Best mppt charge controller for LiFePO4?

[fafrd]

SmartSolar vs BlueSolar -

In a nutshell......

Is the only bluetooth difference Internal vs External (dongle) Bluetooth ?

As far as I can tell from the specs, yes. Perhaps one of the Victron Pros could confirm...

 

[fafrd]

That is definitely a difference. Here's Victron's detailed comparison sheet for all models:

https://www.victronenergy.com/upload/documents/Datasheet-BlueSolar-and-SmartSolar-charge-controller-overview-EN-.pdf

At the 150V/60A class which I’ve been interested in, the only differences other than integrated Bluetooth versus optional Bluetooth dongle are that Smartsolar supports Remote On-Off and integrate a programmable relay while BlueSolar does not...

 

[fafrd]

I agree with the concept, but there is a voltage difference. "floating" at absorption and floating at float have different long-term implications, i.e., reduced battery life.

Understand. So if your preferred algorithm to extend LiFePO4 battery life is to charge up to a specific Charge/Boost Voltage in CC mode and the drift down to Float with little or no time spent in CV mode @ Charge/Boost voltage, it’s better to have that control (over any CV period). Thanks

Because after about 30-60 minutes, your LFP battery will be full at the absorption voltage.

So a cut-off current sounds like it would be the best criterion to switch from CV to Float. Or skip CV entirely and accept a bit less Rated SOC at ‘full’.

The EVE Standard Charge specs are for a relatively meaty CC charge-current of 0.5C (140A for 280Ah battery) and a charge cut off of 0.05C (14A for a 280Ah battery).

Why is it that few/none of these SCC manufacturers supporting LiFePO4 charging have implemented CV->Float transition criteria based on cut-off current?

If that allows you the ability to override the default T1 value permitting a maximum DV duration of 15-120 minutes, you're good.

The T0 / T1 language was regarding Sigineer (where I don’t believe there is any override control, but I am confirming).

I’ve had no indication from WZRELB that they are implementing a similar algorithm. They clearly have a parameter to control CV time (so I believe transition is based purely on this parameter and not associated with any calculation related to CC time like Sigineer), and I don’t yet know what minimum and maximum range they may impose on that setting.

What both WZRELB and Sigineer have in common is language regarding ‘Float’ state only being supported for Lead Acid batteries and ‘Stop Charging’ state being supported instead for Lithium and LiFePO4 batteries.

I’m still trying to clarify with both vendors whether they can supply load current as needed in this ‘Stop Charging’ state as long as sufficient solar power is available...

But at the moment, based on your input that only SCCs supporting first user-settable CV time as well as second a CV-like Float mode that can maintain battery at Float Voltage while supporting load current as needed, the lay of the Tier-2 land looks like this:

Epever: YES, YES
Sigineer/iPanda/PowerMr: NO, MAYBE
WZRELB/Reliable: YES, MAYBE

 

[snoobler]

Ideal (for fully charged typical LFP specs):

CC to 3.65V
CV @3.65 to 0.05C tail current cut-off (14A for a 280Ah cell)
Float at 3.4

With Victron, I get to specify both absorption time and tail current. The first one hit triggers float. This is typical of Tier-1 products.

If both aren't available, control of either means of charge termination means is acceptable. CV time is the most common, and it's fine.

 

[OnTheRoadAgain]

I'm not positive the Epever is really ready for LiFePO4 yet.

When you read their literature it seems to skirt around the direct mention of LiFePO4 batteries?




Specifications

Nominal System：12/24/36/48VDC or Auto
Battery Input:8V～68V
Battery Type:Sealed(Default)/Gel/Flooded/User
Battery fuse:80A/58V
Rated charge current and discharge current:60A
Rated charge Power:750W/12V 1500W/24V 2250W/36V 3000W/48V
Max. PV open:150V
Temperature compens:－3mV/℃/2V(Default)
Grounding:Common NEGATIVE grounding
Enclosure:IP20
Pollution degreeD2
Dimension:340×236×119mm
Weight:4.5kg

 

[OnTheRoadAgain]

Ideal (for fully charged typical LFP specs):

CC to 3.65V
CV @3.65 to 0.05C tail current cut-off (14A for a 280Ah cell)
Float at 3.4

With Victron, I get to specify both absorption time and tail current. The first one hit triggers float. This is typical of Tier-1 products.

If both aren't available, control of either means of charge termination means is acceptable. CV time is the most common, and it's fine.

In one of his YT videos, I believe Will (forum admin) said Victron controllers ran very hot.

 

[snoobler]

I'm not positive the Epever is really ready for LiFePO4 yet.

When you read their literature it seems to skirt around the direct mention of LiFePO4 batteries?




