On Sat, 21 Aug 2010 09:41:41 +0100, Eno at Yahoo <[email protected]> wrote:
> Hi, > >Has anyone any idea how long in general terms it will take a normal >sized alternator (50 amp) to recharge two 110amp batteries, and >recharge the starter battery back to its pre starting level assuming it >was fully charged before starting the engine. > >I know there are a number of variables that would need to be known to >give an accurate answer, but just for general everyday type use and >using normal levels of power, example:- TV for 2 hours, 2/3 (20w) lights >for 5 hours and the water pump and 12 volt compressor fridge. > >As a general guide how long would you think the engine would need to run >to replace the energy lost. > >Thanks There is a significant problem with your question, if it assumes running the main engine while the vessel is at rest. That's because this is a very inefficient use of the engine. Recharging is much better (and more sustainably) done using a for-the-purpose generator with an engine sized for the job and running at an efficient load level. Also, it is very worthwhile to have a smart charger. This can be in the form of a smart alternator controller, but many systems use a multi-level dedicated charger (which raises the voltage, etc., as the battery nears full charge). This significantly reduces the needed recharging time. It also lengthens battery life, by achieving a full charge (which conventional alternators usually don't achieve). During the several years I had no mains at my mooring, I ran my generator every day to replace the energy I used for domestic purposes (fridge, electronics, lighting, pumps, the works). I have a good charger (50 A, 24 V) and a 500 Ah 24 V battery. I found the battery could reach float level after about 2.5 hours of charging( per day). Does that help? Adrian Adrian Stott Tel. UK (0)7956-299966
