Hashtag Key Excessive Battery Use

There have been a small percentage of people stating that they are having to replace the battery in the Hashtag key fob regularly where really, the battery should last for 1 year at least.

Firstly – Good Battery

It’s common sense so I thought I’d better point it out since some people have no common sense.

Not all batteries are the same. A Duracell, Panasonic, Maxell or Renata battery will be infinitely better than a card of 15 nameless batteries from “the pound shop”. Also, check the date on the packaging because batteries self discharge over time so even a good brand could be old and low on power before you even use it.

Secondly – Proximity

The key regularly transmits a signal which the car is looking for. This transmission doesn’t take a lot of power when the key is out of range of the car. However, if the key is within range of the car, it sends a consistent stream of information to the car. They have a full on conversation. If that full data transmission goes on continuously, the battery may only last a month.

If the key is just out of range, the car can still occasionally boost the signal to check for the key.

That’s 1 of the reasons you should always keep the key in a faraday bag when the key is not in use. This blocks the signal so the key never has the full conversation with the car until required.

These are the ones that I bought – Click. They are 11cm wide.

You may get away with smaller ones like shown below if you don’t have a protective cover on your key fob.

I bought these – click. They are 9cm wide.

Thirdly – Key Problems

There’s a small but notable number of keys that just seem to have a high drain, probably due to a failed or out of spec component.

If you have checked off the 1st two issues and are sure it’s the key, contact smart and let them know. The issue here is that dealers don’t really have any means to test the key in a suitable way.

The smart dealer will ask to have the car for a day or 2, They’ll fit a new battery, they’ll check the key works and then just claim there’s no issue because it worked ok for the day that they had it.

So – What To Do?

Firstly, move over to using the spare key. Statistically, it shouldn’t have the same problem.

If smart have had the car and claimed everything was fine, report every single time you replace the battery. The more complaints they receive, the more they’ll look into it.

Eventually they’ll agree it’s an issue and from that point onwards, Smart HQ will send out a bulletin to all dealers saying to just code and supply a replacement key under warranty.

Alternatively you could pay to buy and code a new key and then try to claim the money back from smart once they have admitted there’s an issue. I don’t fancy your chances though.

What Happens If…

…the battery runs out whilst I’m out with the car?

Firstly, the key contains a hidden physical key which can be used to open the door. Click here.

It would make sense to have at least 1 brand new spare battery in the car somewhere. You don’t need any tools to change the battery.

However, even though the battery is low, it’s rarely ever dead. So according to Ben C, placing it in the front of the arm rest storage…

…places the key close enough to the antenna that the car can pick up the key’s presence enough to activate and drive the car.

This is unconfirmed but worth a try.

Turning Off Approach To Unlock

A few people have speculated that turning off the “approach to unlock” feature (that’s activated as standard) will stop the battery from depleting as quickly.

This is not the case as the key still transmits the same. The only difference is that the car opens automatically instead of expecting you to also touch the indent in the door handle.

Contacting Smart

You can phone your local smart/Mercedes dealer if you like but you’ll just get through to a woman on the reception desk who will have no idea. It’d be better advised to contact them through their website or through the Hello Smart app.

That way, you are more likely to get put through to someone more technical.