Use of Inverters to power chargers

[Elbert Hill]

Just wondering if anyone has had experience with using inverter to power the chargers to charge batteries in the field.

I just got a new inverter, 750 watt, . When I connect 2 DJI chargers, which should be drawing, I think, about 300 watts total. Well, they seem to work fine, except the fact that they "humm" ! When plugged in to a receptacle in my home, they don't hum .And yes it is the chargers that are humming, not the inverter.

Is that something I should be concerned about ?

 

[Silverado6x6]

On other forums i read that its very desireable to use a pure sine wave inverter.

 

[jtludwig]

Just wondering if anyone has had experience with using inverter to power the chargers to charge batteries in the field.

I just got a new inverter, 750 watt, . When I connect 2 DJI chargers, which should be drawing, I think, about 300 watts total. Well, they seem to work fine, except the fact that they "humm" ! When plugged in to a receptacle in my home, they don't hum .And yes it is the chargers that are humming, not the inverter.

Is that something I should be concerned about ?

You really should be using a pure sine wave inverter.

 

[alokbhargava]

Humm is being produced because the inverter output is possibly square wave. This kind of waves might heat up your charger. There are many ways to take care of. If heating is not notable, just forget it and keep using it. If you notice extra heat use external fan. Alternatively you can buy a 1:1 110v ~80VA transformer and use it between inverter and charger.

 

[solentlife]

Personally as a long term user of inverters on boats and RV's .... I try to not use them if possible and look for direct 12V DC converter. For DJI batterys - there are direct car 12V chargers for peanuts on eBay and they deliver similar 70W as OEM mains charger.

Inverters in this work - are extreme wasters of energy .... taking 12v ramping up to 120 / 240v and then charger dropping back to 17.5v ...

Yes the HUM is due to the switch mode charger being pushed by square wave. Many electronics will not accept such feed ...

My suggestion is get a direct 12v DC to DC car adaptor .....

Car Charger For DJI Phantom 3 Professional & Advanced Quadcopter Accessories #IP | eBay

or even a 3 in 1 ..

Digital Display Car Charger 3 in 1 Charging Accessories for DJI Phantom 3 Drone | eBay

Nigel

 

[Elbert Hill]

Thanks solentlife, actually I just saw those 12 volt adapter/chargers on ebay yesterday. I think that's the route I'll take.

I'm somewhat familiar with squarewave technology, but mainly as it applies to welding power supplies, but I didn't associate that with my problem.

Thanks to all who responded !
Elbert

 

[Silverado6x6]

Just a heads up about something similar, two years ago i was in Australia and was using a voltage converter adapter to power my charger for my Samsung Tab Pro tablet and it ruined my battery.
They use 220v at 50hz while we are of course 120v and 60hz. It was a cheap converter.
I will be using my vehicle battery power to charge out in the field, might even carry a dedicated deep cycle marine battery along thats charged only when the SUV is running though i have several sealed AGM motorcycle batteries on hand. Those jump start packs are basically just an AGM battery, i see no reason why they cannot be used to power a 12volt charger.

 

[solentlife]

I have a $5 one from eBay and it works a treat ...

I have Car USB adaptor and a powerpack to charge the Controller / tablet if necessary as well.

I also have a Telesin discharger for DJI batterys - and that supplies USB power from the energy discharge ... so if you have a spare DJI battery with a bit of charge left in it but not safe to fly - that can also charge the controller or tablet ... funny enough - loads before but now ? Hard to find ... shame.

But there is this which also can power USB etc, as well as do the discharge etc. :

Smart Battery Quick Discharge Module Discharger For DJI Phantom 3 2 Inspire 1 | eBay

Nigel

 

[peter west nz]

Normally, in a switch mode power supply, the sine wave from the mains, is rectified to dc, and then chopped, via a transformer to provide the the output supply at the required voltage. However, when the mains itself is also a square wave - ie the inverter - called a "modified sine wave", the result is a buzzing noise set up by the common mode inductors, which are part of the input filtering, designed for a sine wave input, but being driven by a near square wave. It works, but the filtering capacitors are given a pretty rough time, and being electrolytics, have a limited lifespan with this treatment. My suggestion is : do it if you have to, but be aware that the life of the dji charger will be limited in this useage.

 

[knowmad]

The only time you need a pure sine wave invertor is if you are using a appliance that needs it like laptops tvs snd other products.

 

[embayweather]

I have used one for a few years on my mobility scooter batteries. Never as good as charging from the mains. Hence I do not charge the Phantom batteries the same way, I always charge from the mains supply, and 8 seem to get a better result. Purely subjective as I have forgotten the relevant maths equations about these square to sine wave machines.

 

[solentlife]

If you have an inverter already - then why not use it ...... fair game.

But if you don't have one - then why spend a lot more for one than a decent car adaptor charger costs ? I can buy a whole boxful for the price of a common inverter !

Mains vs cheap inverter : (simple explanation)

Domestic Mains has multiple sine waves overlapping slightly offset from each other which creates a smoother ripple and maintains required voltage more over a period.
Cheap inverter does not have multiple square sine waves and therefore has far more time at effectively zero voltage.

Nigel

 

[y2khardtop]

I have one of these, works fine. $16

BESTEK 200W Power Inverter DC 12V to AC 110V Car Inverter with 4.8A 4 USB Ports Car Adapter and Car Cigarette Lighter Socket – NeweggFlash.com