Question about battery charger selection with EU2000 generator.

BB. · January 2011

Re: Question about battery charger selection with EU2000 generator.

The inverter outputs a "pure" voltage sine wave... The current output from the inverter/generator is the result of the characteristics of the load (power supply front end in this case).

For a simple power supply... Basically just a diode rectifier (frequently a voltage doubler for 120 VAC input) into a capacitor.

So, the capacitor gets charged (initial inrush current), then stays near its peak voltage. The Diode only "allows current" to flow into charging the capacitor near the crest of the voltage sine wave... So, you have a current cycle with mostly zero current, then a very high peak right at the crest of the voltage sine wave.

Because voltage or current wave form energy can be looked as the square of the current/voltage (P=I^2*R=V^2*R) the "average" is done using Root Mean Square as opposed to a simple average... So a high current peak (say 3x "average") really is 3^2=9x wasted heat... As well as 3x higher peak magnetic field (saturation of transformers/magnetics in generator).

Here is a beautiful picture showing the relationship between voltage and current for a rectifier/capacitor front end (from here):

BB. · January 2011

Re: Question about battery charger selection with EU2000 generator.

To add to the information--The Iota has a (typical for non-PFC supply) a PF~-0.65 ... For our AC power formula:

Power = Voltage * Current * PF

But generators and transformers also usually have a VA (Volts * Amps) rating too which (more or less) accounts for "poor power factor" devices.

Non-Power Factor Corrected power supplies, typically, have a non-linear wave form (as in the picture above).

Motors tend to have the current "lagging" or following the AC Voltage Sine wave by ~Cos^-1 0.6 ~ 53 degrees ...

All in all, the full current affects wire heating / transformer saturation etc... So the use of VA ratings for transformers and generators (for small gensets, VA usually equals Watt rating... For larger gensets, you may see VA*PF=Watt rating).

For the motor that drives the genset--It mostly sees the Watts as a load.. VA includes both the "real power" and "imaginary power". The Imaginary power does appear as a loss for I^2*R heating losses (and probably magnetic losses too).

The math behind AC circuits gets amazingly complex very quickly (and I don't claim to understand but a very small part of it).

The math has stymied better people than us

:

Several undercurrents lay beneath this rivalry. Edison was a brute-force experimenter, but was no mathematician. AC cannot be properly understood or exploited without a substantial understanding of mathematics and mathematical physics (see AC power), which Tesla possessed. Tesla had worked for Edison but was undervalued (for example, when Edison first learned of Tesla's idea of alternating-current power transmission, he dismissed it: "[Tesla's] ideas are splendid, but they are utterly impractical."[3]). Bad feelings were exacerbated because Tesla had been cheated by Edison of promised compensation for his work.[4][5] Edison later came to regret that he had not listened to Tesla and used alternating current.[6]

-Bill

SteveK · January 2011

Re: Question about battery charger selection with EU2000 generator.

Brock, the Iota was ruled out because it would've nearly maxed out my 1600W generator while producing only 675 useful watts of power to the batteries. From the POCO I wouldn't mind but the generator is already stretched thin.

BB. · January 2011

Re: Question about battery charger selection with EU2000 generator.

That works out to ~48% more power into the battery bank with the same sized generator...

-Bill

SteveK · January 2011

Re: Question about battery charger selection with EU2000 generator.

Well, the generator arrived yesterday and I think it is a sweet piece. Never saw or heard one before today, so far so good. Decided on the Victron BMV-602 monitor. That'll be here tommorrow and will be setup in time for the charger testing. It is to arrive next Tuesday.

E-dub · January 2011

Re: Question about battery charger selection with EU2000 generator.

Bill, thanks for the last couple of posts. Good reminders of the sly side of electrical loads for those of us who learn and forget too quickly.

Steve, we'll be waiting.............

Rick

Brock · January 2011

Re: Question about battery charger selection with EU2000 generator.

Thanks Bill, I get the wave form problem and PF problem, but I thought a motor didn't care or is the problem using a 2000i the inverter part not actually the motor?

BB. · January 2011

Re: Question about battery charger selection with EU2000 generator.

Brock,

I am not quite sure I understand the question--With poor power factor, the gasoline engine does not "see" the extra current... Just the wiring (and generator's inverter electronics in this case) must be sized to carry the extra current to avoid overheating with (I^2)*R heating losses.

The motor only drives the Watts (and heating losses--V*A*PF)--The wiring must be rated for the V*A loading.

For most (many?) small generators, the Watt rating is equal to the VA rating.

For some larger generators and many inverters, the VA rating is larger than the Watt rating.

As an example, I have seen many PC UPS's (uninteruptable power supplies) advertise their VA rating on the side of the packaging instead of their Watt rating--probably because the VA rating is often around 50% larger than the Watt Rating because of the ability to support a higher VA rating with a smaller battery (my guess).

