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Old 29-09-2011, 00:38   #1
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Battery Switch Confusing Me

i dont want to damage my alternator by switching from one battery bank to another while the engine is running. So the question i have is can i buy a switch that will not damage the alternator. I read that i can buy a make before break switch. So then i went to west marine and was about to buy a switch that said it had alternator field disconnect protection but then the store employee said that you had to wire it up to the alternator and it was a big pain in the butt. I have an older volvo penta 2 cylinder engine. I just redid my entire dc system and have it set up for 4 batteries. It seems rediculously stupid to shut off my motor to switch battery banks. Please school me!
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Old 29-09-2011, 00:52   #2
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Re: battery switch confusing me?

i just did a little research and again it looks like i need a make before break. THe BIG thing is that i just cant turn the switch to off. See i just dont remember seeing( make before break) anywhere on the package of any of the switches at west marine nor does it say anything on there website.
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Old 29-09-2011, 01:41   #3
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Re: battery switch confusing me?

to make things worse i dont have a place to mount one of those standard type switches that are the only type i have discovered there to be in my late night search. Those types are crappy anyways in my eyes as the terminals are behind the switch that is mounted. So in order to access the terminals one may have to disassemble the mount. then with that type you also have to bend the terminals and this whole thing is so stupid something that should be soooo simple of course is such a pain in the ass
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Old 29-09-2011, 02:47   #4
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Quote:
Originally Posted by albergsailor
to make things worse i dont have a place to mount one of those standard type switches that are the only type i have discovered there to be in my late night search. Those types are crappy anyways in my eyes as the terminals are behind the switch that is mounted. So in order to access the terminals one may have to disassemble the mount. then with that type you also have to bend the terminals and this whole thing is so stupid something that should be soooo simple of course is such a pain in the ass
Can you either describe or upload a basic drawing of what goes where? Where does the alternator output go and why do you wish to switch battery banks? I'm in this same process. SC
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Old 29-09-2011, 02:58   #5
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Wire the alternator directly to the house bank side of the switch. With a breaker or fuse. No worries ever again. Use some other practice to charge the start battery. Lighter. Simpler. Safer.
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Old 29-09-2011, 03:02   #6
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Originally Posted by daddle
Wire the alternator directly to the house bank side of the switch. With a breaker or fuse. No worries ever again. Use some other practice to charge the start battery. Lighter. Simpler. Safer.
Exactly. It has been strongly suggested to use an echo charger or combiner to achieve the start bank charging. SC
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Old 29-09-2011, 04:42   #7
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Re: battery switch confusing me?

Sounds like you have space/connection limitations. However I installed a BlueSeas 8080 (I think that was the part no.) which has separate small switch for the start batt... and Echo charge to charge that batt and the Blue Seas has a 100amp breaker for the house bank *switch* AND a way to combine house and start banks... so there is no alternator disconnect unless you turn the swtiches off... Why would you do that?

With this system my start batt.. an Optima 55AH batt is always 100% topped up... it only cranks the starter... and is *trickled* charged 24/7.

All charging sources... such as the alternator are connected to the house bank as are all other loads.

The one-two-both switches are outdated for the most part because you need a small batt for starting and a large one for loads. With the start batt always topped up...even if you drain the house... you can start the engine and recharge the house bank.
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Old 29-09-2011, 05:07   #8
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Re: battery switch confusing me?

Quote:
Originally Posted by albergsailor View Post
to make things worse i dont have a place to mount one of those standard type switches that are the only type i have discovered there to be in my late night search. Those types are crappy anyways in my eyes as the terminals are behind the switch that is mounted. So in order to access the terminals one may have to disassemble the mount. then with that type you also have to bend the terminals and this whole thing is so stupid something that should be soooo simple of course is such a pain in the ass

Best thing I ever did with my old boat in which I circumnavigated was increase the battery bank size, install a high output alt with smart ext reg
set the battery switch to both and never touched the battery switch again, ever! Fridge cycled continuously, motor started without hesitation & everything electrical functioned and never an issue with..... should I switch over now or later!
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Old 29-09-2011, 05:55   #9
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Re: battery switch confusing me?

