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Old 23-10-2012, 18:04   #1
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Very Overwhelmed

Hey everyone,

My head is spinning from the suggestions i have recieved. My question is should I use a battery combiner or echo-charge to charge my two battery banks? I have 3 125 solar panels with a controller, I have a wind gen. with no controller, I have two battery banks with two 8ds in both and a simple 1,2 both switch. My plan is to alternate weekly from bank to bank for my house while the other bank for start. Any simple clarification is apprec. Thanks in advance Randy
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Old 23-10-2012, 18:11   #2
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Re: very overwhelmed

It depends on how you are using your battery banks. If one bank is used to start your engine then you definitely want a battery combiner so you never find yourself with two dead banks of batteries where you cannot get your engine started. Solar power charging alone could take far too long to provide enough power to charge up your engine start battery enough to start your engine.

One idea is to add a third dedicated start battery. It could be a 4-D or a Group 27, depending on the minimum sized start battery (minimum cranking amps) that your engine manufacturer recommends. Doing this would double the stored energy of your house system. You would no longer have any reason to alternate your two 8-D's. For smaller marine engines (under a few hundred horsepower) an 8-D is overkill as a start battery. You might as well put your two 8-D's to better use, both as house batteries and save yourself the hassle of charging your house battery bank as often.
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Old 23-10-2012, 18:14   #3
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Re: very overwhelmed

Is your wind generator self-regulating, such as the Air Breeze? If so, don't run it through a controller, because when the controller tries to shut it down it will freewheel.
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Old 23-10-2012, 18:19   #4
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Re: very overwhelmed

A one-two-both switch doesn't designate one bank for house and the other for the starter. It just decides which bank(s) you're running off. If you select for Bank 1, Bank 2 is off.

You might get more info by giving more info. Is this a sailboat? Are you living aboard? Is it moored or....?
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Old 23-10-2012, 18:27   #5
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Re: very overwhelmed

Thanks for the quick replys, My wind gen is a kiss and they do not feel the need for a contriller and I never leave unattended unless I am very confident with weather conditions. My logic with the two 8ds in each bank was that I could get tons of starting power but also alternate them weekly to get longer life?
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Old 23-10-2012, 18:31   #6
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Re: very overwhelmed

It's not worth the possible additional battery life to risk not being able to get your engine started.

Get a controller so you don't risk your wind vane destroying your batteries and your marine electronics. I think it is a false economy not to get one. Too much is at risk. With a controller you can also walk away and have peace of mind that you are not cooking anything.
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Old 23-10-2012, 18:33   #7
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Re: very overwhelmed

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Thanks for the quick replys, My wind gen is a kiss and they do not feel the need for a contriller and I never leave unattended unless I am very confident with weather conditions. My logic with the two 8ds in each bank was that I could get tons of starting power but also alternate them weekly to get longer life?
Again, I can't give an opinion about whether your system is adequate unless I know more about the boat and its uses.

The system you describe would not be adequate for my use.
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Old 23-10-2012, 18:39   #8
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Re: very overwhelmed

Very simply, I think the best system features a dedicated starting battery that does nothing else but start the engine, and then a much larger house bank that gets the feed from every charging source. The starting battery can be recharged the small amount it loses by connecting it to the house bank with either a combiner, an echo charge, or you can go the cheap route like I did and use a Trik L Start. For you, combine the 8Ds into a house bank, get a dedicated starting battery. I used a wind generator for more than a decade without a controller--just keep an eye on things and don't leave it running when you are away from the boat for long periods of time.
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Old 23-10-2012, 18:40   #9
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Re: very overwhelmed

I am living on a 37 ft sail. my consumption by todays standards are minimal. I have a 3 cubic ft frige, all leds and I may watch movies and play music. We will be traveling in the Bahamas soon. Im sure I am over kill on my batts and solar, Does this shed more light
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Old 23-10-2012, 20:04   #10
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Re: very overwhelmed

So you have 2 8D's per side??? Seems like more then enough. I just have two Group 27's per bank (I can just lift a G27) and don't have a separate start battery.

I have the solar connected to my DC panel Buss which connects to the battery switch with a short bit of #2 I believe. I just use the battery switch to charge which every battery i'm using. Plus may switch over to the opposite bank half way thru the day if needed. Simple is good... Been working for me for years...
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Old 23-10-2012, 21:13   #11
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Re: very overwhelmed

i have a similar boat, similar power draw, same destination (bahamas cruising). i have fewer batteries, fewer solar panels, and no windcharger. you have far more than you will need for your circumstances.

keep it simple. get the battery combiner. easy to install and mostly foolproof. you don't want to be anchored at double breasted cay trying to understand what went wrong with your electrical system....
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Old 23-10-2012, 22:16   #12
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Re: very overwhelmed

Here I go doing the contra thingy. OK, the echo charge is designed to be used with a dedicated start battery. You have two banks of house batteries. Looking at the echo charge installaion instructions, there is a voltage drop to the start battery side. That's what you don't want with solar at all. There is more of a voltage drop with the echo charger then there is with a battery combiner

Same thing applies to the voltage combiner, there is a 0.5V drop across each diode. If your solar charge controller is putting out 14.4 volts your batteries only see 13.9. Thats ok for a start battery but not so nice for a second house bank your trying to get back to full charge.

