Best mppt charge controller for LiFePO4?

[HRTKD]

I've watched my system and have seen the PV side supply all the watts needed for a load and the battery supply zero. Victron system.

 

[rickst29]

I was getting set to jump on an Epever MPPT charge controller but between reading some of the struggles members have had getting their Epever MPPTs to not overcharge their LiFePO4 batteries and this warning I found in this Epever document: https://www.epsolarpv.com/upload/file/1812/EPEVER Tracer AN_Main_Pres.pdf

“High current series doesn’t have self-activation function for lithium-ion battery, thus it cannot be used with lithium-ion battery.”

I’m having second thoughts about Epever and broadening my search for the easiest/best MPPT charge controllers for LiFePO4 batteries.

Specifically, what I am looking for:

8S/24V
60A (or possibly 50A)
100V minimum (but ideally 120V or 170V)

As easy/failsafe to use when charging LiFePO4 as my 10A AC charger (specifically not having to worry about either overcharging or wasting solar power when the battery is discharged enough to take charge).

The EP-EVER "AN" Series was a very bad controller, in several ways. The "BN" Series is far more programmable (and also supports Series-connected PV panels up to a much higher voltage), I'm using one in my own "12 Volt" RV without bad results. Victron is certainly BETTER, but Tracer-BN has given me good results. I charge at only 14.5 CV, and I drop to "float stage" a bit early, at only 13.3 Volts. Float Voltage runs at 13.6 Volts. These tuning parameters do not balance the cells from Solar alone (I AM "wasting" some Solar Power, in not charging to 100% SOC). But it's a bad idea to an LFP battery string to 100% SOC every single day anyway. My batteries never 100% SOC by charging from Solar alone (as viewed on my very accurate Coulomb-Counter), but it does appear to be totally successfully avoid any risk of overcharging. The BMS is not strained or overrun by the Solar Charge Controller in this way.

The LFP cells eventually get balanced by plugging in at home (at full 14.6V "constant Voltage" after I get home). I leave them plugged in until current falls to zero.

In sunny weather, the LFP batteries in my RV are my RV usually fully charged by about 2 PM Daylight Time (an hour past Solar Noon), with later sunlight accomplishing nothing but "float charging". With EP-EVER, your desire for 60A would require splitting the Solar Array through two "BN" controllers - something you probably don't want to do, even though I've read that uncoordinated dual BN controllers, attached to the same battery bank, tend to behave pretty well until approaching Float Voltage. You would probably have to upgrade into a master-slave relationship (using their more expensive inter-connectable controllers) if you wanted them "finish" the charging process correctly.

 

[rickst29]

(deleted duplicate)

 

[fafrd]

The EP-EVER "AN" Series was a very bad controller, in several ways. The "BN" Series is far more programmable (and also supports Series-connected PV panels up to a much higher voltage), I'm using one in my own "12 Volt" RV without bad results. Victron is certainly BETTER, but Tracer-BN has given me good results. I charge at only 14.5 CV, and I drop to "float stage" a bit early, at only 13.3 Volts. Float Voltage runs at 13.6 Volts. These tuning parameters do not balance the cells from Solar alone (I AM "wasting" some Solar Power, in not charging to 100% SOC). But it's a bad idea to an LFP battery string to 100% SOC every single day anyway. My batteries never 100% SOC by charging from Solar alone (as viewed on my very accurate Coulomb-Counter), but it does appear to be totally successfully avoid any risk of overcharging. The BMS is not strained or overrun by the Solar Charge Controller in this way.

The LFP cells eventually get balanced by plugging in at home (at full 14.6V "constant Voltage" after I get home). I leave them plugged in until current falls to zero.

In sunny weather, the LFP batteries in my RV are my RV usually fully charged by about 2 PM Daylight Time (an hour past Solar Noon), with later sunlight accomplishing nothing but "float charging". With EP-EVER, your desire for 60A would require splitting the Solar Array through two "BN" controllers - something you probably don't want to do, even though I've read that uncoordinated dual BN controllers, attached to the same battery bank, tend to behave pretty well until approaching Float Voltage. You would probably have to upgrade into a master-slave relationship (using their more expensive inter-connectable controllers) if you wanted them "finish" the charging process correctly.

Well first, I’ve got a total of 4.5kW / 150A @ 8S as well as shading issues, so I will have at least 3 MPPTs (2S2P, 2S2P, 1S2P) if not 4 (2S2P, 2S2P, 1S1P, 1S1P) charging the same 8S LiFePO4 battery.

The new EPEVER AN Series offers a relatively inexpensive ‘parallel adapter’ which configured multiple high-voltage AN-Series MPPT charge controllers to operate in master-slave mode so that they are all synchronized as far as charging state: https://www.epsolarpv.com/product/71.html

This is a nice capability but it is unclear if it is necessary. It also means I’d need at least a 50A AN-Series for my 3rd MPPT (the two 2S2P strings will need 60A in any case).

