How to completely screw up electrical.

[smackdaddy]

I asked the following question about how to wire batteries for house power using a battery switch in another thread:

Hey tip, I just bought one of those BlueSea battery switches and am planning to wire two batteries up for overnight power. Have you found a good wiring diagram on SN or anywhere else for that?

Anyone else have one?

PS - Nice work on the chainplates dude!

And then somone asked me what kind of switch I had, so this:

It's the BlueSea 6007 that I bought HERE.

It's got 3 posts - and the switch is the Off/1/2/1+2 config. The question I have regards wiring the negative terminals. Do I gang those across the 2 batteries - then go into the buss with single wire? Or what?

This is just a house bank. I have an OB so don't have to worry about a starting battery. I just need extended power for the lights, etc.

This electrical stuff is hard.

(PS - surely there's already a thread for this. I just haven't found it.)

And then I tipped my hand of flaming ignorance when asked why I needed a switch for house power...

Thanks for the advice guys.

The idea was to use the switch to go from one battery to the other as one draws down. For example, I'll use battery A during the day for the instruments, tunage, and margarita machines, then switch to battery B for cabin lights and anchor light at night. That kind of thing. Of course, that may be where I'm wrong.

The switch does have an off position. So it should be good.

And I guess I could use the 1+2 (combined setting) to gang them like Bene said above. Instead of running them single. But then that starts getting into the whole series versus parallel stuff about which I don't have a clue.

Like I said...what do I know about batteries?

And I started get some good feedback - but it started hijacking the original thread.

So I'll bring my impressive display of electrical ignorance here and learn something about batteries if you fellas don't mind...

[smackdaddy]

An reply from bene...

Originally Posted by Bene505

Smack -- Why even use a switch, if it's just for your house bank? Batteries last a lot longer if they are only partially discharged. By switching your house load to one battery, you'll have 1 deeply discharged battery instead of 2 partially discharged batteries. Deep discharge=bad thing to do.

If you have two dissimilar batteries that were bought years apart, then I could see the reasoning. Or if one is Gel and the other Lead Acid, then OK. But if you got the batteries at the same time and they are similar, then return the switch or put it on eBay, and use the money elsewhere.

(If you just bought a battery, thinking you need the switch because you have 1 old battery and 1 new battery, return the switch and get a second new battery instead and recycle the old battery.)

Those switches are pretty much for people that have a house bank and an engine bank, IMHO, not your Smacktanic.

Regards,
Brad

[smackdaddy]

And a follow-up from tap. Thanks guys.

Originally Posted by tap

That's not how you want to do it. The more power you use out of a battery, the harder it is on it. One at a time, you drain battery A half empty and have battery B full. Both at once and battery A and battery B are a quarter empty for the same usage. Your batteries will last a lot longer with the latter method.

You can try to switch back and forth to keep using both batteries equally. But this requires you keep track of your usage and manually switch. Do you have a good idea of how much power one hour of instruments use vs one hour of cabin lights? You're probably not going to split it very well. If you use both at once, and the two batteries are matched, your usage will automatically be split equally between the batteries.

Another thing is that the faster you draw power out of the battery, the less efficient it is. This matters most for high power things, like a blender. If you make one margarita on A and then another on B, it will drain your batteries more than if you made two margaritas using battery A+B.

You would have been fine with just a simpler on-off switch, which would be wired simpler and with less wire, but the switch you have is fine too. Just leave it set to 1+2. If somehow one battery goes bad, then you can set it to use just the other.

[smackdaddy]

Originally Posted by tap

If you make one margarita on A and then another on B, it will drain your batteries more than if you made two margaritas using battery A+B.

Now that's math I can understand.

I'm starting down the road of eventually adding an inline charger, etc. and might even throw in one of those fancy inverters for kicks. Of course, since I don't have a clue how this stuff works, I will try to ask questions BEFORE I purchase.

Thanks for the help dudes.

[tip]

drew this up real quick, hope it helps:

[Capnblu]

Where is the Margarita Tip? How many is your drawing good for? What flavors? Couldn't help myself Smacky hahaha.

[smackdaddy]

You think I'm kidding?!?!



Nostalgia Electrics HSB-590 Margarator Margarita Machine - Stainless Steel | BeverageFactory.com

Ooohhhhhhhhh yeeeaaaaaaaahhhhhh. It's da Margarator....

[jaschrumpf]

For what it's worth, here's the drawing of my battery setup. The benefits of partial-discharge-better-for-battery-longevity aside, I decided to go with the don't-make-it-possible-to-drain-your-starting-battery-with-the-blender setup.

My house circuit draws on only one battery -- my deep-cycle -- while the starting/charging circuit can use the 1/2/both configuration. I'd rather replace a house battery once every four years instead of every three (hypothetically speaking) than forget about my switch setting and have no starting juice when I want it.

[smackdaddy]

Originally Posted by tip

drew this up real quick, hope it helps:

Thanks tip!

[smackdaddy]

Wow Jas - I'm going to have to study that one. One question I have concerns the ground. There is a ground and hot buss - but I'm not sure what the ground buss is grounded to (we don't have an inboard). What should it be grounded to?