How much power can I drain from my bike?

[centaurus]

I am planning to to a couple of weeks touring on my bike this year. Considering that I'll be using a tent too, I started thinking about electricity: charging my phone, camera and probably laptop.

The easiest/cheapest way would be to attach a lighter plug to my bike's electrical system and use a 12V - 240V transformer like the ones used for cars. However I need to make sure I don't use one too big and fry my bike's electrics.


Does anyone know how can I calculate what is the max. Wattage converter I can use and still be safe?

The plan is to use the adapter only when riding, to charge one device at a time.


My bike is a 1999 ZX6R G2.

[p.dath]

If you always park on a hill it will make crash starting it much easier in the morning ...

I would forget using a 12 to 240V inverter. Too bulky, and too inefficient. Go an get the actual 12V adaptors for the devices mentioned. A cell phone will use bugger all power. Ditto with a camera.
A laptop might use a bit more, 72W is not uncommon. That's quite a bit of juice to use.

[davereid]

Phone and Camera will be no problem at all. I looked at the power supply for my laptop, and it is 65 watts. But thats rated for operating the laptop. If its turned off and just charging, you will be using much less. If you are riding at normal Highway speeds, you should find this to be no problem. Wire a DC outlet directly onto the battery, with a 5amp fuse as close to the POS terminal as practical.

[centaurus]

Phone and Camera will be no problem at all. I looked at the power supply for my laptop, and it is 65 watts. But thats rated for operating the laptop. If its turned off and just charging, you will be using much less. If you are riding at normal Highway speeds, you should find this to be no problem. Wire a DC outlet directly onto the battery, with a 5amp fuse as close to the POS terminal as practical.

Also, what does POS stand for?

I am worried about the transformer itself. There are 150W, 300W or even 600W ones and I don't know whether they drain that power anyway or that's the max they can handle before bursting into flames. If it's the latter, I would buy a bigger one so I can use on my car too, if not, I have to buy one of the smallest ones available.

[p.dath]

Also, what does POS stand for?

I am worried about the transformer itself. There are 150W, 300W or even 600W ones and I don't know whether they drain that power anyway or that's the max they can handle before bursting into flames. If it's the latter, I would buy a bigger one so I can use on my car too, if not, I have to buy one of the smallest ones available.

POS = Postiive terminal on battery. Go an buy an actual 12V "transformer" for your laptop. Most laptops have an option for a DC fed "transformer".

No laptop would need 150W or more of power. That is desktop territory.

[davereid]

Yeah P is onto it. Buy an adapter with a cigarette lighter type plug, that is designed for your laptop and you will be fine. Just remember to unplug it when you are stopped for a break.

[centaurus]

Yeah P is onto it. Buy an adapter with a cigarette lighter type plug, that is designed for your laptop and you will be fine. Just remember to unplug it when you are stopped for a break.

Problem is I need to charge at least four things: laptop, camera, ipod and phone (not all at the same time, obviously). I already have a car charger for Ipod but for the rest I would have to purchase one car adapter for each. That's why I'm trying to go the 12V-220V way - only one device to purchase. However, if I go that way, I would like to buy a big one (300W or 600W) so I can use it in my car too - the car would have enough juice to carry multiple devices at the same time.

question is: is a 300W or a 600W transformer gonna fry my bike, or it drains only the ammount of power that the devices attached to it use (i.e. only 40-60W if only a turned off laptop is connected to it).

[p.dath]

Problem is I need to charge at least four things: laptop, camera, ipod and phone (not all at the same time, obviously). I already have a car charger for Ipod but for the rest I would have to purchase one car adapter for each. That's why I'm trying to go the 12V-220V way - only one device to purchase. However, if I go that way, I would like to buy a big one (300W or 600W) so I can use it in my car too - the car would have enough juice to carry multiple devices at the same time.

question is: is a 300W or a 600W transformer gonna fry my bike, or it drains only the ammount of power that the devices attached to it use (i.e. only 40-60W if only a turned off laptop is connected to it).

