autolights fooled by Mitchell Fwy Bridges Perth Western Aust

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g4qber

Well-known member
Joined
May 15, 2012
Messages
46
this also happens with Lexuses

and the lights also don't come on when overcast, have to manually turn them on.
or wait until it gets really dark.

Golf TDi 2.0 DSG,
autolights, rain sensing wipers, auto locking doors, auto dimming mirrors
no problem.
 
The owner's manual mentions the auto-lights sensitivity can be adjusted by the dealership. I find the lights come on when I go under overpasses and bridges and then the flick off after I pass. So, the are a bit too sensitive for me, but I'm going to leave it as its not a major annoyance.
 
If I understand the purpose of the auto-lights correctly, I'd guess they were put on this particular car just to save battery energy? . . . . and they do that just fine as they are. I never turn mine to 'auto' until it begins to get dark (why would you do otherwise?) so I can forget about them and they come on automatically when it gets dark enough and not when I first thought about turning them on, so I've saved a few minutes of unnecessary headlight operation. If they do come on and then go back off when passing under a bridge that's fine . . . . they would have already been on constantly if I had turned them directly to on when I first thought about it, so I'm still saving. Visibility wise, I don't worry too much - My car came equipped with the DRL's and they make the car very easy to see as dusk approaches, even with the headlights off

Don
 
Just trying to put some numbers on headlight energy usage....

Assuming low beam 45W ea. + tail lights 10W ea. + clearance lights 5W ea. total 120W
Assuming DC-DC efficiency 90% (330V to 12V) this gives load of 133W
So 0.133kWh per hour from traction battery of 16kWh = 0.8% for each hour headlights are on.
High beam would double that consumption.

I can't see that I would notice that as a change in range.

Heater / aircond on the other hand would be more like 2kW average so 2kWh/hour of operation.
This would be 12.5% of traction battery used per hour and potentially less than 8 hours to use all the battery pack even if iMiEV was not moving.

So don't worry about lights, it is the heating and cooling that chew energy.
One enthusiastic stab of the accelerator probably uses more energy than the lights on a trip !

Re: auto headlights.... I've noticed that the instrument lights dim under the overpass bridge scenario if the headlights are turned on (manually) during daylight, i.e. no matter if auto is selected or not.
Not a problem when you know what the little i is thinking. Just made me think there was a "faulty voltage regulator on the alternator" when I first saw it. Then remembered there was no alternator ;)
 
Actually, the lights and all accessories (except for AC/Heat) run off of the 33aH Starter Battery. So, there is really no drain on the Traction Battery at all. Unless the Starter Battery is depleted, then it gets a recharge from the Traction Battery.

I keep my light switch on Auto. I like using the gadgets on my i and its one less thing I need to think about. Being a Canadian i, I have the DRL for visibility. I just think its cute that my i is thinking about my safety when I go under an overpass or through a tunnel, and my lights go on.
 
MLucas said:
...the lights and all accessories (except for AC/Heat) run off of the 33aH Starter Battery. So, there is really no drain on the Traction Battery at all. Unless the Starter Battery is depleted, then it gets a recharge from the Traction Battery....
Not exactly… as soon as the iMiEV is turned on, the dc-dc- converter is activated and keeps the 12v battery fully charged at all times. Thus, any load on the 12v battery is immediately 'seen' by the traction pack.
 
Yup - Even the radio is running off the traction battery all the time, along with every other 12 volt accessory on the car. Whenever you turn anything on, you're decreasing the range by some amount. Although most of the smaller loads will have a negligible effect, they still add up - Even using the power steering costs you range

Don
 
Yes, all energy comes from the tracion battery in the end.
My point re headlights is that they represent a rather small amount of enegy. All adds up but don't be 'penny wise and pound shy' as the old saying goes. :)
 
Not to put too fine of a point on this:

General Information/Charging pg 1-2 said:
The 12V starter battery provides power to the vehicle systems and features such as the audio system, supplemental restraint systems, headlights and windshield wiper.

UK i MiEV site said:
The traction battery pack, located below the i-MiEV’s floor, consists of 88 lithium-ion 3.7V/50Ah cells connected in series to deliver 330V/16kWh, and powers the electric motor (via the inverter), air conditioning and cabin heater. Other devices are powered by a conventional 12V auxiliary battery, charged by the traction battery via a DC-DC converter integrated with the on-board charger. Safety features include a cell monitoring device, electrical leakage detector and a very strong protective casing.