-Bill

Brock · January 2011

Re: Question about battery charger selection with EU2000 generator.

What I am wondering is if you had a 900w resistive load on a Honda 2000i and a 900w iota charger with a PF of say 65 on the same genset what would the motor do in economy mode? Would it run the same speed?

In this same case I am assuming the 2000i would be close to maxed out with the iota charger because of the PF yet still have some capacity with the resistive load correct?

BB. · January 2011

Re: Question about battery charger selection with EU2000 generator.

Brock wrote: »

What I am wondering is if you had a 900w resistive load on a Honda 2000i and a 900w iota charger with a PF of say 65 on the same genset what would the motor do in economy mode? Would it run the same speed?

A resistive heater will pretty much have a PF = 1.0 (need inductance or capacitance to get PF <> 1.0 and there is not much for small devices/short wiring at 60 Hz).

The other issue brought up is that many materials used for heating have a positive temperature coefficient for resistance (as temperature rises, resistance rises too--Filament lamps have this this "surge" issue too)... So when cold, they draw significantly more than rated steady state power.

In this same case I am assuming the 2000i would be close to maxed out with the iota charger because of the PF yet still have some capacity with the resistive load correct?

No, not really... As far as the electrical system is concerned--It "cares" about Volts*Amps and NOT about V*A*PF... If you have hit the VA (RMS based) limit with a poor PF load--you cannot add any more loads of any type.

One possible way around such a limit... If the load is inductive (like a motor), adding a motor run device (aka the notorious Power Save 1200) can bring the lagging current wave form (like PF=0.65) back to near 1.0 (I think a 1.0 capacitive correction is not ideal for other issues).

A resistive load adds additional current over the non-linear (or lead/lag current) of the other loads. It will exceed the VA rating of the genset--possibly popping a fuse and/or overheating the windings/inverter section (if present).

Most "cheap meters" measure peak voltage and assume 1/sqrt(2) for sine wave to RMS calculations. Non-RMS reading meters are only accurate on AC voltages/currents when measuring sinusoidal waves. Other wave forms will not be correct at all (i.e., MSW -- modified sine wave -- inverter output measurements).

The "True RMS" meters actually take multiple readings per cycle and "do the math" to figure out the RMS (root mean square) area under the curve.

-Bill

BB. · January 2011

Re: Question about battery charger selection with EU2000 generator.

Regarding economy mode--In theory, the engine power required to power a PF=0.5 load would be only 1/2 the watts vs VA load--and the motor should only run at 1/2 power even though it is at 100% VA rating...

In practice, I do not know... The Inverter needs to supply the "out of phase/non-linear" current and it may need the higher engine speed to have enough "energy" to temporarily (during part of the AC cycle) supply the excess VA current.

Does the ECO "logic" take this into account? Does the inverter have significant Capacitive/Inductive energy storage to supply poor PF loads at low RPM? I don't know.

By the way, the Motor Run Capacitor (previous post) only works with Motors and other "true" inductive loads.

Non-PF corrected electronic loads (like those with a Diode/Capacitor front end) cannot be "corrected" with motor run capacitors.

-Bill

mike95490 · January 2011

Re: Question about battery charger selection with EU2000 generator.

All,

Just measured my Iota (48V/15A version ) over the holiday, and I recorded the following from my kill-a-watt:
1030w (AC)
11.9A (AC)
.67pf
This was going into battery bank that had some charge from the solar, so it was not full rate. I was using a Honeywell i2000a, and after I switched the load on (Iota) I enabled the auto-throttle and for the next hour, I could hear the engine RPM's notching down.

So, if the batteries are low enough, the genset may not hold up, in which case, I'd use "big blue" a 5kw Generic till they come up enough for the little inverter genset to run it. The 5Kw Generic really sucks fuel, but it does run the arc welder.

Listeroid is not bolted down yet, too cold for epoxy anchors to set properly, so I've got no 240V for charging the via the XW6048, which DOES have power factor correction in the charger ckt.

my math theory :
48x15 = 720w x 1.67pf = 1202W x 1.2 efficiency =1443 watts burned

SteveK · January 2011

Re: Question about battery charger selection with EU2000 generator.

Thanks for that Mike. I've no real reference besides you guys' test data. It's great for me to hear, for example, that the Honeywell pushed through the inrush current requirement no problem.

I searched high and low for those Listeroids around here. I understand there were reasonably priced Indian machines, that needed some refinement, available not too long ago and nevertheless all Listers are now banned from importation. I really am jealous, what a neat machine they are.

After just getting in from a late night repair I see the Meanwell charger will arive a day early today. Been running my batteries down the last couple days in preparation for it. The battery monitor is installed to test it. I'll have some numbers on it this evening.

