► Lights, indicators, electrics and alarm

[Canuck]

Sounds interesting...

I know very little about electrics... but won't it draw the full current the product requires until the battery starts dying?

 

[TexasMule]

That's what I'm trying to ascertain.

Will the GPS voltage readout indicate any drop in voltage when I turn on lights/etc.?

I'll find out in a couple hours.

 

[AberdeenAngus]

You should only see a noticeable drop when the system starts to struggle.

 

[Canuck]

You should only see a noticeable drop when the system starts to struggle.

Thats what I was thinking... I interested to see how quickly the battery takes to significantly discharge.

 

[John Armstrong]

There's a battery monitor here:

http://www.corrosion-doctors.org/MatSelect/corrtitanium.htm

and I'd guess you'd not want to see much less than the 13.7v if you assume you want to keep the battery charged.

 

[Myke Rocks]

Thats what I was thinking... I interested to see how quickly the battery takes to significantly discharge.

Ignore battery. When running, electrical loads are driven directly by alternator, up to the point where the load exceeds the capabilities of the alternator.
So: Once the voltage starts to drop off when excessive load is applied, you already have too great a load on system. Shed some of the load.
If you have the system at 100% load all the time, the battery will maintain it's charge, but not recharge in the event of discharging slightly by E.G. using starter a lot, so one wishes to be slightly under 100% load at all times.
Regards Myke.

 

[smaytum]

It's not as simple at that. The voltage will shift a little but will stay around 12 volts - no matter how many devices you plug in. What will change is the current drawn from the battery/alternator.

The formula is watts divided by volts = amps. W/V=amps. So sum up all power (in watts) of all you devices and divide it by 12 volts. Now you have the draw in amps. You battery should have a lable indicating amps per hour or "ampers". Now you know how many hours your battery can power all your devices. The only other consideration is that your batttery is being charged all the time by the alternator (when the engine is running). So now you have to know how many amps the alternator delivers (which must be documented somewhere).

 

[TexasMule]

One Data Point

OK, on the way in this morning, (rush hour last night was a nightmare), steady 70mph/4.5Krpm (in the HOV lane), GPS indicating 13.7V.

Turned on the Hella DEs 2x55W, voltage barely dropped, maybe 13.5+/-, turned on the 35W HID from Les, voltage dropped to 12.8+/-, turned on the heated grips on high, voltage dropped again to 12.5+/-. It regained a little the more
I rode. That's without the heated liner turned on.

I guess what this tells me is I should be careful if I've got too much load on the bike, especially when not running above 4K rpms.

 

[roddy]

Turned on the Hella DEs 2x55W, voltage barely dropped, maybe 13.5+/-, turned on the 35W HID from Les, voltage dropped to 12.8+/-, turned on the heated grips on high, voltage dropped again to 12.5+/-. It regained a little the more I rode.

The battery voltage will start to creep back up the longer you ride since the energy you used to start the bike from the battery is replaced by the alternator while the bike is running so the load the battery take will start to reduce hence the voltage will start to creep up.

I don't know the 800GS so unsure the ease of doing this but I would suggest if your going to use that sort of load on a regular basis it maybe beneficial to look into upgrading the alternator to a higher output model to help take the electrical strain out of the system

 

[Greggers]

This might be complete b@llocks, but is the output voltage what you need to be watching for?

Personally speaking, and of course YMMV ... try counting watts instead.

Current (defined as 'amps' = watts / voltage) in any electrical system is what does the work, not voltage. AFAIK, the GS alternator output is 400 watts, so as long as the current drawn by any accessories INCLUDING the other 'on-all-the-time' systems (think ignition, OBC etc...) doesn't exceed this output, then there will still be enough current left to charge the battery. As soon as this draw exceeds the alternator's output, then the surplus current required to satisfy the total demand has to come from somewhere, which in our case is the battery. Once the battery is out of charge, then the alternator cannot supply demand and only then will the voltage show a drop, and that's the time to start turning off the heated vest...

Here's an easyish way to look at it - assume the 'on-all-the-time' draw is about 150w (55w light, 50w ignition/50w obc/dash lights/tail light etc..) that means you've got 250 watts left... Add a heated vest at say 50w, a pair of additional driving lamps at 55w each , heated grips maybe 30w (so far 190w extra ..) you've only got 60w left ... indicator bulbs are 20w each, main beam another 55w, GPS ..? Don't forget that you also need to maintain an amp or so (12w x 12v) to charge the battery ...see how it works?

Hope this helps, and I hope I'm not talking the proverbial shinola!

Greg

 

[Myke Rocks]

This might be complete b@llocks, but is the output voltage what you need to be watching for?

Personally speaking, and of course YMMV ... try counting watts instead.

Current (defined as 'amps' = watts / voltage) in any electrical system is what does the work, not voltage. AFAIK, the GS alternator output is 400 watts, so as long as the current drawn by any accessories INCLUDING the other 'on-all-the-time' systems (think ignition, OBC etc...) doesn't exceed this output, then there will still be enough current left to charge the battery. As soon as this draw exceeds the alternator's output, then the surplus current required to satisfy the total demand has to come from somewhere, which in our case is the battery. Once the battery is out of charge, then the alternator cannot supply demand and only then will the voltage show a drop, and that's the time to start turning off the heated vest...

Here's an easyish way to look at it - assume the 'on-all-the-time' draw is about 150w (55w light, 50w ignition/50w obc/dash lights/tail light etc..) that means you've got 250 watts left... Add a heated vest at say 50w, a pair of additional driving lamps at 55w each , heated grips maybe 30w (so far 190w extra ..) you've only got 60w left ... indicator bulbs are 20w each, main beam another 55w, GPS ..? Don't forget that you also need to maintain an amp or so (12w x 12v) to charge the battery ...see how it works?