Basically, the electrical system works just like an ICE car where all accessories run off of the the 12V battery and the 12V battery is recharged by the alternator. In our case, the 12V battery is recharged when the traction battery is being recharged (pg. 1-17) or from the DC/DC convertor when the 12V is depleted.

Another good link: http://www.autopressnews.com/2009/06/Mitsubishi/EV_i-MiEV.shtml
 
MLucas said:
In our case, the 12V battery is recharged when the traction battery is being recharged (pg. 1-17) or from the DC/DC convertor when the 12V is depleted.
Not really - The 12 volt battery never gets 'depleted' because when the car is running, it's not doing anything. From your link: "The DC/DC converter is used to charge the 12-volt auxiliary battery and power the electrical equipment of the car (radio, wipers, lights...)." Yes, if the auxilliary battery was somehow depleted, the Converter would indeed charge it, but because it (the converter) "power(s) the electrical equipment of the car (radio, wipers, lights..." the 12 volt battery is basically not in use, so it never needs recharging . . . . unless the car sits for a month or so between uses and the radio clock runs it down

When the vehicle is in operation, the DC to DC converter is always running, so the 12 volt battery isn't actually powering anything - When you put a 5 amp load on that 12 volt battery, the DC to DC converter outputs 5 more amps, so the battery never really sees that load . . . . all 12 volt loads are actually running directly off the traction battery via the converter all of the time, so the 12 volt battery never runs down and there's never any need to 'charge' it. It's only real function is to power everything at startup . . . . without it, you can't start the car, but once it's started, the car would operate just fine if you removed the auxiliary battery. All 12 volt loads actually run directly off the converter all the time . . . . the power comes from the traction pack through the converter, not from the 12 volt battery itself

You are correct that it works very similar to an ICE car with an alternator. Nothing 'runs' off the 12 volt battery there either - When you turn on the headlights and present the battery with a 10 amp load, the voltage regulator outputs 10 extra amps from the alternator toward the battery, so the headlights are really running directly off the alternator, so the battery never runs down. The same thing is happening continuously with an i car - Whatever 12 volt loads you present to the battery, the DC to DC converter outputs that amount of current so that the battery is never allowed run down, much the same as with an ICE car - When you pull into the garage after either a long or short drive with either car, the SOC of the 12 volt battery is the same as it was when you left - Fully charged because you never actually ran anything off the battery in either car during your drive

You're probably too young to remember, but Chrysler introduced the first mass produced car using an alternator in 1960. Prior to that time, cars all had DC generators and they could not output enough current at an idle to run the engine electrical system, much less the lights and accessories, so everytime you came to a stop, the headlights would dim, because they were running off the battery. Chrysler's big advertising blitz included a demonstration where they started the car and then removed the battery and drove it around. "This was the year of the "alternator test" - when Chrysler introduced the first alternator, it dramatized the event by driving a Fury from Detroit to Chicago, without any battery!" You could not do this in an ordinary car, because the engine would die when the RPM's came down low enough that the DC generator could not keep up . . . . but you could with an alternator because nothing (except the starter motor) actually ran off the battery

We could do the same - Start the car, remove the battery and then drive around using only the DC to DC converter, because our battery is also only needed at startup

Don
 
Spotted a land rover discovery that does the same

Volt and leaf have no problem either.
 
Re lights, I often leave them on even during the day. Can not be 100% on that but it reduces the number of people who tend to cut the priority of the i because of tits size. The bulbs being Xenon, even in bright sunlight, the beams are very visible, a real plus with such small car.
 
Llecentaur said:
Re lights, I often leave them on even during the day. Can not be 100% on that but it reduces the number of people who tend to cut the priority of the i because of tits size. The bulbs being Xenon, even in bright sunlight, the beams are very visible, a real plus with such small car.


The fog lights are standard in Canada just for that purpose. DTRs are required on all vehicles here. I also updated my rear reflectors to be lighted reflectors. I found a pair of LED reflectors the same size as the factory originals and replaced the ordinary reflectors. I now have DTRs front and rear which greatly helps with my visibility on the road. I've noticed some European and high-end Luxury models have these. One other thing I did for conspicuity was to add a row of LED lights up front between the headlights and hood.

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