Multiple Charging Sources to the Same Battery Bank

[btrayfors]

Don't forget that the pulsing is EXTREMELY RAPID...so much so that even sensitive solid state devices won't notice. I wouldn't have any hesitation using the Iota's as a power supply.

One thing I failed to make clear: the Iotas are constant voltage chargers, i.e., they supply their pulsed average 13.8VDC (default setting) irrespective of the state of charge of the batteries they're attached to. The pulsing makes for a much larger average transfer of power to the batteries, while virtually eliminating the possibility of overheating (hence, no temp sensors needed). This makes for a fast, full, and safe charge scenario.

Nick...no need to isolate the batteries being charged. Case-in-point: many of my HF and VHF radios are run from a single bank of two T-105 batteries which is ALWAYS under charge from the DLS-45/IQ4. The batteries act as a big capacitor, so I doubt that much if any of the pulsing action is actually transmitted to attached devices.

Nick, again... the Iotas are supplied with and without the IQ4 regulators. Some models have the IQ4 built-in (I have one of them on my boat...a DLS-55/IQ4). Others have a plug-in IQ4 module as an add-on, which provides the "smart charging" features. These little devices cost about $35 and plug in via a short RJ-11 terminated cord.

BTW, I am NOT IN ANY WAY CONNECTED TO IOTA. I just think they make a pretty damned good and unique product, and do so at what has to be considered to be an extraordinary bargain price in today's market.

Bill

[s/v Jedi]

Bill,

Thanks for the info. I think I now understand how the Iota works. But I see several problems with them for use on a live aboard cruiser:

• The Danfoss inverter/controller boards are very sensitive. They take DC input and make a high frequency 3-phase AC (!!) out of that. You can get into a lot of trouble when mix products of both frequencies start interfering with the power feed to the compressors.
• The IQ-4 smart controller might not do much looking at your results. But to be fair, it should be tested at half-full batteries. However, it should at least do bulk and absorption phases because that is within the definition of a "smart charger". But it is impossible to do that when the pulses are always 13.8V, so what does this smart controller do, what charge-phases does it introduce and how do these work?
• The 13.8V pulses from the Iota regardless of state of charge of the batteries is a problem. For example, the Trojan batteries you use really need 14.4V. Iota might be proud that they don't need a temp.sensor but the 13.8V pulses also mean that 1) the battery charging process takes much longer; 2) the battery never gasses so you get stratification of the electrolyte as the result.
• Can the Iota do an equalization phase? I bet not because the design doesn't allow for that. This means you will also get sulfate crystal build-up on the plates, resulting in a shorter service life of the batteries.
• Even though I realize that these Iota's are built for battery charging, they look very much like power supplies to me. That IQ-4 module strengthens that idea. But who would make a DC power supply that pulses?
• I would like to hear what battery manufacturers have to say about that 13.8V pulse charging of their batteries. All I read is that they want you to use pure DC chargers; pulse charging isn't mentioned.

I would love to have a test bench with batteries, loads, Iota and Victron chargers. I would want to see how fast each charge the batteries, what the specific gravity of the electrolyte is before and after charge and how many Ah they put into the batteries during a charge cycle.

As I don't have that anymore and can't find detailed info on the Iota's, I wouldn't consider them for myself with the little that I know about them now.

ciao!
Nick.

[Bash]

Originally Posted by ka4wja

But, I have worked on a few wind gens....and I read stories about those with both wind and solar having troubles with their controllers "fighting" each other....

If the solar charge controller is set to shut down at 4.5, set the wind generator to turn itself off at 4.2. That way, if the batteries are almost topped up, the turbine shuts down before the solar, rather than vice versa.

(BTW: A self-regulated wind generator, such as an Air Breeze, should never be run through the charge controller for the solar, because when the controller shuts off the charge, it will actually cause the turbine to freewheel.)

[Joli]

Timely subject. Our inverter/charger just took a dump so we'll install a Iota DLS2740 with the IQ4 smart charger. Not sure what we want for next year but since the season will only last another 3 weeks we may as well try something cheap and easy. I'll let you know how the Iota works out for us.

[btrayfors]

Nick,

The 13.8 volts is AVERAGE. The pulsing is both positive and negative. Think of the Iota's 13.8V output as RMS, like in AC systems. Peak voltages in a 120VAC system are more than 170 volts positive and negative, or some 340 volts positive peak-to-negative peak. But the average is 120 volts.

Your concerns, IMHO, are largely unfounded. I believe the concept of PWM and it's use in battery charging just hasn't sunk in yet. And, I admit, it's pretty hard to get one's head around the concept of a basically DC system with a basically AC overlay which is variable in it's principal components: amperage, voltage, phase, duration (pulse width), and frequency (cycles). Don't forget, all this pulsing is happening at a varying but extremely high rate.

In fact, the Iota's work just fine with Danfoss compressor circuits, and with motors.

The IQ-4 is in fact a smart-charge device designed to tailor the output of the Iota's to the state-of-charge of flooded and AGM batteries.

The benefits of pulse charging have been investigated by large automobile manufacturers. Those scientists actually involved in the research have stated that, indeed, pulse charging is the BEST way to quickly and fully recharge a deep-cycle automobile battery designed for electric cars.

The "equalization" cycle performed by the Iotas is still a bit of a black box to me. I haven't seen any data, but I do know that periodically the AVERAGE voltage is raised. Presumably, the pulsing continues, perhaps at some more intense rate.

