Hi Edd- I have considered one of those devices, but it seems you have to still have to know the rate of draw of the refridgerator,fans,lights and what is the acceptable lowest voltage/charge of the house battery. I guess that device will tell you the rate of draw in amps. If I know those parameters, it seems to me it should be just as good to look at the voltage in the evening and know that you do or do not need to charge the battery before going to bed or turn off the fridge. So I guess the question is: 1. What is the lowest voltage you can safely let your house battery get to? 2. How would you measure the overnight draw on the battery if power is left on to fans +fridge + lights to prevent going lower than that battery voltage given that the fridge draw is not continuous. Dave
> On Feb 12, 2018, at 3:23 PM, Edd Schillay via CnC-List > <cnc-list@cnc-list.com> wrote: > > David, > > While there are calculations you can use, rate of battery discharge is also > affected by battery age and temperature. > > And, since I’m really, really good at spending other people’s money, I’d > suggest installing a Battery Monitoring System: > https://www.defender.com/product3.jsp?path=-1%7C328%7C2289954%7C2289950&id=1130644 > > <https://www.defender.com/product3.jsp?path=-1|328|2289954|2289950&id=1130644> > > > I have a similar system on the Enterprise — A Heart Interface Link 2000. See > https://www.ebay.com/itm/Xantrex-Heart-Interface-Link-2000-Complete/132499499047?_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D1%26asc%3D20160908110712%26meid%3Dfe0fb3de9f6c425585c79ccae997251d%26pid%3D100677%26rk%3D1%26rkt%3D4%26sd%3D302615330618%26itm%3D132499499047&_trksid=p2385738.c100677.m4598 > > <https://www.ebay.com/itm/Xantrex-Heart-Interface-Link-2000-Complete/132499499047?_trkparms=aid=222007&algo=SIM.MBE&ao=1&asc=20160908110712&meid=fe0fb3de9f6c425585c79ccae997251d&pid=100677&rk=1&rkt=4&sd=302615330618&itm=132499499047&_trksid=p2385738.c100677.m4598> > Properly installed and programed, you can see how much time you have left on > your house bank with the draw you are using at any given time. > > All the best, > > Edd > > > Edd M. Schillay > Starship Enterprise > C&C 37+ | Sail No: NCC-1701-B > City Island, NY > Starship Enterprise's Captain's Log <http://enterpriseb.blogspot.com/> > > > >> >> On Mon, Feb 12, 2018 at 3:01 PM, David Knecht via CnC-List >> <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com>> wrote: >> This discussion raises an issue I have struggled with as I have started >> cruising more: deciding how much battery power I have. I have 2 AGM >> batteries, one house, one starting and a panel voltmeter for monitoring. My >> batteries are now separated so I no longer have to worry about being able to >> start the engine if I run the house too low. The fridge is the only major >> power draw, so I usually am just conservative, running it only periodically >> to make sure I don’t overdraw the battery. So what is the most efficient >> way to figure out how much I can safely run the fridge? If I just watch the >> voltage, how do I decide if I can leave the fridge on overnight? Dave >> >> Aries >> 1990 C&C 34+ >> New London, CT >> >> <pastedGraphic.tiff> >> >>> On Feb 12, 2018, at 2:33 PM, Josh Muckley via CnC-List >>> <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com>> wrote: >>> >>> Much of your problem is a matter of battery capacity as much as a matter of >>> charging capacity. I have ~450 Ah of capacity on one bank, a 90 Amp >>> alternator that never reaches full load, and 200 watts of solar. Even >>> without the solar I was able to comfortably keep the the fridge running and >>> the lights on when cruising for ~2 weeks. The half hour to hour of engine >>> operation to anchor or moore in the evening and the same in the morning was >>> always enough to keep the batteries charged. >>> >>> Keep in mind that the battery capacity should be at least 4x of the charge >>> capacity for flooded lead acid and at least 2x for AGM. So a 400 Ah or 200 >>> Ah respectively for a 100 amp alternator. >>> >>> Josh Muckley >>> S/V Sea Hawk >>> 1989 C&C 37+ >>> Solomons, MD >>> >>> >>> >>> On Mon, Feb 12, 2018, 12:55 PM Damian Greene via CnC-List >>> <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com>> wrote: >>> A question for your collective wisdom: >>> >>> I am scoping out upgrading my stock 55A alternator to a 100A Balmar, and >>> related upgrades to the controls. I had a very productive discussion with >>> Rod Collins at Compass Marine (mainesail), and we worked out the details. >>> Unfortunately he's booked out through the spring, so this job will wait >>> until next winter. >>> >>> So thinking then about keeping the batteries charged, and the fridge >>> running on our long summer cruise - where we may go for weeks without >>> access to shore power, I got wondering about using a portable generator to >>> charge the batteries - as an alternative to many hours of running the >>> diesel. There are a couple of Hondas that might do the trick 2000 Watt, >>> weighing 47#, 1000 Watt weighing 29#. >>> >>> Have any of you tried this? What could (would) go wrong if I plugged this >>> generator into my inverter, to charge the batteries? >>> >>> Regards, >>> >>> Damian >>> >>> 1986 Sabre 38 Freefall >>> Previously 1984 C&C 34 Ghost >>> Bass Harbor, Maine >>> _______________________________________________ >>> >>> Thanks everyone for supporting this list with your contributions. Each and >>> every one is greatly appreciated. If you want to support the list - use >>> PayPal to send contribution -- https://www.paypal.me/stumurray >>> <https://www.paypal.me/stumurray> >>> >>> _______________________________________________ >>> >>> Thanks everyone for supporting this list with your contributions. Each and >>> every one is greatly appreciated. If you want to support the list - use >>> PayPal to send contribution -- https://www.paypal.me/stumurray >>> <https://www.paypal.me/stumurray> >>> >> >> >> _______________________________________________ >> >> Thanks everyone for supporting this list with your contributions. Each and >> every one is greatly appreciated. If you want to support the list - use >> PayPal to send contribution -- https://www.paypal.me/stumurray >> <https://www.paypal.me/stumurray> >> >> >> >> >> >> -- >> Joel >> 301 541 8551 >> _______________________________________________ >> >> Thanks everyone for supporting this list with your contributions. Each and >> every one is greatly appreciated. If you want to support the list - use >> PayPal to send contribution -- https://www.paypal.me/stumurray >> <https://www.paypal.me/stumurray> >> > > _______________________________________________ > > Thanks everyone for supporting this list with your contributions. Each and > every one is greatly appreciated. If you want to support the list - use > PayPal to send contribution -- https://www.paypal.me/stumurray > <https://www.paypal.me/stumurray> Aries 1990 C&C 34+ New London, CT
_______________________________________________ Thanks everyone for supporting this list with your contributions. Each and every one is greatly appreciated. If you want to support the list - use PayPal to send contribution -- https://www.paypal.me/stumurray
