I have the dreaded flat battery after not using the Eunos Roadster during the bad weather and it has been suggested I buy a smart or maintenance battery charger to rectify the issue when the car is not used regularly, particularly in the cold weather ( I know I should know better!) Can you please tell me if it is ok to use these in situ without removing the battery when charging? Also having looked at a couple of options for these chargers the instructions say to connect the positive lead from the charger to the positive terminal on the battery (pretty obvious) and the negative lead from the charger is to be connected to a bolt or other metal part on the chassis or engine block instead of the negative battery terminal? Is this right and how do I do this as the battery is in the boot? Why can’t I just attach the positive lead from the charger to the positive battery terminal and the negative lead from the charger to the negative battery terminal?
Be careful here there are very inexpensive trickle chargers available that have terrible voltage regulation and these should not be connected to the car battery while it is also connected to the car as they can damage the alternator.
The more expensive smart chargers based on an IC chip are designed to be connected to the car battery while the battery is also connected to the car.
Typical makes are Ctek, otimate and from tiMe to time Lidl and Aldi sell them for about £15.
I tend to connect both leads to the battery and then plug in the charger; but I guess the reason for the advice you have read is the possibility that connecting up can create a spark, and that batteries can also gas in certain circumstances.
By connecting the positive lead first, and then connecting the negative lead well away from the battery, any spark that does occur is not so proximate to the battery and less likely to cause an explosion.
Of course if you are disconnecting the battery from the car then you will need to use the terminals anyway. Just don’t plug in the charger until after the connections are made.
I don’t disconnect the battery to use the CTEK, but as already mentioned a cheap charger or one of unknown reputation is risky - even some low current so-called trickle chargers can have a high unconnected voltage which could do some damage before the voltage drops.
Don’t charge a frozen battery. A charged battery won’t freeze at any temperature you are likely to encounter in the UK but a flat one might.
I agree with the advice to use CTEK or Optimate - but I believe the Aldi / Lidl ones are multi-stage and I have used them too.
Thanks for the advice guys - I have bought a Smart Battery Charger from Halfords today which is currently on offer at £30 (reduced from £50) so hopefully that will do the job! Apparently it will charge a flat battery to the level required to start the car but then go into maintenance mode/ trickle charge setting and can be left on without the danger of overcharging. Having also spoken to a reputable Car Battery supplier I intend to attach the crocodile clips to the appropriate terminals on the battery itself without disconnecting from the car - I have been told that as long as this is done before switching on at the mains there is very little risk of a problem.
With most good chargers these days you should be able to buy an accessory which is a short loom to connect permanently to the battery. Then charging is just a matter of plugging in. Here’s a link to the ctek one.
If you can get a halfords trade card (they give them to anyone) and use the club discount, you’ll get a very good price on any of them.
I have a CTEK. I bought it last year after loads of research and it seemed to do everything that I needed I connected the accessory lead to the battery terminals and just plug the charger into that no need to move any trim or anything it has lights on the lead to let you know the battery condition. I usually plug it in if I don’t use the car for a few weeks especially when it’s cold. Great bit of kit.
Mmm…I didn’t want to pay more than £30 as I can get a new battery fitted for £50. The Halfords charger was the only one I could find at that price that actually charges a flat battery and then maintains it.The Lidl and Aldi versions are only trickle chargers and are good for maintaining charge but will not charge a dead battery apparently. The reviews on the Halfords Smart Charger are mixed to say the least so I guess I will just try it for myself and return if it doesn’t do the job! Has anybody else bought one of these?
The battery on my mk2 would be well more than that cause it’s not a standard size also it’s hidden in the boot. If you don’t want to spend too much on a charger it gives you a great excuse to go out for a drive to keep it charged.
Must say, from the awful reviews posted for that Halfords charger, I wouldn’t have gone near it.
I’ve owned a Lidl charger (£13.99 as I recall) for 3 years, and it’s considerably more than a trickle charger. It charges the battery, and if you choose, you can leave it connected
and it goes into maintenance mode. It has the LED display, so you can see what voltage is in the battery, and the ‘charging bars’ on the display tell you at what stage the charging is at.
On the matter of charging a completely discharged battery, the instructions seem rather contradictory, so am unsure about that bit. I’ve used mine on my MX5 for when the car has been sitting, in winter, and the voltage has dropped below what’s necessary to start the car, rather than completely discharged.
I’m not a fan of leaving a so-called intelligent charger permanently connected. I do have one for my motorcycle but only leave it on a couple of days at the most. I once found it had dried off most the liquid electrolyte of another battery, something I have never found before or since so I don’t completely trust it.
I’ve just bought a “RING” RSC612 charger and analyser, after a lot of research. If it’s as good as the many reviews and recommendations state, it should see me out and do everything I need for our family fleet. I’ve already used it to revive a dead battery and top up a couple of others in the garage.
As far as connecting direct to the terminals where the battery is left on the car, the biggest risk of explosion is when the battery is fully charged and “gassing off”. Hydrogen gas is given off but as that is significantly lighter than air, it should quickly dissipate from the boot of an MX-5 if the charger is switched off at the mains and given a few minutes to settle down, with the boot lid open. No spark and no gas, no explosion.