I plan to test mixing and matching different brands of MPPTs charging the same battery in a trial-phase first to decide whether explicitly controlled ‘synchronization’ is really that important (since all MPPTs with identical settings should be synchronized by the common battery voltage in any case).

And second, while many here prefer the BN Series to the AN Series, the BN Series is no longer being updated and is slowly falling behind.

The new AN Series has a 200V offering, while BN Series maxes out at 150V (so 2S maximum with my panels versus 3S on the new AN Series).

The master/slave controller supports the new high-voltage AN Series but not the BN Series (or older low-voltage AN Series).

And finally, the AN Series has been designed for Lithium support, while the BN Series has not. The below is a direct quote from EPEVER support:

‘BN series do not support lithium battery, AN series support lithium battery.’

And:

‘If a charge controller is claimed to support lithium battery, it should be able to wake up the lithium battery when the built-in BMS of the lithium battery actively cuts off the battery output because of low energy left. Trancer-BN lacks of both hardware and software to support such feature. The user wouldn't need this feature if the user would configure the charge controller setpoints so that the battery wouldn't go that low.’

I understand that by using USR settings and being careful to avoid LVD using inverter low-voltage-cutoff settings, the BN can be configured to work very well with Lithium batteries, but this is just a further indication that EPEVER is investing new engineering/capability in the AN Series while the BN Series is essentially end-of-life (they will continue to manufacture and sell as long as their is demand, but they are no longer investing improving the product line).

This can always change, but that is the status today...

And I’m only focusing on 24V MPPTs - for 12V the situation is likely very different.

At 24V, it’s disappointing that Victron is not doing a better job (especially with Multiplus) - they consider 12V the sweat spot for boat/RV and 48V the sweatspot for residential/Off-Grid, so 24V is just a token effort on their part (while 24V is the sweatspot for both large boat/RV systems as well as small residential/Off-Grid systems).

 

[unsubscribed]

At 24V, it’s disappointing that Victron is not doing a better job (especially with Multiplus) - they consider 12V the sweat spot for boat/RV and 48V the sweatspot for residential/Off-Grid, so 24V is just a token effort on their part (while 24V is the sweatspot for both large boat/RV systems as well as small residential/Off-Grid systems).

So I have a MultiPlus 24/3000. What could it do better?

 

[unsubscribed]

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.

Hmmm, while I realize that LiFePO4's don't need a Float phase - and so EpEver is technically correct in their approach - I find that my Victron will power my load while keeping my Battle Born's "floating" at 27.2 Volts. (i.e. 100% SOC.) This way I don't lose any current from the battery bank at the end of the day.

Whereas if there were no Float stage, my batteries would begin to drain down after the (fixed) absorption phase, and likely not come back up to 100% by the time Bulk kicked back in in the late afternoon.

 

[DerpsyDoodler]

So I have a MultiPlus 24/3000. What could it do better?

He might be talking about price point.

 

[TGPB]

Not a brand I’m familiar with, so thanks for the recommendation.

Unfortunately, 150V will limit me to 2S.

As I mull-over my options to charge both 24V and possibly 48V batteries, I’m thinking 3 160V+ 60A MPPTs may be worth a modest premium.

Charging 24V, I can go 2S2P + 1S3P + 3S1P (the best to deal with my shade pattern).

If I ever switch to 48V, I can switch to either 2x2S2P + 2S1P or 2S2P + 2x3S1P.

So yeah, 150V is the minimum so so can go 2S (panel Voc_max is 52V) and 170V while 200V would provide me the freedom of going 3S on a string or two.

Morningstar has a 600v version of the Tristar MTTP

 

[TGPB]

Just a heads up for anyone considering the Epever BN. Newpowa is selling the exact same SCC with their name on it for less. Comes with the same 2yr warranty. I picked one up for $156 here.

 

[DGnts]

please forgive the fact that I am a nube here , Just set up my first solar system and my friend gave me this charge controller ....can't say that I like it ....here is my question I have a 48v 5120W lipo 4 battery ..first problem was this controller kept driving my inverter into voltage overload ...my inverter OL is at 62V, the battery states the upper voltage should be 56.4 to 58.6 but had to set the upper limit at 54.2 and the actual battery voltage reads 56.4 so for the time being problem solved but here is the thing that just does not seem to be right ...the charge controller tells you to set the FLoat charging setting to 48 since there is no float charge for lipo's so here is what happens ...it charges up to 56.4 then the charge voltages shuts off ....(good for lipo) however it can take days to reach that 48v threshold so the whole time you have solar power available its not charging or supplying the load ....this does not seem right to me but the manual states it must be 48

 

[snoobler]

