Can Iota chargers run with less power?

hillbilly

A stupid question (my favorite kind) about Iota chargers: is it possible to run it only partially powered via a generator? Specifically, a 55amp charger with a "Max AC draw" of 1620VA or 1053Watts powered by a single Honda eu1000? I wasn't sure if it would operate at a lesser output, or if the generator would bog down by trying to deliver the full load, or....?
Thanks
HB

BB.

Re: Can Iota chargers run with less power?

If the Iota had a programmable current output (where you could manually cut it back to 20 amps or so)--you probably could.

However, I don't ever remember seeing anything to adjust the maximum current.

I believe that Icarus/Tony said before that the old Xantrex TC 20 amp (12 volt) charger ran fine on a Honda eu1000i. However, the TC 40 amp required a eu2000i.

The Xantrex TC was Power Factor Corrected (PF~1.0)--which reduces the VA (amp) draw. The Iota is not PF corrected (1053 watts / 1620 va = 0.65 PF)

1,620 VA would probably require a 1,600+ watt genset to power.

-Bill

hillbilly

Re: Can Iota chargers run with less power?

Yes the Iota chargers have NO user input, unless you count the telephone jack that you can plug in and out to adjust the voltage slightly. I kind of thought that might be a bit too optimistic of me....

halfcrazy

Re: Can Iota chargers run with less power?

the iota wont back off it will overload and trip a breaker in the generator

icarus

Re: Can Iota chargers run with less power?

Actually Bill, if memory serves, the Xantrex TC series were not PF corrected and that was the reason the 40 amp wouldn't run on the Eu 1000. I had an e-mail from Xantrex Tech support speaking to the PF issue, and if memory serves the PF was in the .65 range. Of course I have long tossed the Email. I am away so I can't test mine with a killawatt to confirm the pf, but I think I am remembering right.

It was something like the 40 amp output times the full battery voltage, times the PF times the conversion ef equalled something in the range of 1200 watts.

What the Xantrex chargers do quite well is accept funky input voltages as low as ~75vac with out complaint.

Of course the Xantrex web site document specs don't speak about PF, but I will look a littl further,

T

PS I was close,, PF for the TC 20 is .66, for the 40 .68. Efficiency of .83. I'll leave the math to others! LOL.

T\
http://www.xantrex.com/web/id/462/docserve.aspx

BB.

Re: Can Iota chargers run with less power?

Tony,

You are correct... Found the manual here (Xantrex site is changing--not working now). Is not power factor corrected:

Truecharge20+ / Truecharge40+
AC input voltage range90 – 135 VAC, 50/60 Hz
Maximum AC input current at
90 VAC
6.5 Arms / 12 A rms
Typical AC input current at
120VAC
4.6 Arms / 8.5 Arms
No-load AC power draw
without remote panel)
less than 3 watts / less than 3 watts
Power factor rated load 0.66 / 0.68
Efficiency—peak 83% / 83%
Surge protection: Line-to-neutral surge protector rated at 150 V

-Bill

Brock

Re: Can Iota chargers run with less power?

You can't back off an Iota charger that I am aware of, but what you can do is add a length of wire on the output side to "trick" the charger in to thinking the battery is at a higher voltage than it is because of line loss. I did a setup like this to run a DLS 48v 15a unit. At the time I only had a 1000w inverter and it would trip out every time I plugged in the iota. So what I did was add 30 feet of #14 between the positive output and the battery bank connection. Then the charger thinks the battery voltage is higher than it really is and starts backing off on the current. The problem with this setup is that it is dependent on the battery bank voltage. If they are less 51v I needed 60 feet of cord to limit to about 700w of charging.

On the plus side it still eventually gets the battery bank up to voltage, but you obviously lose some power in the added wire.

The other thing I have noticed with iota chargers is they have a strong hit when they start, pulling about 3 times he running wattage for 2-4 seconds and then falling off to the running load. I think they may be charging an internal cap or maybe just running at full until they figure out where they need to be.

hillbilly

Re: Can Iota chargers run with less power?

