Battery does not reach float Voltage after upgrade to MPPT and Lithium.

[Katsikas]

Greetings
I recently made a controller and battery upgrade from PWM and Gel to MPPT and Lithium, but I’m a bit disappointed by the poor performance of the MPPT controller and I need help please, it hardly reach the Float Voltage when in use and never the Boost voltage neither. I use a day permanent load of 30 Amps 12 Volts in sunny days and with the old configuration the battery reached the Boost and Float voltage from the morning until evening but now almost never.
This was my old and new configuration.
3 x 300 Watts. 12 Volt 16.5 Amp Solar panels. Connected in parallel.
Epever 60 Amp PWM ControllerVS6024AU
250 Amp. 12 Volt. Gel battery.
New Configuration.
3 x 300 Watts. 12 Volt, 16.5 Amp Solar panels. Connected in series.
Epever 60 Amp Tracer 6415AN
300 AH LIFEO4 Lithium battery
The MPPT controller reaches easily a 50 Amp but voltage hardly 13.5 when in load and the result is not a 100% charged battery at the end of the day.
The controller configuration was set in the place where I purchased it. It was done for a 300Amp lithium battery (Wifi using the android application). I remember as I was watching quickly the parameters that float was 13.8 Volt and Boost 14.4 Volt (not sure maybe 14.6) and reconnect 13.2 Volt.
Can anyone please let me know if it is normal not to reach float and boost voltage with a clear day with a load of 30 Amps like my old setup or a malfunction?
If I do not use the system the battery reach 100% and the voltage reaches float.
Thanks very much ahead

 

[Mattb4]

....
Can anyone please let me know if it is normal not to reach float and boost voltage with a clear day with a load of 30 Amps like my old setup or a malfunction?
If I do not use the system the battery reach 100% and the voltage reaches float.
Thanks very much ahead

It seems that your panels are not delivering sufficient wattage to fully recharge your batteries in a day for your amount of loads. The fact that with no loads you reach full charge and go into float would indicate no problems with the SCC.

Wattage generated by your panels during sunlight hours if you are recharging you battery has to be greater than the amount of wattage depleted from your battery. There is conversion losses to account for as well.

People frequently find themselves with discharged batteries after several days because they take from them more than they get from the sun each day. One of the biggest causes for this is loads that run 24 hours versus charging that only runs for a few hours.

So you can either reduce loading or you can add more panels.

 

[Katsikas]

Thanks a lot for taking the time to answer, I really appreciate it.
It looks to me that the old configuration was doing better, I'm suffering now for lack of power to run the small AC. I run towards MPPT and Serial panel connection too fast. Tried to read as much as I could but didn't find a bad word about MPPT and a good word about PMW, maybe only one that said that if panel voltage is close to battery voltage then PMW will perform better, I thought it was talking about very near voltage (2 Volts+-). I think this is the situation I'm in.
At the beginning of my update I was still using the 3x300 Watts panels connected in parallel. And the expensive 60 Amp MPPT was performing not as good as the PWM and I thought it was because they needed to be connected in series to reduce looses. It is true that the cables look more relaxed with 60 Volt than 12 but I get at the end less power. To be honest I'm really surprised, didn't expect this, I thought the MPPT controller was not working fine.
I'm planning to use back the old PMW controller in Gel mode, with the 12 Volts panels in parallel. With the load I use, it will easily reach Float 13.8 Volt and Boost 14.2 Volt and then I will have a 100% full battery when the sun will begin to fall.
Any suggestions are welcome.
Thanks.

 

[JWLV]

An MPPT controller's main advantage over PWM is when the solar voltage is much higher than the battery. Ideally you should shoot for about 10% less than the maximum open voltage of the MPPT controller. The max open circuit voltage of the Epever 60 Amp Tracer 6415AN is 150 volts. Given that you have 3 x 300 watt 12 voltage panels, you should definitely connect them in series. A 12 volt panel is typically about 20v open circuit (check the label on the back of your panels). So connecting 3 of them in series would give you around 60 volts. That is still under the 150 maximum and you'll be taking advantage of the MPPT since the voltage is much higher than the battery that it's charging. Note that it is not actually trying to pump 60 volts to your battery. It's the MPPT controller's job use the higher voltage to give more current at the proper voltage to charge your battery.

 

[HRTKD]

I would double check the parameter settings of your MPPT solar charge controller. If the voltage is set too high, the BMS could be disabling charging due to a cell going over the high voltage disconnect amount.

Take screen shots of the parameters and post them here. Someone with experience with that solar charge controller will look them over.