SteveK · January 2011

Re: Question about battery charger selection with EU2000 generator.

Well got it hooked-up and runnoing with the EU2000 generator. The measurements using a Kill-A-Watt meter on the input side and the BMV-602 on the output side are as follows:

PF = .99
Initial start-up input power = 1124W
Initial start-up input VA = 1126VA
Initial start-up input Amps = 9.14A
Initial Voltage = 123.2VAC

This is a real slick charger, does multiple checks and qualifications before it switches on. It would not start-up or transition to absorb stage in ECO mode. It did not like ECO mode but never did load the genset when determining it's start-up requirements? curious.... Anyways it does run in ECO mode very well but will not begin Bulk charging or switch to Absorb in ECO....Otherwise it is brilliant and I'm happy to have it.

Battery bank was drawn down to 24.4V resting for 3 hours. The following table was manually recorded and began after staying close to the charger for 30 minutes or so looking for smoke and such. Here's the data:

BB. · January 2011

Re: Question about battery charger selection with EU2000 generator.

Looks about perfect!

-Bill

SteveK · January 2011

Re: Question about battery charger selection with EU2000 generator.

Yes Bill thanks to you all for helping me make an informed choice on this. Without the help I doubt I'd be satisfied. I'm so lucky to have asked questions before buying and you have taught me a thing or three about such items.

We are very fortunate to have this forum.

westbranch · January 2011

Re: Question about battery charger selection with EU2000 generator.

thank you Steve for such fastidious researching.

I don't quite know how you manged to find all those options so fast...

Please let us know what your impressions/ experiences are after a week or so.

Eric

RCinFLA · January 2011

Re: Question about battery charger selection with EU2000 generator.

SteveK wrote: »

It would not start-up or transition to absorb stage in ECO mode.
will not begin Bulk charging or switch to Absorb in ECO:

The charger appearently does not like the sinewave slump (peak clipping), with ECO mode on gen, when added load kicks in during charge mode change.

I am a little surprised it has an issue going from bulk to absorb as there is no real change in charger function other then it has reached absorb voltage regulation point from the current limited bulk phase. It may be momentarily stopping charge as it transitions back into voltage regulated absorb mode creating another load surge change.

It wouldn't be too bad if you could switch to ECO after initially starting the bulk charge so gen would automatically back down as current tapers off during absorb and transition to float mode.

mike95490 · January 2011

Re: Question about battery charger selection with EU2000 generator.

RCinFLA wrote: »

The charger appearently does not like the sinewave slump (peak clipping), with ECO mode on gen, when added load kicks in during charge mode change......

bummer, charger too smart.

BB. · January 2011

Re: Question about battery charger selection with EU2000 generator.

SteveK,

If the charger folks are talking with you--I would give them a call to praise their product and ask if they can reprogram it a bit to allow it to give the generator time ramp up the throttle.

-Bill

SteveK · January 2011

Re: Question about battery charger selection with EU2000 generator.

Eric, thanks. Yep it took some time searching but with the web I was able find some EV archives that had some brief mentions about this charger and also some power supplies from Meanwell. I think Meanwell did a fantastic job on this machine but their specs are misleading albeit in the direction that benefits the customer which is great for us...

For all the time I spent finding this product it will be actually the least used piece of the system (used only in the worst case scenario). My system is pretty well balanced for what it needs to do and the charger will sit there most of the time. I'll run it several more times over the coming weeks and let you know how it pans out though.

SteveK · January 2011

Re: Question about battery charger selection with EU2000 generator.

RCinFLA wrote: »

It wouldn't be too bad if you could switch to ECO after initially starting the bulk charge so gen would automatically back down as current tapers off during absorb and transition to float mode.

Yes I agree RC. It would be best if I could leave it in ECO through the Bulk to Absorb transition but I really just wanted this charger to bring me to the Absorb point with the genset... From there the panels will do the rest of the Absorb stage even on a not so perfect day.

The charger does run Bulk in ECO mode but you need to start the Bulk stage in Normal mode. Just for a second until the charger starts, then switch to ECO which really does nothing anyway because I think the genset doesn't throttle back anyways while Bulk charging. I'll have to verify this.

I don't want to waste generator time in Absorb.

Interesting what you explained about clipping. I just want to point out that the generator never bogged down at all when the charger was attempting/testing/clicking to begin the charge cycle both beginning Bulk and then beginning Absorb. I didn't seem to feel there is any load surge if listening to the genset is any indication, no bogging at anytime...

Thanks for your more advanced insight into the reason for this.

SteveK · January 2011

Re: Question about battery charger selection with EU2000 generator.

