not at all!!!!!!!!!
not at all!!!!!!!!!

I agree...
many non-working electric clocks get changed to battery without losing any value to the clock. An exception to this is if the battery motor doesn't fit the clock hands properly...and there WERE variations on the motor peg sizing!

If, however, the clock is a wind clock, changing it to a battery WOULD affect the value. I know; I have a rare model that was wound so tightly that the spring had broke and rusted, so it couldn't be repaired. I had a standard battery motor put in and now it has a small wind-up hole in the front of the clock for no reason.

Many people change their electric clocks to batteries because they dislike the cord, but I keep my electric clocks original. The cords don't bother me.

LRF
Don't think he's ever sarcastic....

Batteries?
If you're talking about a ball or spike clock (less rare color combination especially), it doesn't impact value much to replace the works with batteries. That is principally because they are fairly prevalent [at least one or two on ebay at all times] and do not sell for much more than their contemporary Vitra reproductions, which already come with batteries. But if you're not getting a premium for a vintage model, and replacing the works reduces the value of a vintage model, why not just buy the Vitra or leave the vintage clock the way it is?

But when it comes to the rarer clocks, I think it would be foolhardy to replace the works. For instance, eye clocks with replaced works garner half as much as those in original condition at auction. Why? Most people who collect Nelson for historical significance would not want to see the clock modified and would never buy one.

I liken it to the situation where, on Antiques Roadshow, the furniture expert tells the person their piece is worth $x, but would be worth at least $2x if it hadn't been refinished.

For those who are collecting the clocks because of their historical value, the original works, backing, etc. are critical. Moreover, what is so bad about using the chronopack, having a wire showing, or simply removing the wire for display purposes?

By the way, for those who might still be reading after this diatribe, I'm going to see the Vitra-sponsored Nelson Exhibit in Spain this weekend. Has anyone been to the Fundacio Barrie or seen the exhibit there yet? I'm looking forward to seeing it.

Practice?
We talkin bout practice??

thanks
I appreciate reading the replies and differences of opinion. I think I will follow barry's and Midmod's advice. LRF, these clocks are a big investment for me. While I love them, I may not keep them forever. I may sell them or trade them for different models. I also will want to leave them to a niece or nephew, (if they appreciate them). So, to me, maintaining the value is an important question. Midmod, I wish I could attend the vitra attribute to GN. But, I am coming close...spending thanksgiving in Palm Springs shopping with my parents who are looking for a mid century house with a view. Some neat architecture out here!

LRF...one thing I did do with my electric cords
was to replace a couple of the brown or yellowed cords with brand new white ones, as my walls are white. They almost disappear.

It makes sense for anyone to consider changing their electric cords to a color that matches exactly their wall color.