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?

[j-d]

I'm not an electronics guru, but I have a friend who truly is. We talked about running a laptop in the RV. When I said I was going to run an inverter off 12VDC in the RV when using the onboard ONAN genset, he said a genset puts out cleaner power than most inverters. I've never had an IBM or Lenovo laptop, only Compaq and ACER, but their "bricks" have handled charging with shore tie, genset and MSW inverter.
I don't know why the Lenovo is being so fussy, just thought I'd share what I'd been told, as well as my own actual experience.

[eichacsj]

We run our Dell, ACER, Samsung using a 2000i while boondocking. Wife sewing radio on. No issues.

[kneal44]

i run my tishaba on msw inverter and generator no problems.
the lap top power supply hucky puck rectifies and filters what ever voltage you give it. i even have qa 200 watt inverter i use in my car to keep lap charged and even my cpap runniung for knaps .

[willald]

Well, to answer some questions:

The 'brick' (power supply) for the laptop is the one that came with the laptop, a Lenovo one.

I like the idea, to look at that power manager screen on shore power, then again when on genny power. I may just do that, see if it provides any hints.

Sure hope this is not an issue with the generator, as this generator is still basically brand new. Has barely been broken in.

As to why not let the kids watch movies on the 'house' TV: TV is not viewable when living room slideout is in. The TV is behind the dinette. Soooo, that ain't an option. Yes, they have TV with DVD players in their bunks, but we don't let them lay in their bunks when on the road, for safety reasons.

As to the 'high horse' suggestion about not letting the kids use the laptop to watch DVDs: All I can say is, in the interest of keeping this thread on topic and to prevent starting yet another online p*ssing contest....I ain't even going to comment on that. We'll just move right on along...

Anyway, good to know that a 12V power adapter from Lenovo is an option, and probably a good one. Requires me to put in a 12V power outlet near where they'll use it, but that shouldn't be too hard, there is a big junction box right under the dinette seat. Its just a question now of which will be cheaper: A small (true sine wave) inverter, or a Lenovo 12V power supply..

[jrnymn7]

mlts22 wrote:
This gets me curious as well. I've seen laptop chargers run on extremely dirty power, as from one of the Yamaha ET800 clones that one occassionally finds at Harbor Freight for about $100 on sale.

Until recently, I was under the impression laptops didn't really care how clean or dirty the power was, and that a psw was not required. But apparently I was mistaken. I think someone explained the issue in another thread, a while back.

[ryanw821]

Willald, Is this the original Lenovo brick, or is this one of the knockoff adapters frequently found on Amazon/eBay? I ask because the actual Lenovo ones send a signal to the laptop to say how much power they can provide, and many knockoffs don't do this correctly and frequently "charging" is disabled when the computer cant sense the proper adapter.

Can you launch the Lenovo "power manager" application, and go to the "battery" tab, it will tell you what it thinks is connected for an AC adapter, that may provide some insight as to whats going on, do it when plugged in on shore power, and once again on generator to see if its reading changes. See attached pic below:

[mlts22]

This gets me curious as well. I've seen laptop chargers run on extremely dirty power, as from one of the Yamaha ET800 clones that one occassionally finds at Harbor Freight for about $100 on sale.

[BurbMan]

Interesting...on more than one laptop I have seen the brick power the device but not charge the battery and it was always a software issue. I've not experienced this type of behavior based on power supply. Maybe time to check the genny output, maybe it needs adjusting?

Just curious, if you're running down the road with the genny on, why not let the kids watch a DVD on the house set instead of a small laptop?

NinerBikes, careful you don't fall off that high horse you're on...yes it's good for kids to look out the window and experience the big beautiful countryside, but depending on how long of a trip OP was on, there's only much stuff to look at before it all looks the same. Nothing wrong with breaking up the monotony a little a with a DVD.

[willald]

jrnymn7 wrote:
"When we got to our destination and hooked up to shore power, of course, the laptop batteries charged up quickly and easily."

willald,

Does the laptop charge up on shore power while watching a dvd?

Yes, it charges fine on shore power, whether playing a DVD or doing anything else with it.

It does NOT charge the battery when connected to generator power, whether playing a DVD or not.

Thanks for the responses, please keep them coming. Definitely good stuff to know here, as I did not realize our generator is actually supposed to be putting out a true sine wave output, so that should not be the issue as I figured it was. Unless of course, like already said, there is an issue with the generator, or its output wave is a little 'dirty'.

Might just have to get me a Kil-o-watt device, one of those have been 'on my list' for a while..

[beemerphile1]

First thing I would check is the voltage output of the generator, if off the hertz would also be wrong. The sine wave should be fine.

[jrnymn7]

"When we got to our destination and hooked up to shore power, of course, the laptop batteries charged up quickly and easily."

willald,

Does the laptop charge up on shore power while watching a dvd?

[DrewE]

The laptop power brick generally doesn't care much about what sort of power it gets. My Lenovo laptop brick has written on it "100-240VAC 50-60Hz". Even more generally speaking, most switching power supplies are not all that sensitive to input waveforms (by design)—they rectify the AC into relatively high-voltage unregulated DC power, and then run a comparatively high-frequency (well, supersonic—tens of kHz) oscillator off of it through a physically small transformer and rectify its output to get their DC output. So long as the input waveform can be rectified into DC power of a reasonable voltage, everything should more or less work.

There are some wrinkles that get thrown in sometimes with power factor correction circuitry.

At any rate, the laptop battery charging is not controlled by the power brick, which basically just supplies juice, but by circuitry in the laptop itself. It may be that playing a DVD (with the DVD drive spinning and presumably the screen brightness turned up) simply uses all the power the brick can supply, leaving none available to charge the batteries. The screen backlight is a fairly large consumer of power in a laptop.

[2oldman]

willald wrote:
I'm almost certain, this is because our generator must not be putting out true sine wave power (probably modified sine wave?),

I'd say you were likely correct.

[Bobbo]

I bought a 12v charger for my laptop for when I boondock. That is what I use in the RV. I don't even take a 120v charger. The 12v works under all conditions.

[jrnymn7]

It was the laptop batteries that went dead, not the house bank. The laptop converter (brick) works fine on 120Vac Shore Power, and is able to pass thru suitable power to the laptop's internal charging system, but it does not work on 120Vac Onan Power. Seems to me the issue is an obvious one.