The battery fitted to my Roadster is very similar to all the other Banner batteries fitted to smarts
at the factory. It's not a great battery, in fact the label only has 2 stars on it which usually means
it is guaranteed for 3 years. After that, it'll start becoming less efficient at starting your car,
moving the clutch, selecting gears, running the engine and powering your headlights.
However, good battery maintenance can increase the life and efficiency of your battery
by many times. In the "good old days", battery maintenance was practiced by most people
and many old and classic cars are still on their original battery.
Batteries haven't changed much but attitudes have. The throw-away culture we live in
plus the need for companies to sell you a new battery every 3 years has lead to us
leaving the battery alone and changing it for new when it dies.
Car batteries contain lead and an acid solution. Both of which is bad for the planet. So surely it makes more sense to look after what you have, save yourself money and not fill your municipal dump with acid filled boxes.
Batteries are very basic. They have lead plates and acid all housed in a plastic box.
The acid solution is 35% Sulphuric Acid and 65% water.
Gassing And Venting
When a lead acid battery is charged it turns some of the water back to Hydrogen and Oxygen.
Hydrogen is flammable and the oxygen will make it burn more vigorously.
The battery in the smart fortwo has a pipe leading from the battery to the outside of the car.
If it didn't, the cabin could fill with an explosive gas which wouldn't be good.
If you run a battery flat, a process called sulfation occurs. This is where the lead and acid react to create lead sulfate. The lead sulfate turns into crystals on the lead plates which reduces the amount of surface area in contact with the acid. The less surface area you have, the less power the battery can create. A battery that has been flattened will only hold about 50% of the amperage yet the voltage will remain the same and it will seem to charge OK.
Some battery chargers have a desulfation setting that attempts to break down the crystals on the plates. This is only really effective on newly flattened batteries and even after desulfation, it will never hold the same charge. The best thing to do is to get a new one and look after it.
Checking The Electrolyte And Topping Up
When the battery is charged, some of the water is converted to gas and vented. So, over time, the fluid level goes down. Luckily enough it is only the water that is used and not the acid so you can top up the fluid to maintain the battery.
Remove the battery from the car following this guide.
This is a standard smart battery. On the top are lids to the separate cells, these unscrew.
As I have previously said, batteries contain acid and it won't do you any favours if you get it on your skin or in your eyes so be careful and any safety wear like goggles or gloves would be a bonus.
Once you have unscrewed the lids, look inside and you should see a maximum level indicator.
Chances are, your fluid levels will be low as mine were. Time to top them up.
Your cheapest option is to go to a car place like Halfords and buy distilled water, de-ionised
water or "battery top up water". Even from an expensive company like Halfords, 1 litre of
this will only cost about £1. This is 39 times cheaper than a new battery.
Alternatively you can buy premixed acid solution but in most cases this is unnecessary.
Top each cell up until you get to the maximum indicator mark and nearly/just cover it.
If you are going for a long drive (more than 1 hour) then that's fine, if not, get the
battery on charge. A proper charge is better than a quick cycle charge. I bought this
charger from Argos and I only bought it because it was orange.
When the battery is charged fully, remove it from the charger and refit it to the car.
It's worth checking the battery levels every 6 months.
Check your battery charger instructions to make sure that when the battery is charged,
charging is stopped. Over charging a battery can damage it just as much as flattening it.
What Do I Do With My Old Dead Battery?
It goes without saying that you should take it to the dump so it will be dealt with properly.
Even though the acid solution is almost exactly the same make up and ratio as patio cleaner,
I can't recommend that you use the contents for that purpose.
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