Issues with multiple charge controllers

[ericfx1984]

Help?!?!

So I've been running multiple charge controllers for quite a while.. and it's never really been an issue.. but what I've noticed now that I've increased my battery size is that a few of the charge controllers basically start doing nothing I also did a little looking and realize that the church controller seem to be reporting a higher voltage than they should be

I have a pretty huge battery Bank all together over 1600 amp hours at 12 volts

The charge controllers I'm running are:

-1x EPEver 4210 40amp MPPT

-1x Victron 100/50

-3x EPEver 6415an 60 amp

The charge controller seem to pick up if I put a load on the battery.. or rather on the inverter


I'm guessing there's got to be a setting or parameter that can make these work a little better

 

[DThames]

They will all behave according to the battery voltage and the boost/float settings. Just pretend you have 2 EPEverAN 60amp and one sees 12.80v and the other sees 12.75v when the battery is really 12.78v. To hold Float at 12.75v, one will do work while the other one will think you above float and do nothing. If you can get the voltage down to 12.60v, you would expect both to be doing some reasonable work. That is just the behavior of having more than one trying to control the voltage.

 

[ericfx1984]

They will all behave according to the battery voltage and the boost/float settings. Just pretend you have 2 EPEverAN 60amp and one sees 12.80v and the other sees 12.75v when the battery is really 12.78v. To hold Float at 12.75v, one will do work while the other one will think you above float and do nothing. If you can get the voltage down to 12.60v, you would expect both to be doing some reasonable work. That is just the behavior of having more than one trying to control the voltage.

Well there has to be a way that I can manipulate those readings right?

 

[ericfx1984]

So I decided to fire at my generator and pump 100 amps into the battery

There has been no drop in power on the smaller 40 amp EP ever nor on the victron... Fight the fact that the40a EPever is now showing 14 volts

I think I need to play with some of the parameters on the 60 amp EPevers

 

[ericfx1984]

The biggest differences I noticed is the smaller controller as the load function turned on whereas the larger ones did not.. after turning on the load function the power output increased in the larger units.. so I think that might be helping

 

[Samsonite801]

If you had all Victron charge controllers you could sync them together in a bluetooth network group all reading off a single shunt / battery monitor (to read voltage, current, and temperature from common measurement point), then it picks a master, and the rest are slaves, and while it allows the current to be variable, all of the charge controllers with operate in the same charging stage in tandem (i.e. bulk, absorption, float, etc.)

Example application:

Synchronizing multiple MPPT 150/70 charge controllers - Victron Energy

Synchronizing multiple BlueSolar charge controllers MPPT 150/70 is now possible! Synchronizing chargers, also known as paralleling, has several advantages: Don't waste solar power: all chargers will always be in the same state, no risk that one of them switches to float to early Simple...

www.victronenergy.com

I currently do this with two 250|100 chargers syncing to a BMV-712 battery monitor shunt, and it works seamlessly...

Without syncing ability, you just have to try and set all your charge controllers to identical settings on custom charge profiles and hope they read the same battery voltages based on their own sensing (since they can't read from a common point, nor are they all calibrated the same, they are inferring their own-found voltage measurements, based on what they think they see).

 

[ericfx1984]

If you had all Victron charge controllers you could sync them together in a bluetooth network group all reading off a single shunt / battery monitor (to read voltage, current, and temperature from common measurement point), then it picks a master, and the rest are slaves, and while it allows the current to be variable, all of the charge controllers with operate in the same charging stage in tandem (i.e. bulk, absorption, float, etc.)

Example application:

Synchronizing multiple MPPT 150/70 charge controllers - Victron Energy

Synchronizing multiple BlueSolar charge controllers MPPT 150/70 is now possible! Synchronizing chargers, also known as paralleling, has several advantages: Don't waste solar power: all chargers will always be in the same state, no risk that one of them switches to float to early Simple...

www.victronenergy.com

I currently do this with two 250|100 chargers syncing to a BMV-712 battery monitor shunt, and it works seamlessly...

Without syncing ability, you just have to try and set all your charge controllers to identical settings on custom charge profiles and hope they read the same battery voltages based on their own sensing (since they can't read from a common point, nor are they all calibrated the same, they are inferring their own-found voltage measurements, based on what they think they see).

So maybe I would need to adjust parameters a little bit? Perhaps increasing the charge voltage on the units that are lagging behind a little?

 

[Samsonite801]

So maybe I would need to adjust parameters a little bit? Perhaps increasing the charge voltage on the units that are lagging behind a little?

First you should get to understanding the charging stages better. Study the charts in each of your charge controller manuals. Figure out what charging stages each of them are on based on their trigger voltages, understand what CC and CV mean, so you can try to manipulate your settings for Bulk, Absorption, Float, also know how LFP requirement is different (if you're using LFP vs a lead type, AGM, GEL, flooded, etc. battery)...

