Joe, the damage I was considering would be caused by exceeding the charge rate for the bank size. The conventional wisdom is that typical lead acid batteries should not be charged at a rate greater than 25% of their capacity. A 100 AHr battery would be limited to 25 amps. Isn't it possible to exceed the charge rate with a good regulator? Particularly applicable when the battery is more deeply discharged.
All of the 3 and 4 stage regulators I've ever seen will ramp up to max amps and hold there until ~14.6 volts is reached (80% full - end of bulk charge) at which time the voltage will be held constant at ~14.6v as the amps are reduced. Once the amps lower to ~2amps the regulator shifts to float mode and lowers the voltage to ~13.3v and holds it indefinitely. As an example lets say that you are using a 100 amp alternator and regulator to charge a 100AHr battery bank that has been discharged to 50% capacity. Isn't it likely that the charge current will ramp to 100 amps? Or at least greater than 25 amps? What other regulator function would prevent this from happening? I suppose battery temperature could input to the alternator so as to reduce charge current. Though, I'm not sure that battery temperature responds quickly enough to prevent early over current damage, only overcurrent damage as a result of longer term charging current which has been applied long enough to raise temperature to the threshold. Josh On Oct 16, 2017 3:01 PM, "Della Barba, Joe via CnC-List" < cnc-list@cnc-list.com> wrote: Wrecking batteries with a big alternator is why you need a good regulator. If you are counting on the alternator itself to just be unable to do any damage because it can’t, you are taking a big risk or and have a very suboptimal charging setup. For an extreme example, given a decent regulator, a 1000 amp alternator should do no harm and you can very much destroy batteries with a 35 amp alternator. I once worked on a boat whose genset had a 35 amp alternator set to 16 volts. The owner was buying several batteries a year and didn’t know why. Joe Coquina *From:* CnC-List [mailto:cnc-list-boun...@cnc-list.com] *On Behalf Of *Josh Muckley via CnC-List *Sent:* Monday, October 16, 2017 2:50 PM *To:* C&C List <cnc-list@cnc-list.com> *Cc:* Josh Muckley <muckl...@gmail.com> *Subject:* Re: Stus-List New Engine, now what size alternator Not only will they not absorb the charge quickly enough, exceeding the charge rate will boil the batteries more than staying within the charging guidelines. An alternator that is too big for the bank will seriously risk damaging the batteries. Larger alternators under full load will also strain the v-belt. Additional tention will need to be applied to prevent the belt from slipping. The additional tension puts additional side loads on the crankshaft end bearing. Lets also remember that full output is only achieved under full RPM. Many people enjoy the idea of idling along or running the engine for a few hours in neutral. Not only does this not achieve the full rated output of the alternator but it can also coke up the exhaust elbow and glaze the cylinders. Diesel engines should be run at 80% as often as possible and for as long as possible. Josh On Oct 16, 2017 2:19 PM, "Joel Aronson via CnC-List" <cnc-list@cnc-list.com> wrote: With a small battery bank you will not benefit from the larger alternator. The batteries can't absorb a charge that quickly. Joel <http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail> Virus-free. www.avg.com <http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail> On Mon, Oct 16, 2017 at 1:25 PM, David via CnC-List <cnc-list@cnc-list.com> wrote: Let me expound a bit on alternators and engine size. When replaced my dumb alternator with a Balmar set-up (alternator, smart Charger, digital Duo etc ) on my 33 hp diesel Balmar recommended no more than the 80 amp because of the loss of HP which I could ill afford. If you have HP to spare...go for it. If not reconsider. 1981 40-2 David F. Risch (401) 419-4650 (cell) ------------------------------ *From:* CnC-List <cnc-list-boun...