A couple basic questions about starting with lifepo4

[tanglewood]

My first guess wold be that it's temperature related. What is the battery voltage when this is happening? If it's at the bulk/absorb voltage, then the charger is regulating current as it should to keep from exceeding the desired voltage. If the voltage is below the bulk/absorb voltage, then it's current limiting for a different reason.


Does the charger have temperature compensation built into it somehow, and if so, how and where does it measure temperature? Some use an external sensor, and others just measure their own ambient temp as assume it's the same for the batteries. With LFP, you don't want any temperature compensation. If you can't disable it in the charger, then you need to be thinking about a different charger.


It's also possible that the charger is current limiting because it's internals are hot. Most all chargers have reduced output capability as temps get higher. So if you are now in a warmer environment than before, that can result in reduced charging rates.


But first step is to note the battery voltage when this is happening.

[Chotu]

It’s about 20 degrees COOLER now than the first time I used the AC charger. Not warmer.

The solar wasn’t hooked up though during the first charge.

It’s at 13.5 charging right now. I set solar to 14.2 as suggested by the manufacturer. The big charger is 14.4, using its lifepo4 charging profile.


No idea why they are so much lower now than they were first try.

My AH reading on the monitor show down 160 to start but it’s not charging quickly like it did the first time.

[newhaul]

Originally Posted by jordanbigel

I wish I could help, your description certainly makes it sound like something has changed, but not knowing much about your setup, I hesitate to spout off like I am qualified!

I do know that the amount of amps a LFP battery can accept is governed by the BMS, the first thing I would do is check the specs on the battery/BMS and see what the max charging amps is - some drop-in batteries of that size, from what I have seen, have a max charging capacity of only 50amps (.25C), a better battery would be 100amps (.5C) or even 200amps (which would be 1C). For example Battle Born drop-ins are .5C max.

If the battery was taking 70amps one day and another day its only taking 30amps, if I understand you correctly, and nothing has changed on the charger side, I would wonder if something in the BMS has changed - I have no idea what these things do when the "go bad", or if this is a feasible outcome of something failing internally, but this is where I would investigate.

Hopefully someone more knowledgable will pipe up here and offer better advice.

Charging just fine . The 30 amps was out of his solar array. The 70 was from his shore charger. Voltage shown is relative to the actual voltage of the battery th charging voltage will increase as the battery comes up to full charged . Lifepo4 is awesome that way .

[newhaul]

Originally Posted by Chotu

It’s about 20 degrees COOLER now than the first time I used the AC charger. Not warmer.

The solar wasn’t hooked up though during the first charge.

It’s at 13.5 charging right now. I set solar to 14.2 as suggested by the manufacturer. The big charger is 14.4, using its lifepo4 charging profile.


No idea why they are so much lower now than they were first try.

My AH reading on the monitor show down 160 to start but it’s not charging quickly like it did the first time.

Ok what is the current charging source ? What is its potential output ? What is your daily usage ? So many questions.

[smac999]

It’s not going to hit 14.4v untill it’s full. It’s in bulk stage.

[Chotu]

Originally Posted by newhaul

Charging just fine . The 30 amps was out of his solar array. The 70 was from his shore charger. Voltage shown is relative to the actual voltage of the battery th charging voltage will increase as the battery comes up to full charged . Lifepo4 is awesome that way .

Damn. If I only knew what voltage they were at previously when I was doing that big initial charge. They must have been extremely low.

But what’s not making any sense is if I’m down 160, that is extremely low on a single 200AH battery. . It should be about the same as it was when I got it unless it was dead empty in a bad way upon arrival

[Chotu]

As a sanity check, under a 10 amp load, what voltage (and state of charge) should a 200AH lifepo4 show?

I’ll pay attention to voltage on the discharge this time as a check against my battery monitor.

[Chotu]

Actually, here it is.




So I think the batteries were super empty upon arrival.

Now I’m just working in the 13’s and it’s slower going.

[Chotu]

Originally Posted by newhaul

Ok what is the current charging source ? What is its potential output ? What is your daily usage ? So many questions.

I can answer the questions, but I don’t think they have much to do with what I’m asking.

I’m mostly solar charging. Since I was making bread today using the electric oven I thought I would use the speedy charging of the 90 amp AC powered battery charger that was shooting 70amps into this battery the first day.

My solar puts out around 20-30amps. Because only half the system is hooked up.

I use 80AH a day. Refrigerator, freezer, etc.

