Inverter temperature ratings ?

sunbunny

Some of the inverters I've read about, the specs say the operating range is only above 0C/32F. Others say they work to -20C. What's the deal ?
It goes to -30F here sometimes and -20F quite often. Is the temp. rating for real or a "CYA" spec ?

Thanks

Cariboocoot

Re: Inverter temperature ratings ?

Differences in how well sealed the components are against moisture condensation and/or variations in component values affecting performance. Most electronic components can take much lower temperature ratings.

BB.

Re: Inverter temperature ratings ?

Probably a lot depends on the Electrolytic capacitors selected and the design ripple current.

Regarding cold, the electrolyte in the capacitors can freeze around -10C. And cold capacitors have much higher dissipation vs warm/hot capacitors (very cold inverter may not operate correctly because of poor capacitor performance--May have problems with local "hot spots"??? due to poor dissipation).

On the hot side, you may have capacitors rated to 105C with 1,000 hour life--So, if you want an inverter to last longer than 1 year (~8,000 hours), you better run it significantly cooler (doubling of life for every 10C drop in operating temperature).

Otherwise, a significant failure mode for electronics is temperature cycling... The more cycles and the deeper the cycles, the shorter the life.

I used to test disk drives in the early 1980's... I could get the "bad drives" to fail in a couple weeks with ~2-4 temperature cycles per day by just running between their Min/Max limits. The "good drives" would go for months and still function reliably.

-Bill

sunbunny

Re: Inverter temperature ratings ?

I don't have a plan to keep the inverter warm.
Can anyone recomend one that performs well in cold temperatures or has at least survived being below freezing for 6 months ?

I've been looking at 1000-2000 watt ones by Samlex and Exceltech. As much as I desire an Outback or Magnum, my battery situation may change and so my voltage may change and so I'd rather have a less expensive inverter to start with.

BB.

Re: Inverter temperature ratings ?

Will you be operating the inverter or just storing it (unpowered) when freezing?

The Exeltech are rated to -25C (supposed to be popular/rugged brand from government use).

http://www.solar-electric.com/exsiwain.html

You can try and call them and ask for details about your install.

My suggestion--If you have a "frozen" inverter, either heat the room to -10C or warmer, and/or run at 10% or so of rated power to get warmed up a bit before hitting them with full power if below -25C.

-Bill