Hey guys,

I made a search but nothing came up for this. I am thinking about charging my laptop from the bike (GS500) while on the go. After a bit of research it seems that I have two options. I could get a laptop car charger (65w, 18.5V, 3.5A) or I could get an inverter and use it to charge my DSLR batteries and my phone, too. I am wondering, would it be too much to ask from the gs500's charging system? I think I could get away with using a 65W laptop charger and riding with my lights off... but what about a 100w inverter?

Are there any previous threads about this, that I could browse through? Any help would be greatly appreciated.

Where do you live?  In the U.S. any bike made after 1978(?) has to have lights on at all times.

He's one of the good guys that indicated location in the profile: Spain

I doubt you could run an inverter for very long. Also the problem I have with it is all the wasted power. You'd basically be going from 12V up to 115V back down to like 18 and 9V. I would use car chargers and use them one at a time.

This might be helpful: http://www.donrowe.com/inverters/inverter_faq.html

Like others suggested, you would get better energy efficiency if you avoid the unnecessary DC to AC to DC conversion.
If you must use an inverter, say one rated at 150W-200W, the load on the bike's electrical system should theoretically be OK (between 15-20A). To help things, you could run LED brake/rear lights and LED signals that significantly reduce the load on the system.

there is an inverter in a 18.5v charger that runs on 12dc.  its just on the inside.  You can probably hear a whine like a camera charger.  There is no way to get around it.  there would be one device instead of two, but it is still making the dc to ac to dc conversion.

So it's what I suspected, I could only use a car charger. Not using the lights is not an issue... the only time I will need to charge my laptop and camera is when I will be in the middle of nowhere in Africa

What's the max power you would suggest, a 65w charger would be OK you think? It's like the main beam of the reflector.

Quote from: randomway on December 08, 2010, 04:24:50 PM
I am wondering, would it be too much to ask from the gs500's charging system? I think I could get away with using a 65W laptop charger and riding with my lights off... but what about a 100w inverter?

The 65W is the worst-case power requirement of your laptop.  The charger is about 80-90% efficient.  So taking the worst case power requirement and efficiency:  65W x 1.25 = 81.25W.  Then you plug that into the inverter, which is also about 80-90% efficient.  So that's 81.25 x 1.25 = 101.5W  (100W inverter would be fine) So the current from your bike would be 101.5 / 13V = 7.8A  You have a 10A fuse...

Now, that was worst case.  In other words, screen on, hard drive spinning, processor working on quantum physics calculations, charging...  If you just need to charge the battery, the power requirement is a little less.  http://batteryuniversity.com/index.php/learn/article/charging_lithium_ion_batteries suggests 0.8C maximum charge rate for Lithium-Ion batteries.  The battery on my Compaq laptop has a capacity of 4160mAh (C=4.160).  So it would charge at 0.8 x 4.16 = 3.3A  3.3 x 18.5V = 61.6W   Well, not much less than the maximum!

Yep, probably too much to ask, unless you want to run without headlight.  Or get a netbook.  My son's Aspire One with the 7 hour battery only requires half as much power as a full size laptop.

Thanks for all that info. I wouldn't be using the laptop while charging. It's a half-netbook, HP Mini 311 by the way. It has the potential to play hd movies and edit photos, videos on it but at the same time it can be switched to power saver mode and run really efficiently. I'm giving up on the idea of using the 100w inverter, it looks like a big waste of energy. I have two batteries for the camera so charging that is not essential.

If I was only using a 40w charger for the laptop instead of the factory 65w, would that work and just charge slower or would it cause any problems?

If you can turn the headlight off, running a 100w inverter will be no problem if you are driving and not idling.  If you plan to just run the bike and idle to charge it, then it *might* not make enough power.

Best thing to do is buy or borrow a 100w inverter, hook it all up, and check the voltage of your charging system while using it.

Yep, he's right about not using it while idling. The GS charging system doesn't even start charging till 3K (approx) RPM. Under that, you are pretty much running on the battery. It would still run your inverter and charge your stuff... BUT.. you will probably not be able to start the bike afterwards and your battery will end up dead soon. Not to mention the fact that you will be idling an air cooled engine and possibly overheating it. 

Cheers guys. I have a cigarette lighter socket on a long cable that reaches my side panniers, and that's where I store my laptop. I would be charging it only when on the go of course. In general the bike likes to run at 4-5k rpm's and I checked the charging system, it's working well. I am leaning towards choosing the 40w charger instead of the 100w inverter. I don't want to risk frying my electrical system in the middle of nowhere... and I think the laptop will still charge just fine at less than 65w. It only takes an hour or two with the factory charger, so I can expect 3 hours maybe.

What's the peak performance of the charging system on the gs500 anyways? If you take away the ignition and other bits, how many spare watts would you have?

I have never been able to find the stock output.

In case you need more power...Electrosport claims their stator ( small motorcycle version of an alternator)  puts out 20% more power than the factory one.

http://www.electrosport.com/street-bikes/suzuki/gs500f-01-09/stator-3-phase-suzuki.html

Maybe you can find the max stock output if you do some digging based on cross compatibility using the list on their site (i'm not too sure on some though). They say the same stator will fit these bikes:

»Kawasaki
    KZ650CSR (81-82)
    KZ700 (1984)
    KZ750E (80-83)
    KZ750 Spectre (80-83)
    KZ750LTD (80-83)
    KZ750R GPZ750 (twin shocks) (1982)
    ZR-7 / ZR-7S (00-05)
    ZX750 GPZ750 (83-85)
    KZ1300 (79-81)
    KZ1300B2 Touring (1980)
    KZ1300 (79-81)
    KZ1300 (1980)
    KZ1300 Voyager (1982)
    KZ1300 Voyager (1982)
    ZN1300 Voyager SE (1983)
    ZN1300 Voyager SE (1983)
    ZN1300 Voyager SE (87-88)
    ZN1300 Voyager SE (87-88)

»Suzuki
    GZ250 (99-09)
    GS300L (82-85)
    GS450 (80-82)
    GS450 (82-88)
    GS500E (89-96)
    GS500E (97-00)
    GS500K/F (01-09)
    GS550 (81-82)
    GS550L/M (80-82)
    GS650E (chain drive) (81-82)
    GS650G/GL (shaft drive) (81-82)
    GS650 Katana (chain drive) (1983)
    GS750E (16-valve models) (80-83)
    GS850G (80-81)
    GS850G (82-83)
    GS1100S Katana (GSX1100 Katana) (83-83)