Mahe 36: Batteries And 12vdc Systems

[Oliver66]

Originally Posted by DotDun

I learned something today....

Me too !!!

thanks Jef !for your explanation !

I'm also ok with only 300w solar panel... when mooring the only use of the engine is to make hot water...

[Seastream]

I went thru all posts on this thread before posting and still have this Q:
My boat is a 2008, hull 91. If the battery banks are tied together (with the emergency start/combiner switches) AND both engines are running, then will either/both alternators be damaged or has FP/Volvo provided isolation between the alternator outputs so that both alternators can be used to charge the batts faster?

Regards, Bob

[Cotemar]

Originally Posted by Seastream

I went thru all posts on this thread before posting and still have this Q:
My boat is a 2008, hull 91. If the battery banks are tied together (with the emergency start/combiner switches) AND both engines are running, then will either/both alternators be damaged or has FP/Volvo provided isolation between the alternator outputs so that both alternators can be used to charge the batts faster?

Regards, Bob

Do not know for sure, as I have never done it and have not heard anyone else doing it.
Each alternator puts out 115 amps. The batteries charge really fast on one 115 amp alternator.

[Jef & Marin, Netherlands]

There is no isolation, the 2 alternators will be connected to both battery banks, everything in parallel.
To my opinion nothing will be damaged by this.
Due to alternator voltage tolerances and cable length difference, the alternators will deliver a different current. Seeing cable length, in general the port alternator will deliver more.

But there is no sense in starting both engines with the switch connected. Generally you'll see 80 amps or so running into the house battery. After a few minitus this decreases to maybe 50 A. So there is no sense in having both engines running, a single alternator will already supply more than the house battery accepts.

That it does no harm us supported by the following:
Imagine your house battery is flat. You'll start your starboard engine; then connect the emergency switch; then you can start the port engine, with the starboard still running. That brings you in the same situation.

By accident, in the lifetime of our ship, I have already done a few hours with the switch connected. No harm done.

[Seastream]

Thanks, all. We're bringing our boat from Tortola to Boston via Bermuda in May. Figuring 2-3 weeks for the trip. What with running 24X7 and all the required electronics running I figured the power budget might be tight. I want to charge the batts quickly, to minimize engine runtimes. This boat has no other charging source. I'll fix that (and other items) once she's at her new home.

[Cotemar]

Seastream,
Your first land fall from Bermuda should be Block Island R.I
We go in the water on April 1st, so we will be in the area of Block Island R.I.
Would be nice to hook up with you on your way by, before you hit the Cape Cod Canal.

[1rkghost]

Ready to replace lead acid batteries they are to hard to maintain. Does anyone have agms and what brand size do you recommend

[Cotemar]

May want to go with LiFePO4 batteries.
They will most likely last longer than you own the boat.
They weight 1/2 the weight of lead acid batteries

http://www.balqon.com/store.php#!/~/product/category=4388904&id=18852825

http://www.cruisersforum.com/forums/...65069-160.html

[oranaman]

[QUOTE=Cotemar;1187772]May want to go with LiFePO4 batteries.
They will most likely last longer than you own the boat.
They weight 1/2 the weight of lead acid batteries

http://www.balqon.com/store.php#!/~/product/category=4388904&id=18852825

I was going to say haven't you forgotten one small point? - the cost.
Then I followed the link and found our friends in the US now only pay 4.5 times the cost of Pb batteries for LiFePO4 batteries. Last time I looked in Europe it was 8 or 9 x.

[Cotemar]

Three of the LiFePO4 12 volt batteries equal 270AH at 99 lbs is equal to 540Ah lead acid batteries at 195lbs

More power, less weight in the same space

[1rkghost]

Any one consider putting an access panel behind aft berth to monitor and service batteries?

[1rkghost]

Does anyone have a xantrex inverter charger

[foggysail]

Yeah, I own one of those #$%*&^

[spiv]

Originally Posted by Cotemar

Seastream,
Your first land fall from Bermuda should be Block Island R.I
We go in the water on April 1st, so we will be in the area of Block Island R.I.
Would be nice to hook up with you on your way by, before you hit the Cape Cod Canal.

Where is that mate?
I am in Antigua going to Florida, would be nice to catch up for a glass of wine and a chat.

[1rkghost]

My xantrrx kicked bucket any suggestions on a replacement