Help!
GENERAL
EV question
Q I have had my smart forfour electric vehicle for over three years now. It went for its first MOT a couple of months ago, and as I suspected, it came back with an advisory on the front discs starting to rust/get pitted.
This will be a common problem that will affect all EV’s into the future and something we will have to factor into our running costs. Speaking for myself, I love my regenerative (regen) brakes but because I am mechanically-minded, I knew the discs were not getting enough heavy braking to keep them clean and pit-free. My question to you is about regen brakes.
Am I correct in saying that the regen is done purely 100% through the electric motor and the discs have nothing at all to do with putting energy back into the battery? Basically, are the front discs/ pads just the same as an ICE (Internal Combustion Engine) vehicle and I can go ahead to fit the new discs/clean them up myself and not have to worry about any special electronics on the disc calipers? Andrew Dunn
A The use of regenerative braking system on electric and hybrid vehicles has two advantages. The first is that the wear on the friction linings is greatly reduced and the second is that the electricity produced from the recycled kinetic energy can extend the range of the vehicle by around 10-15%.
The downside you have discovered is that the lower use of the friction braking system can allow rust to accumulate on the brake discs, and this rust that would normally be cleaned-off from hard braking can remain in place and deteriorate the braking surfaces.
As the regenerative braking operates by converting the kinetic energy into electricity, for the system to work the battery for the EV systems must have capacity to accept a further charge.
On a hybrid vehicle it is possible to allow the power battery to fully-charge, then using the brakes, as the vehicle systems will detect that there is no further capacity for the battery to charge, the brakes will operate fully using friction braking.
On a fully electric vehicle, this situation will not occur because as soon as you begin to drive and use the stored energy, there will be sufficient space for any current from the regenerative braking system to feed back to the main battery. Although the best opportunity to utilise the friction braking would be when the vehicles battery is fully-charged.
You are correct that the working end of the friction braking system (discs/pads) is the same as an ICE vehicle and the components can be changed without any electronic recoding or resetting.
GENERAL
Vehicle storage
Q I see in the May 2021 issue it mentions in the ‘Life After Lockdown article that regarding filtration, “The main enemy is water contamination, caused by condensation within the fuel tank – especially if the tank was not kept brimmed with fuel over lockdown”.
I’m sure I’ve read within CM in the past that it’s not wise to have a tank full of petrol when wintering a car for a few months especially with E5 that absorbs water. Presumably this is the same for a car stored for lockdown? I’m concerned that my car that regularly gets wintered for five or six months is suffering – and with E10 coming this will be worse.
I can’t drain the petrol so even if I was happy to waste a tankful after winter this is not an option?
What’s best – rusty nearly empty tank or weeks of driving around with stale watery fuel? Guidance appreciated.
Pete Rowe
A With the sudden onset of the pandemic and the vast change in lifestyle with many people finding themselves working from home, the feature was aimed at the motorist who unexpectedly found that they had not used their vehicle as opposed to those who run a vehicle through the summer and then store it over the winter or longer.
Many of the fuel tanks now in use are made from high-density polyethylene, or HDPE. And so, the corrosion in these is not a problem, but of course on many of the classic vehicles that get stored regularly over the winter this is not the case and the tanks are made from metal.
The difference is that when storing a vehicle, the owner is aware that the vehicle will be stored and as such I recommend adding a fuel stabiliser before storage. Widely used in the marine industry and for garden equipment the fuel stabiliser will prevent ethanol related-problems as well as isolating water preventing it from becoming a hazard.
This bottle http://bit.ly/CMiFfsa at under £8 will treat up to 150 litres of fuel, and so this is a worthwhile investment.
Adding the additive before the vehicles last journey of the year will allow the treated fuel to then run through the system ensuring that the fuel sitting in the complete system is treated with additive.
The advice would be to store the vehicle with a full tank to prevent the condensation but with the added fuel stabiliser which will also prevent the absorption of moisture.
GENERAL
Coolant info
Q Several manufacturers (Land Rover and Kia for instance) give a first change time for coolant of ten years. Whereas longlife aftermarket coolant is unlikely to last longer than five years.
Is the original coolant really twice as good? If so why isn’t 10-year coolant available aftermarket?
Or is this just an example of manufacturers reducing servicing cost at the expense of engine longevity?
Les Lumb
A Antifreeze is a very stable liquid which when kept under the correct conditions does not degrade. When first used in a
