I have a 68 plate 1.5 sport nav. I want to make sure my battery is kept charged up as I have not been able to use it much lately. I have a Stellar Components 4amp GP4 battery charger which I probably bought in the 1980’s. Would this be ok to use on the mx5? Would I need to remove the leads from the battery terminals first or just charge it as is.
Hmm, I would not risk leaving that charging a battery unsupervised. It has the capability to boil a battery.
By all means keep it as a museum piece and an example of how not to charge a car battery, or as simple un-regulated un-smoothed 15V power supply, or as a way to very briefly wake up a really flat battery sufficiently for a Smart charger to take over and finish the job.
Just don’t expect it to care for your battery in the same way as a modern Smart charger.
I would agree. I don’t think that old 4 amp charger is the right tool for the job. Modern battery conditioners aren’t very expensive (plus they’re a lot smaller and lighter in this era of switch-mode power supplies which don’t need hefty transformers) and you can leave them plugged in long-term and they’ll just keep your battery topped up as required.
They’re also “kinder” to the battery as they typically trickle charge at less than an amp. That gives the built up sulphates in the battery more time to dissolve during charging which restores capacity more effectively than fast charging.
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Lidl and Aldi sell really good smart chargers for about£15.00. They are not always available but I did see some recently, so worth a look if you’re there shopping for essentials
Aldi XS smart charger online £12.99 + p&p
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I have the Aldi smart charger. I assume it’s ok to connect this with the battery “in situ” and connected? On our old Mk 2 I used to take the battery out as we took the car off the road for 6 months over the Winter anyway.
However we now have a mk4 and we keep it “on the road”. Just checking that it is OK to connect (this Aldi) charger while the battery is still fully connected?
(I understand that you should not turn the ignition on while the battery charger is connected!)
Thanks for any feedback…
Well, I once started mine with the CTEK connected.
No, please don’t ask, but I now velcro tape a bright red ‘Remove before flight’ tag to the steering wheel every time it’s parked up to remind me.
But, anyway the good news is that nothing was broken, either car or the charger, so I wouldn’t worry too much.
For the other forgetful forum users, check the bay of E for sources of supply of said tags.
Oh, yes, one of my lockdown jobs was to get the CTEK extension cable and screw the charger to the garage wall so things are somewhat tidier.
JS
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I’ve used both my Aldi and Lidl chargers on the cars with battery in situ.
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I also use the tag as a reminder after travelling 70 miles with my Ctek still connected and not realising until I got home and found the extension lead laying across the driveway snapped 
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The latest version of the Lidl charger is £1 more then the Aldi one. It offers a slightly higher charging rate than both the previous Lidl one, and the Aldi charger.
Someone on Youtube, pulled both apart and concluded that the Lidl charger was slightly better built than the Aldi.
I actually had the previous Lidl version for about 3 years, quite happy with it, bar the business about smart charging below 7 volts. Thought I’d upgrade, so bought the new one, and sold the old on eBay. Upgrade cost, £5 !
I used to have an old Bradex charger, that I dumped when I bought the smart charger. It was 30+ years old. Never had any problems with it, such as the often mentioned frying/boiling of batteries.
If I wanted a fast charge, just popped it on for an hour or two. For a slow charge, I left it on overnight. No batteries ever boiled, no dramas. All that happened was that as the battery became charged, then the charging rate on the charger’s ammeter slowly dropped down to more or less zero.
Wish I’d kept that Bradex. Handy for the less than 7 volts scenarios.
Thank goodness it’s not just me then. Our MX5 is kept outside so I have to run a couple of CTEK extension leads from the charger in the garage to the car and to avoid driving off with the charger in tow again I filed the catch off the last lead so worse case I drive off with a lead dangling out the boot but the charger and the other leads will be undamaged.
I like your idea though.
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Ruberdub…good plan…rather than a “Remove…” reminder you simply need a longer extension lead…you could then go all electric!! 
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Patent pending 
Of course, as with all long leads (for example on the good old high-powered vacuum cleaner), it will still be a couple of feet too short at a vital moment far from the plug…
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Most modernish motorbikes have a permanently attached lead and plug especially for plugging in a smart charger, so no problem there.
It’s easy to install your own lead and plug with a motorcycle battery, as they have relatively small terminals, which leads just bolt on to.
Car terminals are entirely different but maybe there is provision to bolt onto the leads where they attach to the terminals?? Having had company cars for decades until now, it’s not something I’ve looked at.
I wouldn’t expect any problems from turning on the ignition with charger attached.
As said, just don’t drive off with it attached…
Yes, that is one big advantage of the old-style battery charger but I think that’s all I’d use it for, to get some charge into a deeply discharged battery
I added the CTEK plug in ‘comfort connector’ very easily. The bolts on the battery clamps had sufficently long bolts to enable the eyelet connectors to be fitted using additional nuts on the spare thread.
JS
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…I was referring to a really long power lead…ie 70+ miles, then you could run the car off the mains…
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Ah yes, that’d work 
Murphy’s law’s umpteenth corollary applies:
“No matter how long the lead, it will always be a couple of feet too short at that crucial moment when you need it the most.”
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