| Author | Message | ||
     Jimincalif |
Folks, I'm considering Sturgis this year, pure motorcycle camping but I want a way to charge my laptop on the road. Max recharging amps required in AC is 50. I'll get hold of a very good quality 125amp inverter so with conversion losses figure 65amps drain max. Will that melt the stator of a '97 S3?  Or more likely, would it trigger constant battery drain? I would hook it up to a manual switch so that I'd only charge at freeway speeds rather than in-town or idle. Doable? | ||
| Dennis_c |
I bet you mean .50 amps at 120v At 12v that would be about 6 amps  | ||
| Jackbequick |
I think the alternators on the Buell tubers are rated at 22 Amps at 2,500 RPM. What brand is your laptop? You might look and see if an auto/airline DC-DC adapter or a combo AC/DC adapter is made for your model laptop. Either of those can be plugged into a cigarette lighter DC outlet. They would let you charge your laptop on the bike while your engine is running and it would be smaller, lighter, less complicated,and more efficient than using an inverter. The AC/DC combo adapter would let you carry one charging adapter that could be used anywhere. I think either of those would draw around 6 Amps or so at max draw. Adding that much load to a Buell (engine running) would put the electrical system at any risk of overload. In theory, with the engine off, that load would kill your typical 22AH battery in 3-4 hours. Jack (Message edited by jackbequick on March 26, 2006) | ||
| Jimincalif |
God. What a screwup on my part. I meant *watts* at 110v AC. 125 *watt* inverter, computer eats about 50 watts. Sigh. It hardly matters...22 amps? Yikes. Anyone make a bigger aftermarket variant? That said though...I have the Manta tank. Assuming a manual switch to the inverter, I could charge the laptop for about an hour at a time, then switch off the inverter and charge the battery back up before the next stop. It means putting a switch on the dash with a light showing inverter power "on" and some careful management but...it's doable. I agree a straight DC setup would be better, except I wouldn't be able to charge my cellphone or camera batteries (both together are practically nothing in terms of drain). I could drive the cellphone with DC with an adapter but not the camera battery. And DC converters for laptops are expensive and not made for my Fujitsu that I've been able to find so far... | ||
| Jackbequick |
There are aftermarket stators that are 38 Amps, I think Accel makes one. One advantage of the Accels is that they have a lifetime warranty. The stock ones are known to fail occasionally. Usually from shorted windings or a short at that clamp that holds the wires down at the stator. You might try an eBay search for "fujitsu auto charger" you may find one there cheap. I've used the generic ones on several different laptops and they work fine. As long as the voltage is stable and right and the amperage is there, DC is DC. I think the stock 22 Amp stator will keep up with all the load you're talking about there with no problems. A battery monitor would be a nice thing to have, to let you know for sure what's going on. Jack | ||
| Jimincalif |
I've had a stock stator puke and die on me once so yeah, I know how that goes. Checking around, looks like the stator alone isn't real expensive, $100 range or so. Is that all I need for an upgrade, or do I replace other bits? | ||
| Jackbequick |
I've not replaced or upgraded one. Maybe one of the other electrical guru's can tell us more about the upgrade. I've read comments that the Buell charging system is pretty simple/older technology. I think it is smart enough to throttle back the charge rate at higher RPM and with lower demands. It converts the excess output to heat and wastes it through the VR or something like that. So I don't know if a better VR is needed or not. I'll bet the answers are in the KV... I need to do some electrical work on my M2 to accommodate handwarmers grips and an electric vest outlet. Jack | ||
| Blake |
My gut feel is that even just your Buell's battery alone should be able to handle charging up the laptop no problem. I've used a 12V to 115V converter to run a battery charger to charge another motorcycle battery before. It worked fine. Ask Loki. 50 watts at 12 volts equates to around five or six amps is all. And, I'm guessing but that 50 watts is probably a peak value with the steady state quantity being significantly lower. Try it before you decide? I could be wrong! | ||
| Reepicheep |
It's a shunt type system, so you won't hurt anything trying it. You will actually be making the voltage regulator dump *less* heat. Also, if you are just *charging* the laptop, you won't be drawing anywhere near 65 watts. Your power supply must be rated for the system to be running at 100% CPU drain (15 watts right there for a modern CPU), a completely depleted battry charging, CD Drive at full spin, hard drive at full spin, video subsystem fully utilized, all USB ports at full load, firewire at full load, PCMCIA at full load, LCD at full brightness. If you just want to charge the battery with the computer turned off while you ride, I would be suprised to see you pulling more then 15 watts peak, and expect it to be more like 5 watts most of the time. If you are worried about it, pull the headlight fuse when you are riding during the day and charging. There's 60 watts right there. |
