I was sure the battery on my Honda Jazz was original, however when it failed a couple of weeks back it said Halfords so could not be original, but the Jaguar battery was changed by the dealership around £300 because the car would fail to start, I did not think it was battery, as after leaving it for 5 minutes, it would start the car and engine flew over, no sign of struggle, so I blamed engine management, seems I was wrong, new battery did same, and RAC man found the foot, wife has too light a right foot, not what I would have said as I cling to the car the way she drives, but seems she had been touching the brake while parked and depleted the vacuum so it needed more pressure on brake peddle to start the engine, she was giving enough pressure so warning did not come up saying press brake peddle, but not enough to make the sensor allowing it to start.
Lucky I keep old battery to use on caravan, and have noted using smart charger with just a 0.1 amp charge rate it would sit at 13.4 volt, and left for 3 months without charge, it was back to fully charged state within the hour, with a charger with max output of 3.8 amp. Which did not seem to be the behaviour of a failed battery.
Now the failed battery off the Jazz that would drop voltage as soon as taken off charge, and clearly had a failed cell.
But when I was an auto electrician I simply did not have the time to fiddle with batteries, if the battery did not recover in a couple of hours enough to start the car, it went in scrap. Today I have time on my hands to play, and I have in last 5 years had a few batteries which would have gone in scrap, which I have had time to leave on a charger for an extended time, and also an energy meter so I could monitor what the charger used, and this produced a surprise.
The charger a Lidi ULGD 3.8 A1 3.8 amp smart charger will not charge a battery below 3.8 volt (6 volt) 7.3 volt (12 volt) or above 15 volt, so only way was to put the sulphated battery in parallel with a good battery, other wise it would simply switch off, the charger has 4 charge rates 3.8, 3, 0.8 and 0.1 amp plus zero when under 12 Ah is selected, but once it has been through the 3.8 and 3 amp stage it will not auto return to those rates it will only alternate between zero, 0.1 and 0.8 amp rates. This was good as far as I was concerned as if the sulphated battery has a shorted cell I don't want a high charge rate.
So the pair were put on charge, and the charger went through the stages, and sat at zero output, and it sat there for 10 days, had I not had an energy meter connected to PC I could have not monitored a battery for so long, but basic thing they were just left and I would glance on the PC every so often. Then it was as if some one had flicked a switch, the charge rate jumped to 0.8 amp and remained there until battery fully charged. Then returned to 0.1 then zero charge rate, this was with a 7 Ah battery, so repeated on second 7 Ah then a 75 Ah battery, all three had basic same result, with the 75 Ah once it started to charge I removed leads and reconnected so it charged at 3.8 amp rate, which it turned down to 3 amp rate very fast as voltage hit 12.8 volt then held at 3 amp for reasonable time until hit 14.1 volt then for a very long time at 0.8 amp until hit 14.4 volt then settled down to 12.8 volt as soon as it drops below 12.8 charger ups the charge rate, and at 14.4 volt it drops it again, so a fully charged battery sits at 12.8 volt 95% of the time, the raise to 14.4 and drop again is so short of a time that one would be very lucky to see it.
These recovered batteries seemed non the worse for their time left abandoned, and I realised my attempts in the past to recover batteries before the smart charger likely killed a potentially good battery.
So then we look at history, back in the days of the dynamo, we had flooded batteries only then, and we were told once a month to use an equalising charge, we over charged the battery at a very low charge rate over night so any poor cells would come up and good cells would loose water which we would replace once equalising charge complete. So as far back as we can look, we knew charging a battery took time, which we don't have when fitted to the vehicle.
We know unless a battery is fully charged every so often, it looses capacity, either active material falls off plates, or it becomes part sulphated, now I now know it can take 10 days to remove the sulphur from the plates, time on charge is important, so what seems a faulty battery, leave it on a smart charger for a couple of weeks, and it may well recover. It just simply takes time.
However with cars being not used during lock down, this has become a problem, I have three cars in the family and other batteries, from caravan, the jump start set, the mobility scooter, the e-bike is not lead acid so that's no problem being left. But it seems the smart charger is doing its rounds, no soon has one battery been charged, and it is moved to the next.
want to see how it goes, and if voltage raises, yes I know I could likely simply take it off charge now, however in the back of my mind I remember it took two weeks for the sulphated battery to start charging, so there could be some sulphation, but also have read pulsing is not good for the battery, so will leave a day and see what happens.