 

[GSXR1000]

did you run the AC the same number of hours and same outdoor temperature?

your agm would run-down quicker (and charge quicker) might lead you to run less hours?

 

[Katsikas]

did you run the AC the same number of hours and same outdoor temperature?

your agm would run-down quicker (and charge quicker) might lead you to run less hours?

Yes, the AC is a very small 300 Wats. unit. The compressor is running all the time (it does not depend on heat) and it is demanding no more than 30 Amps together with computer and lights I know because I check all the time the PWM controller and turn it off the AC everyday as soon as it began to demand from the Gel battery (when the sun begin to give me less than 30 Amps) because I need energy battery for the evening-night. I normally began evening with no less than 12.5 Volts with the Gel battery 12.6 was common . It is exactly the same amount of power that I use but now with an expensive battery and controller is not sufficient. Amazing.

 

[Katsikas]

I would double check the parameter settings of your MPPT solar charge controller. If the voltage is set too high, the BMS could be disabling charging due to a cell going over the high voltage disconnect amount.

Take screen shots of the parameters and post them here. Someone with experience with that solar charge controller will look them over.

Thanks for the suggestion.
These are the parameters for a Gel battery according to the table that I'm planning to use for Lithium (presets cannot be changed)
Equalize Charging Voltage: NO
Boost Charging Voltage: 14.2 (boost Voltage is lower than the recommended for lithium)
Float Charging Voltage: 13.8
Low Voltage Reconnect: 12.6
Low Voltage Disconnect 11.1
I don't see Over Voltage Connect and Disconnect, and Boost reconnect , how sensitive are those parameters for a lithium ... It seem to me not critical.

 

[HRTKD]

That charge profile for Gel is safe.

 

[GSXR1000]

An MPPT controller's main advantage over PWM is when the solar voltage is much higher than the battery. Ideally you should shoot for about 10% less than the maximum open voltage of the MPPT controller. The max open circuit voltage of the Epever 60 Amp Tracer 6415AN is 150 volts. Given that you have 3 x 300 watt 12 voltage panels, you should definitely connect them in series. A 12 volt panel is typically about 20v open circuit (check the label on the back of your panels). So connecting 3 of them in series would give you around 60 volts. That is still under the 150 maximum and you'll be taking advantage of the MPPT since the voltage is much higher than the battery that it's charging. Note that it is not actually trying to pump 60 volts to your battery. It's the MPPT controller's job use the higher voltage to give more current at the proper voltage to charge your battery.

are you turning off your AC every day when your solar is less then 30 amps with the Lithium battery?

 

[GSXR1000]

at 13v your battery could be almost drained

 

[Mattb4]

Thinking upon this a bit and researching where I can there is another possibility for why your new setup is not achieving the same as your previous setup with the same loading. Different battery chemistry might be giving a increase in charge needed compared to discharge available. It seems for lithium battery vehicles the loss for charge discharge is around 70%. What this means is for every 100 watts of charging done you get 70 watts usable into/back from the battery. The excess wattage is turned into heat. Faster charging makes the issue worse.

I do not have the numbers for your previous gel batteries but it is possible that they were better for the charge/discharge cycle. If they reached a 80% overall efficiency than they would need less solar power to reach full charge.

It is one aspect of lithium batteries that is hard to explore compared to lead acid. Everyone is concentrated on DOD (depth of discharge) and hardly no one is testing or listing efficiency.

 

[GSXR1000]

Thinking upon this a bit and researching where I can there is another possibility for why your new setup is not achieving the same as your previous setup with the same loading. Different battery chemistry might be giving a increase in charge needed compared to discharge available. It seems for lithium battery vehicles the loss for charge discharge is around 70%. What this means is for every 100 watts of charging done you get 70 watts usable into/back from the battery. The excess wattage is turned into heat. Faster charging makes the issue worse.

I do not have the numbers for your previous gel batteries but it is possible that they were better for the charge/discharge cycle. If they reached a 80% overall efficiency than they would need less solar power to reach full charge.

It is one aspect of lithium batteries that is hard to explore compared to lead acid. Everyone is concentrated on DOD (depth of discharge) and hardly no one is testing or listing efficiency.