Bill, I'll try that route. Im not sure the people I'm talking with could help me directly but maybe they can put me through to someone that can.

The generator never responds to the "wake-up call" of the charger....just sits there idling in ECO mode.....charger goes through a routine of clicks several times trying to start-up. Genny never revs-up....or boggs down....just hums along.

Wouldn't it be great if it was a simple RC time constant setup..

They do deserve praise for this charger though, great idea!

SteveK · January 2011

Re: Question about battery charger selection with EU2000 generator.

mike90045 wrote: »

bummer, charger too smart.

Mike, that's TBD. You just wait and see, give it time, I've been here before, it will wring out as "operator too dumb"!...:cool:

mike95490 · January 2011

Re: Question about battery charger selection with EU2000 generator.

SteveK wrote: »

......
The charger does run Bulk in ECO mode but you need to start the Bulk stage in Normal mode. Just for a second until the charger starts, then switch to ECO which really does nothing anyway because I think the genset doesn't throttle back anyways while Bulk charging. I'll have to verify this.

I don't want to waste generator time in Absorb........

I could hear my i2000 throttling back as my Iota tapered off in bulk.

SteveK · January 2011

Re: Question about battery charger selection with EU2000 generator.

mike90045 wrote: »

I could hear my i2000 throttling back as my Iota tapered off in bulk.

Mike our charge curves must be different because this charger increases the load on the genset as time in bulk increases as shown in the table.

Only when in absorb does the ECO throttle down slowly as the load on it decreases..

mike95490 · January 2011

Re: Question about battery charger selection with EU2000 generator.

SteveK wrote: »

Mike our charge curves must be different because this charger increases the load on the genset as time in bulk increases as shown in the table.

Only when in absorb does the ECO throttle down slowly as the load on it decreases..

Yeah, the Iota is just a 54V power supply, not a full blown charger, but it's on hand for emergency bulking.

RCinFLA · January 2011

Re: Question about battery charger selection with EU2000 generator.

You will need to stay in absorb mode until current drops off at least to 10% of rated AH-hrs, in amps.

At point where batteries reach the normal absorb voltage they are only about 80-85% SOC. This depends on absorb voltage set point.

During my last hurricane outage, with gas a precious commodity, I also cutoff of gen after a short absorb cycle. I noticed the battery capacity decline on each successive day. I did raise the absorb voltage setting on the short absorb cycles which helped some and kept the gen loaded. After four days I let them have a full absorb cycle until current dropped to less then 3% of AH-rating in current. It took about 2 hours in absorb stage.

If you have enough power from PV then you can let that do the top-off.

SteveK · January 2011

Re: Question about battery charger selection with EU2000 generator.

After using this charger a bit more I'm even more impressed with it. Just an update.

In previous posts in this thread I stated that I was apparently using 30% of my bank capacity overnight. I believed this was because of the temps being around 50F at the bank. Boy was I wrong.

Come to find out I had a fair bit of sulphation and that was the culprit.

My bank was formed in two stages. First 4 of the batts (date code 2/10) were purchased last March and sat around unattended and unused for 4 months...no trickle charge. These were then put into service as a 12V bank using the Rogue and a cheapo MSW inverter. Playing round here getting feet wet.

Then I decided to add 4 more batts and 2 more panels. The batts (date code 6/10) were purchased in August and put into service immediately in a 24V configuration.

Two weeks ago I would run my system (identical loading) from full and end up in the morning with 24.72V slightly loaded at 31W. Now after desulphating (8 Stage Charge Setting) several times using the Meanwell charger, I am ending up at 25.03V from full to morning (identical loading). This is far more efficient and I am happy.

I have used the Meanwell now to charge each 4 batt string individually and together. Both worked well while considering the longer times needed to charge the 450aH vs 225aH. The charger does a great job increasing charge volatges based upon temperatures at it's sensor. I've now seen up to 30.4V at the batts when required by the ambient temps.

So yesteday I thought that maybe my Rogue was deficit charging the batts all along. I tested for this by running my batts down using the Northroad Hot Water Heat Pump while letting the Rogue supply it for 3 hours then charge the bank back up yesterday. It did well and today I've the same result in the morning....25.02V after using 36aH from the bank.....the perk constant makes much more sense now.

So I no longer believe that desulphation could be hooey. It works! I'm sure sometimes better than others though.

Sometimes the problems are staring me in the face and a good look in the mirror is all that is required. Sometimes there are problems that can go unnoticed for far too long. I know am gonna now include a scheduled desulpation step in my battery maintenance routine in order to keep those plates clean.

Thanks!

mike95490 · January 2011

Re: Question about battery charger selection with EU2000 generator.

So, what is the charger you are using now (8 stage, desulfate) ?

Question about battery charger selection with EU2000 generator.

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