Brock wrote: »

You can't back off an Iota charger that I am aware of, but what you can do is add a length of wire on the output side to "trick" the charger in to thinking the battery is at a higher voltage than it is because of line loss. I did a setup like this to run a DLS 48v 15a unit. At the time I only had a 1000w inverter and it would trip out every time I plugged in the iota. So what I did was add 30 feet of #14 between the positive output and the battery bank connection. Then the charger thinks the battery voltage is higher than it really is and starts backing off on the current. The problem with this setup is that it is dependent on the battery bank voltage. If they are less 51v I needed 60 feet of cord to limit to about 700w of charging.

On the plus side it still eventually gets the battery bank up to voltage, but you obviously lose some power in the added wire.

The other thing I have noticed with iota chargers is they have a strong hit when they start, pulling about 3 times he running wattage for 2-4 seconds and then falling off to the running load. I think they may be charging an internal cap or maybe just running at full until they figure out where they need to be.

Thanks for the info Brock, I wouldn't have thought of such a solution! I doubt that it would really be of much help in this situation, but the next time I've got some extra wire that I'm dying to use I'll think of your suggestion :-) In this case I could use either a 55A or a 30A charger (both 12V), as I have two that I really don't have a use for at the moment. I was hoping to use the larger size charging unit as we're using a 212AH concorde AGM battery, and the 55A size seems a perfect fit.

Just curious when you mention the higher power draw initially (not surprising), how did those numbers compare with the listed specs from Iota. I ask because even with the 30A charger, I think we'll be fairly close to the Honda's max output depending on the "real world" numbers. I'm off to run some tests today to try and get a better sense of that, but it'd be great to hear some more from someone who has used those chargers a LOT more than I.
Cheers,
HB

Brock

Re: Can Iota chargers run with less power?

I haven't really measured the draw from the iota, but when I use it on an inverter I can see it is about 1500w on startup and drops to about 700-800w when running normally (one led per 100w), and again it is at 1500w for maybe 2 seconds then falls in about 5 seconds to the 700-800 range. I am not sure if they all max out at the 1500w range; I am currently using the DLS 54-15.

Since you’re on 12v a much shorter piece of wire would work, but again it would be messing with the length to get it right.

I would be curious if the Honda would run the DLS 55 or not… 30 is safe, 45 is probably safe, 55... it should work... but...

dwh

Re: Can Iota chargers run with less power?

hillbilly wrote: »

Just curious when you mention the higher power draw initially (not surprising), how did those numbers compare with the listed specs from Iota.

I note again (I've mentioned it here before) that the specs listed on the web site for the 30a Iota seem a bit dodgy.

The 15a specs show:
Max Inrush Current, Single Cycle 30 Amps

The 30a specs show:
Max Inrush Current, Single Cycle 27 Amps

The 45a specs show:
Max Inrush Current, Single Cycle 40 Amps

I suppose it's possible that the 15a unit draws less than the 30a unit, but I don't believe it.

I would be very interested to know "real world" numbers from anyone using Iota chargers.

BB.

Re: Can Iota chargers run with less power?

Yep--a lot of DC type power supplies (computer, chargers, motor controllers, etc.) take a pretty healthy starting current. If you have nothing else plugged into the genset--it is usually not a problem (circuit breakers are too slow to trip).

However, if you have your desktop computer running and plug in that larger charger--it may cause the computer to reboot (loss of power for a few cycles).

Using a switch is a nice solution for the "arc"... Cheaper to replace the switch than a custom outlet in the generator.

-Bill

hillbilly

Re: Can Iota chargers run with less power?

dwh wrote: »

I note again (I've mentioned it here before) that the specs listed on the web site for the 30a Iota seem a bit dodgy.

The 15a specs show:
Max Inrush Current, Single Cycle 30 Amps

The 30a specs show:
Max Inrush Current, Single Cycle 27 Amps

The 45a specs show:
Max Inrush Current, Single Cycle 40 Amps

I suppose it's possible that the 15a unit draws less than the 30a unit, but I don't believe it.

I would be very interested to know "real world" numbers from anyone using Iota chargers.

