Carver Owners Forum

I "like" 3/4 of Vipers last post. I agree with the flooded vs/agm batteries. But I personally do not worry much about dual purpose batteries, especially with newer engines with reduction gear starters, they don't draw what the older engines did, and draw what they draw for a matter of a couple seconds on fuel injected engines vs sometimes 30 plus seconds with multiple tries on older cold carb engines.

That being said (IMHO) if you anchor often for long periods and don't want to run the genny (why not for a bit) to charge batteries, I guess you should divide the banks and use deep cycles for the house.

Just another thought, if you have electric heads, jabsco or especially Raritan, they most likely draw nearly the same amperage as your engine starters, same with the windless. So if you are on house batteries, you are subjecting them to starting duty when you flush!

tomschauer wrote:Source of the post ....I personally do not worry much about dual purpose batteries, especially with newer engines with reduction gear starters, they don't draw what the older engines did, and draw what they draw for a matter of a couple seconds on fuel injected engines vs sometimes 30 plus seconds with multiple tries on older cold carb engines....

One would think so as it seems logical except that the new engines with the more efficient, smaller, reduction gear starters that don't draw as much as their older counterparts along with EFI systems are what precipitated the OEM change in their battery requirement mindset. The recommendations specifically refer to "Start" battery and note minimum "Start" battery specs. This was born out of tech feedback in the field that were experiencing some puzzling anomolies. If you must go with a dual purpose design because of the way your application is wired, technically the best design to go with is AGM as they can handle deep cycle discharges a little better than their flooded counterparts but don't assume/expect to get proportional longevity for this trait and additional expense. The recommendation for Verado outboards is now AGM for a few reasons but based on what I've experienced and heard, it doesn't extend the length of time for battery replacement.

The absolute best way to go is to isolate each system with it's own bank of batteries specifically designed for the systems they are powering and the types of draws those systems will impress on the battery. Ideally this means each engine gets it's own start battery, the generator gets it's own start battery, and the house bank is one or more deep cycle batteries with a means to charge all banks while maintaining isolation and NO battery selection switch. With the addition of more and more electronics these days, some applications are incorporating dedicated deep cycle electronics banks to isolate the electronics from other systems.

A complicated system/topic for sure.

The absolute best way to go is to isolate each system with it's own bank of batteries specifically designed for the systems they are powering and the types of draws those systems will impress on the battery. Ideally this means each engine gets it's own start battery, the generator gets it's own start battery, and the house bank is one or more deep cycle batteries with a means to charge all banks while maintaining isolation and NO battery selection switch. With the addition of more and more electronics these days, some applications are incorporating dedicated deep cycle electronics banks to isolate the electronics from other systems.

After living with this for a few years now I must agree with you. When I got this boat I could not believe there was no way of combining the battery systems mainly because every boat I ever had was set up this way, call it habit if you want. Fast forward to today, it is the best thing since sliced bread. I have a dedicated battery for each engine, one for the generator and a separate dual L16 435AH house bank connected to 300 watts of solar dedicated to the house bank. There are also 2 dedicated batteries, one for bow and the other for stern thruster.

Bottom line is there are no switches to fumble with. I cannot end up with a no start situation because I combined and drew things down or forget to un combine. I think the builders realized there were too many issues going on and decided to make it fool proof hence this type of setup on newer boats. Worse case scenario is lets say a dedicated start battery gets an internal short and becomes useless. Just need to physically exchange it with a thruster battery until I can get it replaced.

Hans, you like tinkering, consider this for a future project if your application doesn't already have it; install an emergency start system that would at the touch of a button on the helm, parallel banks in case one of the start batteries failed. Sky’s the limit here as far as redundancy is concerned, you can even do it for the generator if you wanted to. As long as you use a momentary switch that will re-establish isolation once you let go so there is nothing to remember, it’s the easiest and safest way to get a boost if you will. That, a solenoid and some wiring, is pretty much all you need unless you want to go a more complicated route such as ACRs, etc. If the vessel is wired as I described above and as you touched on, you need a quick way to parallel in an emergency for safety’s sake.

Thanks for the replies! Got tied up finishing the install. The minimum starting amps for the Crusader 6.0 mpi is 650 amps. I bought NAPA AGM commercial with 950 CCA which matches what I had. We tested everything yesterday and it all worked as planned.

So, to recap.
1) We installed 4 6 volt batteries in a box we built above the fresh water tank for the inverter. The inverter is attached to the front of the box which limits the length of the 2 O cable. We used a 2 O cable for the ground.

2) We installed a ProIso 2 alternator 4 battery isolator which charges the old house battery, the two engine start batteries, and the new inverter system.

3) We installed a Victron battery monitor with temp sensor for the inverter bank.

4) We connected the three outlet breakers, the microwave, and the fridge to the inverter. That has the added advantage of moving the fridge to the 4 battery bank with 400 ah from the old house battery (105 ah) when the inverter is running. There is capability to move the ice maker in the future to the bank though we don’t ever use it and am thinking about removing it.