I have seen various posts and questions over the years about the various interior lights in classic Hymers. Changing to LEDs has been all the rage recently, but for many this is at odds with preserving the classic style, and for others they just don't like "colour" of the new LEDs. Add to that the fact that some fittings and bulbs are getting obsolete and hard to find so it's no wonder there is confusion. So let's clear it up.
In an "average" classic Hymer there are 3 types of light - tube, halogen and incandescent. There are photos below of the common types.
Tubes. These are easy to identify - they are long and thin, and are mini versions of the fluorescent tubes us baby boomers all grew up with at home and work. They work on the principle of trapping a fluorescent gas inside a vacuum tube, and applying voltage at each end. This causes the gas to glow and give out light. They were "new technology" once upon a time. For many years the only type of domestic light was the good old fashioned lightbulb, but these were very inefficient, giving off only about 20% light and 80% heat, so when fluoros came along, giving off more light and less heat, they became instantly popular, especially in the workplace and in institutions - ie hospitals! They give off quite a harsh bright white, which is great for brain surgeons, but not so good for the bedroom. So fluros tended to be found in utility areas, kitchens, garages etc. However it was possible to get a softer light from tubes by using shades and covers made for glass or plastic, and this is what we find in our classic Hymers - a white tube covered by a smoked plastic cover, and the result is a reasonably pleasing light for the van interior.
Tip - when did you last clean your tube shades? Most classic tube lights in Hymers have 2 thumb screws that enable you to easily remove the shade. A good wash can make a big difference if yours haven't been cleaned for many years.
The tubes themselves are still easily available. They last a very long time, so many of us still have the originals and are unfamiliar with changing them. They can blow suddenly, or gradually. The sign of a tube on the way out is they go black at the ends and occasionally they will flash, or take a while to light up. If this is happening you should replace the tube asap because a tired tube is placing extra stress on the transformer. Tube lights work at a much higher voltage than 12v, so each light has a transformer in it - usually a small box at the end of the light. It is the transformer circuit that is important, because if that goes faulty, then you have a problem, because they are not readily available. In extreme cases they can get hot and give off foul smelling acrid smoke - this is the smell of the chemicals used in the capacitors in the circuit. Once this happens, you need a whole new tube light.
As far as I am aware, the tube lights used in classics are no longer available. I am not sure who manufactured them, but it is not just a matter of phoning a dealer and ordering a new one. Your only options are to either replace the whole thing with a different, more modern one, or, if you fancy a bit of DIY, you can convert the old lamp to LED. LEDs work off 12v so don't need a transformer. There is usually a white or silver reflector running the whole length of the fitting, and this is ideal for sticking one or two strips of self adhesive LEDs. You then take the 12v wires that were originally going to the transformer, and connect that to the LEDs. Done properly, the whole fitting appears unchanged, and if you use "warm white" leds as opposed to "cool white", the final result will be satisfactory compared with the original. This is an easy job for kitchen lights that have an external switch, but less so for the lights that have the switch built into the unit, as this is usually part of the transformer unit. However it can be done if you are happy to use a soldering iron.
Another option is to embark on a quest to find an original second hand - they were used on many vans and caravans, not just Hymers, so there will be one sitting on the shelf of a breaker somewhere. You don't even need the correct size, as the transformer units are pretty standard, and if you are even slightly handy at DIY you can cannibalise a transformer and transplant it into yours.
So with all that kerfuffle, it is easy to understand why people may chuck in the towel and install a new lamp - but the thing to remember is this - it can be done!
Halogens. These are the small round spot lights found above the bed and in some dining areas. A halogen light is just like a normal filament bulb, but with a bit of halogen gas inside the bulb. This makes the filament burn more brightly, and gives off a lot more light for the same power - but also a lot of heat. For this reason people think they are very inefficient. Well they are when compared to an LED, but the halogen spots in classics are quite small, and in reality they don't use a huge amount of power. They give off a warm light, and again, the colour of this light is in keeping with the classic feel. If you like them, you can keep them. If you don't like them you can change them. There are several LED equivalents. Because you are only changing the bulb there is no major surgery and you can revert back to halogens easily, or experiement with different types of LEDs.
