AOWYN
Well-Known Member
the proper way to do it
I hesitate to contribute to this string in the light of some of the heated exchanges elsewhare in the string. But having decided to put in my penny's worth I might as well do it with confidence!
The best combination is to put a separate battery up front, add a 12volt to 12volt charger up front with the battery and then run a modest twin-core cable back to the main batteries. The max current draw will be about 8 amps so the twin cable does not need to be very large and will be very much easier, and cheaper, to run through the boat than the alternative method of using heavy cables capable of carrying the full load of the windlass in use.
Re the alternative of simply having a charging cable for an auxilliary battery up in the bows. Be careful about assuming that you do not need a decent size of cable for simply "charging" the auxiliary battery since, once the windlass is operating it will impose a load on the aux battery which in turn will lead to a voltage drop at that battery which will then "suck" power from the main batteries via the charging cable. If the engine is running then the amount of power available for the aux battery to draw will be high, possibly right up to the max output of the alternator depending on engine revs and alternator gearing and specification. At that point the "only for charging" cables to the aux battery will need to be heavy enough to take a much bigger current than envisaged and will get very hot if not sized correctly. Even if the engine is not running the draw down the charging cable can be enough to exceed their power rating. You might not want to worry about a bit of overheating, but as you only expect to do this job once you might as well do it properly and not take chances with cables being taken above their rated capacity.
Of course, if the aux battery is physically disconnected from the main batteries when the windlass is used the issue described above will not apply, but it seems to be counter-intuitive to disconnect a battery from a charging source at bexactly the time you are going to take a heavy current load from it.
On my boat the disruption, dismantling and rebuilding required to run heavy cables was out of the question, so I went the solid state 12v to 12v charger route as recommended by ADVERC and it works beautifully. In addition, the cost of the charger from ADVERC at about £100 did not change the overall cost very much as the saving on the massive cable required for my 1200watt windlass was significant. (I think it finally cost me less, but I did not keep the detailed costings.
Hope this helps and I will not be offended by the responses from others with even stronger opinions (I will simply ignore them....)
I hesitate to contribute to this string in the light of some of the heated exchanges elsewhare in the string. But having decided to put in my penny's worth I might as well do it with confidence!
The best combination is to put a separate battery up front, add a 12volt to 12volt charger up front with the battery and then run a modest twin-core cable back to the main batteries. The max current draw will be about 8 amps so the twin cable does not need to be very large and will be very much easier, and cheaper, to run through the boat than the alternative method of using heavy cables capable of carrying the full load of the windlass in use.
Re the alternative of simply having a charging cable for an auxilliary battery up in the bows. Be careful about assuming that you do not need a decent size of cable for simply "charging" the auxiliary battery since, once the windlass is operating it will impose a load on the aux battery which in turn will lead to a voltage drop at that battery which will then "suck" power from the main batteries via the charging cable. If the engine is running then the amount of power available for the aux battery to draw will be high, possibly right up to the max output of the alternator depending on engine revs and alternator gearing and specification. At that point the "only for charging" cables to the aux battery will need to be heavy enough to take a much bigger current than envisaged and will get very hot if not sized correctly. Even if the engine is not running the draw down the charging cable can be enough to exceed their power rating. You might not want to worry about a bit of overheating, but as you only expect to do this job once you might as well do it properly and not take chances with cables being taken above their rated capacity.
Of course, if the aux battery is physically disconnected from the main batteries when the windlass is used the issue described above will not apply, but it seems to be counter-intuitive to disconnect a battery from a charging source at bexactly the time you are going to take a heavy current load from it.
On my boat the disruption, dismantling and rebuilding required to run heavy cables was out of the question, so I went the solid state 12v to 12v charger route as recommended by ADVERC and it works beautifully. In addition, the cost of the charger from ADVERC at about £100 did not change the overall cost very much as the saving on the massive cable required for my 1200watt windlass was significant. (I think it finally cost me less, but I did not keep the detailed costings.
Hope this helps and I will not be offended by the responses from others with even stronger opinions (I will simply ignore them....)