[jordanbigel]

Originally Posted by newhaul

Charging just fine . The 30 amps was out of his solar array. The 70 was from his shore charger. Voltage shown is relative to the actual voltage of the battery th charging voltage will increase as the battery comes up to full charged . Lifepo4 is awesome that way .

My comment was based on Chotu's statement, specifically "...I’m not seeing charging rates of even half that..." - half of 70 would be 35, he said it was not even half, so I estimated he is now seeing 30. Shrug.

The day I got them, I charged them all the way up like it says to do, and I was getting 70 amp charging rates on a 200AH battery.

Now I am down to say, 140-160AH missing and I’m not seeing charging rates of even half that on the same charger.

[Chotu]

Originally Posted by jordanbigel

My comment was based on Chotu's statement, specifically "...I’m not seeing charging rates of even half that..." - half of 70 would be 35, he said it was not even half, so I estimated he is now seeing 30. Shrug.

The day I got them, I charged them all the way up like it says to do, and I was getting 70 amp charging rates on a 200AH battery.

Now I am down to say, 140-160AH missing and I’m not seeing charging rates of even half that on the same charger.

Yes. This is the behavior I’m seeing. Your estimate is exactly what I’m seeing

But I really think I was just spoiled in charge rate by an empty battery.

[newhaul]

Originally Posted by Chotu

Yes. This is the behavior I’m seeing. Your estimate is exactly what I’m seeing

But I really think I was just spoiled in charge rate by an empty battery.

One issue I have found wrt my own charging is the input voltage and exact cycle of htz aka 50 or 60 htz . Showing 162 volts and fluctuating between 57and 62 hrz I can only get about 60 amps charge into my bank . The quality of shore connection affects us at these higher charge rates.
Test the actual output of your generator . It may not be putting out power at peak for high charging rates

[Chotu]

Originally Posted by newhaul

One issue I have found wrt my own charging is the input voltage and exact cycle of htz aka 50 or 60 htz . Showing 162 volts and fluctuating between 57and 62 hrz I can only get about 60 amps charge into my bank . The quality of shore connection affects us at these higher charge rates.
Test the actual output of your generator . It may not be putting out power at peak for high charging rates

It’s the same set up that did the 70 amp charging.

I have never been plugged into shore power yet. Ever.

That makes sense on your end because the battery charger circuitry would behave differently if not specifically designed to run on varying AC frequencies.

In my case, my generator output is controlled electronically and kept at 115V, exactly 60hz, even if there are small changes in the rpm.

Larger changes in RPM will cause voltage to rise or fall, but the electronic part that produces the power regulates it very tightly. It’s quite a perfect output and the same output of the same physical generator that charged it at 70

[newhaul]

Originally Posted by Chotu

It’s the same set up that did the 70 amp charging.

I have never been plugged into shore power yet. Ever.

That makes sense on your end because the battery charger circuitry would behave differently if not specifically designed to run on varying AC frequencies.

In my case, my generator output is controlled electronically and kept at 115V, exactly 60hz, even if there are small changes in the rpm.

Larger changes in RPM will cause voltage to rise or fall, but the electronic part that produces the power regulates it very tightly. It’s quite a perfect output and the same output of the same physical generator that charged it at 70

I am attempting to assist remotely and collecting information to that end.
So 115 volts and I would assume 30 amps output?

Ok I was not specificly pointing to shore power but the conditions that can affect the chargers output and efficiency and if your conditions are exactly the same now . Then your bank is not as low as it was before. Another possibility what are the parasitic loads when you were charging this time ? Anything else drawing power becide the battery charger? If nothing else has changed significantly then recomend checking all connections .

[Chotu]

Originally Posted by newhaul

I am attempting to assist remotely and collecting information to that end.
So 115 volts and I would assume 30 amps output?

Ok I was not specificly pointing to shore power but the conditions that can affect the chargers output and efficiency and if your conditions are exactly the same now . Then your bank is not as low as it was before. Another possibility what are the parasitic loads when you were charging this time ? Anything else drawing power becide the battery charger? If nothing else has changed significantly then recomend checking all connections .

It’s much appreciated. But I think I was just confused because the batteries were so empty upon arrival. That’s not how flooded lead acid batteries arrive.

I guess in order to ship them, they have to keep them pretty empty.

I’ll just keep an eye on things. I still have to integrate the second battery anyway. This is just one battery out of two of them.