Hope this helps, and I hope I'm not talking the proverbial shinola!

Greg

Much to complicated.
Just monitor the voltage, as TexasMule did. No need for calculations. Ignore the suggested alternator output. Once the voltage starts to droop, you have too great a load on the alternator.
Myke

 

[Rushy]

This might be complete b@llocks, but is the output voltage what you need to be watching for?

Personally speaking, and of course YMMV ... try counting watts instead.

Current (defined as 'amps' = watts / voltage) in any electrical system is what does the work, not voltage. AFAIK, the GS alternator output is 400 watts, so as long as the current drawn by any accessories INCLUDING the other 'on-all-the-time' systems (think ignition, OBC etc...) doesn't exceed this output, then there will still be enough current left to charge the battery. As soon as this draw exceeds the alternator's output, then the surplus current required to satisfy the total demand has to come from somewhere, which in our case is the battery. Once the battery is out of charge, then the alternator cannot supply demand and only then will the voltage show a drop, and that's the time to start turning off the heated vest...

Here's an easyish way to look at it - assume the 'on-all-the-time' draw is about 150w (55w light, 50w ignition/50w obc/dash lights/tail light etc..) that means you've got 250 watts left... Add a heated vest at say 50w, a pair of additional driving lamps at 55w each , heated grips maybe 30w (so far 190w extra ..) you've only got 60w left ... indicator bulbs are 20w each, main beam another 55w, GPS ..? Don't forget that you also need to maintain an amp or so (12w x 12v) to charge the battery ...see how it works?

Hope this helps, and I hope I'm not talking the proverbial shinola!

Greg

I think that sounds about right, plus you have to allow for fuel pump / FI . You'd also probably need to allow a cushion of say 50W between the draw and the alternator output

PS TexasMule ........Slightly off topic but I went for a rideout the day Wacko Jacko died................look where I was

 

[Greggers]

Much to complicated.
Just monitor the voltage, as TexasMule did. No need for calculations. Ignore the suggested alternator output. Once the voltage starts to droop, you have too great a load on the alternator.
Myke

Fair point, but I'd rather have a rough idea of a safe load on the alternator, rather than finding out I've had a voltage droop when the battery's flat... like I said, YMMV, and I don't have an on-board volt meter...

G

 

[Rushy]

Fair point, but I'd rather have a rough idea of a safe load on the alternator, rather than finding out I've had a voltage droop when the battery's flat... like I said, YMMV, and I don't have an on-board volt meter...

G

My BMW has an onboard voltmeter as standard

 

[everywherevirtually]

My BMW has an onboard baby monitor as standard

fixed it for you

 

[Greggers]

My BMW has an onboard voltmeter as standard

Hmmm ... is this something I've missed on mine or is it an 'extra'?

 

[Fanum]

HID's draw less current once they're on than a 'normal' halogen bulb.

The fuse in a GPS wiring system is normally .5a, or in other words, fekk all.

You'd have to go some to take 'too much' power out of most modern bikes, although heated vests and grips are big thieves of elecktrickery...

In short, don't worry about it, unless you're doing lots of short journeys with everything turned on all the time.

Do you also run a spreadsheet that tells you to the nearest penny what the running costs per tenth of a mile are by any chance?

 

[TexasMule]

PS TexasMule ........Slightly off topic but I went for a rideout the day Wacko Jacko died................look where I was

That looks vaguely familiar... I think I know that place.

Looks like you had decent weather.

 

[Rushy]

[

fixed it for you

Mine has a baby monitor that monitors how many (few) times i can get to actually ride it

Hmmm ... is this something I've missed on mine or is it an 'extra'?

The X Challenge has a smaller, lighter low output alternator so BM Stuck a voltmeter on it to compensate

That looks vaguely familiar... I think I know that place.
Looks like you had decent weather.

Decent weather?.......fekking 110 to 120 degrees every day for a week. Took a ride up to Muenster on FM455 via Celina & Pilot Point, Ray Roberts LAke & Sanger that day and on the way back I had to stop for an hour on the 380 somewhere close to Navo to re hydrate 'cos I just couldn't go any further, I felt that shit. I don't really do heat, much prefer riding in the autumn even over here .

 

[Greggers]

HID's draw less current once they're on than a 'normal' halogen bulb.

The fuse in a GPS wiring system is normally .5a, or in other words, fekk all.

You'd have to go some to take 'too much' power out of most modern bikes, although heated vests and grips are big thieves of elecktrickery...

In short, don't worry about it, unless you're doing lots of short journeys with everything turned on all the time.

Do you also run a spreadsheet that tells you to the nearest penny what the running costs per tenth of a mile are by any chance?

Yeah -and no I'm not a spreadsheet junkie (if that was headed in my direction...) but I do have experience of a rather interesting ride on my old XR250R after a long laning day - headed home at dusk with 20 odd miles to go, and my 'uprated' headlamp (55w from 35w..!) was enough to plunge me into darkness each time I put the brake on ...

With the oft irresistible temptation of the odd farkle or two that the 'average' BMW rider has, IMVHO it would be quite easy to get close to using the alternator's max output - you just have to add up the watts !... And Rushy's voltmeter is on an X-Challenge, so I can stop looking for the secret access code for the meter on my 800 *phew* that's a relief! Don't forget the OP's a Chartered Accountant and like to see things clearly and nicely illuminated (and is probably quite used to adding things up too... outgoings greater than income creating a deficit and all that malarkey)

Personally I rely upon a nice woolly jumper and a cup of thick hearty broth for warmth in the winter months...

G