Using two charge sources with different charging parameters at same time.

[SoakedUp]

Is there any harm if my solar charge controller is set to a 14.2 absorption, 13.6 float and my 120v to dc charge parameters are set to 14.6 absorption and 13.8 float . I typically keep the SCC set with lower parameters to keep the battery from sitting at 100%. Every now and then on a cloudy day I may supplement charging power with the AC charger or if I want to top balance the battery cells.

Do the chargers need to have the same parameters? What happens if the battery gets to 14.2volts and the solar charge controller wants to go into absorption but the other charger is still charging up to 14.6?

 

[MisterSandals]

I am more concerned that you are charging to 14.6V than using different chargers with different charge profiles.

 

[TomC4306]

Why would the solar charge controller want to go back into bulk at 14.2?

 

[TomC4306]

Hinky. Just set them the same.
I charge at an equivalent 13.9 and get full capacity from my packs. Zero reason to charge that high.

 

[Rocketman]

14.6 seems a bit high…

I use different charging levels: (these are the bulk amounts - float is 13.5 for all)
Shore 14.2 - because when plugged in we are plugged in for a while.
Dc-Dc 14.1- this one is the least smart - stop for fuel and it will redo the 14.1 bulk again.
Solar 14.3 ( or 14.4 when I want a good cell balancing).

They could be the same - but I like my setup

 

[John Frum]

Having bulk and absorption at different levels doesn't make much sense.
Perhaps you are referring to float.

 

[TomC4306]

14.6 seems a bit high…

I use different charging levels: (these are the bulk amounts - float is 13.5 for all)
Shore 14.2 - because when plugged in we are plugged in for a while.
Dc-Dc 14.1- this one is the least smart - stop for fuel and it will redo the 14.1 bulk again.
Solar 14.3 ( or 14.4 when I want a good cell balancing).

They could be the same - but I like my setup

I just don't understand the reason for the complexity. Pick a charge voltage set everything to one charge voltage that way you're not chasing down phantoms when something is misbehaving.
Whatever floats your boat.

 

[timselectric]

It doesn't hurt if they aren't the same. But it will slow things down. Because one will be satisfied and just sitting there, while the other one has to do all of the work to complete the charging.

 

[SoakedUp]

I am more concerned that you are charging to 14.6V than using different chargers with different charge profiles.

It’s the suggested voltage to charge the battery to from the manufacture. I also thought it was a bit high and why my day to day charging on the SCC is set at 14.2.

Why would the solar charge controller want to go back into bulk at 14.2?

Sorry I’m using a renogy CC which uses mppt (bulk), boost, and float. And a victron 12v charger that uses bulk, absorption, and float. I keep mixing up the terms.

If the renogy CC hits its 14.2 boost(absorption) but the victron is set for 14.6 absorption what will the CC do is my question. Will it still go into boost(absorption) mode?

Same for the float. If the CC is set to 13.6 but the victron charger is set to 13.8 what happens?

 

[SoakedUp]

I just don't understand the reason for the complexity. Pick a charge voltage set everything to one charge voltage that way you're not chasing down phantoms when something is misbehaving.
Whatever floats your boat.

Because the solar setup is at an off grid cabin. I don’t want the batteries being charged up 100% every day, I’m trying to keep them in the 10-90% range especially during the warmer days. When I get out to my off grid spot some times I like to hook the charger up if/when I start the generator so I can get the batteries 100% full for the night. So the charger parameters are a bit more aggressive to get a full charge and also balance the cells out every couple months

 

[TomC4306]

Because the solar setup is at an off grid cabin. I don’t want the batteries being charged up 100% every day, I’m trying to keep them in the 10-90% range especially during the warmer days. When I get out to my off grid spot some times I like to hook the charger up if/when I start the generator so I can get the batteries 100% full for the night. So the charger parameters are a bit more aggressive to get a full charge and also balance the cells out every couple months

Anything over 3.45 v per cell is 100%
Two biggest enemies of lithium chemistry batteries is heat and extremes of voltage. The working range of these cells is 3.0 to 3.4 volts not 2.5 to 3.65 volts I charge to 3.45, absorb for 60 minutes, float at 3.375, and get 100% capacity from my 16 kwh bank.
If your purpose is to only run 10% to 90% your overcharging your batteries.
Watch this.

 

[SoakedUp]

Anything over 3.45 v per cell is 100%
Two biggest enemies of lithium chemistry batteries is heat and extremes of voltage. The working range of these cells is 3.0 to 3.4 volts not 2.5 to 3.65 volts I charge to 3.45, absorb for 60 minutes, float at 3.375, and get 100% capacity from my 16 kwh bank.
If your purpose is to only run 10% to 90% your overcharging your batteries.
Watch this.

Thanks for your input. I’m still pretty new to LFP chemistry so I really appreciate these kinds of comments. Why does the battery manufacture suggest 14.6 charge or 3.65/cell? But regardless of charge voltages I was more curious about different parameters for two different charge sources being used at the same time and if there was any concerns with that.

 

[Rocketman]

There is no concerns from using different charge sources At slightly different voltages. What happens is both are running, then the lower one drops out and the higher one keeps going until it finishes.

I believe the reason the some battery manufacturers say 14.6 is that’s 3.65v - which is the top of the cell’s voltage. This gives the bms longer to balance the cells.

I would rather not stress the cells and balance a bit tomorrow.

 

[SoakedUp]

There is no concerns from using different charge sources At slightly different voltages. What happens is both are running, then the lower one drops out and the higher one keeps going until it finishes.

I believe the reason the some battery manufacturers say 14.6 is that’s 3.65v - which is the top of the cell’s voltage. This gives the bms longer to balance the cells.

I would rather not stress the cells and balance a bit tomorrow.

“Drops out”? As in shuts off? If the solar charge controller reaches its absorption voltage and the victron stand alone charger is still in bulk will the solar charge controller go into absorption and then eventually float?

 

[timselectric]

“Drops out”? As in shuts off? If the solar charge controller reaches its absorption voltage and the victron stand alone charger is still in bulk will the solar charge controller go into absorption and then eventually float?

No
It will just stop. Because the other charger is charging at a higher voltage.