Got the CTEK today. Keep the car outside, is wise to charge the battery with the bonnet closed?
No reason why the bonnet needs to be left open; a CTEK is designed to be left on all the time and the cable goes through a closed bonnet edge with no problem. Defintely close it if the car is outdoors.
JS
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I have a CTEK MXS 5.0 which I use on my 2011 MX-5 2.0L RC and my wifeâs 2011 Mazda 2 TS2. We both only do a small mileage - 3000-4000 p.a. - and I was recommended to buy it by Carl Smith of CBS AUTOS in Nelson who supplied me with my first MX-5 - a MK 2 - in 2013.
It is a quality product with a 5 year warranty and has been a very good investment.
Unfortunately, it is not suitable for my Skoda Yeti 1.2TSI which has a stop start mechanism. CTEK do make a version which caters for vehicles with this feature. The CTEK MXS 5.0 was a best buy in Auto Express and motoring guru Honest John similarly recommends it.
My 2011 MX-5 2.0 RC and my wifeâs 2011 Mazda 2 TS2 still have their original batteries. The latter does mainly short runs - supermarket, hairdressers, leisure centre etc., - whereas the MX-5 is taken on runs which are usually a minimum of 30 miles. However, we lower the top as often as possible on the MX-5 and as it is powered by 4 motors that will no doubt use a fair amount of juice.
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My understanding, and Iâm happy to be corrected, is that the battery takes a huge hit on first-churn to start the car, but thereafter the alternator supplies power to the entire loom for the rest of the carâs usage, and just tops the battery up a smidge. ( That, from me, was getting technical!) If Iâm not misguided, then the power hood motors, or anything else, should not be a concern.
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Well,
Iâm an utter dork. Iâll need to use my Optimate DC-DC on SWMBOâs 2002 Sport.
Itâs still on itâs OEM PanasonicâŚand hail & hearty it was. âWasâ may turn out permanent.
I left the boot open a few days back in the lock-up. 
I keep a stonking good Yuasa out a scrapped Honda in my workshop on Condition Charge so it should be OK by tomorrow. Got a few old-folks prescriptions to distribute on Monday with the car so hereâs hoping.
I would use the Mk1, but the bother is itâs low on itâs new Koni SRTâs and will definately ground itâs newly refurbed floor on the humps into some of their houses.
Darn it.
If you select windscreen only on the heater distribution controls it will cancel out the Vitara start/stop function.
Well it does on my 2017 1.4S.
Correct!
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For those of us who donât have any cars under ten years old, whatâs the issue with start/stop function and battery chargers?
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Itâs not an issue with stop/start but rather with the battery management system (BMS) that underpins it. Newer cars need to know the precise state of the battery so that the stop/start can be activated and/or the alternator switched to charge mode or idle (more new tech to reduce engine load and fudge mpg).
As far as I understand it, if you top up the battery with the ignition (and BMS) off, the 2 systems get desynchronised. Also, if you connect your charger directly to the -ve charger, there is a chance of frying the BMS as it usually sits on that terminal, so you use the +ve terminal and an earth point in the engine bay. This especially applies to jump starts - in fact BMWs have a dedicated point.
The other downside of BMS is that whilst you can change the battery yourself, you need a dealer visit to theyâll the system the new battery is installed otherwise it will only charge to the old batteryâs last known capacity, which will be well under 100%
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It does indeed, but as Iâm out recharging the battery I need to know when itâs job done so I leave stop/start engaged. When it works, I know Iâve gone far enough and go home.
Was I overthinking this âcan of wormsâ.
I have charged my battery with the ignition off and assumably the BMS must then be off also. I connected the charger crocodile clip as per the Mazda user manual away from the battery terminal and to the recommended earthing point on the body.
So If I read this right, according to BarnsleyRob I shouldnât have fried the BMS but there might be a synchronisation issue with two (mysterious) systems.
This causes me concern that the start stop may be compromised in our Mazda 3 Sport Nav and, bearing in mind the current guidance restricting driving, leaving me with no quick way to confirm or deny my concern
Maybe the way round all this would be not to buy âall dancingâ top of the range models that include start stop (our Mazda 3 Sport Nav).
Since the latest MX5âs seem to come with all the âbellsâ as standard maybe the purists were right to get annoyed when they first introduced electric windows and heated rear view side mirrors with the NC in 2006/7.