Specifications

Nominal System：12/24/36/48VDC or Auto
Battery Input:8V～68V
Battery Type:Sealed(Default)/Gel/Flooded/User
Battery fuse:80A/58V
Rated charge current and discharge current:60A
Rated charge Power:750W/12V 1500W/24V 2250W/36V 3000W/48V
Max. PV open:150V
Temperature compens:－3mV/℃/2V(Default)
Grounding:Common NEGATIVE grounding
Enclosure:IP20
Pollution degreeD2
Dimension:340×236×119mm
Weight:4.5kg

"USER" means you can completely customize for whatever parameter you need. As I've mentioned a few times in this thread, I will ALWAYS choose USER over any default LFP setting due to flaws in those programs.

In one of his YT videos, I believe Will (forum admin) said Victron controllers ran very hot.

My Victron 250/100 pushing 3000W of Solar is uncomfortably warm to the touch. All charge controllers generate heat because they are not 100% efficient.

 

[fafrd]

Ideal (for fully charged typical LFP specs):

CC to 3.65V
CV @3.65 to 0.05C tail current cut-off (14A for a 280Ah cell)
Float at 3.4

With Victron, I get to specify both absorption time and tail current. The first one hit triggers float. This is typical of Tier-1 products.

If both aren't available, control of either means of charge termination means is acceptable. CV time is the most common, and it's fine.

Thanks. Now that I know exactly what a Tier-1 SCC should provide, I found the manual for the Outback Flex and confirmed it supports both user-settable time as well as user-settable charge current thresholds (whichever is first).

In addition, the Outback manual stated this (which I found to be a succinct description of the desired functionality in Float and may use to confirm Float functionality with the Tier-2 vendors I’m in contact with):

‘Floating: The FLEXmax is in the Float stage of a three-stage cycle, regulating the battery voltage at the Float voltage set point. This stage is temperature compensated. (See page 99.) If the battery voltage drops below the Float voltage, the FLEXmax will employ the MPPT function to draw more power from the PV array. (This may occur if the batteries are powering loads.) If this happens, the operating mode will change to MPPT Float. (See below.)’

 

[snoobler]

FM60/80 are good controllers. I helped my neighbor configure his 2X FM80 and concur they perform as desired.

One of his has been buggy. It gets stuck in the "charged" mode between absorption termination and float. It falls below float and even below re-bulk where it should trigger a whole new charge cycle. It's done this a few times. Once he wired the second one into the system, it hasn't happened with either.

One other forum user had this problem, and you can find a handful of accounts of similar behavior.

@uptopsolar - any input on that?

 

[fafrd]

I'm not positive the Epever is really ready for LiFePO4 yet.

When you read their literature it seems to skirt around the direct mention of LiFePO4 batteries?




Specifications

Nominal System：12/24/36/48VDC or Auto
Battery Input:8V～68V
Battery Type:Sealed(Default)/Gel/Flooded/User
Battery fuse:80A/58V
Rated charge current and discharge current:60A
Rated charge Power:750W/12V 1500W/24V 2250W/36V 3000W/48V
Max. PV open:150V
Temperature compens:－3mV/℃/2V(Default)
Grounding:Common NEGATIVE grounding
Enclosure:IP20
Pollution degreeD2
Dimension:340×236×119mm
Weight:4.5kg

Here is a direct quote from an email I received from Epever Support:

‘That presentation was made in 2018, it supports lithium battery now.

To be sure you get the new version, you can check with the vendor and ask them whether the label on the package box has
i. 12/24/36/48
or
ii 12/24/36/48/Li

The 'Li' means it supports lithium battery.’

So if you want to purchase a new Epever SCC with support for Lithium battery, you need to make certain your box label ends in ‘/Li’

It’s very confusing that they did not introduce a new product code or model.

I suspect it was a running change and all older Epever AN-Series do not fully support Lithium batteries (boxes without ‘/Li’ label) and all newer Epever-Series do support Lithium batteries (and have boxes with the ‘/Li’ label...).

This is a reason to only purchase Epever SCCs from a vendor with no-cost return rights if you have a lithium battery...

 

[OnTheRoadAgain]

Here is a direct quote from an email I received from Epever Support:

‘That presentation was made in 2018, it supports lithium battery now.

To be sure you get the new version, you can check with the vendor and ask them whether the label on the package box has
i. 12/24/36/48
or
ii 12/24/36/48/Li

The 'Li' means it supports lithium battery.’

So if you want to purchase a new Epever SCC with support for Lithium battery, you need to make certain your box label ends in ‘/Li’

It’s very confusing that they did not introduce a new product code or model.

I suspect it was a running change and all older Epever AN-Series do not fully support Lithium batteries (boxes without ‘/Li’ label) and all newer Epever-Series do support Lithium batteries (and have boxes with the ‘/Li’ label...).

