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Hooking up alternator output to house battery

semperfih2o

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"Hi, I'm a newby here and

"Hi, I'm a newby here and need your help.
I re-powered my Chris Connie 41 with 5.7 mpi crusaders. I run the boat slow, it's old, and am very happy with the performance. I replaced the 427 fords and after playing with props my flowscan says im using 8 gal/hr combined at 9kts.@1900 RPM using 21X24 4 blades.
Now my problem, the installer didn't hook up either engine to the house 8D for charging it.Can I just hook up one of the port or starboard starting batts to it in parallel? If so, will I need an isolator between them?"
 
I would put in an isolater wit

I would put in an isolater with multipal battery hookups. It is what we did with the boat I use at work. The genset battery was not getting charged up so we put the isolater in to charge the three batterys as needed. It works very well for us.
 
I'm with Paul on this - us

I'm with Paul on this - use an isolator.

The only exception is when your 8D and your starting batteries are made with differing technologies - say one is traditional wet cell and one is an AGM type. Things get complicated and the solution varies by the mix.

You may want to consider one with dual inputs and outputs so either engine may charge the house battery...may save you aggrevation if you do a lot of cruising.
 
"Thanks for the info. My start

"Thanks for the info. My starting batts are 2 6volt golf cart wet cells for each engine in series and my 8d is also a wet cell;no different technology here. At this time the port alternator charges port side, starboard the other.
Thanks again for helping out an old Marine.
Semper Fi, Robert"
 
"First of all, thank you for s

"First of all, thank you for serving our country, Robert.

I've finally come to understand--took me 5 years (what a dolt!)--that the port battery on my boat has only one job: starting the engine. All it needs is a trickle charger, and that's all it's gonna get.

The starboard batteries (3 of them) are house batteries that run the inverter, lights, bilge pumps, etc. They need a good, modern charger with enough amps to keep them UP. (It took me 5 years to figure all that out!)

So.... Bought a rebuilt, factory guaranteed, two bank charger over the winter and will be installing it on the house side, one bank for one battery, the other bank the other two batteries(with the Perko switch left in position #1 or 2--not BOTH). No isolator required this way.

Hope that helps.

Jeff"
 
"Thanks Jeff,
I'm using a


"Thanks Jeff,
I'm using a Pro Mariner triple bank 50 amp marine charger which is hooked up to the engine starting batts and to my house batt. This is how I discovered that the 8D wasn't being charged by the engine alternator. When I would return to the boat house, the batt charger would run for a long time charging the house batt. With no input I measured 12.45 volts on the 8D and it remained the same with either engine running.Turning on the charger brought the reading to 14.2 volts, showing that it was being charged. I'm going to purchase a two bank isolator which will allow me to charge the 8D from one of my mains.
Thanks again all, you folks are a valuable resource.
Celer, silens, mortalis.
(But now the old....)
Semper Fi, Robert"
 
"I run two big Red Surrettes f

"I run two big Red Surrettes for the house. They are charged, while in cruise, by the Port Engine Alternator...the 350 engine alternator was changed for a 125 amp alternator. The two starting batteries are charged by the Alternator from the Starboard Engine.

If I use the Westerbeke Genset then I can select a CHARLES 3 bank 60 amp charger to charge everything. If I use shore power the same thing applies.

The fun will begin next year when I install two thrusters...each requiring 24V !!!! Looks like I will add another 4 12V batteries!!"
 
"Don,

I have 3 group 31 ge


"Don,

I have 3 group 31 gel cells that power our inverter. Placing them all on one side outweighed the genset and the boat leans to starboard from the extra weight..Total of 7"
 
"Hi Al,
I guess I am lucky. M


"Hi Al,
I guess I am lucky. My two Big Reds sit midships, just infront of the Genset. The total weight of the two is just under 400lbs (wet). The starter batteries sit outboard of each engine. The two stern thruster batteries will sit midships, between the genset and the Big Reds as there is just enough room for them.
The bow thruster batteries will be on the port side about 24 inches left of midships, just to the left of the anchor chain locker,,,,,
Total batteries next year = 8...and so far no listing !!!!
biggrin.gif
"
 
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