New Computer & Old Inverter vs New Full Sine Wave Inverters

souler

I'm wondering if anyone here has used older pulse wave inverters with newer computers. I have a (yr)1998 Trace DR1512 and used it mostly as backup power when grid shut down in storms. (We have very low to moderate winter sun, as main discouragement for big pv system investment on low income). Yet good backup power with maybe one panel is valuable for several needs..... My computers are younger macs. I had some old salvaged batteries which died log ago but am wanting to buy new ones along with a panel or two.

So my question: Is there a big risk plugging newer Macs into my old Trace inverter? (Having the short pulsed wave AC)... My 1990s Macs seemed to run fine, on the DR1512. Although my total hours of usage were sporadic and infrequent. My 1998 pv panels seem almost dead now except for powering very small fans in greenhouse. So my pv experience was not so rewarding, (in terms of low dead batteries and low budget to start with).

mike95490

Re: New Computer & Old Inverter vs New Full Sine Wave Inverters

souler wrote: »

.......My 1998 pv panels seem almost dead now except for powering very small fans in greenhouse. So my pv experience was not so rewarding, (in terms of low dead batteries and low budget to start with).

only 12 years for your panels ? Who made them, and what was their warranty ?


As for the laptops, it's the power supply that does not like the square wave inverters. If the supply module is heavy, with an iron core transformer, you are more likely to have trouble, than if it's a universal switcher, that feels nearly empty. (it's just diodes to feed a DC-DC converter)

If after 5 or 10 minutes, the module does not feel overly hot, and did not die in the first minutes, you are likely OK.

Mike

Cariboocoot

Re: New Computer & Old Inverter vs New Full Sine Wave Inverters

I don't know about Mac power supplies, but I've run PC's off MSW inverters (first a Statpower then a Xantrex) for years with no difficulties. In general, computers have really good power supplies because they can't tolerate a lot of fluctuation.

Not sure if they still use this method, but the old power supplies (including Apple II) turned the AC into DC, used that to run an oscillator to convert back to AC, reconverted that to DC, then monitored the output and adjusted the oscillator frequency to maintain proper final DC Voltages. Complicated, but very "clean" power.

Sounds like you're looking to re-try the whole solar experience?

souler

Re: New Computer & Old Inverter vs New Full Sine Wave Inverters

I'll need to climb up on the roof to look for brand label. My current need is to determine minimal upgrade possibilites. To save money on the inverter side. While not hurting my more recent Macs. Ya, it would seem power-supply filtering should be pretty good but steep wave fronts beg for answers. Have pv people experienced greater equipment burn-outs or dead power supplies? Are grid sine waves so clean, besides? Also, on the nerdy side, it might seem that the new sine wave inverters will consume power to make the sine wave, while the steep pulse wave might pump infinitesimally-more water or drive power tools with less loss or more vigor? Or, does a steep wave just get clipped and dumped as waste heat? ....Direct, long-standing experience with pretty old inverters would give me some hope to start with. Besides, keeping old stuff working reduces waste.

As to laptop-- The external wall warts always heat up, just a tiny bit, on the grid-- I'd half-guess that a charging-battery should act a little bit like a filter-capacitor.

Ya, i'm at the least buying brand new batteries for storm back-ups (plus looking ahead, where a major solar mass ejection is expected, besides hard times developing) plus maybe buy some pv panels and study up on big surge suppressors. I had no idea warrantees could last long for pv panels. Mine are second hand panels besides. Glad to hear it, if pvs are lastingfor years. I'd love to break away from the grid, if a ship comes in. (None so far)

Thanks for replies and any other insights.

BB.

Re: New Computer & Old Inverter vs New Full Sine Wave Inverters

Sine Wave vs MSW (Modified Square Wave) affects different devices different ways...

Transformers tend to create circulating currents in the iron core with MSW waveforms. Motors tend to take the non-60Hz higher harmonics from a MSW waveform and turn it into heat (around 20% of the total energy in the MSW voltage/current flow).

And some simple electronics and LED lighting ballasts use a capacitor to limit current flow/voltage (acting like a regulator). The square wave has much higher frequency components which go right through a series capacitor--tending to overheat the capacitor/diode/resistor/devices.

The idea that you can filter a MSW waveform into a TSW via transformers or capacitive filter circuits its generally a non-starter. The extra energy is significant and has to be turned into heat for the higher harmonic energies to be "dissipated".

Older electronic power supplies tend to have a Diode Rectifier charging a high voltage capacitor. This means that most of the current flow is right at the crest of the wave form. For sine wave that is a current spike right around the crest/peak of the waveform. For square waves, that can be a very high current spike at the leading edge of the wave (excessive current can cause diode/cap to overheat). Both power supply types create non-linear current wave forms which are hard on transformers and create I^2*R heating in the wire.

The utility power sine wave (and TSW inverters) are defined to have 5% or less in harmonic energy. A couple of Inverter FAQs:

All About Inverters
Choosing an inverter for water pumping

Power Factor Corrected electronic power supplies (modern computers, some laptop power supplies), resistive heaters, filament light bulbs will usually work just fine on MSW power supplies. Small wall wart transformers, sealed motors, high duty cycle motors, and such typically run hot on MSW inverters and may have shorter life. 80% will work fine, 10% will not, and it is not always easy to know which is which. Some electronic timers (clocks/etc.) may not read the 60Hz waveform correctly.

You might try a kill-a-watt meter and anything with poor power factor on utility power may have problems with MSW inverters.

-Bill

Cariboocoot

Re: New Computer & Old Inverter vs New Full Sine Wave Inverters

To be fair to MSW inverters (and confuse things more) they're not all the same; some have more steps and more closely mimic a sine wave. Unfortunately they don't tell you this in advance, and even with a lot of 'digging' you can't always find the answer.

bryanl

Re: New Computer & Old Inverter vs New Full Sine Wave Inverters

Those old Trace inverters should present no problem as power sources for modern electronic devices. Most UPS's you are encouraged to use with home computers provide nowhere near the power quality.

I think the MSW inverters got a bad rap from a few bad apples. Some devices with very cheap power supplies (e.g. the old Kill-a-Watt devices) had a significant dependence upon the input waveform and would overheat if they didn't get something fairly close to a sine wave. These sorts of sensitive devices are getting more rare.

But consider the UPS devices being sold for consumer electronics protection or those cheap (under $50) inverters intended to be used in vehicles to power the backseat DVD's or game toys or other such stuff.

I put the MSW scare stories in the FUD mongering category. Yes, you do need to take appropriate precautions but let's not go overboard.

RCinFLA

Re: New Computer & Old Inverter vs New Full Sine Wave Inverters

MSW is fine for an old MAC. They have always had switching power supplies.

Just about every small computer UPS you can buy is MSW output.

I have not tried a new PFC (power factor corrected) switching power supply on a MSW inverter.