This is a reason to only purchase Epever SCCs from a vendor with no-cost return rights if you have a lithium battery...

This is the current "Contact" information for Epever at the Epever.com website........

Beijing Headquarter
BEIJING EPSOLAR TECHNOLOGY CO., LTD.
Add:BLDG#18,CO.PARK,NO.8HEYING ROAD,CHANGPINGDISTRICT,BEIJING,CHINA.102200.
Tel:+86-10-82894112
Fax:+86-10-82894882
Sales enquiry:info@epsolarpv.com
Technical support:support@epsolarpv.com

Good Luck. This was after Googling 'Epever USA"

I was just shopping for a CC when I read some horror stories at this forum about EPEVER (lack of) support.
Some said support involves sending the units back to China ($200) at your expense for service?

May have to settle for a less capable (Amps/Volts) controller from Victron.

But in all fairness, I also went to the Victron website and it's based in the Netherlands.
No clear cut USA based office to call and get support within the continental USA.
Support seems equally difficult to obtain.

You buy it, you try it, you fry it, you cry it

 

[fafrd]

This is the current "Contact" information for Epever at the Epever.com website........

Beijing Headquarter
BEIJING EPSOLAR TECHNOLOGY CO., LTD.
Add:BLDG#18,CO.PARK,NO.8HEYING ROAD,CHANGPINGDISTRICT,BEIJING,CHINA.102200.
Tel:+86-10-82894112
Fax:+86-10-82894882
Sales enquiry:info@epsolarpv.com
Technical support:support@epsolarpv.com

Good Luck. This was after Googling 'Epever USA"

I was just shopping for a CC when I read some horror stories at this forum about EPEVER (lack of) support.
Some said support involves sending the units back to China ($200) at your expense for service?

May have to settle for a less capable (Amps/Volts) controller from Victron.

But in all fairness, I also went to the Victron website and it's based in the Netherlands.
No clear cut USA based office to call and get support within the continental USA.
Support seems equally difficult to obtain.

You buy it, you try it, you fry it, you cry it

I’ve found Epever to be far more responsive in my requests to them than Victron thus far.

If local technical and customer support is a top priority for you, you should only purchase from a US-based company (or a foreign company with a well-established US support organization)...

 

[DerpsyDoodler]

I’ve found Epever to be far more responsive in my requests to them than Victron thus far.

If local technical and customer support is a top priority for you, you should only purchase from a US-based company (or a foreign company with a well-established US support organization)...

you do have to be careful and take your time getting familiar with it, but settings are straight-forward, and the manual covered what I needed to know. I used the lfp conservative numbers documented in the forum resources download. I’ve seen as high as 34.86a. And it’s a completely overcast day.

 

[fafrd]

you do have to be careful and take your time getting familiar with it, but settings are straight-forward, and the manual covered what I needed to know. I used the lfp conservative numbers documented in the forum resources download. I’ve seen as high as 34.86a. And it’s a completely overcast day.

View attachment 41896

Nice!

Which model do you have (and what voltage LFP battery are you charging)?

 

[DerpsyDoodler]

Nice!

Which model do you have (and what voltage LFP battery are you charging)?

Tracer 4215bn negative grounded. Currently charging a 12v battery pack, but final install will be a 24v system. This is capable of both.

 

[uptopsolar]

FM60/80 are good controllers. I helped my neighbor configure his 2X FM80 and concur they perform as desired.

One of his has been buggy. It gets stuck in the "charged" mode between absorption termination and float. It falls below float and even below re-bulk where it should trigger a whole new charge cycle. It's done this a few times. Once he wired the second one into the system, it hasn't happened with either.

One other forum user had this problem, and you can find a handful of accounts of similar behavior.

@uptopsolar - any input on that?

I don't know about getting stuck in charged state. If I saw it in that state when I didn't expect to, I would go to the MATE, OpticsRE or the Misc screen to see if I can find clues on what it thinks it should be doing and current target values.

"Charged" state aside. In general, if it's falling below the float or re-bulk, I would consider your load demand and solar harvest at the time you are seeing this drop. See if any of the settings might be influencing a lower production rate, like current limit. Or your inverter settings that might conflict with the CC. This forum string, might be helpful.

My 2 FM80 CCs Keep Cycling to Snooze Mode with Bright Sun - OutBack Power Technologies User Forum

forum.outbackpower.com

The OB manual has some troubleshooting if you're not getting enough solar harvest as you expected "FLEXmax not producing expected power".

 

[snoobler]

Standalone FM80. No Mate. Off-grid, no AC-input unless deliberately running the manual-start generator, and the issue has never occurred concurrent with the generator running.

