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453 Stop/Start Fault

Modification Details

Not Just Stop/Start

The 453 models have an electrical issue. Well, they have several electrical issues.

I know what you're thinking.
"It's a Renault, what did you expect".

However, almost all of the electrical quirks found on the 453 fortwo and 453 forfour can be accredited to 1 thing.

Cheap Shitty Battery?

Give that man a gold star. Although, you may misunderstand the word "cheap".

Enlighten Us Oh Great One

Cars with the stop/start nonsense can't just use your standard lead acid batteries.
Sealed lead acid (SLA) batteries are cheap and very good at starting a car and storing power.

What they aren't good at is repeatedly starting a car, accepting a charge and powering the car on
its own when the engine stops. This abuse will kill the best lead acid battery in no time at all.

In a car with stop/start, you have to use a different type of battery.
AFB/EFB batteries are the bare minimum but these aren't recommended.

The best option for these cars is an AGM battery.
These are magic batteries but that causes a problem.

Magic batteries are expensive because magic doesn't come cheap.

Imagine a car company like Daimler who own a lot of other car companies such as smart and Mercedes.
Now imagine that all of the cars they make are having stop/start fitted as standard.
Then imagine how much more money they have to spend on batteries when the AGM type are
4 or 5 times more expensive than the old SLA type. We are talking millions in lost revenue.

Mercedes on their own sold 2.3 million cars in 2018. So that's probably 150 million paid just in AGM batteries.

Other Daimler Cars Don't Have Battery Problems

Car manufacture is a fine line of cost cutting against quality.

If you have an expensive Mercedes, they can easily lose the extra cost of an AGM battery into the total.
However, with a cheap smart, that's not so easy. Smarts don't make anywhere near the same profit margins.

So, because smarts are seen as the deformed cousin that the rest of the family doesn't like, they are far more
happy to cut costs and reduce the overall quality of the product. Because we don't matter. We aren't their market
demographic so there's little point pleasing smart owners as almost none of them trade up to a Mercedes.

Smart AGM Battery

When smart started looking for a source of AGM batteries, they only looked at 1 thing. Final cost.
They didn't care about output, longevity or quality.

So, ultimately, we got the cheapest shittiest version available.

That Seems Counter Productive

You'd think so but no because it's never going to be a recall. It's not a safety issue.
Replacing the batteries that fail to operate the car properly is a money saver in the long run.

Not to mention the extra cash they can make charging for diagnostics time and selling full price replacement batteries to people who don't know any better.

The majority of the batteries were good enough to get you out of a warranty period. Then it's your problem.

What Faults Can Occur?

The main one is the stop/start system coming up with an error. The system monitors the battery's
power and determines whether it has the power to start the car if it cuts the engine.

If the power is too low, the car will show a fault code and turn off the stop/start system indefinitely.
At which point, the battery is usually damaged so would never work properly, even if charged.

So far, most of the errors flashed up on the dash have been due to low battery power.
ESP, ABS, etc have all brought up errors because of this.

If you get any unusual errors at all, suspect the battery first.

Can I Do Anything To Prevent Issues?

Always turning off the stop/start will go a long way to preserving the battery.
Without start/stop, the cheap AGM battery should be much better than an SLA battery.

If you turn off the stop/start totally using DDT4All (see here), I don't see why you couldn't
fit a cheap SLA type battery instead. They are much cheaper for a higher quality battery.

If you do swap the AGM out for an SLA and deactivate the stop/start, let me know how you get on.
There is a possibility that the 453 alternator is designed to a much wider voltage range and a much
more agressive recharge cycle to keep the battery full. This might not be favourable to SLA batteries.

And If It's Not The Battery?

I'll add here any other info I get told. I can't confirm any of this but check it just in case.

Simon B said that his air conditioning was low and the stop/start began to work after an AC refill.

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