@cnc-list.com> on behalf of Josh Muckley via CnC-List <cnc-list@cnc-list.com> *Sent:* Monday, October 16, 2017 12:47 PM *To:* cnc-list@cnc-list.com *Cc:* Josh Muckley *Subject:* Re: Stus-List New Engine, now what size alternator Paul, Thanks for these more accurate "ratings". It definitely helps to give an answer to the question of "what does good look like?" I have never saught out actual ratings for refrigerator loads and I've never gotten a AHr meter installed - besides the plethora of variables which make single point AHr usage almost impossible to determine. It seemed like nobody else had provided a frame of reference besides examples of their own setup and I was kinda trying to describe a worst case numbers scenario to provide an upper boundary to the project. Your numbers bring further clarity by providing a lower boundary. You and other listers are absolutely correct that adding insulation is the best way to reduce refrigerator AHr load. Thanks, Josh Muckley S/V Sea Hawk 1989 C&C 37+ Solomons, MD On Mon, Oct 16, 2017, 9:20 AM Dreuge via CnC-List <cnc-list@cnc-list.com> wrote: If you have a refrigeration load of 120AH/day, don’t waist money on increasing battery and charging capacity. Spend a little cash on better insulation or rebuild your box with more and better insulation. It is not unreasonable to shoot for a refrigeration load under 30AH/day. Just have a look at Wally’s Stella Blue page titled “Marine refrigeration and freezer on 22AH/day”(I recall he has a Frigoboat unit with keel cooler). Technautics claim that their CoolBlue system consumes “24AH/Day for a 7 cubic foot fridge/freezer with R-30” and “operates at ambient temperatures up to 120F without a loss in system efficiency.” Even the Isotherm claims their ASU SP3751 can achieve loads under 20AH/day. Now making ice or cooling down warm beer on a really hot day will likely have higher load demands, but the message is still the same. Insulation is cheaper than batteries and lasts a lot longer too. - Paul E. 1981 C&C 38 Landfall S/V Johanna Rose Fort Walton Beach, FL http://svjohannarose.blogspot.com/ <https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fsvjohannarose.blogspot.com%2F&data=02%7C01%7Cdavidrisch75%40msn.com%7C174374313e324a76649608d514b5ae0e%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636437692893291062&sdata=3Z6nZDYREvjXOkTwuBgdW3OftsiN%2B4KI22XBkKfEUaQ%3D&reserved=0> On Oct 14, 2017, at 2:02 PM, cnc-list-requ...@cnc-list.com wrote: Lets consider some hypothetical numbers based on the rep's info. If a 100w panel were %100 effective and operated for 8 hours, you would get 800w-hrs of power per day. 800w divided by 12v = 67amp-hrs. 67 divided by 24hrs = 2.8amps current draw on average. That kinda gives you a ball park for what type of loads you'll be facing. Round up to 5amps/hr if you like for margin. 5 *24=120AHr per day. _______________________________________________ The bills have started coming in for the year 2018 and have gone up again. October will be our fund raising month. Please consider sending a small contribution to help keep this list running. Use PayPal to send contribution -- https://www.paypal.me/stumurray <https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.paypal.me%2Fstumurray&data=02%7C01%7Cdavidrisch75%40msn.com%7C174374313e324a76649608d514b5ae0e%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636437692893291062&sdata=7kc%2FxlWlAIBdFI5P498w2ktOhdYBxaO1jBXoIheJqII%3D&reserved=0> All contributions are greatly appreciated! _______________________________________________ The bills have started coming in for the year 2018 and have gone up again. October will be our fund raising month. Please consider sending a small contribution to help keep this list running. Use PayPal to send contribution -- https://www.paypal.me/stumurray All contributions are greatly appreciated! -- Joel 301 541 8551 <(301)%20541-8551> _______________________________________________ The bills have started coming in for the year 2018 and have gone up again. October will be our fund raising month. Please consider sending a small contribution to help keep this list running. Use PayPal to send contribution -- https://www.paypal.me/stumurray All contributions are greatly appreciated! _______________________________________________ The bills have started coming in for the year 2018 and have gone up again. October will be our fund raising month. Please consider sending a small contribution to help keep this list running. Use PayPal to send contribution -- https://www.paypal.me/stumurray All contributions are greatly appreciated!
_______________________________________________ The bills have started coming in for the year 2018 and have gone up again. October will be our fund raising month. Please consider sending a small contribution to help keep this list running. Use PayPal to send contribution -- https://www.paypal.me/stumurray All contributions are greatly appreciated!