Lifepo4 is over 90% way better then gel.... Via solar there isn't much heat generation vs a EV that have very high charge current

 

[Checkthisout]

Greetings
I recently made a controller and battery upgrade from PWM and Gel to MPPT and Lithium, but I’m a bit disappointed by the poor performance of the MPPT controller and I need help please, it hardly reach the Float Voltage when in use and never the Boost voltage neither. I use a day permanent load of 30 Amps 12 Volts in sunny days and with the old configuration the battery reached the Boost and Float voltage from the morning until evening but now almost never.
This was my old and new configuration.
3 x 300 Watts. 12 Volt 16.5 Amp Solar panels. Connected in parallel.
Epever 60 Amp PWM ControllerVS6024AU
250 Amp. 12 Volt. Gel battery.
New Configuration.
3 x 300 Watts. 12 Volt, 16.5 Amp Solar panels. Connected in series.
Epever 60 Amp Tracer 6415AN
300 AH LIFEO4 Lithium battery
The MPPT controller reaches easily a 50 Amp but voltage hardly 13.5 when in load and the result is not a 100% charged battery at the end of the day.
The controller configuration was set in the place where I purchased it. It was done for a 300Amp lithium battery (Wifi using the android application). I remember as I was watching quickly the parameters that float was 13.8 Volt and Boost 14.4 Volt (not sure maybe 14.6) and reconnect 13.2 Volt.
Can anyone please let me know if it is normal not to reach float and boost voltage with a clear day with a load of 30 Amps like my old setup or a malfunction?
If I do not use the system the battery reach 100% and the voltage reaches float.
Thanks very much ahead

Do your panels have bypass diodes?

We're you able to measure total wattage in before your controller upgrade? If so, what is the difference between that and the new setup?

I think you might be experiencing shading issues with your 3S vs your old 3P setup if you're experiencing lower kwh output.

 

[Mattb4]

Lifepo4 is over 90% way better then gel.... Via solar there isn't much heat generation vs a EV that have very high charge current

This is claimed but mostly due to the ability to have greater depth of discharge and higher rates of charge. Being able to charge quicker is not the same as the charge watt-hour in compared to being charged. In order to have a fair comparison of Lithium and LA you would want to publish how much energy it takes to start from a equivalent state of capacity and reach full charge. Time is not a consideration nor is the charging curve.

No where do I see this done.

 

[Checkthisout]

This is claimed but mostly due to the ability to have greater depth of discharge and higher rates of charge. Being able to charge quicker is not the same as the charge watt-hour in compared to being charged. In order to have a fair comparison of Lithium and LA you would want to publish how much energy it takes to start from a equivalent state of capacity and reach full charge. Time is not a consideration nor is the charging curve.

No where do I see this done.

Huh?

It's well known that lithium has greater charge efficiency than LA.

 

[Mattb4]

Huh?

It's well known that lithium has greater charge efficiency than LA.

Oh? Where is it known at and can you point to results of the test I asked for. Thanks for any link that goes directly to such a test and not to all the ones that talk about charge time and DOD capacity or other comparisons of lithium to lead acid.

It is likely that for a given charge the lithium battery does have more usable power but that is not the same thing as what power it takes to reach full charge.

 

[Checkthisout]

Oh? Where is it known at and can you point to results of the test I asked for. Thanks for any link that goes directly to such a test and not to all the ones that talk about charge time and DOD capacity or other comparisons of lithium to lead acid.

It is likely that for a given charge the lithium battery does have more usable power but that is not the same thing as what power it takes to reach full charge.

Be nice.

You lost me. Your answer would vary based on capacity i.e. how big the fuel tank is which is not a measure of efficiency.

This also gives the OP nothing to chew on.

 

[Mattb4]

Be nice.

You lost me. Your answer would vary based on capacity i.e. how big the fuel tank is which is not a measure of efficiency.

This also gives the OP nothing to chew on.

I was being nice. Sorry that I lost you. Batteries are not fuel tanks that take a fixed volume. They are a load. Efficiency can be applied in different ways and formats.

The reason it might give the OP something to chew on is if (and I really do not know without testing done) it takes more to fully charge a lithium battery than it takes to charge a same rated capacity LA battery than that would indeed be something to allow for.

 

[Checkthisout]

I was being nice. Sorry that I lost you. Batteries are not fuel tanks that take a fixed volume. They are a load. Efficiency can be applied in different ways and formats.

The reason it might give the OP something to chew on is if (and I really do not know without testing done) it takes more to fully charge a lithium battery than it takes to charge a same rated capacity LA battery than that would indeed be something to allow for.

This wording overcomplicates things.

All you're saying is that the lithium is better at producing advertised capacity vs gel, flooded or agm.

This issue would be solved in a single charge cycle by letting the battery reach float 1 time.

I.E. our new gas tank holds more gas so we need to put more gas in it initially. If all other things are the same we simply maintain more reserve (more gallons in our larger tank) than with our old tank.