small cabin light drained battery while on shore power?

Stu Jackson · Sep 8, 2010

Electrical system

Don't go near the ProMariner, they have a horrible reputation, well deserved. Read this: http://c34.org/bbs/index.php/topic,5179.0.html Please, read the links in my first reply on that topic. And I don't think Terry's conclusion that lightning was his problem is the right answer. Their equipment s*cks.

It's simple, and I think you got it

1. Employ what MS and I promoted on the link in the C310 Forum on this mb earlier. It also answers your question about combiners and echo chargers. Please, please, please, read and reread the links we already have given you (#35 page 2 above). Please...

2. Buy a good charger with equalization. Your old one is inadequate and toast.

3. Do what Ample Power suggests.

4. Draw a wiring diagram for your boat. The simplest wiring diagram that reflects what MS & I have been saying is this one, Reply #12, here: http://c34.org/bbs/index.php/topic,4949.0.html

5. Buy a battery monitor - Victron is a good one (like MS already said), do a search on this board. Xantrex Link Lite and Link Pro are good, too. What goes back in is less than what comes out, so you can't do the energy budget backwards. Do a search on "acceptance" and learn.

Why not print all this stuff out and have time to read it leisurely instead of online?

Stu Jackson · Sep 9, 2010

Clark said:
L
2) Monitors are important if you have a large bank and cruise for days at a time. They give you good info as to how much energy goes into a battery and how much you take out. Voltmeters by themselves won't do that. If you are a day sailor or typically only spend 1 or 2 nights away from a dock, they may be a bit overkill.
Hope this helps.

Not necessarily true. The reason is that two things kill batteries: undercharging & overcharging. Most folks have no clue about battery acceptance, which simply means that as the bank gets fuller, it accepts less charge. Sometimes it could take all night to fill the last 20% and can only be done from shorepower. So if you don't plug in all the time when you're away from your boat (and there are compelling reasons to not do so - like a fire) then you will leave your batteries regularly undercharged and kill them.

Those of us who have been doing this for a while continue to recommend that the very best bang for your buck, even before a higher output alternator, is to buy a simple battery monitor so you can understand what's happening to your charging systems and your house bank.

Stu Jackson · Sep 11, 2010

Good job, Jonny

1. Correct the numbering between the banks and switch. Make the house (NOT Primary) bank #1.

2. With the echo charger you don't need to feed the charger to both banks. Just go to the house bank.

3. Clearly indicate that your house bank is two six volt batteries - they are NOT a bank 1 and 2, as you've noted correctly, they are simply two batteries that make up the house bank. A bank is one or more batteries hooked together. Just for clarity, consider calling them house bank battery A and B, rather than 1 & 2 to avoid confusion with the numbering of your two banks, and call your reserve bank bank 2. I've looked at your diagram a few times and understand what you're doing, but it's confusing things along with the switch numbering. Reserve is Bank 2 (you don't have to # the battery), House Bank is bank #1, battery A and B. Just the engineer in me...

Re:

Stu

Click to expand

, could you elaborate a bit more for me here? If my 55amp is currently wired to the switch and then from there to the batteries, how does moving the alternator wiring directly to the primary battery which then feeds back to the selector switch change anything other than direction of flow? (ref: http://c34.org/bbs/index.php/topic,4949.0.html reply # 11)

In your case, it doesn't, just the different ends of the same wire. But, you've shown it correctly. Reason is that IF you had a HIGH OUTPUT alternator, you could be putting out 50A from a 100A alternator and the OEM wiring COULD be too small for that 50A load from alternator to switch to house bank. Think about it: your distribution panel will NEVER be pulling even 30A even if everything you have on it is turned on at the same time - batteries to switch to DP. But, with an alternator output from a HIGH output alternator, the current could get real high in that wire IF it stayed on the switch. Plus, you want to get it AO to house bank anyway, not AO to switch (regardless of C or 1 on the switch).

With your 55 A alternator, all you'll see would be about half of that amperage, plus the acceptance of your 225 ah bank would limit it anyway.

Still, go AO to house bank as you've shown.

Don't worry about the location of the reserve bank, just size the wire properly. You will most likely get a lot of "You should relocate the reserve bank closer or closest to the engine." Hogwash.

