- Joined
- Mar 17, 2012
- Messages
- 4,280
- Location
- Australia
- Vessel Name
- Insequent
- Vessel Make
- Ocean Alexander 50 Mk I
My existing thruster/windlass bank is 4 x 75Ah batteries, 2 x C&D Technologies DCS 75 HIT and 2 x Interstate DCM 0075. The last few times I have anchored the windlass has struggled to get the anchor up onto the bow. By the time it is near the surface the bank's capacity is pretty much exhausted. They all charge up again fine, resting voltages 12.8 or higher.
I have a conductance tester which would seem to be a reasonable way to test the batteries without doing a full load test. The C&D's test out really well - internal resistance of 3 m-ohm, 100% health. The Interstate's have internal resistance of 9-12 m-ohm, and a health reading of 31-39% depending on whether rest charge was 12.8 or 13.1 V. So they are basically shot. The interstate's are 4.5 years old, whereas the C&D's are older. The PO used the C&D with a long cable run for the windlass, but seldom anchored. I now have the batteries in the bow near the thruster. My cable length is about 12' in total (negative plus positive), and the cable is all 2/0 between batteries and thruster. The windlass cable length is probably 8' longer, and is a little smaller in size. My thruster has a 500A fuse and the windlass a 200A fuse.
I am trying to work out which way to go for a new bank. The Interstate's ought to have lasted longer IMHO, so what killed them? Is the current draw too high for too long, or is the total Ah insufficient? I would typically have 75-100' of chain out, but occasionally it is 200-250'. I think the windlass load is the greatest challenge for the bank as the high thruster amps are for short bursts only.
I am thinking that as well as a higher Ah bank I should also go for high max current draw batteries, or a high 'constant current discharge rating' spec in particular. This would favour using 6V batteries. But how much Ah would be enough? I could use a pair of Fullriver DC250-6 in series, or 4 x DC 224-6A in series-parallel. Any thoughts?
I have a conductance tester which would seem to be a reasonable way to test the batteries without doing a full load test. The C&D's test out really well - internal resistance of 3 m-ohm, 100% health. The Interstate's have internal resistance of 9-12 m-ohm, and a health reading of 31-39% depending on whether rest charge was 12.8 or 13.1 V. So they are basically shot. The interstate's are 4.5 years old, whereas the C&D's are older. The PO used the C&D with a long cable run for the windlass, but seldom anchored. I now have the batteries in the bow near the thruster. My cable length is about 12' in total (negative plus positive), and the cable is all 2/0 between batteries and thruster. The windlass cable length is probably 8' longer, and is a little smaller in size. My thruster has a 500A fuse and the windlass a 200A fuse.
I am trying to work out which way to go for a new bank. The Interstate's ought to have lasted longer IMHO, so what killed them? Is the current draw too high for too long, or is the total Ah insufficient? I would typically have 75-100' of chain out, but occasionally it is 200-250'. I think the windlass load is the greatest challenge for the bank as the high thruster amps are for short bursts only.
I am thinking that as well as a higher Ah bank I should also go for high max current draw batteries, or a high 'constant current discharge rating' spec in particular. This would favour using 6V batteries. But how much Ah would be enough? I could use a pair of Fullriver DC250-6 in series, or 4 x DC 224-6A in series-parallel. Any thoughts?