Expert answer

Hi Philip,

You are correct on all of the above. The chances of there being a high enough concentration of hydrogen in the air (when the bonnet is open) to cause an explosion are slim, but it's still good practice to take the potential spark of connecting the negative cable away from the area. 

Incidentally, older batteries and those being charged up are more likely to emit hydrogen, though it's no harm to do the same with the 'donor' car. The key thing here of course is that there's no spark produced when you connect the leads to the first battery. 

Expert answer

Hi Jim,

If you're talking about a regular combustion-engined petrol or diesel car and their 12-volt battery, then yes, assuming the alternator is working properly, it will be driven by the engine and will charge up the battery so long as the electrical load from the battery is less than it can supply.

If you're referring to plug-in hybrids, and their high-voltage lithium-ion batteries, then it's not as simple as that and it differs per model and even depends on the driving mode. Most will, by default, use the battery to the fullest before starting up the engine and then may not charge the battery much except for kinetic energy recovered during braking. The idea is that you plug them in to charge up the battery regularly for maximum efficiency. However, most of them have a setting to override that and actively charge up the battery using the engine. It's usually activated by a button or option in the infotainment menu.

Expert answer

Hi Ricky-Lee Morgan,

In the vast majority of cases this is down to either a battery that is not in perfect health or a dodgy sensor. See our feature Why won't my car's stop-start system work? and if that doesn't help then you will need to get the car plugged into a diagnostic computer by a mechanic.

Expert answer

Hi Barry, 

Yes it can. You can toggle through various modes with the eDrive button on the centre console to the Save Battery setting and then the engine combines with regenerative braking to charge up the battery.

Expert answer

Hi Patrick,

You certainly can do, but just be aware that you’ll have to pay some import duty on it, which may reduce any potential saving compared to an Irish market car. Do your research carefully and get in touch with your local Nissan dealer to make sure that they’ll honour any outstanding vehicle or battery warranty.

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Hi Chee,

The Countryman SE plug-in hybrid can, potentially, be capable of tremendous fuel economy, but it all depends on how you use it. If you (a) have a driveway or a garage and (b) can install a home charger and (c) tend to do short hops around town most of the time, then conceivably you could get from one end of the week to the next without burning any petrol at all. The Countryman SE will do in and around 30-35km (realistically) on a full charge of the battery. If you’re regularly taking on longer journeys, though, it gets a bit thirstier and can dip as low as 25mpg if you’re really using all the power. That said it is, as with pretty much all MINI models, really good to drive.

The RAV4 is not. Well, not that it’s bad to drive or anything, but it’s not sharp and rewarding like the MINI. That said, it’s squishy and comfortable, so if you’re on lots of long journeys, it’s great, and it’s massively roomy inside, much more so than the MINI, so with one kid and another on the way, that’s worth taking into account. Being a closed-loop hybrid with no plug-in version (yet) it’s also better for you if you don’t have a driveway or can’t install a charging point. Figure on about 6.0-6.5 litres per 100km overall, although you can get better than that on longer, gentler runs. Oh, and it should be more or less faultlessly reliable, too. 

Read our MINI Countryman reviews here

Read our Toyota RAV reviews here

Expert answer

Hi Stephen,

Currently, there isn’t one. Volvo Cars Ireland has confirmed to us that it hasn’t yet made many plans to introduce the Polestar brand or models here as yet, although given the huge success that Tesla has had in Ireland, we’d be surprised if it doesn’t happen at some stage. Most likely, it’ll be a combination of waiting to launch a couple of core Volvo electric models (the battery-powered XC40 especially) and then, once initial European and US roll-outs have taken place for Polsetar, then they’ll start to think about us.

If we had to hazard a guess, we’d say 2022 at the earliest. 

Expert answer

Hi Ann,

We'd suspect the battery or alternator aren't performing at their best. Stop-start issues are very commonplace, across all cars. So much so that we've written a feature for drivers on the subject: Why won't my car's stop-start system work?

Expert answer

Hi Mark,

The first generation 330e has an electric-only range, on a fully-charged battery, of 40km (about 30km in real-world use) and the new, and current, version is claimed to be able to get 65km out of a full charge. Here are links to our reviews of both, which may give you more information:

2017 BMW 330e review

2020 BMW 330e review

Expert answer

Hi Tanya,

It sounds to us like the alternator may have been struggling to produce enough electrical power and that perhaps your battery could do with replacement. If the problem has not reoccurred then it's nothing to worry about, but no harm getting your battery checked before winter sets in.