[RE-wrenches] Off-grid non-inverter battery charger recommendations?

[Drake]

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.chamberlin at redwoodalliance.org>drake.chamberlin at redwoodalliance.org>
>Date: Fri, October 26, 2012 6:23 am
>To: RE-wrenches 
><<mailto:re-wrenches at lists.re-wrenches.org>re-wrenches at 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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