It should only drain as much power as being drawn from it plus the overhead of the conversion to supply it. You wont fry your bike as long as you put a fuse inline to the inverter to prevent it drawing that much power. Have a look at the sizes of the other fuses on your bike. I probably wouldn't risk anything larger than 20A, which is 240W. But even then, your battery couldn't sustain that kind of power output for long. Probably a 5A (60W) or 10A (120W) fuse would be more appropriate. If you want to charge a laptop your going to need a 10A fuse.

Be conscious of the heat that the inverter might generate under load as well. It is likely to have external heat sink fins.

EDIT: I would also try checking the temperature of the battery after running a load on it like this. Over-heating the battery (often through rapid charging following the load being removed) could result in cell damage. You could also try deliberately buying a battery with more cells if you can get it to fit on your bike.

[p.dath]

If you have the space, because you have saddle bags or something, I'd seriously consider about buying a second battery and storing it in the carry space. That would double the cell count. Charge the battery while riding (by connecting it to your existing battery and hence the alternator), and then use the battery to charge everything else while stopped (and have it disconnected from the bike supply).

Note I only really consider this an issue if you want to charge your laptop. The other devices don't pose much of a load.

[scumdog]

The phone and camera won't need bugger-all charging, can't speak for the lap-top but I doubt it would be a serious drag on your bikes system, hell if it can run heated grips it should be able to charge the lap-top.

[davereid]

Problem is I need to charge at least four things: laptop, camera, ipod and phone (not all at the same time, obviously). I already have a car charger for Ipod but for the rest I would have to purchase one car adapter for each. That's why I'm trying to go the 12V-220V way - only one device to purchase. However, if I go that way, I would like to buy a big one (300W or 600W) so I can use it in my car too - the car would have enough juice to carry multiple devices at the same time.

question is: is a 300W or a 600W transformer gonna fry my bike, or it drains only the ammount of power that the devices attached to it use (i.e. only 40-60W if only a turned off laptop is connected to it).

You will have to buy a side car to carry all the crap with ya...

The "transformer" (actually an "inverter") will draw a small amount of "tare" current regardless of the load. It will also draw a little more than the load you are supplying, as it is not 100% efficient. It should be rated to cope with the largest load you intend to operate.

Your bike has around 300 watts available at 5000rpm.
Ignition uses about 85
Head, instrument and tail Lights about 65
Battery charging about 30 tapering off..
Fuel injection.. 85 (not fitted to your bike?)
Fuel pump ..50 (not fitted?)

You have about 80-100 watts of freeboard.

The battery will supply as much as your inverter asks for, as it discharges if the engine is spinning, the alternator will supply more and more of the balance.

Ideally, you will find with all loads on, your alternator can maintain 14 volts, and your battery will be AOK.

[sidwyz]

Just thinking out loud here but why not just take a phone with you?

My ph is pretty old and crap but it has,

A camera,

Can access internet,

Can play music,

So why would you need all that excess with you?
your only away for a couple of weeks surely you could do without.

[centaurus]

Just thinking out loud here but why not just take a phone with you?

My ph is pretty old and crap but it has,

A camera,

Can access internet,

Can play music,

So why would you need all that excess with you?
your only away for a couple of weeks surely you could do without.

My camera has much better quality and resolution than the camera in the phone and the laptop is for the sole purpose of emptying the camera card in case i have more than 16GB worth of photos which is quite conceivable if I use it for two weeks in a row.

I am still thinking whether to take the laptop or not but the camera and phone are a must and the Ipod won't need that much recharging - probably once, max twice during the whole holiday.

However even with only camera and phone, the problem remains the same.

[Squiggles]

However even with only camera and phone, the problem remains the same.

You need to charge them all at once? Just wireup a ciggy lighter socket and get the appropriate adapters... Are you really taking the 6R to the middle of nowhere where you wont find a powerpoint?

[CookMySock]

It [the inverter] should only drain as much power as being drawn from it plus the overhead of the conversion to supply it.

Only if its a pure sinewave inverter. Non-sinewave inverters can supply quite a lot more current, even on standby, from computer switching power supplies, even when they are on standby.

I'd just try it. Try a 150watt inverter and hook everything up to it and see what it does. Check its' current draw with a clamp meter.

Steve