We may not be answering the OP's question. He said he'd just redone the 12V system, and had it set up for four batteries. He also mentioned "two banks".

Question: How is your 1-2-Both-Off switch wired now? Why do you need to switch from 1 to 2?

If you have two (house batteries) in one bank wired to one position on the switch, and you have two other (house batteries) in another bank wired to the second position on the switch, then the solution is easy: just switch to the "Both" position and leave it there. It's good practice to run just ONE large battery bank, rather than two smaller ones. "Good" for both electrical and psychological reasons.

This topic has been discussed ad nauseum on this and other Boards. Bottom line:

1. Wire your house batteries together and treat them as a single bank;

2. If you have a separate start battery, use an EchoCharge or DuoCharge to maintain the start battery, automatically;

3. Connect all onboard charging sources -- alternator, battery charger, DC generator, solar panels, wind generator, etc. -- directly to the house battery bank;

4. Be sure you have appropriate fuses in the right places; and

5. Never worry about switch positions or charging again.

Bill
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Old 29-09-2011, 12:56   #10
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Re: battery switch confusing me?

so using a echo or duo charger is the way to go then. That does sound quite alot easier and better. sorry for not specifying. What i had planned on doing was having 2 deep cells on one bank and 2 high cca starting batteries on another. Having a normal switch appealed to me in that it just seemed more reliable then some type of solenoid or the like that automaticly monitered the batteries. I will check out the echocharge or duocharge but im still upset that this has been such an issue to just find a decent on/off switch that specified make before break. The product that defjef uses seems pretty nice. thanks so much for all the advice i will be looking into everything and i will let you know how it all turns out
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Old 29-09-2011, 14:06   #11
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Re: battery switch confusing me?

A book I have found helpful has been by Nigel Calder:
Boat Owners Mechanical and Electrical Manual: How to Maintain, Repair and Improve Your Boat's Essential Systems.

I checked it out from my local library to look it over and really find it helpful. I use a number of sources but this helps me figure out what the thinking is. Don Casey is another author I like. I'm sure there are more but I like to read something written to what I can understand.

Hope this helps ! BTW look at a combiner too. I don't know if it would help you but that is what was installed on my new to me boat. It's from West Marine.

SC
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Old 29-09-2011, 15:42   #12
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Re: battery switch confusing me?

Quote:
Originally Posted by albergsailor View Post
so using a echo or duo charger is the way to go then. That does sound quite alot easier and better. sorry for not specifying. What i had planned on doing was having 2 deep cells on one bank and 2 high cca starting batteries on another. Having a normal switch appealed to me in that it just seemed more reliable then some type of solenoid or the like that automaticly monitered the batteries. I will check out the echocharge or duocharge but im still upset that this has been such an issue to just find a decent on/off switch that specified make before break. The product that defjef uses seems pretty nice. thanks so much for all the advice i will be looking into everything and i will let you know how it all turns out
Let's take these in turn.

1. EchoCharge or DuoCharge. These are voltage follower devices. They are not combiners and they are not relays and they are not isolators. What they do is sit between the house and starting battery banks and, whenever they sense a charging voltage (i.e., about 13VDC or above) on the house batteries, they bleed off some amperage to top up the start battery. The EchoCharge can handle up to 15A. The DuoCharge can handle up to 30A and is programmable. For most installations, the EchoCharge is more than enough. When you start your engine, you typically only draw less than one amp-hour from the start battery (lots of amps, but only for a few seconds). That energy is replaced in a very short time.

2. Battery bank configuration. Normally, it does not make much sense to have more than one start battery. You're just wasting space and $$$. You can hook up your system so that in the event of a start battery failure you can simply use the house batteries to start. Much better to use the space for an additional house battery, in many cases.

3. Battery types. Yes, by all means you want true deep cycle batteries -- not "dual purpose" -- for the house bank. 6V golf-cart size batteries in series are often the best choice for a house bank, as these have thicker plates and handle the deep cycling better and longer than do comparably-sized 12-volt batteries. And, you do want a true starting battery for the engine. On most boats a group 27 is plenty, or a group 31 if you want a bit of overkill. Flooded batteries are by far the best price-point. AGMs have their place, but have significant problems, too (you've got to be sure they're fully charged at least once every week or two). Also, several users have reported catastrophic failure of AGMs. Gelled batteries are often a very good choice, though pricier than either flooded or AGMs. In particular, they're good for boats kept on a mooring, and those in weekend-mostly operation. They are very long lived, compared to both flooded and AGMs.