Welcome to the forum

please forgive the fact that I am a nube here , Just set up my first solar system and my friend gave me this charge controller ....can't say that I like it ....here is my question I have a 48v 5120W lipo 4 battery ..first problem was this controller kept driving my inverter into voltage overload ...my inverter OL is at 62V, the battery states the upper voltage should be 56.4 to 58.6 but had to set the upper limit at 54.2 and the actual battery voltage reads 56.4 so for the time being problem solved but here is the thing that just does not seem to be right ...the charge controller tells you to set the FLoat charging setting to 48 since there is no float charge for lipo's so here is what happens ...it charges up to 56.4 then the charge voltages shuts off ....(good for lipo) however it can take days to reach that 48v threshold so the whole time you have solar power available its not charging or supplying the load ....this does not seem right to me but the manual states it must be 48

Assuming you mean LiFePO4 or LFP, you've just discovered the reason why LFP actually does need a float voltage with a solar charge controller. They need a float voltage, so you can power loads with available solar rather than nearly emptying your batteries.

LFP can be safely floated at 3.4V and lower. They will actually charge to 95%+ SoC @ 3.4V.

In your case, float should be 54.4V assuming 16S of LFP.

 

[DGnts]

sorry meant LiFePO4 and yes its 16S ....ok just set the 48 figure to 52.4 since the actual battery voltage as measured with a fluke 87 multimeter and the indicator on the battery reads 2V higher then the displayed voltage on the unit and will wait to see what happens tomorrow.

 

[snoobler]

anything is better than 48V

 

[DGnts]

so that did it ...went down this morning and it was overcast but the panels were taking the load and charging the batteries finally up and running
thanks snoobler

 

[Napalm]

also have an EPsolar 20amp MPPT solar charger.. and want to get the Mecer 200ah Lithium (Lifepo4) battery. They got very specific settings.

I'm not sure how to set it though. as there are so many settings on EPsolar and the provider of the Lithium has different wording. (so i'm worried to buy it.. and i don't want to damage it)

Epsolar 2210an has these options : (custom is an option). The charger is lithium compatible (i'm guessing on item 4 - User)

Mecer Lifepo4 200ah

Mecer only mentions Bulk of 14.6v, Floating of 13.6 and charge voltage of 14.6v. Nominal Voltage of 12.8. Cutoff of 10v.

But how would i set that on my MPPT. My MPPT has Boost, over voltage, Equalize, Boost Reconnect, Boost duration, Low voltage. Discharge limit voltage 10.6.

I don't want to buy it.. and break it.. (or possibly damage it in the long run)

 

[DGnts]

the charge controller should have a LiFePO4 setting, you do not want float or equalize settings ....floating charge will damage the batteries ....You should be able to set the upper charge voltage and the Float charge setting so in the case of a 12v battery you specified the upper voltage would be 14.6 and the float voltage would be around 14.2 .....so what happens in this scenario is after you have run on your batteries at night you will be below the 14.2 so your panels will start charging your battery until it hits 14.6 then the charge current will stop and you will be on batteries until it goes down to 14.2 ....I know this sounds strange because your expecting what lead acid does you charge up to float and your panels take the load and keep the batteries at float charge so you start the night with the highest possible charge. With LFP batteries you can't do that so you have to do a scenario like stated above so you go into the night with the highest charge

 

[Sojourner1]

the charge controller should have a LiFePO4 setting, you do not want float or equalize settings ....floating charge will damage the batteries ....You should be able to set the upper charge voltage and the Float charge setting so in the case of a 12v battery you specified the upper voltage would be 14.6 and the float voltage would be around 14.2 .....so what happens in this scenario is after you have run on your batteries at night you will be below the 14.2 so your panels will start charging your battery until it hits 14.6 then the charge current will stop and you will be on batteries until it goes down to 14.2 ....I know this sounds strange because your expecting what lead acid does you charge up to float and your panels take the load and keep the batteries at float charge so you start the night with the highest possible charge. With LFP batteries you can't do that so you have to do a scenario like stated above so you go into the night with the highest charge

This reply is confusing or I haven't had enough coffee yet. ?

I charge to 14.2v (3.55vpc) and then float at 13.6v (3.4 vpc), at float voltage solar is carrying all loads unless the draw is greater than the solar production. Entering evening with full batteries.

 

[rickst29]

also have an EPsolar 20amp MPPT solar charger.. and want to get the Mecer 200ah Lithium (Lifepo4) battery. They got very specific settings.

I'm not sure how to set it though. as there are so many settings on EPsolar and the provider of the Lithium has different wording. (so i'm worried to buy it.. and i don't want to damage it)

Epsolar 2210an has these options : (custom is an option). The charger is lithium compatible (i'm guessing on item 4 - User)

Mecer Lifepo4 200ah

Mecer only mentions Bulk of 14.6v, Floating of 13.6 and charge voltage of 14.6v. Nominal Voltage of 12.8. Cutoff of 10v.

