Does anyone have experience using a 110v to 220v transformer in a mobile application to run 220v appliances? I'm thinking of using a toroidal based transformer that's typically used for US to Euro appliance conversion. The specific use case is to run a 220v mini split which typically has better efficiency than a 110v unit. If you're only running a small inverter based mini split (6-9k btu), you're looking at ~1200w max input on heating. Since the mini splits are inverter based, there isn't a need to over-size the transformer for large start up currents.
Looking at efficiency of the transformer, this site claims that from about 10-80% of rated load you're above 95% conversion efficiency. Looking at a basic mini split offered in both 220v and in 110v configurations, the 220v achieves 18.5 Btu/W in cooling while the 110v only achieves 17 Btu/W. I'm estimating I'll need ~8000btu of cooling to maintain 75F interior temperatures at the worst case, which means the 220v unit would need ~455W including a 95% efficiency hit converting up to 220v. The 110v model otoh would need 470W.
For heating, I'll rarely be below ~20F, and with people and electronics in the vehicle I shouldn't need more than ~3000BTU of heat (~880-1000W). The 220v with a COP of 3.42 should only need ~308W to keep things warm including transformer, the 110v needs ~357W.
For basic units there appears to be a small advantage in efficiency for the 220v. There are other benefits of a wider power range (lower minimum and higher maximum), smaller diameter wire runs, and slightly lower cost than the 110v option.
NVM, SEER2 is not a good method to determine peak draw.
If you have the budget for a high end model though the 220v really shines. The Fujitsu H series is the current record holder for 9000BTU SEER2 at 33.1 according to the energystar ratings. 33.1 SEER2 means a peak consumption of 254W with transformer losses. For heating, an LBG LBH series claims an HSPF2 of 22 which translates to 163W to keep things warm with transformer losses.
These transformers can be bought for <$100 on amazon (example) which makes them significantly cheaper than buying an inverter capable of 220v output (or two split phase 110v).
Looking at efficiency of the transformer, this site claims that from about 10-80% of rated load you're above 95% conversion efficiency. Looking at a basic mini split offered in both 220v and in 110v configurations, the 220v achieves 18.5 Btu/W in cooling while the 110v only achieves 17 Btu/W. I'm estimating I'll need ~8000btu of cooling to maintain 75F interior temperatures at the worst case, which means the 220v unit would need ~455W including a 95% efficiency hit converting up to 220v. The 110v model otoh would need 470W.
For heating, I'll rarely be below ~20F, and with people and electronics in the vehicle I shouldn't need more than ~3000BTU of heat (~880-1000W). The 220v with a COP of 3.42 should only need ~308W to keep things warm including transformer, the 110v needs ~357W.
For basic units there appears to be a small advantage in efficiency for the 220v. There are other benefits of a wider power range (lower minimum and higher maximum), smaller diameter wire runs, and slightly lower cost than the 110v option.
NVM, SEER2 is not a good method to determine peak draw.
These transformers can be bought for <$100 on amazon (example) which makes them significantly cheaper than buying an inverter capable of 220v output (or two split phase 110v).
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