Total NOOB question about SCC settings.

[Sean Steele]

I've had my Renogy SCC installed for a few days now, running off of a small portable panel until I can get the two rooftop panels installed. Today is the first day that the monitor has shown the battery to be fully charged. Shouldn't it kick down to a float voltage or something? Monitor readings and settings in pics.

 

[snoobler]

No.

The 100% is purely based on the voltage. It is completely unreliable as a true measure of the state of charge, and it should always be ignored.

Once absorption voltage is attained, it must dwell there tapering current to maintain it until the battery is fully charged. It will remain there for the "boost charge time" period of 120 minutes.

 

[Sean Steele]

Thank you for a very thorough answer. I swear I thought I understood all of this. When I saw it sitting at 14.6 for an extended period of time, I thought it was damaging my battery. I've probably been doing more damage only running my generator to charge with the converter/charger for 2 hours in the morning and 2 hours at night.

Wife and I have been full time for five years but this is our first winter boondocking in AZ.

Of course, when my lifepo battery gets here in Feb, I'll have a whole new set of parameters to figure out. The SCC has presets for LI, I hope they match what the battery wants. I also bought a new converter/charger that can be stitched from 3 stage to one stage and has adjustable voltage output. Hopefully I can read/learn enough by Feb that I don't have to come back to the beginners section to ask another NOOB question.

 

[Sean Steele]

Snoobler, I just read in another thread that you have the Powermax PM4 converter/charger. That is the same one I bought, months ago, but haven't installed yet. Do you leave yours in three stage mode for lifepo?

 

[snoobler]

At the recommended 0.1C charge rate (50A for 500Ah battery), when you hit the bulk voltage, you're at about 80% SoC. It takes at least 2-3 hours to fully charge the battery. If you're hitting absorption, you're getting to at least 80%. Not the best, but not bad.

Technically the PM4 is a 4 stage charger. IIRC, it's 4th state re-bulks every 24 hours, but that only matters if you're on grid power. Otherwise, it's just like a 3 stage.

I would leave it in charger mode and set the OCV to 14.4V.

What capacity LFP and what PM4 current?

 

[pollenface]

The 100% is purely based on the voltage. It is completely unreliable as a true measure of the state of charge, and it should always be ignored.

Amen. I once bought a "ctek battery sense Bluetooth dongle" It said 100% from 12.1v to 13v. It went in the bin shortly after.

 

[Sean Steele]

At the recommended 0.1C charge rate (50A for 500Ah battery), when you hit the bulk voltage, you're at about 80% SoC. It takes at least 2-3 hours to fully charge the battery. If you're hitting absorption, you're getting to at least 80%. Not the best, but not bad.

Technically the PM4 is a 4 stage charger. IIRC, it's 4th state re-bulks every 24 hours, but that only matters if you're on grid power. Otherwise, it's just like a 3 stage.

I would leave it in charger mode and set the OCV to 14.4V.

What capacity LFP and what PM4 current?

The PM4 I have is the 100A model. I bought it before I knew anything about charge rates. The LFP I have coming is the 170AH power block from Big Batteries.

The "manual" I got with the PM 4 says that the 4th mode is the single stage mode. It's very confusing in the way it talks about "modes" and "stages".

 

[Sean Steele]

Finally got my big battery power block today. Not sure how soon I will get it installed. I need to decide if it will be ok to have the converter/charger that came with the camper charge the battery when I have the generator running or if I should disable it until I get the new converter installed. I don't know the specs but it looks like it charges at 13.8 volts all the time going by what I see on a voltage display.

 

[snoobler]

If it never drops below 13.8V, do not use. If you float LFP above 13.6V, you damage it. Some converters hold 13.6-13.8V for several hours and then drop to 13.2V. If that's the case, it's fine.

 

[Sean Steele]

When I run the generator, it's to power other things, not necessarily to charge the battery. Usually 2-3 hours, maybe 4 once in a while. I don't think I have ever seen the voltage drop or even change. I think I will just disable it to be on the safe side. Once I get the PM4 installed, I'll set the OCV to 14.4 like you said.

Thanks again for a quick concise answer.

 

[snoobler]

In our 5th wheel, we have a 50A, 13.8V constant voltage converter. It trashed some LFP before I knew better.

I have a spare PM3 somewhere. I should just install it.