I have been successfully using an Optimate 3 battery charger to eak out the last useful drop of energy out of my motorbike and car batteries for around 10 years.
Should know better than to try and improve on perfection but decided to take a walk on the wild side and splashed out on a brand new, all singing and dancing Optimate 4 charger.
To cut a long story short this does not settle with my Panasonics of which I an currently(excuse pun) have 6.
All are old and in varying states but all will work on a car. My test has and always will be does it spin the starter at sufficient speed to consistently start the bike/car first time. Problem appears to me to be the voltage the Panasonics settle at. Most ordinary batteries settle at around 12.7 volts whereas my Panasonics tend to be 12.3 - 12.5 volts.
The Optimate 4 runs a 30 min voltage retention test at the end of its routine which consistently fails on all these batteries resulting in a charge/test loop rather than the maintenance state desired.
As these batteries all work on a car I am thinking that the Optimate 4 is too strict in its operation to be fully functional on our MX5 original batteries. Anyone else care or better still had similar or different experience with the optimate 4 and Panasonic?
The original Panasonic batteries don`t seem to have any date markings on them so no way of knowing how old they are. However after having a heated rear window relay failed causing the battery to completely discharge I used an Ultimate Speed charger bought from Lidl for £13.99. It fully reconditioned the battery which has been working great throughout the horrible weather.
Have now got a plug in the cig.lighter socket that shows the charging rate. Only a couple of quid on Amazon. I`ve also bought a new Panasonic replacement as I was convinced the old one would die soon. Plugged the new one in straight out of the box to make sure it was fully charged and it took a few hours to top up. The readings on both the batteries are the same.
After six weeks of the old battery sitting doing nothing on my work bench it still shows full charge when attached to the Ultimate Speed device to Panasonic and to Lidl for sure.
I was tempted by the Lidl charger and only bought the Optimate 4 because I have too many batteries for the one charger I had and no Lidl nearby:-)
You can tell the exact date of a Panasonic battery as it is printed on the mainly yellow sticker opposite the positive pole. On the right of the sticker is the date in DDMMYY format
Nobody with an Optimate 4 in use with their Panasonic battery? Always the case when I could use some information:-)
Could it be that over the years the batteries have retained a “memory” of the charging with the optimate 3, the sort of thing that happens with other rechargeable batteries/chargers?
Thanks for the suggestion but I think it is something more fundamentally different about these batteries, particularly when they are old.
They or rather the ones I have, some of which have been abused for years but still work on the car when in regular use do not seem to hold the level of voltage of an ordinary battery. It’s only a little below the standard but I am thinking its enough to cause a problem with the voltage test that is performed by the Optimate 4. Basically the Optimate 4 charges the battery to a particular level but my Panasonics settle back quickly to the level they are happy at 12.3 - 12.5 volts - this fails the Optimate 4 voltage test and sets up the test/charge loop. If I am right and all older Panasonics do this, an Optimate 4 is not a good choice of maintenance charger for these particular batteries.
Surely there is someone out there who uses or has used an Optimate 4 with their original MX5 Panasonic battery?
Perhaps my 6 Panasonics are not typical. Be interested to know if other people with these batteries find that the resting voltage is lower than the 12.7 volts or so for standard car batteries?
All the classic battery literature I have refers to checking specific gravity (different for hot or cold climates) and most significantly the cell voltage when under heavy discharge (ie if at least 70% charged then the cell voltage should hold up between 1.2V and 1.5V for at least ten seconds at no more than a 150A to 160A load for a typical 50Ah car battery).
Of course with a sealed battery both of these tests are difficult, and the only easy practical test possible is to monitor the battery voltage when cranking the engine (no fuel pump, no ignition). So one should watch it with a meter to see how quickly it drops, if at all. If the battery holds up for ten seconds it is a good 'un, if it rapidly drops off then time for a change.
Now we come to the Optimate. It should be doing a light discharge test as part of measuring the internal battery resistance and monitoring how that changes with the charging cycle. An easy way to check this is to put an Oscilloscope across the battery terminals and watch what is going on. Hmm, I can do that with my ‘Smart’ charger; I’ll take a snap.
More on this in half an hour or so if I have a relevant result.
Edit, after a fiddle in the garage.
The variation in voltage appearing across the nearly full good condition battery was too small to see with clearly the digital scope, even when filtered it was still buried in the sampling noise, and being a cheap Picoscope it did not let me dial in an offset of 13.78V. I suppose I could knock together an analogue preamp around an op-amp to fiddle it, but life is too short. One good thing I noticed about my eight year old OE Panasonic battery is that it has screw-plugs for each cell to allow one to check the electrolyte level and specific gravity.
The s.g. of a cell (one intended for a cold climate like ours) measured with the electrolyte at 16C should be no less than 1.11 to 1.13 when fully discharged (less can be bad news). Between 1.19 to 1.21 is half charged, and it should be at least 1.27 to 1.29 when fully charged. Mine were all between 1.27-1.28 with just enough liquid above the plates for the hydrometer to siphon up the necessary amount for a reading, but then the charger was still topping up the last little bit, and the garage was 16.5C.
I have owned a hydrometer similar to this for almost fifty years!