I have a 1999 cadillac deville that has no battery power after charging it every 4-5 days.It has been to the garage many times but dealer cannot locate problem. Battery and alternator are fine.
Does the dealer know what he is doing? When you say “charging it” do you mean with an external charger?
Assuming yes, then your battery doesn’t seem to be charging from the alternator at all. I’d suspect the alternator, or the wiring to the battery or ground. Check the battery terminals for corrosion.
Battery may also be bad, after all these discharges.
This should be a simple problem to solve. Go to a different garage and ask them to check your battery and alternator.
Have they checked for a draw on the battery? There could be something drawing the battery down when the car sits. Something as simple as a glove box light or a trunk light. Make sure no lights are on after the car is turned off.
how often do you drive it during those 4-5 days? do you have remote start on it? assuming you do and that it does not get driving too often-are you using the remote start to “warm your car” then shut it back off? it sounds like your not letting the alternator charge the battery back up enough or you have a slow drain on the battery.
If I understand what you are saying your battery is flat after charging it with a battery charger after about four days. If you are not driving the car during those four days, then the batter has low capacity or it has a higher than normal dark load (power being used when the car is not running). -OR- the battery has a lower than normal capacity, which can happen if it has been allowed to deeply discharge a few times. Now I would guess it may be both.
If you are driving the car regularly, then I would believe the battery is not being properly charged.
Most auto part stores will check both of these for you for free. I suggest you try that.
Don't forget that you should make sure all the cables attached to the battery are clean and tight at both ends.