I would start there. Because it's not just a matter of 'setting the voltage higher'...

 

[ericfx1984]

Because it's not just a matter of 'setting the voltage higher'...

It might be if a unit not calibrated correctly and therefore reading a voltage higher than it actually should be...

 

[Samsonite801]

It might be if a unit not calibrated correctly and therefore reading a voltage higher than it actually should be...

Yeah I guess I was mainly just trying to stress that, so if that was the case like a voltage calibration issue, you might adjust for it, but would presumably have to make the tweak on all stages of the charging curve (like float and absorption)... Like adjust both up .1v and try it for example...

I understand where you're coming from though.

 

[ericfx1984]

Yeah I guess I was mainly just trying to stress that, so if that was the case like a voltage calibration issue, you might adjust for it, but would presumably have to make the tweak on all stages of the charging curve (like float and absorption)... Like adjust both up .1v and try it for example...

I understand where you're coming from though.

Well that's what I'm noticing is each one of them is displaying a slightly different voltage.. if this was let acid we would never even care about a tenth of a volt difference it really wouldn't matter... But we're talking about lifepo4... A tenth of a volt would be the difference between being at 40% state of charge or 90% state of charge...

So I do think it's a calibration issue between them.. I'm going to try and take some readings to get a little more accurate information.. you know for instance when one of them is saying 14 volts and the other one is saying 13.6 that's a pretty big difference

I also need to confirm is that the voltage being produced or outputted by the solar charge controller or is that the voltage that the solar charge controller is reading? I really don't know.. I suppose the two that are working well I could try and adjust them towards that one... I know I'm using the same charge profile for all of them but that doesn't seem to be working

 

[Samsonite801]

Well that's what I'm noticing is each one of them is displaying a slightly different voltage.. if this was let acid we would never even care about a tenth of a volt difference it really wouldn't matter... But we're talking about lifepo4... A tenth of a volt would be the difference between being at 40% state of charge or 90% state of charge...

So I do think it's a calibration issue between them.. I'm going to try and take some readings to get a little more accurate information.. you know for instance when one of them is saying 14 volts and the other one is saying 13.6 that's a pretty big difference

I also need to confirm is that the voltage being produced or outputted by the solar charge controller or is that the voltage that the solar charge controller is reading? I really don't know.. I suppose the two that are working well I could try and adjust them towards that one... I know I'm using the same charge profile for all of them but that doesn't seem to be working

Yeah and try to get a 'feel' for if one charger is on absorption stage while another one already switched to float stage (can be tricky if it is a 'dumb' charger, unless they have some kind of indicator on them, perhaps an amp clamp meter could help)... Anyways, good luck on it.

 

[Samsonite801]

Oh and it just occurred to me that make sure all your cables are plenty beefy, and maybe observe the equal length rule, so all the chargers have a higher likelihood of seeing the same battery voltage without significant voltage drops anywhere. Just something to also be mindful of as a potential contributor... Anytime you go from one-to-many or many-to-one, the equal length path distribution lengths should be balanced...

 

[Warpspeed]

Well that's what I'm noticing is each one of them is displaying a slightly different voltage.. if this was let acid we would never even care about a tenth of a volt difference it really wouldn't matter... But we're talking about lifepo4... A tenth of a volt would be the difference between being at 40% state of charge or 90% state of charge...

So I do think it's a calibration issue between them.. I'm going to try and take some readings to get a little more accurate information.. you know for instance when one of them is saying 14 volts and the other one is saying 13.6 that's a pretty big difference

I also need to confirm is that the voltage being produced or outputted by the solar charge controller or is that the voltage that the solar charge controller is reading? I really don't know.. I suppose the two that are working well I could try and adjust them towards that one... I know I'm using the same charge profile for all of them but that doesn't seem to be working

Quite a few (most ?) of these charge controllers might have a voltage accuracy specification of +/- 1% and might have that kind of error brand new.
After a few years it might have become worse than that.
One percent does not sound like a lot, but its half a volt at 48 volts. Two different units might display a whole volt of difference !

If there is only one charge controller, you might not ever know. But if you have two or more, it becomes rather noticeable. Even if there is a voltage calibration feature, which some of the better units have, getting closer than +/- 0.1 volts is not really possible anyway where the whole thing operates with 0.1 volt steps.

As stated above, if one charge controller sees a slightly higher voltage, it will quickly reduce charge current up at its voltage setting, where the charge controller next to it might still be running at full available current.

Not a lot you can do about it. But once it reaches full battery voltage setting, it really does not matter if one unit is charging at 19 amps and another at 1 amp. It would be nice to see both at 10 amps, but its just never going to happen like that.