:
-I'll be using a Victron smart SCC, will use the settings V absorb 14.2, V float 13.8, and a return from float to Boost as close to 13.8 as possible.
This keeps me in the manufactures (BB) suggested charging range. 14.2 v being the lowest Bulk/Boost charge BB specifies and 13.8 v being the highest float charge BB specifies. Thereby operating the battery in the 13.8 to 14.2 bandwidth when the sun is plentiful. Meets my desire to operate the BB batteries in a narrow bandwidth to optimize SOC at the end of the solar day, and keeping the Boost voltage as low as possible to extend the life of the batteries
RandyP said:
-I'll set the Magnum Hybrid MHS inverter/charger to absorb 14.2 v, float 13.2v so the SCC will perform the battery top off maintain function as long as the solar is good.
These settings are also within the BB recommendations for charging the batteries I have. Buy allowing a low float from the inverter/charger, the top end of the battery charge will be completed by the SCC in the sunlight. Inv/Charge will only be done when shore power is available or when the sun does not keep up with my battery use and a generator is required.
RandyP said:
-Considering an occasional (maybe once weekly when boon docking) SCC or Magnum 14.4v equalize charge to 14.6v maintained for 15-20 minutes to force a BB cell top balance with the BB BMS.
BB CEO Dennis is quite adamant about charging the BB bats to 14.2-14.6 v and holding them there for 15-20 minutes per battery string to top balance the batteries with the BMS BB has provided in the 100AH 12V battery. I believe this is a passive top balance. Then allow the batteries to float at 13.2 with the Magnum in the dark or 13.8 with the SCC if the sun is out.

I should stop now, as this is not within the scope of this post. I apologize now.
 
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