I have both the Lidl and The Aldi Smart Charger and with a completely flat battery they both advise the battery is faulty and that is on a good number of flat batteries.
I also have a cheepo trickle charger that I warn against connecting directly to the battery if it is also connected to the car.
When I get a completely flat battery, I leave it on the trickle charger for an hour or two that gets the battery voltage to about 10 or so volts when not connected to the car, then leave it on the Smart charger overnight to complete the charge of the battery.
For Lead Acid batteries like that in the MK3, you can use a heavy duty charger to get that charged in a shorter time but for Gel type batteries the slow charge of the Smart Charger is the one to go for.
I believe the Panasonic battery is happy to be on a smart charger for a few days to get fully charged.
I’m with Paul. Vehicle batteries are not designed to be continually charged. I believe it shortens their life. I’ve also had an Optimate that I’d left connected to one of my motorcycles in the garage. My wife unplugged it to use the socket for something else and neglected to plug the Optimate back in. It was left for a couple of days connected to the battery but not the mains. It continued to do it’s battery checking by putting a load on the battery, this is how it tests if that battery is holding charge. When I discovered this the battery was completely flat and I tried several things but could not recover the battery and ended up buying a new one. I complained to Optimate about it and supposedly they have changed the design to stop this happening but it still cost me a battery.
I have one of the Aldi ones now and use that in preference to the Optimate but whichever I use I only leave it on for a day at most. More often than not I disconnect as soon as the device shows full charge has been reached.
My wife used to have a Peugeot 106 and it had the longest surviving battery I’ve encountered. She didn’t use the car often, sometimes going a couple of weeks between use. It never got charged other than being driven. The car was 11 years old when we sold it and still on it’s original battery and still turned the engine over well.
The problem with the Optimate draining the battery when switched off, referred to above, did happen with the early models but as I understand it the problem was cured from the Mk.3sp onwards. I certainly doesn’t happen with my Optimate 4 when I’ve left it connected but forgotten to switch it on. They are designed to be left connected to the battery and whether they are on or off will not drain or damage it.
I would not compare the price of a battery charger with that of a battery and expect my 2 x optimate chargers to outlast me and many, many batteries.
As with anything in life you just want it to suit your circumstances and work reliably without unwanted side effects.
My advice is to always keep your battery voltage at at least 12 volts. This means understanding how to minimise the dark current that drains the battery whilst it is unused and connected to the vehicle.
I choose to use my optimates as and when they are required but others seem to get similar satisfaction with having their battery on constant trickle charge. Perhaps there is little difference, particularly with the panasonic battery.
A number of smart chargers will struggle with a battery that has a significantly reduced voltage. The Optimate will be marginally successful on batteries that have dropped as low as 7 volts. When I inherit such as battery I would normally put on a standard old school charger for an hour or so to raise the voltage before transferring to the optimate.
Would never let any of my batteries get to anywhere near 7 volts as this is negligence that would likely shorten the life of the battery. Only know how to cope with this as occasionally get a good panasonic off a colleague that has been left on a dormant car for a period of time.
whilst not in use, keep dark current to a minimum ie <= 20ma. If this is not possible on the car, isolate the battery.
During colder months October - March, check voltage regularly and charge where necessary. Even in the worst of winters where MX5 and motorbike not used, my batteries, car and bike only need to be a charged 2 or three times.
My “smart charger” was one of the earlier ones, not branded as Optimate. I do still use it, but I keep in mind that it’s not any smarter than any other charger I’d previously owned. Unfortunately, I no longer trust the type, which is why I went for the newer “RING” one I mentioned earlier. As well as charging, it can analyse the battery condition and remaining capacity / voltage drop when the engine is actually being cranked.
If you can get a battery fitted for £50, you’re using a sub standard battery. Have a read about smart chargers, they’ll repay their cost many times over during their lifetime.
I use an optima battery in my Taxi that costs about £200. Using the ctek charger to maintain it once a year has almost doubled it’s life expectancy.
I’m not so sure about the term “substandard” in this context. After all, all it’s for is to store electricity, mainly to get the engine started - so we’re not exactly talking spacestation technology here.
I’ve used good quality batteries supplied by my local motor factors for many years (over twenty), for a whole range of cars. They supply very good alternatives to the Panasonic for about £50 -£60 (not just for Mazdas), with a three year, no quibble warranty. Some years ago we had one battery fail just under that period on another car (neglected by an inexperienced young son) and I took it in to them to ensure I bought the correct replacement (they advised me to do this because there were a few alternatives, depending on the spec. of the car). They took one look, pointed out to me that it was still in warranty (only by a few days) and replaced it FOC.
My NB doesn’t have a Panasonic and I see no reason to pay through the nose for one if it ever fails when very suitable alternatives are available for far lower cost.
It’s a false economy buying a cheap battery for an MX5. None of them last half the life of the Panasonic, and being in the boot without ventilation can cause other more serious problems. Mazda didn’t specify the Panasonic battery without good reason.