ChatterBank10 mins ago
Toyota Rav 4 Battery Problems
Is there any test I can do to see if any current is being used when all is switched off and keys out.Battery keeps going flat when car is not used for a few weeks.Even with new battery!!!
Answers
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If you have a multimeter you can test by setting it to DC Amps, disconnectin
12:12 Thu 22nd Jul 2021
Lots of things will still be taking power from the battery when the key is out. If they didn't, your car might not function as well as it should!
Most car stereo systems draw a small amount of power to retain data in their memories. (That's why, if you've had the battery disconnected for any reason, you'll probably need to re-enter the security code to get the system working again).
Similarly, many of the electronic modules in modern cars need power to retain data in their memories, so that (for example) an onboard computer can calculate fuel consumption across multiple journeys.
Even in the 'pre-electronics' era, dashboard clocks could drain power from the batteries of unused cars remarkably quickly. The circuitry for interior lights can similarly drain power, as such circuits often use some power to hold a relay closed until a door is opened.
To check the actual current being drawn, you'll need a multimeter that can measure DC amps. See 'What's draining your battery', here:
https:/
Most car stereo systems draw a small amount of power to retain data in their memories. (That's why, if you've had the battery disconnected for any reason, you'll probably need to re-enter the security code to get the system working again).
Similarly, many of the electronic modules in modern cars need power to retain data in their memories, so that (for example) an onboard computer can calculate fuel consumption across multiple journeys.
Even in the 'pre-electronics' era, dashboard clocks could drain power from the batteries of unused cars remarkably quickly. The circuitry for interior lights can similarly drain power, as such circuits often use some power to hold a relay closed until a door is opened.
To check the actual current being drawn, you'll need a multimeter that can measure DC amps. See 'What's draining your battery', here:
https:/
If you have a multimeter you can test by setting it to DC Amps, disconnecting the negative battery lead and measuring from that lead to the negative terminal on the battery. That will tell you how many amps are being drawn in a fully 'off' state, essentially you don't want to see more than about 50mA as that is pretty standard for alarms etc. Essentially the battery should stay good for the period of time indicated by the quoted capacity of the battery divided by the draw on the battery so if you have a 40A battery with a 50mA draw then that will only last 33 days (40/0.05 = 800 hours)
With a new battery (fully charged), it should be capable of starting the car after sitting idle for 3 weeks.
But over that length of time, the battery charge will have dropped significantly due to the normal low battery drain.
If you regularly leave the vehicle for extended periods, I’d recommend you buy something like this to keep the battery topped up.
Bear in mind that if plugged into the cigarette lighter socket, there must be a connection to the battery with the ignition off (otherwise use the crocodile clips to make a direct battery connection).
https:/
But over that length of time, the battery charge will have dropped significantly due to the normal low battery drain.
If you regularly leave the vehicle for extended periods, I’d recommend you buy something like this to keep the battery topped up.
Bear in mind that if plugged into the cigarette lighter socket, there must be a connection to the battery with the ignition off (otherwise use the crocodile clips to make a direct battery connection).
https:/
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