controller settings for diversion load and generators... [RE-wrenches]

[Darryl Thayer]

Thanks Hugh for bringing this to the attention of
folks.
Your points are well taken and most certianly apply to
PV also.  The battery charging and control issues also
apply to series regulators. The battery charging and
control issues are real and mostly not delt with by
manufactures.  I have done some things with series
diodes to get a voltage drop of half to 3/4 volt per
diode to solve some of the problems.  However with my
age I am no longer able to contribute to the solution
due to the complexity of the issues.

However I feel that things like the smart shunt that
Outback proposed a while back is a step in the right
direction.  Also a remote sense on the battery voltage
allowing the inverter-controller system to function
correctly even when the battery voltage is droped
uning diodes.  In my dreams the charge
controller-inverter system would look at the currents
in the inverter, charge controller and DC loads use an
algorhythem to correctly charge the battery (ie using
the state of charge and voltage to determine the
charge rate to prevent gassing overcharging
undercharging ect).  In Outbacks case this may require
two seperate smart shunts and remote voltage sense,
along with a super Mate to oversee this configuration.
 

To help with the Overvoltage, Maybe there is a circuit
that has no standby load or standby in the mill-amp
range yet can give a 1 or 1.5 volt drop over a very
large current range.  Perhaps a series regulator would
surfice for the voltage control problem, the small
manufactures solar controllers, BK etc. could take the
lead. (As you know, series regulators are easly built
for small current loads using three terminal
regulators. But I always get scared when I build a
special circuit for a customer.)     

Darryl 

--- Hugh <hugh at scoraigwind.co.uk> wrote:
> Hi
> 
> I'd like comments on an old but little discussed
> problem.  It relates 
> to wind or hydro systems (or even PV) where a
> diversion load is used 
> for charge control for example with a c-40 or
> tristar.  There is also 
> an engine driven generator on the system and it
> feeds into the 
> inverter (SW, FX, studer, whatever) and this charges
> the battery.
> 
> At a certain point the charge controller will go to
> float the battery 
> and if the inverter is still trying to bulk it then
> you will have the 
> controller maxed out on heating something at the
> expense of engine 
> fuel.  YOu can tinker around with settings on the
> inverter and the 
> controller but it is hard to get a satisfactory
> arrangement that 
> charges the battery properly.
> 
> I have used a blocking diode to solve this by making
> sure that the 
> diversion current all comes from the renewables but
> this is not ideal 
> - leads to vibration in the turbine and stuff like
> that.
> 
> another question.  What bulk setting do you guys use
> for gel 
> batteries (eg Fullriver HL series) and how do you
> ensure that they do 
> not gas and lose electrolyte.  My supplier recently
> told me to use 
> 29.6 volts for a bulk charge.  I am pretty sure this
> could lead to 
> problems since the controller will not really 'know'
> when exactly to 
> go to float voltage and I can foresee some loss of
> electrolyte, no?
> 
> Then there is temp compensation.  This can push the
> charging voltage 
> up to 31 and trip the inverter.  I have a client
> runnning datalogging 
> equipment and the supply must never go above 30
> volts but in cold 
> weather the battery 'needs' to get up to 31.  what
> to do?
> 
> Lots of little puzzles.  Any comments welcome.  It
> shows how immature 
> the small wind industry is that the controllers you
> buy do not have 
> inherent solutions to these problems (except perhaps
> the outback 
> products that talk with each other - but how many
> people can figure 
> out how to program all of that?)
> -- 
> Hugh
> 
> Scoraig Wind Electric
> http://www.scoraigwind.co.uk/


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