So Michelle correctly pointed out that we're probably going to need to be replacing the Freedom 25 inverter/charger. I've dug around as well as spending quite a bit of time reading though what I can find about the two inverters model/brands we're looking at and I'm not sure I see what the advantages to the Magnum might be? The Victron seems to be more efficient and with a much lower phantom load than the Magnum Hybrid inverter/chargers. What am I missing?
If there really is no compelling reason to go with one of the magnums, the next question is if the 2000 is capable of running a new high efficiency A/C pump for a couple hours given sufficient battery capacity? It's not something we're looking at doing immediately, but it is a design goal once we get our solar array covering the roof, so I need to consider it.
Is there someone at FOT in particular that is a good person to talk to about electrical planning?
James
Check the specs on the inverter and the load demand of the specific A/C you're looking at. Typically an A/C is on it's own 20 amp breaker and can pull 13-15 amps continuous. That's about 1800 watts right there, so a 2 kW could be iffy if there was anything else you'd want to run. Especially since the Victron data sheet reports 1600 watts continuous power at 75F and 1450 watts at 100F (temperatures being ambient in the inverter bay, which generally is much warmer than outdoor ambient.) The 3K unit is 2500w/2200w at those temperatures.
Not sure if there are limits to the input side (or if they're different in the various inverter models) in terms of battery charging and the size solar you are considering. Might want to check with folks who are familiar with such. Victron's 2K unit has 80 amp battery charging capacity, 3K unit is 120 amp (DC of course, both at 75F). How much battery replenishment do you anticipate needing and being able to provide via solar?
ETA you might want to call/e-mail and chat with Alan at Bay Marine since he sells both inverter brands. Chargers, inverters, and refrigerators (http://www.foreforums.com/index.php?topic=22402.0)
Must consider LRA on A/C
Locked Rotor Amps
I've had a heck of a time getting actual specs for equipment. Even when you download the "Tech Specs" They are frequently incomplete or slanted. :: eye roll :: One of the newer A/C units seems to list itself as 8 amps but I have a suspicion that that's just the compressor and the fan adds another couple of amps. Lot of ambiguity.
@Tim Fiedler Thanks for the LRA term, that;s probably exactly what I'm looking for. :-)
@Michelle Good points, thanks. I think you're dead on with the Victron 2000 being too close to the edge of it's capacity especially if anything else is running. If we go with the Victron I think we'll have to go with the 12/3000. I think some of the documentation on Victron's site claimed the 12/3000 draws 20 amps 120 for the charger which works out to about 200 amps charging? I'll have to try and nail that down. One big advantage to the Victron is their "Color GX" electrical monitoring system, watched the video from Technomadia and was blown away by the functionality of having it linked in to the Victron inverter/charger and Victron Solar MPPT charge controllers. Just amazing stuff and still evolving. He mentioned something about eventually having it tied into tank levels and sending you notifications via mobile app? Clearly a company with some vision. :-)
@John S Understood. Yes, we're planning on putting in a MUCH bigger battery bank. At the moment we're looking at replacing the 3 moribund 8D in the battery bay with a single 15 kwh LiFePO4 battery system from Balqon. It will be the equivalent of about 7.3 8d AGM batteries but only weigh 400 lbs which is less than the 3 8ds we are removing. We're planning between 1600 and 2000 Watts of solar on the roof depending on geometry. Still have some measuring to do and will need to talk to folks at AM Solar or a similar company.
So nobody knows of any particular advantages of the Magnum that I'm just missing completely?
James
all that solar and battery and no residential??? 8 CF???? - four people full time? Stay close to grocery stores and farmers markets... kind of fights with boon docking -
Or buy surplus MRE's from the military...
:-)
Datasheet on Victron website http://www.victronenergy.com/upload/documents/Datasheet-Multiplus-inverter-charger_2kVA-and-3kVA-120V-US-EN.pdf
3 kW unit has 120 amps charge current. 50 amp transfer switch.
BTW, Magnum has 125 amps charge current, 60 amp transfer switch, wider operating temperature range. Victron is about 1/2 inch longer and deeper (thicker), about 2 inches less wide than Magnum for space comparisons. Bay Marine has all the specs for both and I would think Alan could walk you through any important differences between the 2 3kW units. Magnum is US-made, 3 year warranty. Victron is NL, I believe. Not sure of warranty.
Not unusual for locked rotor current on an AC compressor to be 6 times the running current. Your inverter will need a large overload capacity to start the compressor. Not really practical in most cases.
Quick check of current offering Dometic Penguin II high capacity units show 63 amps for compressor locked rotor current; 8.5 amps for fan locked rotor current.
And I am aware of a device that reduces LRA by 60%. Dometic actually OEMs it, and I sell them as well.
Many in use off grid with large battery banks and solar arrays in residential usage
Lithium ion uses a dedicated charger as far as I know.
A soft start device for the AC is a definite plus. Otherwise, 63 Amps LRC at 120vac equates to 630 amps draw at 12VDC and that is assuming 100% efficient inverter, which it isn't.
John & Tina,
Are you you transferring from generator to inverter with roof A/C loads running, or do you stop & restart in inverter? Wouldn't transfers with big loads running cause transfer switch points to pit over time?
The few times I've done this I have left the A/C running. Transferring active loads is one of the features of this inverter.
Yes, it would. And the generator is supposed to be unloaded for a few minutes too before being shut down. So not exactly a recommended procedure.