If your boat is wired correctly, your ACR should allow charging the start battery when the house side has high enough voltage (not the other way round). So, the presence of higher voltage on the start side, should not open the ACR.
Btw. If you connect on the house side, your portable battery will be charging your (large, and discharged) house bank, before being able to open the ACR to allow the charge to the start battery and the starter. Marek 1994 C270 Legato Ottawa On -------- Original message -------- From: Charlie Nelson via CnC-List <cnc-list@cnc-list.com> Date: 2020-07-14 17:27 (GMT-05:00) To: cnc-list@cnc-list.com Cc: cenel...@aol.com Subject: Stus-List Jumping the start battery in ACR environment Following suggestions on this list, I purchased a NOCO Lithium battery 'jump starter' to have on board if/when I might need to jump my starting battery. Cheaper and lighter than another 12 volt battery and having done this many times in various cars I have owned over the years, it is no big deal to jump a dead battery. However, my boat has an ACR which, as I understand it, works to keep the batteries charge states more or less equal while they are being charged, either from shore power or the alternator. When no external charge is supplied, it isolates the battery banks. So if it works as it should, and my house batteries are drained accidently or just fail while at anchor (say), I should be able to use the start battery to start the engine. In fact, my battery switch has 2 positions (besides OFF), 1 (Normal) and Combine Batteries. Unless both battery banks fail at the same time, I think I would always have on board power to start the engine. In the very unlikely event that I lose both battery banks, my NOCO might save the day. So here is the question in this unlikely scenario: When I jump start the engine, do I hook up the NOCO jump starting battery to the 'start battery' in the boat? If the ACR has not failed, would it not sense the increased charge state of the boat start battery and immediately share the NOCO jump star power with the house batteries? If these are also depleted, my NOCO jump starter might not have enough power to start the engine, since the ACR would send a lot of this power to the house batteries. If the above is not 'over thought', it suggests that I should isolate the house batteries from the ACR before I try to jump the boat start battery with the NOCO jump starter. Thoughts from the list would be appreciated! Charlie Nelson Water Phantom 1995 C&C 36 XL/kcb
_______________________________________________ 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
