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Robert, UK Qualified Car Technician
Category: Mazda
Satisfied Customers: 5882
Experience:  Fully qualified / self employed garage technician in the UK
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Battery keeps going flat despite a new one being fitted, Ive

Customer Question

Hi. Battery keeps going flat despite a new one being fitted
JA: Have you tested the battery with a voltmeter? And can you see if it's leaking or not?
Customer: Ive called the RAC out on 3 occasions. It's being drained but they can't see where from
JA: What is the model/year of your Mazda?
Customer: 2018 Mazda CX5
JA: Are you fixing your CX-5 yourself? What have you tried so far?
Customer: Not at all. I've been told to take it to a mazda specialist
JA: Is there anything else the Mechanic should know before I connect you? Rest assured that they'll be able to help you.
Customer: The iStop light was flashing a couple of days ago
Submitted: 17 days ago.
Category: Mazda
Expert:  Robert replied 17 days ago.

Hello and thank you for using JustAnswer. My name is***** am a Vehicle Master Tech/MOT Tester located in the UK and I will do my best to assist you. During this conversation, you will be given an automated offer for a phone call.I don’t personally offer this service. I’m sorry that you’re having trouble with your vehicle. Please understand that I do not know your knowledge or capabilities so I may need to ask questions to find out basic information to help solve your specific problem. My aim is to give you the best advice possible and to help you. Sometimes it may take a moment for me to respond because I may have to look up information about your concern. I appreciate your patience and will provide responses as soon as possible. Firstly can i ask who i am speaking with today?

Customer: replied 17 days ago.
Expert:  Robert replied 17 days ago.

Hello Jimmy.

- How quickly does it tend to drain the battery? Did the RAC do a draw test on the battery at all?

Customer: replied 17 days ago.
From what I've experienced, quite quickly. The RAC came out yesterday evening, jump started the car and u went for a*****
Customer: replied 17 days ago.
When I went back a couple of hours later the battery was flat
Customer: replied 17 days ago.
The iStop light was flashing yesterday morning
Expert:  Robert replied 17 days ago.

Ok. the ISTOP will likely be showing up because of the low voltage on the battery. if its consuming that much power then steps need to be taken to identify which circuit or component on the car is consuming power when it shouldn't be..and then take steps to check for water ingress, corrosion issue with that circuit and the components that circuit covers. Testing for a parasitic drain using a decent multimeter or clamp ammeter or a fuse tester that measures the voltage across the test pins. A fuse/wiring diagram is need. and only then systematically pull and replace back one fuse at a time,and which ever one is pulled and the voltage draw drops..then that fuse removed will be the circuit in question at fault and then further steps taken in order to see what components are on that circuit need checked.

Customer: replied 17 days ago.
Sounds complex. Do I need to go to a Mazda specialist
Expert:  Robert replied 17 days ago.

It would be an advantage if you have one locally. However id imagine any decent auto electrician should do the job just as good if you know of any.