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

[Mattb4]

The data is out there. Lots of those tests have been done. Google is your friend.

Everyone gets to choose their priorities. I gave up on LA twelve years ago because I did not like the inconvenience of having to charge them after each run on the ebike I built.

Do you think I did not search for such tests? Your answer is simply a hand wave. I think I am done discussing it with you.

 

[Ampster]

For the benefit of other readers;

https://www.sciencedirect.com/topics/engineering/ah-efficiency

Top 5 Factors That Affect Industrial Battery Efficiency

Lithium-ion batteries are some of the most energy efficient solutions out there, but there’s a lot that affects their efficiency besides just their internal chemistry. This blog will cover 5 factors that influence industrial battery efficiency and help you get the most return out of your investment.

www.google.com

 

[400bird]

Katsikas,
It looks like your reboost is 13.2v, is you battery getting low enough to enter boost the next morning?
In the end, I think your issue is that you are further discharging the new larger battery.

Do you think I did not search for such tests? Your answer is simply a hand wave. I think I am done discussing it with you.

And yet you ignore someone who did post links to studies to prove how far from reality your thoughts are?

If you think lead is more efficient, you should start your own post and stop detailing the OP's issue.

 

[Mattb4]

Katsikas,
It looks like your reboost is 13.2v, is you battery getting low enough to enter boost the next morning?
In the end, I think your issue is that you are further discharging the new larger battery.


And yet you ignore someone who did post links to studies to prove how far from reality your thoughts are?

If you think lead is more efficient, you should start your own post and stop detailing the OP's issue.

Uh, nonsense. I did not ignore anything. I was not derailing the OP post. I posted a possibility for why they received the results for making a change to their system. However I am also happy to add you to the ignore list.

 

[Checkthisout]

Problem is what parameters you select to describe efficiency. If you based it on DOD than indeed the lithium battery is more efficient. 80-90% battery utilization versus 50% battery utilization without impact on total life time. Hard to argue that.

What would be handy is if someone would take both a LiFePo4 battery and a AGM battery of the same capacity. Subject both to the same load for a given time period to achieve around 50% discharge. After that recharge them both to full based on standard charging practices and measure the amount of watts to do so. It would also be of interest to give the time it takes for each style of battery to reach full charge (not keeping them there because as you mention LA have self discharge happening).

This isn't how you measure charging efficiency.

Efficiency equals how many Kwh you put in vs how many you get back out. This won't change at partial discharge with either LA or lithium.

Lithium is more efficient by quite a bit.

The only reason we all don't run lithium is due to cost. That's it.

 

[hclarkx]

The voltage today in the morning was more than 13.2, I understand by what you said that this trigger Boost in the morning and not the sun light reaching the panels. The roof of the Van is cover with panels no option to put more. I'm thinking that if I change Boost Reconnect Charging Voltage to 13.4 it will keep the battery full until the sun will begin to fall. Is it to high?

You nailed it. I keep my "reconnect" at 13.4V to be sure I get into bulk and to 100% each day. Since the full charge resting voltage of a LiFePO4 battery is about 13.34 volts, 13.4V does the job.

More than you wanted to know: The voltage read out by my BMS (sum of the four cell voltages) is always lower than the number input to the MPPT controller. I.e., my battery has to get down to 13.15 volts for the MPPT set at 13.2V to trigger. So, setting 13.34 plus 0.05 ...... call it 13.4 does the job in my case. Probably yours too.

Where I often camp, one never knows when a 5-10 day streak of cloudy or foggy days will hit (California coast) so maximum charge each day is important to me.

 

[Katsikas]

Hello to all friends, thanks again for taking the time to read.
I have news again, I installed back PWM controller. After trying all the options of the MPPT, decided that for what I need from the system was better back to 12 Volts and PWM. Now is two days since I made the change and I'm not disappointed I have more power for longer time and a full battery when the sun begin to fall.
I connect two controllers one to two panels in parallel and the other to a single panel.
(Epever support told me that it was normal for the voltage to go down when I demand 30 Amps from the battery.)
Voltage does not goes down easily with PWM (it needs a lot of load), therefore float is kept at 13.8 all good sun hours long. And that give me at the end of the sunny day a full battery. (PWM is set in Gel Mode 13.8 Float 14.2 Boost No EQ)
I do not recommend Epever MPPT for someone that uses a big portion of the Amps coming form the solar panels (during the day).
In my case I use 30 Amps (permanent approx. in summer) from the 50 Amps maximum from the panels.
Have a blessed day.

 

[Goboatingnow]

How are you determine if your lithiums are charged or not. The SCC not going to float is irelevant

The pwm experience makes no sense , be aware that pwm controllers can overcharge lithiums especially if left connected a long time as they cannot regulate the panel voltage like a mppt can ( due to the power conversion process )

 

[Katsikas]

Thanks for the advice.
This is the way I check if the lithium is charged: First I checking first there is no big load to the system. There is a small display in over the battery with % state of charge and together with that I check battery voltage on a controller depending the time of the day I expect different voltage...

 

[mikefitz]

PWM charger will perhaps reduce the life of your lithium battery.

The MPPT charge settings you need for lithium should be, boost 14.0 to 14.2, float 13.4 to 13.5, boost duration 15 minutes , boost reconnect 13.3.
The efficiency of lithium is almost 100%, 100 Ah in, 100 Ah out, lead acid efficiency is lower, typically 110 Ah in, 100Ah out.