Inverter Voltage Help 90v-107v (1 Viewer)

[landtoy80]

I just bought a Stanly Fat Max 140 watt dc to ac inverter $24 Walmart. Looking to power my Mac computer (battery doesn't hold charge anymore) and what ever else I need to power up when on the road.

I plugged in the inverter and it reads 107 volts with just key on acc. and 90 volts with motor running with my volt meter?

Is the 90 volts going to be ok to run my computer, charge batteries or run other electronic device? It powdered a shop light with no problem so far.

I had a more expensive $80 inverter I got from a Apple store that worked fine for many years till it died. Never thought to check its voltage as it didn't hurt the computer.

How many volts should an inverter put out? What is an acceptable voltage range for a inverter?

 

[e9999]

not measured mine yet but 90 seems too low. Also odd that it would go down when the battery voltage presumably went up (if all OK).
Doesn't seem right.

 

[landtoy80]

Called the manufacturer and they said I need to use a TRUE RMS volt meter to read voltage with the inverter. You get low and false reading with non TRUE RMS meters.

They said the inverter readings with my meter sounds like it should be in spec but as the inverter was an open box item, I should return it for a new one. Its the companies policy for vendors not to resell returned products. He said there is no way to know what the last owner did to the inverter or why he/she returned it and I am better off with a new unopened one.

I bought it from Walmart online as a new, not open box, and I will return it.

 

[Elbert]

you need the right type of inverter to power computer devices....

 

[Walleyeye]

I wouldn't use any inverter with electronic devices unless it was a true sign wave inverter. You could fry electronics.

 

[rusty_tlc]

@Walleyeye Many laptops use a DC supply plugged into an AC source, the one I'm using right now for instance. If you can get a decently stable dc voltage out the quality input signal is kind of moot.


@landtoy80 A true RMS meter will measure a lower voltage than one that measures peak to peak voltage since Vrms=Vpp*.707. Sounds like someone in tech support was doing some hand waving.

 

[Walleyeye]

Just adding my personal experience having fried both a cordless battery charger and a portable construction radio.

I tend to believe what your sayin' Rusty_tlc, but will always heir on the side of caution as nothing sucks more than being out and frying equipment.

 

[Cruiserdrew]

For $24 I would not expect much anything.

Why not get a dc adapter and plug your laptop in directly? They are insanely cheap and avoid inverters. I've shopped them on google with "car adapter" with your computer model. $10 and you are in business.

And, my experience with inverters has been bad. Cheap ones don't last and can damage your gear. Plus they are huge power hogs. Use only with the truck running.

 

[Fast Eddy]

I've had pretty good luck with inverters. I've never fried anything, and I've had a couple cheap ones. AC-to-DC power supplies are just transformers and don't care if it's a sine wave or a modified (square) sine wave. I also use them to charge my phone in camp without killing the battery, even though they have an internal fan running (engine not running). YMMV, of course.

I'm surprised laptop DC supplies are that cheap. Most laptops need about 18v, so you need some kind of step-up DC-DC converter, and it seems to me that a cheap one of those would be as likely to damage the internals of your computer as anything that would damage the (easily replaced) AC-to-DC external supply.

 

[george_tlc]

Actually, AC-DC supplies for laptops are much more than 'just transformers'

There's a whole bunch of electronics in there and typically will take the AC, rectify directly to DC high voltage and that feeds a switcher running at full high voltage DC into a transformer running at many 10's of kHz.

Though, I've used cheap $20 inverters to feed directly into my laptop's AC adapter without any issues.

http://www.newegg.com/Product/Product.aspx?Item=N82E16882021123 is a unit I've used. It is fairly efficient and does not draw too much without a load. No fan, runs quiet. I've used it in 100F weather in the oz bush and not had any problems.

I'd rather run an inverter to power the AC adapter of a laptop given the OEM AC adapter has decent protection circuitry to prevent nasty spikes/surges etc from getting from the AC side to the laptop DC side - most AC adapters are multi-voltage capable (i.e. 100 - 240V 50hz/60hz) so very forgiving on AC variations.

cheers,
george.

 

[Kofoed]

I bought an Anti-Gravity Batteries power pack (capable of jump starting my landcruiser) for 90 bucks. It has a bunch of ports (including USB) and provided connectors to run all manner of battery powered devices. I am presently running/recharging my laptop (non-mac) and can recharge my bike lights, and just ordered a rechargeable camp lantern (USB connector, LED, with on-board rechargeable batteries). I am attempting to do away with all manner of extra cords and chargers, etc., for camping

The power pack itself can be charged via the cig lighter on the cruiser or a 110 ac wall connection.

Something to consider