What battery is correctly for an Aemitron watch? Back plate has # 20/437sv. 1802

This will depend on the back of the watch. Totally smooth watch back is usually a push fit. Using a small precision screwdriver you Gently lever around the back plate until it 'Pops' off. the battery should hook out by CAREFULLY using the screwdriver you used to remove the back plate. *Note* check which way up the battery is fitted BEFORE you remove it. The back plate should just push on and should quietly click when seated correctly.
Some back plates are 'screw on'. You can usually spot these by the dimples or notches on the back plate where the removal tool fits.

The simplest solution to this is to get a watch repairer to do it for you. They usually only charge a small fee to do it and just takes a few minutes.
If you can get the back cover off the watch the battery will have a size code marked on top of it, often an AG- or an SR- number. This will give you the size of battery you need. I think your watch has a 'push fit' back plate.
*Note* If your using something metal as a lever it could scratch the watch.
CAREFULLY using a blunt edged lever GENTLY lever the back plate off. This should reveal the battery. When refitting the back plate it should click into place using a firm, even and gentle pressure.

For a quality watch like that I would recommend using a specialist watch repairer as they can reseal the watch to be water tight after the battery is replaced.
Could you possibly comment below with a photo of the back of the watch?
There are three main types of watch back plate. Push fit, screw down and screw on.
Push fit is usually a smooth back cover with No notches or grooves. These can be gently levered off to replace the battery then pushed down to 'click' back into place. Some have a slight notch on the body or back plate to make removal easier.
Screw down back plates have dimples or notches at regular places around the edge. This is to allow grip to unscrew the whole back plate. Some versions need a specialist tool to unscrew them.
Screw on plates use four tiny screws to hold the back plate down. These are more commonly used on 'Sports' or digital watches.

Spread the towel out on a flat surface.

Remove the watchband if necessary in order to access the back of the watch.

Unscrew the back protector from the watch using the correct size miniature screw driver. Place the screws in a small pile on the towel. Be careful not to drop them as they are difficult to find.

Remove the back plate by unscrewing the small screws. There is a tiny spring on the underneath of the back plate. It may be visible, or not. Make sure not to turn the watch upside down or the spring will dislodge.

Remove the rubber protector to find the battery.

Use sharp point tweezers to remove the clasp covering the battery. There is a small hole at one end of the clasp. Insert one end of the tweezers into the hole to spring the clasp loose.

Remove the old battery with tweezers.

Insert New Battery and Reassemble Watch

Pick up the new battery using regular tweezers and put it into place. Do not touch the battery with your fingers.

Replace the clasp over the top of the new battery.

Perform a reset by touching the AC contact with one part of the tweezers and the back of the battery with the other part. Hold for a few seconds. Lift the watch carefully and look up at the front to make sure the watch is working. Do not turn the watch over.

Replace the rubber cover.

Replace the back plate by screwing the small screws back into place.

Replace the back protector by screwing the small screws back into place.

Reattach the watch band to the watch face.

Feel a bit unnerved by this? Find a local jeweler. Best regards.
Jewel

hi, if the back plate on the watch the part that is against your wrist has four screws holding the silver back plate onto the actual watch then you need to undo these four screw, once undone you lift the back plate off and then this gives you access to the battery, the screws are small philips (cross head screw) so you will need a small screw driver, their is also a little bracket that holds the battery in place you can either push this over to allow the battery out or undo the small screw that holds this bracket in place this will then allow the battery to fall out,

If their are no screws in the back plate then all you need to do is get a very fine flat head screwdriver and look around the edge of the back plate and you should see a little bit on one of the edges that allows you to put a screwdriver into to allow you to lever the back plate off if it has no screws then its just a push fit so just pry the back off and this will give you access to the battery then like above the battery will be held in place by small bracket undo this then remove the battery.

when fitting the new battery make sure you dont touch the top and bottom of the battery as this will flatten it really quick so just push it in place then refit the bracket then either push the back plate back on or screw it back on depending on the type of back plate once this is done you watch will be working again

The noise is very annoying but after some time I have found the solution to your problem.

Remove the back plate which covers the battery. On the inside of the plate there is a conductor. To silence the noise simply flip the back plate and place it on the watch inverted (upside down) from its original orientation. This should stop all noises and the watch should work correctly otherwise. Enjoy!

hi there when you replace batteries in wave ceptors all hands have to be set to the home position (straight up at 12 oclock), as the instructions vary wildly from watch to watch you will have to download the manual from www.casio.co.uk you will need to put in the module number (found on the back plate of the watch), this will be in PDF format, you can download adobe reader for free from www.adobe.com to read PDF files. good luck

If you'd been given the correct answer in the first place you would have simply unscrewed the back, which is what the notches are for. I scratched my back plate trying to follow the answers you got!

The second battery is located underneath the top part of watch movement wich consists of two parts screwed or clipped together. Actually it is the bottom, not the top part, as 99% of watches are opened from the caseback side.
Some watches are assembled in the way, that after extracting the big battery, you can reach the second battery through the hole in movement. If this is not a solution in your particular case, then you have to take apart watch movement to reach the second battery.
If movement parts are held together by screws- simply unscrew them. If movement is held together with 'clip-on' steel plate- you have to unclip the plate by pulling all clips outwards from movement.
Allways memorise the polarity of batteries and the correct position of every watch movement part, even screws. This will make reassembly easy and correct. If there are any screws you need to unscrew- do not mix them up as they can be different lengths and sizes. Screw them back in the same holes they came out.

Don't forget to rate, please.

good after noon ! maybe the problem of your watch is wrong possition of case back because the speaker or buzzer of your watch is attached on the case back , so open the watch and fix the case back at the correct possition ,!thank you ! god bless !.....