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

Thu Aug 19 17:19:50 PDT 2010

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

Voice: 970-731-4675

On Thu, Aug 19, 2010 at 6:00 PM, Allan Sindelar <
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
> NABCEP Certified Photovoltaic Installer
> EE98J Journeyman Electrician
> *Positive Energy, Inc.*
> 3201 Calle Marie
> Santa Fe, New Mexico 87507
> *505 424-1112*
> 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
>
> Voice: 970-731-4675
>
>
> _______________________________________________
> List sponsored by Home Power magazine
>
> List Address: RE-wrenches at lists.re-wrenches.org
>
> Options & settings:http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>
> List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
>
> List rules & etiquette:www.re-wrenches.org/etiquette.htm
>
> Check out participant bios:www.members.re-wrenches.org
>
>
> _______________________________________________
> List sponsored by Home Power magazine
>
> List Address: RE-wrenches at lists.re-wrenches.org
>
> Options & settings:
> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>
> List-Archive:
> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
>
> List rules & etiquette:
> www.re-wrenches.org/etiquette.htm
>
> Check out participant bios:
> www.members.re-wrenches.org
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20100819/4c1e5ee5/attachment-0003.html>