Aloha folks, I have a transformer with 12 volt output and i milliamp. Will this work as a battery tender overnight? Will this keep power to the computers if I change battery's?

 

I would not risk having power applied while changing battery. No need really if your car is in good working order. A battery tender has intelligence built it. I have 2 of these. not too expensive and work great. https://no.co/genius5 Using a proper tender will extend the life of your battery if your car sits for prolonged periods of time.

 

hi SunG, The car doesn't sit for long periods but we don't go far at a time. Often less than a mile. I just wanted to keep it topped up so to speak. It is several years old but still works well. Doesn't the computer need voltage when I do replace the battery?
Thanks for your advice.

 

If you have a garage, I'd get the one I use or something similar because its not much and it will last a long time and keep your battery in top shape. They make a smaller one that is a bit less money but it does less. you'd have to look at the website to see all the options. No need to do anything when replacing your battery, Some things will get reset but after driving 5 or 10 miles all the systems will be back to normal working order. the things that get reset are possibly fuel trim history and if you were to bring your car in for smog test they will know your battery had been disconnected unless you drive a few miles before bringing it there. there may be others, but I've done it many times on our old 2008 ES with zero issues.