Setting My Dump Load Voltage

[WooferHound]

I have solar power and plan to add wind power in the future, so I'm using a Ghurd Dump Controller to prevent overcharging the batteries. A regular Solar charge controller will take the battery up to a max voltage over 14 volts and then back the voltage off to somewhere around 13.1 volts and float it there. But the dump controller lets the battery get up to the Set Voltage and will hold it there until the Sun goes down or the wind stops.

In the beginning I had the Set Voltage between 14.6 and 14.7 volts. I mentioned it in another thread and everyone was barking that it was set too high, and looking back at it, I can see where I killed a few batteries having it set that high. Since then I have lowered the Set Voltage to 14.05 volts and it seems to be working very well so far.

So ,  now I'm asking the group what is the best voltage to set my dump load for when charging a pair of Trojan T-105 batteries ?

[Norm]

I've often wondered about this myself, I have a 75 amp/hr SLA
that I usually PedCharg, seldom....seldom run the risk of over charging!
However ....the number for me is 13.65 so thru trial and caution I come
up to almost 14 and stopping and letting it rest for a 1/2 hr. and
maybeit comes back down to 13.75.

Not saying or even suggesting that you use these numbers, I'm just
saying that I've got this one particular battery that so far 10 yrs.

If I ever get Ghurd's dump controller kit finished and start using it, I'll
know what to actually do....I probably haven't helped and I'm expecting
G to come in and set me straight at any moment now.....  LOL !

Well maybe I'll finish the GDC kit today or at least get started on it.
thanks for listening.

havin' fun here in Conneaut....
cause you guys help to make it so...
Norm.

[ghurd]

For FLA:

I am still big on 14.4V, if the system is somewhat balanced.
Balanced is for the charging power, loads, and battery size.

Solar will only get it up to 14.4V for a few hours a day?  If you are lucky?

Wind is kind of a guess.
In a place where "the wind doesn't blow, it sucks", and there is not a lot of space for a large or tall turbine, I would stay at 14.4V unless it proves to stay at 14.4V for more than 75%(?) of the time, which I don't see happening very often in a 24 hour period.

Woof, you have regular loads on a daily basis, so at the lowest, maybe 14.2V?
But given your circumstances as I figure they are, I'd set it at 14.4V anyway.

For SLA:
13.8V if used much.  Maybe 13.2V if just a standby battery.

Had a car that the alt charged to 14.4V, and it went ~170,000 miles with the factory battery.
Hard to argue with that.
G-

[Norm]

Ah well went to finish the Ghurd dump controller and I'm
certain that everything was in the little box but the ......
oops there they are on a seperate piece of masking tape just like
I remembered now that I've found them .....now to clean up my  tiny
soldering iron and try to go as far as I can before something stumps
me seems like there was something about setting it up for the first
time  ....(stay tuned for further developments)
tweedly dee and tweedly dum for now (probably should lay off the sauce
for awhile?) LOL
 envy you guys being able to wire stuff like that into a complex circuit.....
Norm.

[Norm]

okay all done (I hope) now all I have to do is solder wires from battery .
Okay here I have this battery charger that has input of 66 watts...110 volts
output of 16 volts @2.2 amps. thru a full wave rectifier now I run these 2 wires + and -
to where on the dump voltage?

Don't want to accidentally let the magic smoke out....
even tho' to someone else might be obvious.
I hope I got it all hooked up right
Norm.

[ghurd]

now I run these 2 wires + and -
to where on the dump voltage?

Battery charger (grid, solar, wind, hydro, pedgen, etc) connects straight to the battery.
G-

[MadScientist267]

Woof -

Kinda threw this around while we were talking the other day, figured I'd put it out here for others as well.

For me it is pretty evident that there are numerous factors that affect the highest voltage a battery should see:

    Type (FLA/SLA)
    Design purpose (Cranking/Deep cycle)
    Use case (Cyclic/Standby)
    If cyclic, frequency of use, length of charging time between discharges
    Depth of discharge (prevention of hard sulfation)
    Temperature
    Subtle differences in plate composition from manufacturer to manufacturer

Maybe more, I'm sure that's not it.

The biggest issues affected by the above are:

From excessive voltage:

    Excessive water consumption for FLA
    Cell dehydration for SLA (not reversible)
    Positive plate oxidation (not reversible)

From low voltage:

    Incomplete charging, resulting in less than 100% capacity available for use
    Plate sulfation (not reversible)
    Exacerbates cell balancing issues

So, there really is no "one size fits all" voltage to set a controller for. All of the above factors come into play.
I had a set of deep cycles, where a 13.8V float boiled them COMPLETELY dry in not a whole lot more than a years time. I drew a conclusion on how much water they would need based on an 8D that sat on float at the same voltage for 4 years and only needed water once - level never got NEAR the plates, nevermind dry the cells out.

It all depends. Check with the manufacturer, best bet.

Steve

[Norm]

now I run these 2 wires + and -
to where on the dump voltage?

Battery charger (grid, solar, wind, hydro, pedgen, etc) connects straight to the battery.
G-

Okay after a good nights sleep .....this morning it dawned on me
of course ......thanks Ghurd.
......and I won't need both of those power fets hooked up at 4.4 amps ?
(from the charger) or 2.5 amps (from the pedgen) ?

and Question2 will one of these dump load controls  work on 18volt and 19.2 cordless drill batteries?

Norm
and when I touch the last wire to the battery either the green led comes on
or the magic smoke escapes ?  (probably cross my fingers and hope for the
former ?)

[Norm]

I finally got it all I have to do is the dump load and the power fets
scavenged a 104 cap from a non-working 18volt charger and the Green Led
hooked them up the right way and they worked and before hand lot of
poorly soldered joints that I fixed cheap Walmart soldering pencil works
neat after hooking it up to a dimmer switch so I can adjust the heat.
  Dog tired after all that messing around.....but happy !
Norm.