Now me. I would wire the hot from the solar charge controller and the wind genny to the common lugs a 20 amp 2 pole single throw switch. with the opposite ends to each battery bank. That way you can charge either bank at any time.

Gee sometimes when the suns shining and the batteries are at the same SOC I just put the battery switch to both and let it go.

I personally don't think an echo charger or a battery combiner works all that well with solar. It works fine for an alternator where the sense wire is wired down stream of the combiner so it neutralizes the voltage drop. Not so hot for solar or wind. An echo charger is not designed to be used with two house banks which is what the OP has.
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Old 23-10-2012, 22:24   #13
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Re: very overwhelmed

Quote:
Originally Posted by bamboo View Post
I am living on a 37 ft sail. my consumption by todays standards are minimal. I have a 3 cubic ft frige, all leds and I may watch movies and play music. We will be traveling in the Bahamas soon. Im sure I am over kill on my batts and solar, Does this shed more light
Yes, you are "over kill." Four 8Ds on a 37' sailboat with minimal consumption is excessive, especially on a boat with 375 watts of solar. You say you are living aboard? How low below the boat's original waterline does she sit now? Can she sail at all?

My guess is that your real problem isn't power; it's weight. Trade two of those 8Ds in on a group 27 starting battery. Switch the 1/2/both switch out for a proper combiner. Trade all those movies you've already watched for a Kindle or Nook, and teach yourself the lost art of reading.

Freedom, my friend, is realizing you don't need 720 AH of battery capacity on a 37' boat.
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Old 24-10-2012, 01:58   #14
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Re: very overwhelmed

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............My logic with the two 8ds in each bank was that I could get tons of starting power but also alternate them weekly to get longer life?
Two service banks is not logical. One larger bank and a very small AGM starter battery delivering very high CCA will be a much better option. They are so small they can go almost anywhere, even lying on their side under the floor.

Doubling your service bank size means the life cycle is longer as you are not likely to allow your State of Charge to fall so close to 50%.

Doubling your service bank size also means more than doubling the time needed between re-charging. (worst case scenario - no sun no wind and you have to run your engine). Peukerts law says that the apparent Ah size of your bank is larger if your current draw is lower than the designed rate for your bank. The a 20 hour rate means your bank is designed for a draw that will flatten the battery in 20 hours, so 720/20 = 36 amps. If you use on average 5-10 amps then your "apparent" bank size is larger than 720 Ah. Conversely, which most people probably realize, is that if you were to take 100 amps to run inverters etc for a long period then Peukerts law says your "apparent" bank size is much less than 720Ah. Its a logarithmic equation so I can't do the maths! So a bigger bank is much better if you have the space for it.

You haven't said how you use your boat, but if its all electric or a high user of amps then it sounds like a very good setup.

We have a DuoGen and the manufacturer's advice is not to use a wind regulator when also using a solar regulator, just tie it off when leaving the boat.

Back to the OPs original question if you go for an expensive small AGM starter battery and one 720 Ah Service bank then go for a Balmar multi-stage dc-dc charger. The EchoCharge is only a voltage follower, with a slight voltage drop, so it means your starter battery, which will charge very quickly, could be sitting at around 14 volts for a very long time whilst your large house bank is being charged. Batteries should drop down to 13.8 volts or less in "float" mode when fully charged to avoid gassing. See Odyssey batteries warranty!
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Old 24-10-2012, 02:11   #15
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Re: Very Overwhelmed

Quote:
Originally Posted by bamboo View Post
Hey everyone,

My head is spinning from the suggestions i have recieved. My question is should I use a battery combiner or echo-charge to charge my two battery banks? I have 3 125 solar panels with a controller, I have a wind gen. with no controller, I have two battery banks with two 8ds in both and a simple 1,2 both switch. My plan is to alternate weekly from bank to bank for my house while the other bank for start. Any simple clarification is apprec. Thanks in advance Randy
Right. As others have said, there is no reason in the world to alternate between two house banks. You want one house bank (the bigger the better, but don't overload the boat), and one start battery. It is crazy to use two 8d's as a start battery -- that's extreme overkill and besides that, deep discharge batts are not made for starting. For that, you want an automotive (or truck) type start battery.

Sounds like you have plenty of solar so surely on a boat that size you should be fine with two 8d's -- I'd sell the other two and buy a truck battery to start the main engine. I wouldn't bother with a combiner; just keep jumper cables on board in case you ever need to start the engine with the house batts. An echo charger is a good way to keep the start battery up -- better (really, a lot better, but a lot more trouble) is separate alternators -- big truck type 3-stage regulated alternator for the house bank, and a regular alternator for the start batt.

If you never use the start batt for anything but starting, and it has its own alternator, you don't really need to connect it to your solar and wind, so you don't need an echo charger.
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