Iota DLS-90 choice?

tkc100 wrote: »

Iota DLS series chargers

Iota makes a series of what they call converter/chargers. They do perform both functions but I have bad recollection of the older converters which made terrible chargers. So for me at least the two words are somewhat of an oxymoron. Iota chargers have some strong points and some weak points but seem to be an equitable compromise for someone like myself needing to charge a battery bank. I have yet to actually purchase one and I am posting this thread so that other might profit from what I have learned so far and so that perhaps I might get some additional comments.

The chargers come in a variety of sizes.
http://www.iotaengineering.com/dls.htm
It is important to size the charger to the battery bank. This is not a case where bigger is better. An over sized charger will put a great deal of unnecessary strain on a battery. A rule of thumb I have always used to size a charging source to a battery is as follows.
Charging current (amps) is ~5%-13% of battery capacity
For me it looks like this.
C20 amp hour rating for the battery bank is about 200 ah
13% percent (I want to get the battery charged as quickly as possible) = 26 amps
Here is where the first decision needed to be made. Iota makes six different models none of which exactly match this requirement so I have opted for the 30 amp model. Hey! I was raised in America and isn’t big really better. All kidding aside the model below it is only 15 amps so for me the best compromise was for the 30.
Now on to the next decision, the standard charger comes with a little plug in shunt that will allow for two different charging voltages. (13.6 or 14.2) Leave it out and you get 13.6 volts at 30 amps, plug it in and you get 14.2 volts at 30 amps. They also make an optional IQ4 charge controller that when plugged into the very same jack make the standard charger a “Smart” three stage charger. The DLS-30-M with the integral IQ4 charge controller can be purchase from Northern Arizona Wind and Sun for $162 + $15.97 shipping for a grand total of $177.97 I have done some checking around and that a very reasonable price from both Iota and NAWS. There are some reasons that I will go into a bit later that one might opt for purchasing the charger and controller separately for a few bucks more.

The charger is straight forward and it’s basically a follow the instructions plug it in kind of thing. However I found the instruction for the IQ4 controller to not exactly be misleading but at the very least a bit confusing. I had to read the instruction very carefully and then contact Iota for some clarification before I felt like a really understood. I am going to paraphrase the charging cycle without the oversimplified marketing terms.
Bulk mode:
Begins with the full rated current (ampere) output of the charger.
As the battery charges the actual current delivered or accepted by the battery
will decline and the voltage will increase. This is not an engineered function it is a normal function of any battery being charged by any charger.
When either the voltage hits 14.6 “High Trigger point” or 225 minutes (3.75 hours) have past
the charger will continue charging for an additional 15 minutes and then go into the absorption mode.
Absorption
This mode is a fully timed function (8 hours or 480 minutes)
The controller will regulate voltage to no more than 14.2 volts and the current
delivered will decline as the battery charges. In a simple unregulated charger voltage can exceed safe limits not only for the battery by for
other electronic devices associated with the system. (Control circuits within refrigerators and furnaces) There are no trigger voltages functioning in
this mode. 14.2 volts for 8 hours is it period
Float
This is a constant voltage charging mode.
13.6 volts for 7 days or if the battery voltage drops below “Low Trigger point” of 12.8 volts During the float stage the charger is delivering 13.6
volts with up to the rated current output of the charger. Should the voltage drop below 12.8 volts either from normal discharge or a short term
heavy discharge the IQ4 will start the charging cycle all over with the bulk charging stage
There is one additional mode mentioned in the IQ4 manual called Equalization.
This mode can not be initiated manually but is rater a function of time. If the battery remains in the float stage for seven days the IQ4 will start what they call an equalization charge. This is nothing more than restarting the Bulk mode charging cycle. When seven days have past or the “Trigger voltage” drops below 12.8 volts an equalization - bulk charge is started followed in sequence by the absorption and float stage. The maximum voltage for either the bulk or equalization mode is 14.8 volts. The equalization charge is merely starting a complete charge cycle with the only difference being that it is initiated by a timed function rather than a trigger voltage? There is no real Equalization mode. Most batteries require 15 to 16 volts to equalization.
Since I am on the subject of time, well at least kind of sort of one thing not mentioned any where at all is that should the charger lose AC power all memory is loss of any timed function. Everything starts anew with a Bulk, Absorption and finally the Float charge.
This is an important fact to consider if you anticipate an irregular power source such as operation off a generator. Here is Iota response to this, “Most customers who only use a generator do not use the IQ4. They simply select either the 13.6v or the 14.2v setting depending on what they think the battery needs. Another option would be to purchase the external IQ4 so you can remove it if you ever want to.” Anyone operating off an intermittent supply maybe well advised to get this charger and IQ4 separately.
Finally one additional thing that came to mind for me can be best illustrated with a scenario.
I put a cup of coffee in the microwave, the inverter kicks on and there is a momentary high current draw and consequently a voltage drop over the battery. (2 minutes) If the charger current output is not capable of supplying the inverter demands the difference in operating current will be supplied by the battery. You would not have to draw much current off a battery to a least momentarily drop the voltage below 12.8 volts.
12.8 volts is a really charged battery
Very roughly and this is not taking into account many things (power factor, voltage drop etc.) at 900 watts there will be a demand for 70 some amps.
If I have a 30 amp charger (properly sized for safely charging my battery bank) the additional current, 40 amps will come from the battery. The 40 amp draw will create a voltage drop below 12.8 volts. There is no time delay built into the controller logic.
The entire charging cycle will begin again even though the battery SOC is still good. The voltage will rebound the monument the coffee is done. The bulk cycle will shut down quickly at 14.6 volts but the timed absorption mode will continue for an additional 8 hours regardless of whether or not the battery needs it.

So there it is my rendition for the Iota charger.
What do you think?
Care to comment or add any thing I might have over looked.

I closing I will probably purchase this charger. Seems as all things in life end up in some sort of a compromise.

I don't know know how I got going down that particular road when I wrote the little above mentioned scenario although it's true it would only occur under very unusual circumstances. If the charger is operating then there has to be a 120v power supply, either shore power or generator, it wouldn't matter. The microwave would not in this case be operating off the inverter. Duh!