HDPattaya

I think it depends on the type of cleaning. I have used the sprays etc. and periodically clean the filters. I found that when I get mine done properly it costs about 1400 a unit but this is complete removal of the evaporator (inside unit) and spray cleaning of all the parts new gas etc and additionally I get them to use a rust inhibitor and spray Rust-Oleum primer on metal parts. (usually around the frame areas) the I have 7 and it takes a good part of the day with about 4 to 5 guys. I install or have them insert some condensate drain pan rust/ biological growth inhibitor https://www.airstarsupply.com/products.aspx?cat=29

I think people are talking about different kinds of service here so I would like to see what exactly they get done.

I have used many and found: Typically people place the outdoor ones in the wrong places and it attracts the bugs to the location they do not want the bugs. All the big zappers I have used have a short life span outside. Yes the CO2 works a tad better. Best to place then away from doors and places you sit etc. Use replants in the door and populated areas. Best easy repellent is the fragrant lemon grass. I keep potted ones at the doors. Inside the house I use cheap wall plug bug zappers: https://www.lazada.co.th/products/pest-repeller-light-220v-electric-led-light-mosquito-killer-fly-bug-insect-zapper-trap-catcher-plug-lamp-i980340301-s2115582115.html?spm=a2o4m.searchlist.list.23.4b1a110bFGNBCn&search=1

Lots of good ideas here. Bottom line most all new cars and motorcycle have a "parasitic drain" which is the current used when the system is idle (key off), part of this is clocks, computer memory, sound systems, security systems etc. Sound systems (head units and power amps) often us a trickle to keep capacitors charged so they do not make a pop noise when turning on and can be a substantial drain. System devices should have non volatile memory and or battery/ capacitor backup for short term battery disconnection. However they are all different and disconnecting the battery may cause some functional errors that need resetting most can be found in the manual and reset yourself. The newer the vehicle the more settings that can be affected. Typically a parasitic drain should be less than 50ma as a rule and the battery will last for a month or more. Some systems are much higher with added options and can drain the battery down in weeks. Bottom line I like the battery tender idea and install a plug extending outside from the battery to plug them in.

As mentioned the CTEK is a very good one available local the model MXS 3.8 is a great one (up to 85ah batteries) which will do desulphation also which can extend the life of your battery even if you are not going away. If using regularly can tell you the battery is failing before actual failure as the new batteries can fail without warning.

Always disconnect the negative post (grounded one) of the battery first for safety. When using your tool if it hits the frame or some part then no problem but if on the positive first this can be a disastrous short circuit. When installing reverse the process and install the positive fist. This is true unless you have an old positive ground vehicle which then is reversed procedure but always disconnect the grounded one first..

Older vehicles and some new ones removing the battery is not a problem, however its always a good idea to recharge it first before reinstalling. Often then its just as easy to keep it charged in the vehicle. periodic starting is not bad for long times but it needs to run for a while to get up to temperature and may not charge the battery. Always disconnect the charger before starting.

Using a  battery saver or backup power supply is not recommended as some do not supply enough voltage and or current and can cause damage unless you know your vehicle and the electrical system or one designed for your vehicle.

Another thing to consider is gas stabilizer. In Thailand I have seen gasoline go to varnish within 1 month storage. Its easy to tell as it smells like varnish and will not start then it needs to be drained and sometimes the system cleaned out. To prevent this use gasoline stabilizer which is available local from Amsoil. Even then some of the fuel may varnish or gum up in the lines etc but after short running it should clean itself.