StuartO Posted February 9, 2017 Share Posted February 9, 2017 I am about to replace my Hymer's electrically adjustable doormirrors with electrically heated ones, which I think will be more useful. The question is whether to incorporate a switch, to be able to avoud leaving them on continuously, or just wire them to a fuse which is energised by the ignition switch, so they are on all the time. The reason for my uncertainty is that once upon a time I thought heated door mirrors were low power, leave on if you wish, rather than some sort of vulnerable device. However the heated mirrors on my new Honda CRV cut out automatically after 30 minutes (according to the Honda User Guide) to protect themselves in some way (which is not specified) implying that either that the heating elements are high current users (which would be surprising?) or that they are prone to failure if left on for a long time. This is the first warning of this kind I have come across with any vehicle and on my previous Honda CRV the heated door mirrors could apparently be left on and there was no equivalent warning. There is a spare switch on the Hymer's dashboard anyway, nominally for a heated rear windscreen which the vehicle doesn't have, so I will wire to that if I can get at it. This switch even has a green led incorporated which illuminates to show that the switch is on. But why the Honda warning and cut-out system for heated door mirrors, does anyone know? By the way if you need a replacement mirror for a pre-2007 Hymer A Class MH, this EBay source seemed very good value to me: http://www.ebay.co.uk/itm/Main-Mirror-for-Hymer-Motor-Home-12Volt-Heated-/230985142371?hash=item35c7c99063:g:rRMAAOxyUylTUjHf Link to comment Share on other sites More sharing options...
Keithl Posted February 9, 2017 Share Posted February 9, 2017 Hi Stuart, It's all about fuel economy and CO2 figures! Anything electrical consumes energy and this can only come from one place - your fuel tank! So leaving sidelights on, heated door mirrors on all has a negative impact on your fuel economy. You may think it not worth bothering about but manufacturers pay thousands in design and research to try and improve by fractions of an mpg or grams of CO2 and switching off any thing not necessary is the easiest saving. Switching off items after a pre-determined time is quite simple to achieve. I would suggest wiring your mirrors through a switch so you are in control as the amount of time you will actually need them on is really quite small. My opinion. Keith. Link to comment Share on other sites More sharing options...
StuartO Posted February 9, 2017 Author Share Posted February 9, 2017 Keithl - 2017-02-09 3:50 PM..... I would suggest wiring your mirrors through a switch so you are in control as the amount of time you will actually need them on is really quite small.... Well I do most of my MH touring in France and I have now relocated from Lancashire to Suffolk, so maybe I won't now need heated mirrors quite so much - but in Lancashire it does rain rather a lot and these big rectangular mirrors don't seem to self-clear of rain drops at all well. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted February 10, 2017 Share Posted February 10, 2017 Ducato models that preceded the X250 range (introduced in mid-2006) could have heated exterior rear-view mirrors. Mirror heating was initiated by pressing a dashboard button that also switched on the rear-window heater (if that were present). There’s nothing in the pre-X250 Ducato handbook to say that this mirror/rear-window heating was on a timer. The same press-button method is used for the heated exterior rear-view mirror capability on Ducato X250 (and X290) vehicles, but this is on a timer. The handbook says "Defrosting/demisting (for versions/markets where provided). The mirrors are fitted with resistors that are activated when the heated rear windscreen is turned on (by pressing button). IMPORTANT This function is timed and it will turn off automatically a few minutes later.” The heating operation of my 2005 Transit Mk 6’s exterior mirrors was ‘timed’ and operated by a single dashboard button that also turned on the rear-window heater. The current Transit Mk 8 can have a heated windscreen, a heated rear-window and heated exterior-mirrors, and all are on timers. My 2009 Skoda Roomster car’s rear-window heating is operated separately from the exterior-mirror heating. Rear-window heating is initiated by a dashboard switch that has a tell-tale light and heating switches off automatically after 20 minutes. Initiating exterior-mirror heating involves rotating a door-mounted mirror-adjustment switch to a dedicated position. There’s nothing to suggest that mirror-heating is on a timer, though the handbook does advise that mirror-heating only functions when the vehicle’s engine is running. There is no tell-tale to warn that mirror-heating has been chosen and it’s easy to leave the door-mounted switch in the ‘heating’ position. The same arrangement for mirror-heating continues to be used on current-model Skoda cars (and I’m guessing on other VW Group vehicles). I’m doubtful that vehicle manufacturers ’time’ windscreen/rear-window/mirror heating specifically to improve fuel economy and emissions values as that would suggest that having those heaters switched on was an obligatory element of mandatory fuel consumption and emissions testing. As Keith says, it’s easy enough to switch those heaters off via a timer, and (logically) it’s better to have a driver switch a timed heater back on if it is required rather the heater staying on indefinitely even when it is no longer necessary. Link to comment Share on other sites More sharing options...
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