SW4024 and Pizzo Ignitors [RE-wrenches]

[William Miller]

Colleagues:

In addition to assigning the AC loads as first priority, the SW inverter is
also supposed to boost generator amps:

"If the amount of current demanded by the AC loads is greater than the GEN
(AC2) AMPS AC setting, the inverter is capable of supplementing the
generator's power."

For the generator to be blamed for failing the light the burners on the
stove in the scenario described, both the "back-off" and the "supplement"
features would have to be inoperative on this inverter.  We've heard
skepticism that the SW will "back-off" battery charging, and I'll admit
I've never tested either feature.  Has anyone out there tested either or
both of these features?  Or is anyone going to visit an SW inverter with a
generator in the near future that could test these features?  I imagine it
would be done by setting AC2 INPUT AMPS temporarily to an artificially low
level, turn on some loads and record how the system performs.

William Miller



At 10:31 AM 1/4/2003 -0800, you wrote:
>When I said "ignitor" I was referring to the oven glow bar ignitor. These
>resistance heaters draw huge amounts of juice, which is why this type of
>oven should be avoided in any R.E. system. Because the SW is capable of
>nearly double it's rated output (for short periods of time) it would have an
>easier time of powering the glow bar than a 4 kW genset would, especially
>when there is battery charging going on.
>
>Regardless of what the SW manual says about the charger being circumvented
>when high loads are present, I have never seen this actually take place in
>the field. I always sell clients on at least a 6 kW generator if the
>inverter in use is a 4 k SW to allow for motor starting loads, if just the
>generator is running, or if the batteries are being charged by the inverter.
>Either way, it's the same problem. Also, the little 4 k Onan does not enjoy
>a very great power factor, which is another reason to go with bigger
>gensets.
>
>The cheapest solution is to find a nice, old O'Keefe and Merrit range for
>them. A $350.00 stove sure beats a $3,500. genset!
>
>Matt
>----- Original Message -----
>From: "William Miller" <wrmiller at slonet.org>
>To: <RE-wrenches at topica.com>
>Sent: Saturday, January 04, 2003 12:04 AM
>Subject: Re: SW4024 and Pizzo Ignitors [RE-wrenches]
>
>
>> Colleagues:
>>
>> While this might be a nice pitch to sell a generator, I don't believe it
>> follows logic.  The SW has a feature that prioritizes AC input power (grid
>> and generator) over battery charging.  To wit, from the SW manual:
>>
>> "The SW Series Inverter/Charger includes the ability to automatically
>> "back-off" the battery charger to prevent overloading a generator or
>> tripping a circuit breaker when other AC loads are being operated through
>> the inverter."
>>
>> In other words, the inverter always directs power to the loads as a first
>> priority, and whatever is leftover is diverted to battery charging.  The
>> only scenario that would indicate the generator is too small is if it's
>> total output could not power the stove (and other loads).  I doubt the
>> generator lacks the ability to power a piezo electric igniter by itself.
>I
>> checked specifications on the Whirlpool website, and they do not list the
>> actual current draw of any of their gas ranges, but it can't be that much.
>>
>> If the generator is grossly overloaded, other charging problems would be
>> occurring.  If either the generator output voltage or frequency are too
>> low, the inverter is probably the most sensitive load, I suspect, and it
>> would not be charging dependably.  How about changing out the piezo
>> generator?  They can't be too expensive.  Let us know...
>>
>> William Miller
>>
>>
>> At 06:53 PM 1/3/2003 -0800, you wrote:
>> >Scott,
>> >
>> >My bet is that the genset isn't powerful enough to both run the ignitor
>and
>> >charge batteries at the same time. A bigger generator is the answer (if
>your
>> >customer doesn't want to buy another stove!) I find old stoves for my
>> >clients all the time which use a standing pilot or a match! (The old ones
>> >are better anyway.
>> >;-)_
>> >
>> >Good luck
>> >
>> >Matt
>> >----- Original Message -----
>> >From: "scott" <scott at backwoodssolar.com>
>> >To: <RE-wrenches at topica.com>
>> >Sent: Friday, January 03, 2003 2:48 PM
>> >Subject: SW4024 and Pizzo Ignitors [RE-wrenches]
>> >
>> >
>> >> Any comments on this query? Many thanks.  Scott
>> >>
>> >> Hi,
>> >>
>> >> I have an off-grid house powered by solar, an SW4024, and an Onan 4kw
>> >> generator (everything bought from you except the generator).  My
>> >oven/stove
>> >> is a current model Whirlpool (I think) propane stove with electronic
>> >> ignition.  The lighters are pizzo spark ignitors, not glow plug
>heaters.
>> >>
>> >> I've got a very odd and annoying problem that I can't figure out and
>was
>> >> hoping you might have some ideas.  When running the generator (SW4024
>is
>> >> charging the batteries and passing the generator power through to the
>> >> house), the ignitor for the oven will not operate.  The stove-top
>burners
>> >> work fine.  When the generator is off and I'm running the SW4024 on
>> >> batteries, the oven usually works fine, but with certain other
>appliances
>> >> turned on the oven still sometimes doesn't work.  In particular, when
>we
>> >run
>> >> our christmas tree lights the oven ignitor won't work.
>>
>>
>

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William Miller
Miller Power and Communications
PO Box 50, Santa Margarita, CA 93453
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email: wrmiller at slonet.org
http://millerpowerandcomm.com
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