This is a 6kWh/day installation w/1980W array on one FM80. Exceptional sun year round (high desert in AZ). Loads are very minor in most cases. Largest load is an inverter microwave that runs less than 10 minutes per day.

This is a seemingly random occurrence.

Outback Power Flexmax 60 80 stuck in "Charged"

This is intended for Outback Flexmax 60 or 80 owners. My neighbor went with dual FM80 units for his 4kW array (2X 2kW) and 24V 24kWh battery. One has been working for maybe 3-4 months. The second was just installed this last weekend to work with his 25 year-old 1500W array because - that's what...

diysolarforum.com

FM80 dropout at end of absorb - OutBack Power Technologies User Forum

forum.outbackpower.com

FM80 goes to Charged and stops charging the batteries - OutBack Power Technologies User Forum

forum.outbackpower.com

Flex80 stuck at "Charged" status - OutBack Power Technologies User Forum

forum.outbackpower.com

Since installing the second FM80 running the old Siemens 1500W array (500W actual yield), it hasn't occurred, or at least it hasn't occurred to the point of notice. What triggers it is he notices his trimetric is indicating "discharging" when there are negligible loads, and plenty of sunshine. It may be that the output of the old array is maintaining his system to the point that the trimetric doesn't indicate "discharging".

Don't mean to hijack the thread. @uptopsolar, if you want to continue the discussion, use the above thread.

 

[fafrd]

Update on Sigineer.

First, confirmed that their Constant Voltage charging phase is calculated by an adaptive algorithm and cannot be overridden / controlled by the user through settings:

Q: Is the time period for CV charging phase (T1) with the R48L60 determined in the same way (T1 = 10xT0; min=1hr; max=12hr)?

A: (Sigineer): Yes.

Q: There is no parameter to allow CV time period to be set/controlled by user?

A: (Sigineer): No. The user can't adjust the CV time period.


And second, I clarified that the Sigineer SCCs can not supply any current to supply loads in Float phase:

Q: You have stated that the R48L60 will ‘provide a small trickle current’ when if Float mode with a Lithium battery, and I am trying to understand whether that small trickle current will scale up to satisfy load current demand while in Float mode (assuming there is sufficient solar power available).

A (Sigineer): No, I said there is no float charging for lithium battery, the charging will end once CV is finished.

And further confirmation of this with a real-world example:

Q: Being more specific, here is my real-world situation:

1st) LiFePO4 Battery is fully-charged and R48L60 enters Float state at 3pm (and chokes off additional solar power input even though sun is still shining and there is solar power available if needed).

2nd) No additional charging is occurring and no charge current is being provided by R48L60.

3rd) At 3:30pm, a refrigerator cycles on causing load inverter to begin drawing ~4A of current from LiFePO4 battery.

Question) Since there is still solar power available, will the R48L60 deliver this ~4A of current in Float mode to offset inverter consumption or will it allow battery to supply that ~4A current and re-enter a new Bulk Charge phase once LiFePO4 battery voltage has dropped below Nominal Voltage?

A (Sigineer): it will re-enter a new Bulk Charge phase once LiFePO4 battery voltage has dropped below CV voltage.


That is about as definitive as I know how to make it - the Sigineer SCCs do not supply any current while in Float mode.

Between not having any user control over the length of CV charging phase and the fact that there is no capability to offset even modest current demand by loads during Float phase, Sigineer is off my list of Tier-2 SCCs to consider (at least until they correct those two deficiencies)...

 

[snoobler]

Yet another example of why I think every single "canned" LFP program on chargers/SCC are not to be used.

Setting aside the horror of a potential 20 hour absorption phase, I believe the "can't supply current demands during float" is specific to the LFP settings, and they will perform as desired on a FLA/AGM/GEL or USER program.

Regardless, an absurdly long CV phase is reason enough to remove it from the list.

 

[fafrd]

Just to circle-back of the WZRELB MPPT, I asked the following question:

‘Assume the LiFePO4 battery is fully-charged and the charger is in Float mode with no charge current being delivered to the battery or loads.

Now assume that a refrigerator turns on powered by an inverter drawing ~4A from the LiFePO4 battery.

Assuming solar power is still available to supply current of over 4A, will the solar charge controller supply ~4A to maintain LiFePO4 battery voltage at Float Voltage or will the charger allow the LiFePO4 battery to supply that ~4A and allow the LiFePO4 battery voltage to drop below Float Voltage?’

And I received the following response directly from them:

‘The 4A current is supply by sun power. If the sun power is not enough, the LiFe PO4 battery will supply the power at the same time.’

So unlike Sigineer, it’s pretty clear that the Float Mode of the WZRELB MPPT is similar to that of Epever and the tier-1 brands (will supply load current in float, assuming sufficient solar power remains available).