Laptop use on generator power question

[willald]

..Pretty sure I know the answer to this, but here goes:

Early last month, we tried for the first time, to let the kids use our laptop to watch DVD movies in the RV when on the road. Had the generator running (needed it for air conditioning), so had them plug laptop charger in, so it could keep the laptop batteries from draining.

We quickly found out, that this did not work. Laptop batteries quickly depleted; even when plugged in, they would NOT recharge at all. When plugged into generator power, laptop would work OK even with battery stone dead, but battery would not recharge running off of genny power. When we got to our destination and hooked up to shore power, of course, the laptop batteries charged up quickly and easily.

Sooo, on generator power (Generator is Cummins Onan 5500 watt unit), laptop batteries will not recharge, but will power the laptop itself.

I'm almost certain, this is because our generator must not be putting out true sine wave power (probably modified sine wave?), and the laptop charger cannot charge the batteries because of this. Or, is there something entirely different wrong here? The laptop is a fairly new model, I got it last December, its a Lenovo.

Pretty sure the only realistic solution here, if we want batteries to stay charged up when on the road, is to install a small true sine wave inverter, and wire it to 12V power. Upgrading the Motorhome's generator to one that puts out a true sine wave output is not going to happen, is definitely NOT worth that.

Are there any other solutions to this, that I'm not thinking of? Would I might be able to get a charger for the Lenovo laptop, that would work off of 12 volts?

[dan-nickie]

If your batteries are 'stone dead' as you say in OP an inverter might not solve your issue.

[NinerBikes]

Answer is don't let the kids watch DVD's off the computer while driving. Maybe take their faces off the screen for a bit and let them look out the windows instead while traveling.

You're right, you knew the answer, put down the screens while driving.

[vermilye]

While the Cummins Onan 5500 watt generator technically produces a sine wave, the waveform can be very "dirty", depending on load. Some power supplies have a problem with this, although I've rarely seen a situation where the laptop ran, but didn't charge. In any case, either adding a small pure sine wave inverter, or purchasing a 12V supply for the laptop would likely solve your problem.

[MrWizard]

I suspect an outlet problem, or inverter transfer switch problem
Was the outlet used with shore power the same outlet used while traveling and running the generator?
Was it the exact same test, playing movies while plugged into shore power?

Was the A/c running during the shore power test
One a/c should not being the voltage down so low, as too affect the laptop charger

[jrnymn7]

This issue was mentioned in a recent thread, and IIRC, some laptop converters do not play well with certain generators' waveforms. I run my laptop off a psw inverter and a Honda eu2000i with no issues. It's likely an incompatibility issue. Try using a small psw inverter, like you said.

[zigzagrv]

First, your generator should be putting out a pure sine wave. Modified sine waves are put out by low cost inverters.

Secondly, get a Kill-O-Watt monitor (very inexpensive) and plug into your receptacle. It will tell you what the voltage and frequency output of your generator is.

Voltage should be around 120 volts and the frequency should be 60 hertz. I would suspect the laptop charger as the problem.

[RoyB]

I too find myself off the power grid alot with my OFF-ROAD POPUP camper. What I did was install a PURE SINE WAVE 600WATT INVERTER setup to provide 120VAC for all of my so called emergency power connections for my must have items like CELL PHONE Chargers, Computer and Tablets charger, my WX RADIO setup, a couple of charger stations for my 10-fan 12VDC-120vac-D CELL fans, Home Entertainment setup, etc...

This 600WATT PSW Inverter has two 120VAC Drop Cord connections with one going to the Home Entertainment area and the other going to a table top location near the bed we sleep in. My 600WATT INVERTER is on 24/7 even when we are using shore power...

I have used my 2KW generator to run alot of 120VAC items within the capacity of the generator without any problems. Being the INVERTER TYPE Generator the sine wave produced from the 2KW Honda looks to be very good. Perhaps your larger generator has alot of spike being produced when making power..

My OFF-ROAD setup is run all the things we want to do when camping off the power grid to run off my battery banks. The only reason I run my 2KW Honda Generator is to provide power to the trailer to operate the on-board converter/charger unit when allowed to run my generator for three hours each day which is about the time required to charge up my battery bank using smart mode charging. My battery bank setup is to run all the items we want to use in the one day/night run off the batteries and just be depleted down to their 50% charge state (around 12.0VDC) at 8AM each morning...

Been doing this method for several years now and know what to expect - its all second nature to us now. My batteries and power consumption upgrades were done in 2009 so the batteries are just now starting to fall off some on performance. Time to start a new battery upgrade. I am also going to look into solar panels this time around to help re-charge the batteries during the high sun day which should drop back my generator usage to around one hour each.

This will work great for if I can get over 20AMPS DC current charging source from my 480WATT planned solar setup. Getting alot of DC CURRENT from solar panels would require many panels installed based on the typical 120WATT Panel will only produce around 5-6AMPS when in the high sun. My battery banks wants to see around 55AMPS DC Charge current when I first start re-charging each day from the on-board converter charger. If the solar panels would keep my batteries topped off this would be great. I still expect to run my generator for the first hour each day when I start charging in the mornings and then let the solar panels continue the top off the batteries until the high sun goes away...

I also do a few other thing when the generator is running like make my grind and brew bean coffee for the day. Wife might use some high wattage items cooking up something. etc...

We don't worry abut things like the air conditioner or high wattage microwave etc... when camping off the power grid.

Its all in the planning
Roy Ken

[fcooper]

My Lenova laptop purchased about Sept 2014 works just fine off our onan 7.5kw generator, and it is an inverter based system so I don't know if I'm getting MSW or pure sine wave ac.

I suspect you have some other problem.

Please post your final solution as we're curious.

Fred

[ryanw821]

Lenovo's adapters are usually quite robust, it surprises me its not working right. If its not charging it, I would look into the voltage and frequency of the output from the generator, it must be off a bit. All NON-inverter generators should be putting out actual real sine-wave, so I doubt that is the issue, plus I have run a Lenovo adapter off a cheap non-sine-wave inverter with no problems.

All that said, Lenovo makes a fantastic 12V charger, we use one in our camper, that way we can charge/use the laptop even when we don't have shore power (we don't have a generator in our RV).