PV charge controllers: Absorption algorithm

[Ecnerwal]

The problem is that the current source is a DC generator! I can't
split that across two controller. Can I?

OK, you probably should have mentioned that to begin with.

Generator, or alternator? There are (mostly marine) alternator
controllers which will directly control the alternator by controlling
the field voltage. One such company was mentioned here recently:

http://www.amplepower.com

I'm sure that there are others. I have no knowledge of this place or
their products other than having looked at their web site.

 

[boB]

From what I can trell, as somone still in a "shopping around" rather
than "using" mode:

Buy another C60, or an MX60, or some other 60 amp controller and put 40
amps worth of panel on each one, running in parallel.

If you don't plan any more expansion, get a 20 or 30 amp controller, and
run them in parallel, with the appropriate split in the input from the
panels.

I don't know about the C60, but I assume they parallel adequately well,
as large systems have been built using them - I've read up on the MX60
and know that they can actively communicate with each other. Given that
they all would be looking at the same battery bank voltage, I don't know
how much communication is needed, but presumably a little would help
keep them from fighting over small differences in behavior associated
with component tolerances.

Well, I now know this was for a generator or alternator, but, thought
I would mention that as long as the batteries are not charged, the
voltage on them is going to be enough lower than the bulk, absorb or
float setpoint voltages, that each charger will just put out as much
as they can without needing to communicate with each other.

Then, when the batteries are nearly full, then without communications,
one of the chargers might be floating or absorbing, but the batteries
are at least real close to being full at that point, and one charge
controller will handle all that's necessary to keep the voltage up,
otherwise, another charge controller would kick in again.

Have a day !

boB

 

[boB]

***********************
boB
Does this mean that I could use two Trace C60 controllers and feed the
generator DC output to both inputs and they would share the load
evenly.
Has anyone actually done this? Do the Outback MX60's have a higher
"overload" rating than the Trace?

Well, It ~might~ work, but I seem to remember horror stories about
letting the smoke out. The MX60 will put out more than a C60 I
believe, (the current MX60s can be adjusted to 70 Amps) but I'm not
exactly sure what the C60 will do before it limits. Probably in the
60 amp range somewhere...

Just be careful. Generators have a very low impedance output and
aren't quite like a solar panel.
Also, you really shouldn't parallel INPUTS of these controllers.
Especially the MX60s. Can't do that or they WILL break.
(unfortunately)

Going out of town for a week and 1/2.

Have a day and 1/2 !!
boB