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Wedg1e
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Most (if not all) Optimates come with a lead that is meant to be hard-wired to the vehicle battery in-situ and provides a 2-pin connector to allow quick coupling to the battery conditioner. The manual then states that short-duration high-voltage pulses are used to desulphate the battery. It does not state that it is necessary to disconnect the battery from the vehicle.
Modern automotive electronics should be designed to withstand quite high voltage spikes (I want to say around a couple hundred volts, but it's been a long time since I've read the relevant standards), however not for a sustained length of time.
Anything older (I'd guess over 20 years old), isn't likely to offer that level of protection, so connecting a desulphation spiker isn't likely to them much good, especially circuits at the cheaper end of the spectrum, such as clocks and aftermarket alarms.
Anything older (I'd guess over 20 years old), isn't likely to offer that level of protection, so connecting a desulphation spiker isn't likely to them much good, especially circuits at the cheaper end of the spectrum, such as clocks and aftermarket alarms.
Ubique
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Fortunately the starter battery is a pretty good smoothing capacitor, so will absorb the spikes (as intended), it's not a great idea to have a charger on a desulphation phase connected with the ignition on though.
Personally, I've never had any issues, the spike will be around 20-35VDC max, charger dependent and of a duration of <10mS, that said, I've never connected one to anything older than 2007.
It's worth remembering that an alternator, especially a 'dumb' one can spike upwards of 50VDC for anything up to 500mS when an engine rpm goes high enough for it to kick in and the starter battery voltage is low enough for the alternator to go full output - especially when the jump pack/leads are removed....
Ask any late 90's Jaaag owner ;-)
Personally, I've never had any issues, the spike will be around 20-35VDC max, charger dependent and of a duration of <10mS, that said, I've never connected one to anything older than 2007.
It's worth remembering that an alternator, especially a 'dumb' one can spike upwards of 50VDC for anything up to 500mS when an engine rpm goes high enough for it to kick in and the starter battery voltage is low enough for the alternator to go full output - especially when the jump pack/leads are removed....
Ask any late 90's Jaaag owner ;-)
Wedg1e
They call me Mr. Bodge-angles
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The clocks seemed to have had failures of electrolytic capacitors, so age probably wasn't on their side either. I repaired both of them. The in-car audio was undamaged.
The Clifford alarm (not a cheapie, although the electronics design might be viewed as such) apparently suffered a microprocessor failure despite it being isolated by a 5V regulator and some amount of smoothing (electrolytics that didn't fail). The CPU could see the received pulse train from the decoder but refused to do anything. As usual with proprietary coded items, nothing much more you can do. I found a later Clifford with all the bits for sensible money on Ebay and fitted that; since then I've removed the battery as mentioned - just need to top up the alarm's onboard battery periodically.
Wedg1e
They call me Mr. Bodge-angles
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Yes, I'd always assumed that the low internal impedance of a 75Ah lead-acid would soak up the spikes long before the electronic devices saw them.
Just for a laugh I might hang a scope on, the next time I top-up the car battery, and see how big the Optimate spikes get.
Ross365
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It must be about 10 years since I put a scope on my original pulsator, and it was an old scope with only a 20MHz bandwidth. On that scope, the spike appeared only as a vertical line (i.e. the width of the spot size) whereas I expect that with a better scope, I guess you might see the the spike tail off (and a higher peak voltage). I've never tried to look at whatever pulses come out of the CTEK.
