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

[Brian Teitelbaum]

Mick,

Are you sure that the neutral is isolated from the frame on that "portable" generator?

If so, it's a strange generator indeed.

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 Mick Abraham
Sent: Thursday, August 19, 2010 4:48 PM
To: RE-wrenches
Subject: [RE-wrenches] DR2424 inverters charging poorly: three units in two days!

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.

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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.

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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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