Blimey, these modern Mazdas must be sensitive. When I got my start /stop equpped Audi the battery was a liitle low as it had been sitting at the dealers. Put my CTEK on it over night and the Start/stop worked perfectly and has done ever since. I charged the battery recently and, again, no adverse effects. My understanding of the âconnect the negative to the bodyâ advice is to do with jump starting - it avoids a potential spark near a heavily used and potentially gassing vehicle battery. I canât see how connecting directly to the battery terminal direct can âfryâ anything, whilst connecting to the bodywork does not. The body and the battery negative are connected by a large diameter cable and are electrically the same point.
JS
Hmm. It is a lead acid battery, and it loses charge all on its own if nothing doing. No current will be flowing through the BMS (Battery Management System), so it will know nothing about it. Therefore it will be âOut of Synchronismâ immediately, this has to be a techno-babble red herring.
I cannot believe a mass production vehicle would be in the least bit worried about this. Much more likely it will apply much the same rules as any other Smart charger to check the condition of the battery, and being carefully designed to match the battery it will be a lot better at getting it right and coping with variations like not being used for a month.
One of the caveats is that possibly Stop/Start systems will deliberately not quite fully charge the battery if they can also be clever enough to use the alternator in a boost mode (compared with normal charging) to supplement normal engine braking. I donât think the Mazda i-Stop does this though.
And then you have the Mazda i-ELOOP which is a whole new can of worms, with a mega-capacitor storing lots of power on braking from the engine from a big alternator, and then using a DC-DC converter to charge the usual lead acid battery to power all the standard car electrics at 12V-14V. Again it is often deliberately not charged to full in normal non-braking mode, simply to be able to harvest the maximum of braking energy.
In each of these special cases the lead acid battery will lose charge when not in use, and the BMS will not have a clue about it except the voltage until the engine is run again.
And then there is the Prius method where there are two batteries; one 12V charged as normal for the petrol engine and ancillaries ,and one massive NiMh stack that can be charged by the motor/generator while normal running as well as during braking. In this case they only ever charge the NiMh stack to about 50% on the petrol engine, so as to leave enough capacity to be able to harvest lots of braking energy and also maximise the operational life of the traction battery
If you ever put an oscilloscope on the car wiring at some distance from the battery (which is such a low impedance it sinks everything) you might be horrified to see it is not a nice smooth 12V.
This is because of interference from things like ignition sparks (10KV), the horns (500V like a weak ignition coil), switching on HID lights (2KV ignition pulse), indicators flashing, windows wipers and fans motor brushes, alternator brush noise, starter motor brush noise, DC-DC converters in radios, cameras, satnavs, phone-packs, the list is as long as there are electrical devices in the car.
So all car gear is designed to handle spiky noise on the 12V, and a mere 15V DC from a Smart charger connected straight across the battery is as nothing.
Sidetrack again.
If you had a Montego or Maestro back in the bad old days (around 1984-86), you will know that BL did not think about this interference, and the usual lifespan of several of the electronic modules was about six months before someone blew them (most common fault chit at work was âsounded the horn and the engine diedâ). We had Montegos at work for a whole year when they were first released, and they spent more time waiting for replacement modules than actually on the road. I was asked to look at a couple of dead modules and it was clear BL didnât have a clue about ESD and spike damage on the ICs within, because there was no protection against it on most of the external sensor and data lines. We pointed this out and the design was quickly changed, but we didnât buy/lease any more Montegos.
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The Mazda capacitor system is a lot better in that itâs independent of the battery so they may not have a full blown BMS (bit like they donât rely on turbos either). I guess the best people to comment are those that have replaced the battery and not needed a dealer visit to update HAL.
BMW and JLR obviously need a dealer to plug in a computer so they can bugger something else up while youâre there !
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Relieved to say Penny the Sport has forgiven me.
Started on the button 30 minutes ago, thanks to Mr Optimate.
Prescription duties shall commence!
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One of my smart chargers in use today on my Sonâs Mercedes with stop/start technology.
Lidl special over four years old, the one on the MX5 is a Numax which has been permanently connected for over six months now.
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I concur, no issues with CTEK 3.8 charger and Start Stop (which I dislike and switch off) on my ND 2.00 litre sport tech.
Before I retired I used to work for SUN/SNAP ON ENGINE DIAGNOSTICS so have spent a bit of time
under the bonnet!
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Aldi XS battery charger back on sale. Get one before they run out!
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Lid have CTEK on at ÂŁ69 (reduced from ÂŁ89 elsewhere) at the minute. I got one to replace my 20 year Optimate.