That would be a great way for Iota to set them up at the
factory. The device would be useful for many more applications,
including Mick's (in the link below).
Or, if the charger came with an option with a more durable, user
accessible potentiometer, it would be a great tool. The way it is
now would be better for on grid applications where user tampering
could damage batteries.
At 12:55 PM 10/26/2012, you wrote:
Hi Drake,
Good find. We always adjust the Iota's for different types of
batteries. Since this one is only used for back up purposes with a
generator, you can leave the jumper in and always run at 15.7 volts.
Once the voltage reaches that point, you will be +/-90% charged.
This will not harm a flooded battery.
If the converter is used long term with shore power, I would
recommend that you install a resistor where you soldered the leads
together to drop the voltage back to about 14.2vdc to preserve
battery life. Also add a switch in parallel with the resistor and
you will have the ability to select 14.2, 14.8 (jumper in) or 15.7 volts.
Larry Crutcher
Starlight Solar Power Systems
-------- Original Message --------
Subject: Re: [RE-wrenches] Off-grid non-inverter battery charger
recommendations?
From: Drake
<<mailto:drake.chamber...@redwoodalliance.org>drake.chamber...@redwoodalliance.org>
Date: Fri, October 26, 2012 6:23 am
To: RE-wrenches
<<mailto:re-wrenches@lists.re-wrenches.org>re-wrenches@lists.re-wrenches.org>
Through a strange set of circumstances, I found a way to equalize
batteries with an Iota charger.
My DLS 45 was borrowed on a couple of occasions. I made the mistake
of telling the borrowers how to adjust the voltage through the
potentiometer. Predictably, when I needed the unit, the pot had
been ruined. Calling Iota, they said there was no fix. The pot was
soldered to the board.
The way the device works is that lowering the pot resistance
increases the output voltage. My solution was to cut the pot out of
the circuit board and solder the leads together. Now with the quick
charge plug out, it holds at 15.2 to 15.4 volts. The the quick
charge plug in, it runs at around 15.7 volts. I equalized a pair of
T-105s yesterday without the quick charge plug. It worked like a charm.
This is much more useful for my needs than the factory
configuration. My uses are emergency charges from generators, often
in cold weather, and equalization charges. The operation of
removing the pot was tricky for me, but someone more used to working
with electronic circuit boards might not find it too difficult.
At 01:27 PM 10/15/2012, you wrote:
Hi, Mechanix~
Bill Dorsett polled the group about recommended battery chargers
for connection to a generator. Iota brand is the successor to Todd
brand; I believe Iota bought the designs, tooling, etc. and these
have appeal because of the relatively low cost per rated amp. They
seem generator tolerant.
The Todd design is a "constant voltage" type charger,
however--basically an AC to DC converter with a fixed voltage
output. In my experience, the "75 amp" Todd type charger will
deliver 75 amps only for a relatively short time when first
connected to a low battery. As the battery's voltage comes up that
presents a sort of "back pressure" which slows the rate of charge.
That's not so bad if one has utility power >always on< to drive the
charger, but if an engine generator is running...
The inverter/chargers (with which we are all familiar) begin with a
"constant current" part of the charge cycle--aka bulk charge. The
charger is determined to sock the battery with the amperage we have
requested in the setup; I think a pulse width modulation is going
on where the charger hums up its voltage in order to keep the amps
high even as the back pressure builds. When it's time for the
absorption phase of the charge, the logic shifts to a "constant
voltage" where the amps are gradually dialed lower in order to keep
the battery at the target voltage so it can "absorb". Ignoring the
float phase which would come later, this overall charge regimen
would be called CC/CV for "constant current/constant voltage". The
CV part of that is not much different from what a Todd style
charger does; it's just that the Todd design does not precede that
phase with a CC "constant current" phase.
Some free-standing battery chargers have a CC/CV algorithm but
those seem to cost as much or more than a comparably rated
inverter/charger. Check the Magnum mod-square multi's, Bill, such
as their RD series. As others on this List have noted, just the
charge function is pretty good and since the inverter circuit is
not pure sine, that keeps the cost lower. Built in time delay
before it loads up the generator is an added benefit.
Jolliness,
Mick Abraham, Proprietor
<http://www.abrahamsolar.com>www.abrahamsolar.com
Voice: 970-731-4675
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