[RE-wrenches] DR2424 inverters charging poorly: three units in two days!

Thu Aug 19 20:03:33 PDT 2010

Kent,

Thanks for that info.

Have you tested for voltage between the L1 and ground while the generator is running, or just tested for continuity between neutral and ground when not running?

I wonder how much Honda paid the City of LA for that sticker :)

Brian Teitelbaum
AEE Solar

From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Kent Osterberg
Sent: Thursday, August 19, 2010 7:51 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] DR2424 inverters charging poorly: three units in two days!

Brian,

I also have observed that the Honda EU1000i and EU2000i inverter generators do not have a neutral-ground bond.  Considering that they are intended as a portable power system and have a three-prong plug it does seem strange that there is no bond.  There is also no GFI protection which is normally required for 15 and 20-amp outlets on portable generators.  But then a GFI wouldn't work without a neutral-ground bond anyway.  There is no sign of a UL listing, but mine has a sticker from the City of Los Angeles saying that it is "approved for use".

Kent Osterberg
Blue Mountain Solar

Brian Teitelbaum wrote:
Mick,

Raising the engine RPM will also increase your frequency above 60Hz, which could injure any electronics running in the house, so be careful there.

Allen,

You mentioned that the inverter/generators have no bond between the neutral and the frame. I don't see how they can get away with that and still have a three-prong receptacle on the unit. Since these are designed to be portable gennies, they represent a complete power system, able to directly run loads, and therefore must have a bond. Maybe they don't have any kind of over-current protection on them, and if there is no breaker to trip, the bond is not needed, and they can get away with that. I haven't had a chance to play with any of those enough to look that closely. Are you sure that there is no bond? If so, then this makes them ideal for small off-grid back-up gennies, on top of the many plusses I knew about.

Brian Teitelbaum
AEE Solar

From: re-wrenches-bounces at lists.re-wrenches.org<mailto:re-wrenches-bounces at lists.re-wrenches.org> [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Mick Abraham
Sent: Thursday, August 19, 2010 5:20 PM
To: Allan at positiveenergysolar.com<mailto:Allan at positiveenergysolar.com>; RE-wrenches
Subject: Re: [RE-wrenches] DR2424 inverters charging poorly: three units in two days!

I knew Allan S. & Brian T. would be among the first to chime in with helpful observations. My recollection, however, was that prior efforts with portable generators had worked OK with DR sets...and I know of one setup like that which is working OK in my home county for sure. (That's a portable with fairly big wattage rating, however.)

 I increased the engine RPM on that newly repaired generator but I felt creepy around 125 volts per leg. No more fireworks, please, but should I tweak it up faster?

So...Allan is saying that he suspects these DR units are operating "normally" and therefore could not be helped by a repair. I look forward to receiving additional posts on this topic.

****************************************

Brian T's point (about the neutral usually being bonded to metal frame on portable generators) is well taken. I tried to buzz it out with my continuity meter and read "open" between genset neutral & metal chassis. This was at the end of some hot & hectic overwork, however, so maybe I screwed up on that test...loose meter cable or sketchy switch position on the meter,  maybe. I will test that again next time.

Although it's a portable genset of fairly low price, I think it has some fancy electronic ground fault interrupter or maybe even electronic ground switching. Perhaps that's why it wouldn't buzz out when the engine was off. When the "green wire" on the twist lock power cord was connected to the metal of the Power Panel System--as seems quite reasonable--the generator's voltmeter would drop to zero as soon as the twist lock plug was inserted. That's when they called me...to boldly go where no normal, sane electrician ever would. I loosened off that green wire from the Power Panel and all looked well. I should have stopped there. The manual for the generator was no help at all.

Three poorly charging inverters in two days...plus one Big Bang...that was not one of my better weeks!

