Is the OEM Cayman
battery
maintenance-free? It seems so to look at it, but the owner's manual advises to "check acid level" regularly...which is correct?
Please search Thread in regard to this subject. But the answer is, you should have a
battery
conditioner if you are parking your car for any length of time, as it will drain your
battery
dead as many members found out.
I think that he is referring to the electrolyte level and not the state of charge. The
battery
is maintenance free.
And while we consider batteries to be maintenance-free, it usually is still possible to gain access to the cells to top off the electrolyte. However, most people add distilled water, whereas the proper thing to add is electrolyte.
One would probably only have to add fluid if you have repeatedly run the
battery
way down, requiring lots of heavy charging. At least that has been my experience, mostly with marine applications. And I would be careful about adding electrolyte. All
battery
info I have states that only distilled water should be used.
Marty
The adding of water is to protect the consumer. Water dilutes the electrolyte in a lead-acid
battery
. Generally, very little fluid ever is needed anyway, so the dilution is very minimal.
Automotive batteries arrive at the store in either wet, containing electrolyte, or as dry, without. And the acid has to be added. The dry batteries have a longer shelf life.
What cooks a
battery
, causing the electrolyte to vaporize and vent is overcharging. The main culprit being a faulty
voltage regulator
. That is how the electrolyte level will get low.
Alternator
/regulator performance these days is more stable than the days of old, such that the
battery
should live until its normal life span of 2-3 years or so.
My understanding is that maintenance free
battery
would not have a vent - I believe the Cayman batter does have a vent making it low maintenance ( I looked at the part list for the car, but it did not say for sure - I wanted to know that, as my charger has a setting for the different
battery
type, as it should, since the charging pattern is different ). For this exact reason they do not recommend putting a different
battery
type in cars from what they were designed for - the charging circuit would be different.
If you are into research, here is a page that explains all the differences in good detail:
http://www.uuhome.de/william.darden/carfaq.htm
Maintenance-free batteries will vent, if the internal pressure gets too high. They are designed to vent to minimize the possibility of the
battery
bursting from overcharging or other problems.
All lead-acid batteries need a continuous vent of some sort. When the
battery
lives in an enclosed area (trunk, front boot), it must be vented externally via a tube instead of simply out the top of the
battery
into the enclosed area. (
BMW
and Porsche both do this)
Why? Because the process of charging (or possibly discharging, I've forgotten a bit too much of my chemistry) generates hydrogen gas. Hydrogen is extremely combustable - so you don't want it trapped in an enclosed area where a spark or other ignition source could ignite it!
This has nothing to do with relieving pressure. These batteries should never build up any internal pressures.
Doug
Has been a while since I looked at the
Battery
FAQ, so I looked at it again - they claim that 'most maintenance free batteries are sealed' - not all, but most. It would be nice to know 100% what kind of
battery
is used by Porsche - I suspect it is Low Maintenance since they talk about adding water to it - here is a direct link to the section on the Maintenance free batteries:
http://www.uuhome.de/william.darden/carfaq7.htm#Ca/Ca