Incandescents. These are the normal 12v bulbs and usually found up front around the drop down bed. Also in the cab lights. These are pretty utilitarian in nature, and don't need much discussion. They are not usually left on for long periods of time, so power consumption is less of an issue. There are LED equivalents of all these 12v bulbs, so you can experiement to your hearts content.
However the one exception is the bathroom light! Most CH bathrooms have the "classic" vertical lighting column, behind a vertical plastic shade (which benefits from a good wash occasionally!) adjacent to the mirror, and contains 4 x 23w classic 12v tail light bulbs. Total consumption almost 100watts! This is the light that causes the most consternation for owners because of all the lights in the van, this is the one that causes the "STROM" meter to deflect most noticeably into the red. It is the grandaddy, and the other lights dim in courtesy! But it is also sexy, and very fit for purpose, and typically Hymer. Men hardly notice it - as long as they can find the roll they are happy, but for the ladies and teenage girls it's the most important light in the van. It's the makeup light. So mess with it at your peril! The 4 bulbs and the colour of the shade give off just the right light for doing makeup and girly things. It is also very useful for a decent shower if your van has one. There is nothing worse than showering in the gloom.
Those 4 x 23w lights consume just under 8 amps. A fully charged normal leisure battery will keep the bathroom light shining brightly for about 6 hours. Non stop. The average bathroom visit is 2 minutes for a man and 15 minutes for a woman, unless it's Saturday night, in which case add another hour. But do the maths - even using the monster light in the bathroom for an hour, it will only use about 10% of the battery. And this only applies if you are wild camping - ie not hooked up. When you are hooked up, power consumption is insignificant. Even if you are wildcamping regularly, your battery should do you for 2 days, longer if you have solar, and every hour you drive will charge your battery up 30 to 40%. The worst thing that can happen is that you leave the bathroom light on all night - that will usually flatten your battery - but it's a rare occurrence and easily solved by starting the engine.
Hymer knew the bathroom light would use a lot of power, but they also had decades of experience and the sense to know that some things just can't be compromised, and that of all places, the bathroom needs good light, as with the kitchen to a lesser extent.
So think twice before just buying any old LED bulb for the bathroom, and don't just change it for the sake of it. If you put in bright "cool white" bulbs you will end up with a bathroom that looks like a scene from a horror film morgue. Cool White is a no no and Warm White is the way to go, and experiment - or just leave alone. You can also install LED strips - see photo below of my installation, which is the third version in as many years before I finally got it to our satisfaction. It also helps to fully involve the female members of the team when choosing bathroom lighting.
So that's the lowdown on lights. Other than the technical issues of maintaining the original lights, the main point I am trying to make is to think twice and plan carefully any LED upgrades, and get familiar with the concept of "colour temperature". The wrong colour light can be really annoying. The other point is that that the original lighting was good for 30 years before LEDs came along. Batteries are meant to be used and are more than capable of keeping the lights on for normal use. You only need to consider modification if you really intend to go off grid for long periods of time - ie more than 2 days at a time.
Standard Hymer tube light. The transformer circuits and switch are the white bit at the left hand end. Remove the shade with the thumbscrews.
Standard halogen spot. Easy to replace with an LED bulb. But do you really want to?!
Original kitchen strip light. This one had it's transformer and switch up in the panel. When it blew a year or so ago, I replaced the tubes with LED strips.
Illuminated!
LED strips with door switches are a cool modification. No more peering in the back looking for the Branston. Fiddly to wire, but well worth it.
Before
Same for the overhead cupboards. LED strips fit nicely under the front top lip, and take their power from the wires feeding the normal lights. The overheads are a lot easier to do than the vertical kitchen cupboard.
Before
I replaced the 4 bulbs in the central column with warm white LED strips, and extended the strips over the mirrors. I have a separate shower cubicle to the right, and the idea was to throw more light into the shower. This is a low exposure photo that doesn't show how bright it is, but shows where the LED strips are fitted.