The idea is that the house bank will need about 95% of the charging. The engine start battery will usually be very close to full unless you have issues with the engine. Therefore you are running the most current straight to the house bank and only taking minor charging current through the ACR.
Joe Della Barba Coquina C&C 35 MK I From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Edd Schillay via CnC-List Sent: Monday, March 02, 2015 2:20 PM To: C&C List Subject: Re: Stus-List Alternator Output Question Paul, I guess that’s where I’m confused. When the alternator throws out 14+ volts, the ACR combines the batteries so they all get the charge. They become, essentially, one big battery. Therefore the regulator won’t stop the charging until everything is a full capacity, right? I’ve never seen my alternator kick out less than 13 volts. When the engine is running, the ACR will always be in combination mode. So, why the “best practice” to run the alternator output to the house bank when the ACR will combine them anyway? 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 Mar 2, 2015, at 1:25 PM, PME <dre...@gmail.com<mailto:dre...@gmail.com>> wrote: I've read that it's a "best practice" to run the charging to the biggest bank, but can't find any explanation as to why. Hi Edd, Here is my understanding. The ACR will combine a second battery while there is a voltage present on the first battery. The alternator's voltage regulator will shut off the charging when the first battery is full. The second battery may still need some charging. Therefore it is better to have the alternator charge the battery which is being drained the most, i.e. the house battery. On the same note, most starters draw about 150Amps for less than 10 seconds. This amounts to 150A*10s*1hr/3600s = 0.4 A*hr which should be restored within a minute of charging. - Paul E. 1981 C&C Landfall 38 S/V Johanna Rose Carrabelle, FL On Mar 2, 2015, at 12:00 PM, cnc-list-requ...@cnc-list.com<mailto:cnc-list-requ...@cnc-list.com> wrote: Date: Sun, 1 Mar 2015 13:21:04 -0500 From: Edd Schillay <e...@schillay.com<mailto:e...@schillay.com>> To: CnClist <cnc-list@cnc-list.com<mailto:cnc-list@cnc-list.com>> Subject: Stus-List Alternator Output Question Message-ID: <5a4d6fa4-5e07-41c8-8468-ab498e809...@schillay.com<mailto:5a4d6fa4-5e07-41c8-8468-ab498e809...@schillay.com>> Content-Type: text/plain; charset="us-ascii" Listers, As you know, I'm planning a rewire to a house and starting battery configuration. On the C&C 37+, I have access to three sides of the engine -- the only side without access is the side with the starter and the alternator. From the diagrams I can find, the alternator output is connected to the starter, which then runs back to the batteries. I understand the best practice is to disconnect that wire (as well as the Orange one) and run a new wire from the alternator output to the house bank. This would mean removing, rewiring, and reattaching the alternator, which is a little out of my comfort zone given the access. I recently read on a forum that if you have an ACR instead of an Echo charger (planning to have an ACR), then you can leave the setup as is. The charge from the alternator would go to the starting battery and then, through the ACR, charge the house bank. The ACR auto senses from each side and works both ways. My starter battery and house bank will be the same chemical make-up (Trojan flooded). I've read that it's a "best practice" to run the charging to the biggest bank, but can't find any explanation as to why. So, the question is, with the ACR, can I leave the alternator output as is or do I really need to do some "engine surgery" to run a new cable? And if the latter, why can't the system work the way that the ACR advertises? All the best, Edd
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