Yes - this is the number one cause of battery degradation. Significant plate sulphation starts to occur when the battery terminal voltage drops below about 12.2V (so about 70% discharged), but it is quite soft and easily reversed with a full recharge if done within a few days. Let the terminal voltage go much below this for a number of weeks though and the sulphation crystals harden so much they they can never be recombined back into the electrolyte. I would be putting a trickle charger on anything left standing for more than a couple of weeks.Bertz4 wrote: ↑Fri Dec 01, 2017 10:17 am A big problem with batteries not in regular use is plate sulphating, I forget the exact chemistry but the build up of lead sulphate stops them working properly. The calcium type batteries do not suffer from this problem or at least suffer much less so are generally a better choice for cars not in daily use.
Rob.
It's also important to do a full equalisation charge (i.e. 14.4V) until the battery is 100% charged at least once a month to remove any soft sulphation. If the car is doing lots of short journeys it probably never gets to 100% charge from the alternator and this is a big killer of batteries over time.
Below is a typical state of charge characteristic. The C/100 curve one is the one most applicable when the car is stood...
- battery discharge.png (275.03 KiB) Viewed 242 times