But how would i set that on my MPPT. My MPPT has Boost, over voltage, Equalize, Boost Reconnect, Boost duration, Low voltage. Discharge limit voltage 10.6.

I don't want to buy it.. and break it.. (or possibly damage it in the long run)

First, let's begin with the Mecer battery recommendations - because many (most?) of the experts here disagree with those figures. They are correct to specify only a few parameters for charging an LFP battery. (Their 10v cutoff voltage is too low, IMO, but that is a BMS issue. There is another thing involved in the BMS, the start voltage for balancing - but you can't get at that).

Although it is a widely used charging voltage in LFP chargers, most of us prefer to 'bulk charge' an LFP at slightly lower voltage (perhaps 14.5V, or even just 14.4V). Because the EpEver MPPT will switch to "float" on the basis of voltage, and not current, they provide a timer "Boost Duration" which specifies a time for "Boost Mode" ("Boost" == "Bulk") to continue after the "Float Charging Voltage" has been reached. Maybe a parameter set like my own current values, which are these. I have an EpEver "Tracer BN3215".

Over Voltage Disconnect 14.7 V
Charging Limit Voltage 14.6 V
Over Voltage Reconnect 14.6 V
Equalize Charging Voltage shut off or 14.5 V
Boost Charging Voltage just 14.5V (others use higher Voltages to charge in slightly less time, some use lower to put less strain on the BMS)
Float Charging Voltage 13.6 V
Boost Reconnect 13.4 V
Low Voltage Reconnect 10.9
Under Voltage Warning Reconnect Voltage 11.5
Under Voltage Warning 11.5
Low Voltage Disconnect 10.8
Discharging Limit Voltage 10.5
Equalize Duration 0 (never do it, or set as low as possible)
Boost Duration 60 minutes

 

[Sabre36]

Do not be fooled by Promotion/Advertisements either.
Take Renogy for example, they spend HUGE on ads, promos all nice glossy & shiny to draw in folks, it works too.
There are many people who are OK with their Renogy purchases BUT the complaints & issues on support, product quality and even DOA out of the box issues are Very High ! They are Tier-3 Value product but with a Glossy face painted on it. I can not ever recommend anything Renogy to anyone because I have read more than enough complaints & issues to know better than to foist that stuff on anyone.

Absolute BINGO!

In just a few short years since Renogy started putting stickers on the cheapest products they can source, they have become the #1 most dangerous brand we see installed on boats. These failures are not just DOA stuff, glitches or nuisance failures but, actual fires or darn close to full blown fires.

We've seen more fires/melted controllers/microcracking & hots spots on solar panels etc. related to Renogy products than any other brand over the last 30+ years. I'd have to go all the way back to the ancient ProMariner "flyback" chargers, affectionately named "Fryback", due to so many dangerous failures. It used to be that Xantrex owned the no-support, horrible reliability moniker but now it is Renogy..

 

[Napalm]

First, let's begin with the Mecer battery recommendations - because many (most?) of the experts here disagree with those figures. They are correct to specify only a few parameters for charging an LFP battery. (Their 10v cutoff voltage is too low, IMO, but that is a BMS issue. There is another thing involved in the BMS, the start voltage for balancing - but you can't get at that).

Although it is a widely used charging voltage in LFP chargers, most of us prefer to 'bulk charge' an LFP at slightly lower voltage (perhaps 14.5V, or even just 14.4V). Because the EpEver MPPT will switch to "float" on the basis of voltage, and not current, they provide a timer "Boost Duration" which specifies a time for "Boost Mode" ("Boost" == "Bulk") to continue after the "Float Charging Voltage" has been reached. Maybe a parameter set like my own current values, which are these. I have an EpEver "Tracer BN3215".

Over Voltage Disconnect 14.7 V
Charging Limit Voltage 14.6 V
Over Voltage Reconnect 14.6 V
Equalize Charging Voltage shut off or 14.5 V
Boost Charging Voltage just 14.5V (others use higher Voltages to charge in slightly less time, some use lower to put less strain on the BMS)
Float Charging Voltage 13.6 V
Boost Reconnect 13.4 V
Low Voltage Reconnect 10.9
Under Voltage Warning Reconnect Voltage 11.5
Under Voltage Warning 11.5
Low Voltage Disconnect 10.8
Discharging Limit Voltage 10.5
Equalize Duration 0 (never do it, or set as low as possible)
Boost Duration 60 minutes

Rick. with those settings, it won't damage my battery ? and it will charge to 95%? or to 90% of capacity of the battery.?

My inverter is a 600watt pure sine wave.. but it will connect direct to Battery. How can i calculate howmuch watts i can use.. so that the voltage don't go below 11 (or whatever amount the BMS has issues with). I guess the MPPT will warn but the inverter will just use untill it's flat.