Welcome to TAI
, I feel all the electrical problems you have mentioned are pointing towards your alternator. Here is some info that might help you.
Every car has a Alternator (also called as Dynamo) which is connected to the engine through belts. It works only when the engine is "ON". It's purpose is to charge the battery & supply power to everything (I mean electrical stuff installed & OEM
things) you have in your car.
M800 Type1 : 30Amps or 35Amps
Our Cars (M800 Type1) have a very small (in size & power output) alternator (35A) which is not sufficient to charge battery + bright (100W bubs etc) headlights + Music System + all other indicators.
Try to find if the issues come up only when
1. Engine + ICE is on.
2. Engine + Headlight + ICE is on
3. Engine (only) is on.
Possible solutions are:
1. Swapping/ changing alternator of your car with a bigger one (like swift etc)
2. Remove ICE (I know that no one will choose this
3. Dont use ICE when headlights are switched on till you get a better alternator.
The below ones are the common mistakes we tend to do in this situation:
1. Replacing the battery only
2. Replacing stock alternator with a new MGP 35Amps one
3. Replacing whole wiring to see something drastic happens
I have already replaced whole wiring in my car, it costs around 2.5K (total kit from Minda). It takes almost half day (atleast) to do this. The new wiring kit eliminates all crazy electrical issues we usually face with old cars. It also saves us by reducing the chances of Short circuit etc.
Here is a Mega DIY done by Varun & his friend. DIY Alternator Upgrade of Maruti 800
Here is a pic of Varun's car with the Swift alternator
Here is a picture of the M800 Type 1 (left side) & M800 Type 2 (right side) alternators
Here is a link to my thread, where my alternator too started troubling me. So I just swapped it with a Type 2 Alternator.
Please crosscheck if the alternator is working fine (we can meet if you need any help) & only then decide/ do anything about the swap.
Used swift alternator swap (buying + repair + installation) might cost around 5 or 6K. but its worth it, as you have a good thirsty ICE.