House Battery Upgrade

[C-batical]

I need to replace my original equipment house battery that is a standard flooded 650 CCA starting battery with one that has more reserve power. My 2 starting batteries are both 550 CCA, flooded. I am running twin Honda 40's, three batteries (2 starts & 1 house) with Honda ACR switching system. I also have a Guest 15 amp three bank charging system hooked up to shore power. The house battery runs all of my electronics, that includes a Norcold refrigerator (3 amp draw) and a Raymarine C-80 system with 2KW radar (? draw).

I am finding that when I am fishing and trolling on one motor, that the 10 amp alternator cannot keep up with the draw of the refrigerator and Raymarine C-80 and after four or five hours the house battery starts to fade. I can remedy this situation by shutting the refrigerator off and running the second engine in neutral for period of time, but I prefer not to do this.

I seem to recall requesting a larger capacity house battery when I purchased the boat but was told that the three batteries needed to be "balanced" otherwise it would stress the ACR system and puny alternators of the Honda's.

Is anyone else running a similar setup and what is the size of their house battery? I would like to install the highest capacity house battery I can without overkill. I am considering an AGM, deep cycle, battery in the 850 to 1095 CCA range but am not sure if my current setup will handle it. Any thoughts or recommendations would be appreciated.

Thanks for you help,

[NORO LIM]

I believe if your house battery is too big, your Honda switching system will be chattering all the time as it tries to make your 10 amp alternators keep the start batteries full and charge the house battery at the same time. The BEP Marine site has a chart showing maximum house battery size for their VSR (Variable Sense Relay) system:

Alternator vs battery capacity
Alternator Size Second battery size
10 Amp 60 AH GRP 22
16 Amp 85 AH GRP 24
25-35 Amp 85-100 AH GRP 27
50-60 Amp 100-130 AH GRP 31
80-90 Amp 130-220 AH GRP 80

I think the Honda system may be the same, but am not an expert on this stuff.

[C-batical]

Hi Bill,

Thank you. This is what I was looking for. I guess I will just have to work around the weak alternaters of the Honda's. Hopefully, they will offer an upgrade kit once the 2008 models are launched.

Best regards,
Rollie/C-Batical

[Not For Hire]

Hi Rollie,

When I redid my electrical I used two dual purpose batteries as my start batteries and a deep cycle battery as my house battery. The house battery has more amp hours than the other two but not a whole lot more (as I recollect). I don't get the chattering but that could also be one of the blessings of bad hearing. After a twenty mile run with both engines at speed when I plug into shore power my battery charger shows the house battery is fully charged but the start batteries almost always show a topping off charge. The VSR switches open to charge the house battery at 13.whatever volts and prevent the start batteries from getting the final finishing charge is my guess. I don't think this is a problem. I don't have a refrigerator so I don't have the current draw you do. I seem to keep up even when trolling for several hours on one engine. I did keep one additional switch in the system so I can parallel one of my start batteries with the house battery if I need to. (The switch system has built in ability to parallel the start batteries).

So if you are not hearing any chattering now I don't see how having a larger house battery would be bad. If you connect a fully drained small house battery with the VSR auto switch or a fully drained large house battery the potential for chattering would still be there, maybe for a shorter period of time. I am impressed with my NAPA brand dual purpose batteries. You could do worse than have three of those if you want them equal.

Mark

[C-batical]

Hi Mark,

Do you recall the specifications of your batteries? I may just upgrade all three since I am on my fifth season.

Also, how was your cruise that I missed? I was thinking of you and following the weather. It appeared that some of the powerfull storms that we had in SE Michigan missed you?

Thanks for the feedback,

Best regards,
Rollie/C-Batical

[thataway]

Cold Cranking Amps have little to do with the capacity of the house battery. CCA relates to the starting capacity. You want batteries which have the capacity to run the items you have on the boat. For a C Dory 22 I would consider at least a 110 amp hour battery--probably two, plus one starting battery. 3 group 31 batteries would fill that bill.

Without going into the complexities of using ACR on dual engines and 3 batteries, (this has been covered well elsewhere), the fact is that you need more capacity. In this case you may be better served to get rid of the ACR's and use switch, or at least bypass the ACR.

I have to disagree that a small alternator needs small batteries. The small batteries only compound the problems of not having enough power. I understand that this relates to the ACR which Honda uses, but you need more batteries in the house bank. I also would use one battery as starting, and use two as house. You can turn down the refigeration (most Norcolds use about 5 amps--not sure on the Ray marine, but do you need the Radar all of the time?--if not use only that part of the RayMarine you need.

[C-batical]

Hi Bob,

Thank you for entering into this discussion. Your advice is well taken and very much appreciated. BEP Marine did get back to me on the ACR modules and indicated that an 80 Ah deep cycle house battery would be acceptable for the twin Honda 40's. I suspect though that they are being very conservative. At this point, I am not ready to rewire the boat to replace the ACR module with manual switches as I am tired of working on it this year and need to use it more. Unfortunately, the weather here has been very unsettled with severe storms moving in weekly.

Thanks again,
Rollie C-Batical