Only other thing: consider a circuit breaker or switch on the AO to the house bank, just in case. It's easier than trying to unscrew a nut on a fuse IF something goes haywire.

Don't forget to fuse at the battery banks.

You have TRULY done your homework.

Good for you, well done.

Maine Sail · Sep 13, 2010

In 2005 I purchased a brand new 31 foot Catalina. Because ABYC only requires a fuse on the house bank builders only supply ONE fuse. My system from the factory was two identical 4D batteries to a 1/2/BOTH/OFF switch, which one is house? Either bank could have been considered the house bank or start for that matter.

Before commissioning the vessel I installed a second ANL fuse on the second bank. Seven weeks later I blew the 200 amp fuse.:cussing: The factory had cut the wire for the starter just a tad to short and with the motor loaded in forward it chafed through in a dead short causing a nice burn to the motor mount and a blown 200 amp ANL fuse. The wire was on a side of the engine that was nearly impossible to see and if felt by fingers, which I had during survey, seemed to have plenty of clearance but diesel engines vibrate and move some on soft mounts and chafe happens. I feel fuses are VERY important.

If I had not had that fuse I am fairly confident that would have had a serious boat fire possibly totaling a brand new vessel.

Just three weeks ago we lost one of our junior sailing program Boston Whalers when a short burned the boat to the waterline. We came close to loosing a whole dock full of other boats during the fire. A simple fuse would have stopped this. The club is planning on installing battery fuses on all of our vessels before next spring.

A $30.00 fuse would have probably saved this Boston Whaler:

If installing a fuse it should be first sized for the wire and also to the AIC (Amperes Interrupt Current) for what the battery or bank can supply based on CCA rating of the bank. I actually prefer to use the MCA as most boats are used in warmer temps and batteries can supply more current when warm. ABYC standards want the fuse within 7" of the battery, based on conductor length, but this is sometimes impossible so get it as close as you can.

I fuse my; alternator, battery charger, inverter, house bank & start bank. All are fused within 9" (conductor length) of the battery. Using Blue Seas MRBF fuses gets you within zero inches..

If your wire can't take say a 250 amp fuse then you'll need to go smaller and size to the max current carrying capability of the wire. I prefer to size to 100% of current carrying capability but in certain instances 150% is okay.

The AIC rating is the amount of current your batteries could supply if shorted. I know my house bank can supply 3000 cranking amps at 65 -70 degrees therefore I use ANL fuses which have a 6000 AIC interrupt rating. This means you would need 6000 amps to "jump" across the fuse in the event of a short. With an AIC fuse that is lower than the bank can supply you could literally blow the fuse but current may still be "jumping" and continue to flow, which could be dangerous.

Keep in mind that many fuses, such as ANL fuses, can far exceed their "rating" for short durations before blowing. A 200 A ANL can do about 5 seconds at 200% of it's rating and up to 500 seconds at about 150% of its rating. ANL (LINK)

Most of the time for battery large banks you'll want fuses with a 5000 AIC or more depending upon the CCA of the entire bank. For a start battery a 5000 AIC may not be necessary.

This is a good chart to show various AIC ratings:

I like the Blue Seas MRBF's. They are easy and quick and reasonably priced if you have the height to install them. I've been fusing start batteries on diesels to about 250 HP for a number of years and never once had an issue with them blowing pre-maturely. The only fuse I have ever blown was the chafe to a dead short above which is just when I want the fuse to blow.

On engines that are to large for a fuse I would run the start cabling in conduit the entire length, which is another good option, but your engine is not to big to fuse.

In short electrical boat fires happen and I have seen chafed battery cables on a number of occasions. The potential outcome of this, as seen above, can be devastating.

Starting a small sailboat aux really does not take as much as folks assume it does..

What Happens When I Start My Engine (VIDEO LINK)

So size to:

1) Wire capacity

2) AIC

kenn · Sep 14, 2010

On our small sailboat, the battery is not used for starting and the loads are low, so I've put a 50 A automotive style thermal breaker right by the battery to protect the battery wiring.

The wiring and panel are new this year. When I work up the nerve, I'm going to test this breaker out, as well as the individual breakers in my DC panel.

The biggest electrical hazard on our boat is me with an adjustable wrench.

small cabin light drained battery while on shore power?

Stu Jackson

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JonnyQuest

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Stu Jackson

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JonnyQuest

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