I believe that daytime running lights improve your visibility and probably
can help avoid accidents, so I leave the lights on all the time.

Then I woke up to the drag on the electrical system and was surprised.
A pair of 55 Watt low beam bulbs and four 29.5W parking lamp bulbs equals
16 Amps. Then there's other current draw with dash lamps, relay coils,
and other bulbs so the grand total is more.

My multimeter will only measure up to 10 Amps, so I better not try to measure
the headlight circuit current. Does anyone know what the current draw is?

The bad news is that the alternator charging away at <16 Amps all the time
is providing unwanted drag on the engine and lowering fuel economy.

The good news is that there are LED replacements for many of the bulbs
that use a fraction of the current.

for example the #1156 bulb is rated at 27 watts or it draws 2.0 amps
and an LED replacement draws only 140 ma or 0.14 Amps

There's some websites where people searching for fuel economy unhooked the
alternator and made some jury rig to run the waterpump and they found maybe
10% increase fuel economy/ MPG . No alternator isn't great for an 850 that needs fuel injectors and electric fuel pumps and a computer.

I'd like to have daytime running lights without the high current draw of all
the old incandescent bulbs, and wonder what it will mean to gas mileage.

Then there's the expense of LED replacements:
Here's the first place that I found that has a nice website and lots of options:
http://www.superbrightleds.com/
You can look up a variety of cars , and they seem to have it right.
They have daytime running light replacements, (That must go into my non-existent
fog light sockets) but NO HEADLIGHT replacements.

I was told that there are now aircraft LED landing lights, so perhaps someone
has a headlight replacement for the Volvo 850 now?

Comments?

Bill

oops I meant this for the 850 page, but can work with any Volvo