4. Make-before-break battery switches. They're easy to find. However, IMHO it's not a good idea to trust them to protect your alternator, since an inadvertent switch to the OFF position -- and in the absence of a separate wire to the alternator field -- could wipe out your alternator's diodes instantaneously. In any case, if you wire the DC system correctly this is a moot point, since; (1) the alternator output never goes thru the switch; and (2) there's no need to switch anything anyway, since the EchoCharge or DuoCharge handle things nicely and automatically.

Again, IMHO, these devices are to be preferred to battery isolators and charge combiners, relays, etc., since they do not directly interconnect battery banks which may be of very different capacities (e.g., a large battery bank and a small start battery) and at very different state of charge levels (which could result in high inrush currents and, possibly, to the near depletion of a fully-charged smaller battery into the much lesser charged house batteries.

Bill
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Old 29-09-2011, 16:23   #13
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Re: battery switch confusing me?

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Originally Posted by btrayfors View Post
Again, IMHO, these devices are to be preferred to battery isolators and charge combiners, relays, etc., since they do not directly interconnect battery banks which may be of very different capacities (e.g., a large battery bank and a small start battery) and at very different state of charge levels (which could result in high inrush currents and, possibly, to the near depletion of a fully-charged smaller battery into the much lesser charged house batteries.

Bill
It should be noted that only a key-on/activated type of solenoid or relay can do this.

The VSR or voltage sensitive relays like the Blue Seas ACR or the Yandina combiners will break or open once the voltage drops below the VSR's set point, which is usually around 13.2v. You can not deplete a start battery while at the same time having it's voltage maintained above 13.2v.

While you can get some in-rush, while above 13.2v, it is usually short in duration due to the voltages eventually reaching an equilibrium. As the voltages get closer and closer together less and less amperage moves between banks.

With some older models you could get relay cycling if the alternator was connected to the wrong bank and you can still get this even with some newer ones if you install them incorrectly.

Like an Echo Charger the Blue Seas ACR's or the Yandina's or others should ideally have the alt fed to the house bank, especially if that bank is 2X the size of the starting bank or more. If you don't you will "cycle" the relay. This means every time the relay closes or makes the house bank sucks the voltage on the start bank back below 13.2V and opens the relay. It is a slow way to get current into the house bank especially if you have solar or wind and they are also fed to the wrong bank..

Sadly I see this quite often with the Blue Seas Dual Circuit Plus battery switch, just fixed one last week. Usually the DIY or installer does not understand how the system should be wired to work best and they simply leave the alternator output on the starter lug....

Both ACR's and Echo Chargers are excellent and reliable devices.
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Old 29-09-2011, 22:59   #14
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Re: Battery Switch Confusing Me

i did a little bit of googling and seems like i want a 1 2 both switch with the charge current going directly to the house bank. then to charge the start battery with an echo charge or acr. acr seems a little expensive but probably better. I typed in echo charger on the west marine website and i get xantrax echo charger. By the way they describe this product it seems more of something to be used with a battery charger. So is this what i need? Why does everything have to be such a goosechase?
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Old 30-09-2011, 00:20   #15
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Re: Battery Switch Confusing Me

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Originally Posted by albergsailor View Post
i did a little bit of googling and seems like i want a 1 2 both switch with the charge current going directly to the house bank. then to charge the start battery with an echo charge or acr. acr seems a little expensive but probably better. I typed in echo charger on the west marine website and i get xantrax echo charger. By the way they describe this product it seems more of something to be used with a battery charger. So is this what i need? Why does everything have to be such a goosechase?
You can check if your existing switch is make-before-break easily.

Turn on the cabin lights, and with the engine off, slowly move the switch from 1 to 2 and back. If the lights do not momentarily go out, the switch is make-before-break.
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