Mick Abraham, Proprietor
www.abrahamsolar.com<http://www.abrahamsolar.com>

Voice: 970-731-4675

On Thu, Aug 19, 2010 at 6:00 PM, Allan Sindelar <allan at positiveenergysolar.com<mailto:allan at positiveenergysolar.com>> wrote:
Mick,
You have missed one fundamental point: The DR (and earlier Trace mod-square series) gulp only the peak of the AC supply waveform when charging. They need 164V AC at the peak of the waveform at rated charging load to supply full rated DC current. A small dip in AC peak voltage results in a disproportionate loss of DC charging current. You identified the source of the problem when you identified the gennies as portable units. Cheap generators provide a 120V AC RMS voltage, but the waveform is flat, with a low peak, especially under load. This is described somewhere in the DR manuals, I think.

The best solutions we have found are the inverter/generators, from Honda, Yamaha, and now others. Perfectly synthesized sine waveforms and good DR performance.

Cheap generators are no bargain.
Allan
Allan Sindelar
Allan at positiveenergysolar.com<mailto:Allan at positiveenergysolar.com>
NABCEP Certified Photovoltaic Installer
EE98J Journeyman Electrician
Positive Energy, Inc.
3201 Calle Marie
Santa Fe, New Mexico 87507
505 424-1112
www.positiveenergysolar.com<http://www.positiveenergysolar.com/>

On 8/19/2010 5:48 PM, Mick Abraham wrote:
Greetings, Mechanics~ Please review my problem du semaine and chime in if you are so inspired.

My prior experience with the DR series Trace inverters could be summed up in two words: practically bombproof!

(There was one time...way back in the day...when a barely broken in unit stopped charging with adequate amperage, and...thinking...there was some screwy behavior on the LED indicators and maybe something else. That issue was resolved under warranty and was declared by Trace tech support to involve the "triacs".)

Last month I visited two customer sites right after one another. Site #1 has a single DR2424, 120  volts from the portable generator, transferred fine...no problems...but would only deliver a puny five amps to the battery, regardless of tweaks to the "battery size" & "charge rate" knobs.

Site #2...the very next day...has twin DR2424 units, similar OK voltage from the portable genset, similar normal seeming behavior, series stacking cable in place, but a similarly puny DC amperage delivery to the battery. This pair was slightly higher on DC amperage...about 7 amps per unit. Tweaks had no effect.

********************************************************

In fairness to Site #2, some weeks prior...the genset had been newly purchased and would not maintain output AC when connected to the inverter pair. I inherited a new set of customers when nobody else seemed to know what to try. I ungrounded the generator plug connection and things took off...and the charging amps were A-OK. Then...as a good safety minded technician...I grounded from the metal ground lug on the frame of that generator to the client's ground rod and the otherwise routine service call became much more exciting.

BANG-I fried something in the generator...voltage regulator, maybe. Then I remembered why I try to never help out on equipment purchased elsewhere. I broke my own rule...

After an intense conversation with the generator supplier, the service guy agreed to fix the genny--"one time and never bring it back". When it came time to re-connect the repaired generator, my new customers wanted me to be there. I thought that would all be ho-hum so long as we left the frame ungrounded but then I observed the low charger performance. Now I suspect that something about the generator flame-out also blew important items in the inverter pair.

*****************************************************

I'm writing the Wrenches to ask:

Can anyone point to the likely problem on these three machines?

I probably can't fix this myself but perhaps could be encouraged to try...somebody on Ebay is selling "FET boards" for the DR2424 inverter. Inspiration, anyone.

Failing a local repair, does anyone remember the flat rates for repairs by the authorized fix it shops?

OR: if any List participants have a matching inverter in inventory...or two...or three...perhaps they could contact me off list with pricing, etc. Neither client is likely to have the cash for new TR-2424 inverters.

Oh, yes...if any could offer a Big Bang theory, that would help with my education. The neutral on that portable generator is isolated from ground, so the metal frame should be a non-participant in any electrical activity on the AC side of things. The metal frame is...thinking...connected to the negative of the 12v cranking battery so maybe that's a clue. The ground rod to which I connected is also connected to the negative of the 24v house battery and also is connected to AC neutral from the Trace Power Panel.

Thanks all around. The Wrench List is the Bomb, but with no loud percussive effects!

Mick Abraham, Proprietor
www.abrahamsolar.com<http://www.abrahamsolar.com>

Voice: 970-731-4675

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