calvingloster:
Grumpy_Mike:
Why can you not just charge a lead acid battery with a constant voltage of 14.1v
Because it will then take too much current.
You need a current limiting source until it reaches 14.1V AND then you do not increase the voltage any more.
Ok I get what your saying. But if I have a power supply that is 14.1v and supplies a maximum current of 100mA then it will be fine provided the 100mA is not more than 20% of the battery capacity? The charger might just get hot because it's working at its maximum rated capicity?
It's not a great idea maxing out the power supply all the time but as the battwey voltage rises, the current will drop as it approaches 14.2v, if you have a 100ma supply and the battery is rated 1000mah it will take 10 hours constant current, 11 or higher hours at constant voltage... (as current deceeases nearer to it's charge voltage 14 v)