It's on my list of things to do this week. I have an old marine battery that I think must be totally dead by now, haven't got around to recycling it yet. I'll hook it up to the 30 amp charger and plug that into my Kill a watt. I tried just plugging the charger in, but I didn't have any DC load to connect to it, so it just surged up to 10 watts a couple of times and then stayed at zero (I suppose that wasn't any surprise, but I was curious to try it anyways). I'll be sure to post anything that I can find out.

dwh

Re: Can Iota chargers run with less power?

Whoops! Just noticed how I worded that - and it's backwards:

"I suppose it's possible that the 15a unit draws less than the 30a unit, but I don't believe it."

SHOULD SAY:

"I suppose it's possible that the 15a unit draws more than the 30a unit, but I don't believe it."

jnh

Re: Can Iota chargers run with less power?

dwh wrote: »

"I suppose it's possible that the 15a unit draws more than the 30a unit, but I don't believe it."

I have an Iota DLS-30, and after taking a peek inside at its circuit board, I suspect this one's identical to the 45A model except for a lower current-limit setting (see below) and some components having been left out. From memory, there's space for two main switching FETs, and two large filter caps across the DC output, but only one of each is actually populated on the 30A model. There might have been a cap omitted on the high-voltage side as well. Anyway, the filter capacitance having been apparently reduced by half might explain the dramatically lower inrush current on this model. Compared to the identically-packaged DLS-30 and -45, the -15 comes in a smaller chassis, and might be a different design.

I haven't actually measured inrush current, but can confirm that a Honda EU-1000i will run the DLS-30 without any trouble. I have a similar 40A charger from now-defunct Todd Engineering (PC40 model) that also works well with the Honda, but the Todd PC45 is too much for it.

My Iota DLS-27-25 (25A at 27-28VDC) also slightly overloaded the EU-1000i, so I had to reduce its current limit slightly, down to 22-23A. Here are some notes I made during that process:

Towards the center of Iota's PCB, closer to the fan than the DC lugs, five medium-sized (5W?) power resistors are connected in parallel, partly stacked atop one another. This is on the HV side, with transformer primary current passing through them, R's floating at around 1/2 rectified AC line voltage, so best not to work on them "hot".

Resistor values vary from one DLS model to the next. One or more may be disconnected (one lead snipped) at the factory... DLS-30 is like that.

DLS27-25 paralleled shunt resistors--
red red slv gold 22 * 10^-2 = 0.22
red red slv gold 22 * 10^-2 = 0.22
brn grn slv gold 15 * 10^-2 = 0.15
brn blk gold gold 10 * 10^-1 = 1.00 ohm
gray red slv gold 82 * 10^-2 = 0.82 ohm

Stock configuration, as above -- DC current vs. AC wattage :
// 1/(1/0.22+1/0.22+1/0.15+1/1+1/0.82) == .0556 ohm -- 25ADC 877-885W ~881

Removing one 0.22 ohm drops current limit to 15A @ ~28V:
// 1/(1/0.22 +1/0.15+1/1+1/0.82) == .0745 ohm -- 15ADC 602-627W ~614

Removing 0.82 ohm:
// 1/(1/0.22+1/0.22+1/0.15+1/1 ) == .0597 ohm -- ~800W 1170VA 0.7pf

Removing 0.82-ohm and 1-ohm... AC draw still slightly too high:
// 1/(1/0.22+1/0.22+1/0.15 ) == .0635 ohm -- 740-765W 1000-1092VA

Substituting additional 0.82-ohm R for one of the two factory 0.22 ohm's:
// 1/(1/0.22+1/0.82+1/0.15+1/1+1/0.82) == .0683 ohm -> ~20A DC, still too low

Good compromise setting -- 22-23A, doesn't overload EU-1000i:
->// 1/(1/0.22+1/0.82+1/0.15+1/1+1/0.82+1/1.4) == .0651 ohm - 725W, 980-1020VA

(While you're in there, consider removing the output ballast resistor, which wastes 8-15W and isn't necessary if you always operate the charger with a load).

Are there any chargers around this size available with Active PFC built in? That would be very nice, allowing about 25-30% more DC output for a given size of generator. Most computer (ATX PC) PSUs now include active PFC because of an EU mandate, so it's become much more mainstream than a few years ago, but the old PFC-enabled chargers I've seen on the market have been very large ones intended for electric cars & such.