As earlier mentioned, though, my experience with Iotas and flooded T-105 batteries over the past five years leads me to believe that they maintain the CAPACITY of these batteries better than do pure DC chargers. This would have to mean that, inter alia and ipso facto, they in fact do have some beneficial effect in limiting or preventing the permanent formation of PbSO4 crystals on the plates.

Re: manufacturer's data and disclosures, I doubt we'll ever get full and final engineering data. It's proprietary and, understandably, a manufacturer might be reluctant to disclose all the underlying secrets :-)

So, we poor consumers are left with applying our knowledge and experience to:

- incomplete engineering information from the manufacturer;
- personal experience with the product(s);
- anecdotal reports; and
- semi-scientific and incomplete measurements of our own.

What a pickle :-)

Have we beat this one to death, yet?

Bill

[s/v Jedi]

Originally Posted by btrayfors

Have we beat this one to death, yet?

Oh no, here we go ;-0

The 13.8 volts is AVERAGE. The pulsing is both positive and negative. Think of the Iota's 13.8V output as RMS, like in AC systems.

Ah, okay, now I know where we are.... SNAKE OIL!!

Before I cite a good source about this (with references to other sources), I must state that Iota clearly states that their chargers are not pulse chargers and deliver a clean, regulated constant DC output.

So where this pulse idea comes from is beyond me, but not from Iota itself!

Now, the easiest pointer is this pdf document: http://www.batterypoweronline.com/im...rdesigners.pdf

There has never been a study that confirmed that pulse chargers are better and there have been many studies that show no improvement whatsoever compared to constant voltage charging, and many of these studies were done by General Electric, a decent organization.

The only "good" thing about the whole concept is that the practise doesn't seem to damage your batteries.

So, I would never use a pulse charger but I doubt that the Iota chargers are pulse chargers... if they are, Iota is lying about it.

cheers,
Nick.

[S&S]

Originally Posted by btrayfors

Nick,

The pulsing is both positive and negative. Think of the Iota's 13.8V output as RMS, like in AC systems.
Bill

If that's true then there'd be no net ion movement from one plate to the other. (charge half a cycle, discharge half a cycle).

[btrayfors]

Yeah, it sure is confusing!

Here's a screen shot from the DLS-45 with external IQ-4 regulator. The pulsing can clearly be seen. However, don't pay much attention to the parameters noted, except for the 1.38V average (I was using a 10X probe, so the average voltage was 13.8). The other parameters were constantly changing...frequency, rise time, etc, etc.

But, the pulsing effect was always present, pretty much as shown in this pic.

Haven't had time to investigate further, other than to note that the same measurements taken on a DLS-55 with internal IQ-4 regulator on my boat appeared NOT to show any pulsing. Could they have changed the design? The IQ-4 design?



The plot thickens :-)

Bill

[bill good]

Bill,
Was that measured with a battery bank connected or unloaded?

[btrayfors]

The Iota DLS-45/IQ-4 was connected to a bank of two Trojan T-105 batteries in my radio shack at home. It is on 24/7, so the batteries were full. There was no draw on the batteries whatsoever during the measurement.

Measurement was taken at the ANL fuse lug which is connected to the Iota with 14" of AWG4 battery cable, and at the negative battery terminal to which the negative lead of the Iota is connected. The AWG4 from the other pole of the ANL fuse is 7" long and is connected directly to the positive battery pole.

The probe was a 10X, calibrated.

The 'scope was a DSO GW Instek GDS-1102 100mHz (new).

When I get more familiar with the 'scope maybe I can tease out a bit more info :-)

Bill

[s/v Jedi]

It was with batteries connected if I remember right.

Okay, this is what we see: a 13.8V DC voltage with a 1V peak-peak (98mV times 10 because of the X10 probe) ripple superimposed on top of it. The ripple has a 20 MHz frequency (almost two periods fit in one 100ns unit, so about 50ns period which is 20 MHz. The duty cycle of the ripple looks like 50% to me, even though the scope says 86% but that value is changing all the time.

So, first of all, this is not a pulse nor PWM charger. Even if we take the ripple as a design feature, the output voltage varies between +14.3V (13.8+0.5) and + 13.3V (13.8-0.5), so never reaches 0V and never crosses into a negative value.
A pulse charger outputs a pulse, followed by 0V or by a negative pulse, not a ripple superimposed onto a DC.

What we are left with is a switch-mode power supply with a ripple that looks much like those pulse-conditioners. Everyone has done away with those conditioners because they are snake oil and thus it sounds reasonable Iota also did away with it. However, it is the high frequency that bothers me. This doesn't come from the switch-mode circuitry because that works around 70 kHz. The only 20 MHz frequency I expect in a charger is the clock signal from it's CPU or micro-controller. I also think that those pulse conditioners work at a much lower frequency. At 20 MHz, nothing will happen in the battery.

So, as I think it over I come to the conclusion that this is probably a fault in the charger or that smart module. The second unit aboard that shows a clean DC confirms that and this is in line with the statements on the Iota website: clean, regulated output.

I still think it's a power supply, not a charger. The batteries are full and there's 13.8V which means it doesn't have a float phase and the batteries are gassing more than needed. I really wonder what voltage it will put out with an empty battery. My guess is that it will be 13.8V also, because that's what a power supply does: constant voltage.

The IQ4 module is supposed to convert it into a battery charger. This means the combo of DLS+IQ4 must be tested on partly discharged batteries. If it still outputs 13.8V, the IQ-4 is broken or not doing anything by design (they just take your money, giving you no smart nothing in return... wouldn't be the first time I see that). If this charger never goes above 13.8V, the battery is never fully charged.

ciao!
Nick.