Acceptable Battery Drain from Telematics Box?

March 8, 2017

I was wondering if anybody would be able to help shed some light on my current situation? I have been driving a Toyota Aygo Blue (2009) since May last year and having been having an ongoing issue with my Battery draining. My Battery initially died on the 1st September and I had it replaced by the AA. My new Battery then died about a month and a half later and, again, it was replaced. The battery was then replaced again after dying the following month. I was stumped for some time as it seemed incredibly unlikely that I had been given so many faulty batteries.

I then took my Aygo to the local Toyota garage and they identified that there was a drain on my vehicle but were uncertain of the cause. Following this, it was suggested that the telematics box I had installed as part of my insurance policy could be the cause (the car was previously owned by a member of my family and the battery has always worked fine before I acquired it).

After taking my car back to Toyota, they confirmed that the drain stopped after disconnecting the telematics box and deemed the box to be the cause of my drain. I raised this with my insurance company who passed my information along to RSConnect (the company that installed the box). They requested I take the car back to Toyota to get the amount of power that the box is drawing tested, I happily obliged to do this.

The tests that Toyota did found that the telematics box was drawing between 0.07a - 0.12a and my service advisor told me that this would be sufficient to noticeably drain my vehicle. When I brought this information to RSConnect, they deemed the drain insufficient and said they would not investigate any drain below 3a.

Their expectation of what is a "significant" drain seems very high to me but I wanted to get further opinions? Is the power that my telematics box is drawing high enough where this is worth disputing and pursuing further?

March 8, 2017

That current drain is 70 to 120 milliamps and long term is enough to gradually pull the state of charge of the Battery down. It takes many many hours running to fully charge a partially discharged Battery... the reasons why are complex and with a lot of variables... but to answer your question, yes, that level of current drain could well be your problem. That applies particularly if the car is lightly used.

A current drain of 3 amps sounds like a number plucked from thin air and would fully discharge a 100% charged Battery in less than a day.

March 8, 2017

Thanks for the response. The car does have somewhat light usage but tends to get a good run up the A45 (30 minutes each way) at least once a week. The Battery even died a couple weeks after a 3 hour journey (each way) to visit family with the usual weekly driving also taking place.

I'm no expert in the matter by any means, which is why I wanted further opinions. But the way I see it, is that the telematics box was advertised to me as something that would not impact my vehicles performance despite the fact all evidence seems to suggest that it is.

While driving my car more often and for longer journeys will help alleviate the problem, should I have to do this just to account for the power the box is drawing? Personally, I believe the answer is no.

If the power the box is drawing is significant, I will pursue things further with my insurance company.

March 8, 2017

I have no idea of the purpose of this box. However if you are not using your car very much could you not simply disconnect the Battery in the meantime. There are very easy to fix connectors on eBay designed just for this this job.

my understanding is lots of caravan drivers use the them. Once they are on the Earth terminal you just twist and the Battery is isolated.

March 9, 2017

13 hours ago, Tom Rose said:

While driving my car more often and for longer journeys will help alleviate the problem, should I have to do this just to account for the power the box is drawing? Personally, I believe the answer is no.

If the power the box is drawing is significant, I will pursue things further with my insurance company.

No, you shouldn't have to drive around just to keep the Battery charged because of having this device fitted. The bottom line is that that level of current drain is unacceptable.

The cars alternator, although rated at perhaps 70 amps or more, can not quickly bring a Battery up to full charge for a few reasons.

1/ The alternator voltage will fall to around 13.5 volts when the engine is hot and that voltage is (by design) is not high enough to 'force' a high charge into the Battery. If it were higher then batteries would have a short life and nominally 12 volt rated parts such as bulbs would also have a short life.

2/ As a battery ages it becomes less able to accept charge (that's normal) and so requires the charging voltage to be present for longer and longer periods of time.

3/ Continually drawing a current such as you are doing will cause sulfation of the plates of the battery as the state of charge of the battery never reaches 100%. Sulfation also makes it much harder for the battery to accept charge.

Ideally you should be looking at no more than 5 to 10 milliamps for a 24/7 current draw.