Bruce, The PO put two 4D batteries in the compartment under the stbd settee just forward of the sink. They were shot when I purchased the boat and I needed something to get me 350 miles home. Not being familiar with the local chandleries I found myself in the nearest AutoZone. 3 of the largest amp hour "marine" batteries fit pretty well and got me about 345Ah. They survived ~5 years and cost ~$300. I just replaced them last year with four Trojan T105-RE. They are 6v and 225Ah each so 450Ah total. I had to rebuild the compartment a little and lined it with epoxy and fiberglass. I had to get creative about the mounting and anchoring and then had to shoehorn them in. As with most boat projects it was a bit of a compromise. The terminals where only available in a high format so in order to accommodate I had to add a piece of 1x1 trim under the entire bench.
Too high of a charge capacity exacerbates the boiling of the cells. Typically the only opportunity to see the full current of any charger is when the battery bank is below ~80%. As the charger is charging the battery it is pushing the voltage higher and higher to attain max charger current. Once it reaches 14.7v the charger has completed bulk charge and the battery is roughly at 80%. The completion of the charge is called absorption and the charger will hold the voltage steady at 14.7v by reducing the current. Once ~2amps of current is reached the battery is said to be full charged and the charger will switch to float mode where it holds voltage at ~13.4v and ~2amps. So let's say you where at 50% and had a 100 Ah flooded lead acid battery and a 50 amp charger. The charger will ramp to max current (50amps) and max voltage (14.7v) until ~80% but the lead acid battery is literally incapable of absorbing the power fast enough so excessive heat is generated and while not quite an equalizing voltage boiling will occur. I don't exactly understand the method of destruction but heat is the enemy of lead acid batteries so any time they overheat you are probably damaging them. The boiling is helpful for mixing the electrolyte but will also mean more water is needed more regularly. So yeah, short answer, too high of a charge current will shorten battery life. I have two 100 watt flexible panels that typically put out 5 to 6 amps each for a total of 10 to 12 amps. My 450 Ah bank could accept 115amps(ish) so, 10 times as much solar for a total of 2000 watts! I don't have enough real estate to mount that many panels. But the point is, you probably won't exceed the limits of the batteries. Sizing for your system would probably be limited by your budget and by your available space. I would maximize the use of space and stretch the budget as needed. A Nova-Cool rep told me that a 100watt panel was typically enough to keep up with a properly insulated refrigerator. To minimize potential damage as result of deep deep discharge I have a priority start on my 450Ah bank. In the event of a solar failure, and no shore power, the battery will be disconnected at a low voltage setpoint - conveniently enough that voltage setpoint is 11.7v. http://www.prioritystart.com Josh Muckley S/V Sea Hawk 1989 C&C 37+ Solomons, MD On Mon, Feb 12, 2018, 8:14 PM Bruce Whitmore via CnC-List < cnc-list@cnc-list.com> wrote: > Hi Josh, > > Just curious, what batteries do you have in your bank, and where are they > mounted? > > Am I right to presume that having more charge capacity would result in > shorter battery life? > > Just trying to size my eventual solar panel purchase. > > Thanks! > > Bruce Whitmore > > (847) 404-5092 (mobile) > bwhitm...@sbcglobal.net > > > ------------------------------ > *From:* Josh Muckley via CnC-List <cnc-list@cnc-list.com> > *To:* cnc-list@cnc-list.com > *Cc:* Josh Muckley <muckl...@gmail.com> > *Sent:* Monday, February 12, 2018 2:34 PM > > *Subject:* Re: Stus-List Portable generator question > > 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> 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 > > _______________________________________________ > > 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 > > > > _______________________________________________ > > 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 > >
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