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Old 10-04-2012, 12:01 PM
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Default 12v/24v manual series parallel switch??

Ok, this may be a little over my head, however i have some electronics background so here it goes.... Right now i have three batteries in my boat. one hooked to #1 on the switch for starting, two hooked to #2 in parallel for my radio/gps/etc... I also have a 24v trolling motor that when i want to use i have to manually move wires around to achieve my 24v system from my parallel batteries making them series. Is there a manual switch that will do this for me so that i can switch back and forth? that way as i motor to a new spot i can switch it to parallel for charging purposes?
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Old 10-04-2012, 06:38 PM
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how are you running the 12v stuff after making your 2 batterys into 24v? tapped in the middle?

there is no correct way to do this...

if the batterys only purpose was to provide 24v to the troller, then switch back to 12v to allow charging there are relays that will do this. but having the other 12v stuff on is bad.

I would get 2 more batterys for the troller and leave the existing stuff alone.
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Old 10-05-2012, 06:11 AM
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It's only a matter of switching a few wire. as far as my accessories go they are actually wired to my switch so as long as i switch it to #1 battery they will run off of that. then another switch to go from 12v/24v. if they can make a power switch to momentarily do this why can't they make a manual one? You say there are relays? how would i do it?
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Old 10-05-2012, 06:15 AM
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P.S. i don't troll very much, but i want a simple option for when i want or need to. I don't see paying another $300.00 plus for a couple brand new batteries that will likely go bad from age before wear... not to mention i don't really have the room for them and i like the idea of being able to switch back to parallel to recharge. my boat can not be stored at my house due to asshole neighbors and charging a battery is difficult.... hell an hr after my boat hits my driveway i have code enforcement driving by....
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Old 10-05-2012, 06:34 AM
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how are you running the 12v stuff after making your 2 batterys into 24v? tapped in the middle?

there is no correct way to do this...

if the batterys only purpose was to provide 24v to the troller, then switch back to 12v to allow charging there are relays that will do this. but having the other 12v stuff on is bad.

I would get 2 more batterys for the troller and leave the existing stuff alone.
Sorry dude but electronics is just not your thing. It can be done but the problem is it has to be done in steps. The jumperwire for series connection has to be disconnected then the batteries connected in parallel. When you want to go back to series you have to disconnect the parallel wires before connecting the series jumper. You could do it with a battery on /off and 2 battery selector switch but you would have to switch everything in the right order or you would get a direct short. For sure you would want some circuit breakers just in case it is switched wrong. If you could figure out a way to gang the switches together you might could do it in one step as long as everything disconnected before it reconnected. Risky business so breakers for sure.
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Old 10-05-2012, 06:39 AM
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O yea make sure that battery 3 is only hooked to the trolling motor and not grounded to anything else.
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Old 10-05-2012, 07:01 AM
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Yea, i have figured a way to make it happen with a couple switches. that process would be fairly easy. I was just thinking that there has to be a manual switch out there that would do the same thing, if not then why? they make an electronic one...My goal on my boat is to not have to do EVERYTHING myself... i'd like to be able to say "hey flip that switch" to any one of my non nautical friends...lol! . this could also greatly improve the amount of trolling that could be done in one day and make it much less of a pain to charge the trolling batteries (as long as you didn't completely drain them)
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Old 10-05-2012, 07:52 AM
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Originally Posted by Dookie30 View Post
Yea, i have figured a way to make it happen with a couple switches. that process would be fairly easy. I was just thinking that there has to be a manual switch out there that would do the same thing, if not then why? they make an electronic one...My goal on my boat is to not have to do EVERYTHING myself... i'd like to be able to say "hey flip that switch" to any one of my non nautical friends...lol! . this could also greatly improve the amount of trolling that could be done in one day and make it much less of a pain to charge the trolling batteries (as long as you didn't completely drain them)
Where did you find a electronic switch. I have the same set up an it would be nice to have a switch that would switch it over to parallel when I started my port motor.
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Old 10-05-2012, 08:23 AM
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well, it's just an elect. solenoid. it's only a momentary 24v switch over for an old semi truck starter that is on 24v. but it's only meant for use momentarily.
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Old 10-09-2012, 10:35 AM
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Ok, this may be a little over my head, however i have some electronics background so here it goes.... Right now i have three batteries in my boat. one hooked to #1 on the switch for starting, two hooked to #2 in parallel for my radio/gps/etc... I also have a 24v trolling motor that when i want to use i have to manually move wires around to achieve my 24v system from my parallel batteries making them series. Is there a manual switch that will do this for me so that i can switch back and forth? that way as i motor to a new spot i can switch it to parallel for charging purposes?
As others have pointed out, the only really RIGHT way to do this is to create a permanent third (24V) bank for the trolling motor. No matter how you may arrange a bunch of manual switches in an attempt to make your second bank "convert" from a parallel conection to a series connection, the possibility of inadvertently making dangerously improper connections is just too great, IMCO.

The good news is, on a boat small enough to use a trolling motor, the odds on you really needing more than a single Group 27 or Group 31 battery for the "House" bank (i.e., for the VHF,. GPS, etc.) is pretty small -- especially if that bank is not also driving the trolling motor. So you could presumably get away nicely with just four batteries in total (one for engine starting, one for the "House" load, and two in series to provide 24V for the trolling motor).

Creating the three separate banks is not at all difficult. You will need separate breaker panels (or at least a panel which provides for two completely independent DC "banks", which is unlikely to fit on a boat that size); and you will need separate On/Off master switches for each bank. You may want to use something like the the Blue Seas #5511e "Dual Circuit Plus" battery switch to manage the two 12V banks. This is a dual-pole switch (in a sense, it's two switches in one), whose purpose is to both act as the master On/Off switch for both (12V) battery banks simultaneously, AND permit those banks to be temporarily paralleled in an emergency. An additional single-pole On/Off switch could then handle the 24V bank.

The next challenge will be charging these disparate battery banks, presumably from the same source(s). You have two possible sources for that charging power: The engine alternator and a dockside-powered AC battery charger. There are a couple of ways to handle the latter issue. While I think there are combination 12V/24V chargers available, the simplest approach would surely be to just have two separate chargers onboard: One true dual-bank 12V charger for the Starting and House banks, plus one single-bank 24V charger for the trolling motor bank.

Charging all three banks from a single engine alternator will likely prove the trickiest part of the project; but it can be done, and it need not involve manually switching batteries into and out of the charging circuit. I'd start with a good heavy duty 12V dual-bank charge controller, such as the the Blue Seas #7610 Automatic Charging Relay http://bluesea.com/category/78/79/products/7610. This device will automatically separate your Starting & House banks when -- and ONLY when -- the voltages on either one is low enough that you risk draining the starting bank through overuse of the House bank (such as when the engine is not running). But when the engine IS running (and thus providing adequate charging voltage), the relay automatically closes so that charging current is distributed to both banks. To this, I would then add a DC-DC converter (such as the NewMar #12-24-18I http://www.newmarpower.com/DC-DC_Con...ed_Series.html, but you MIGHT want something which can handle a bit more current than this), hung off the House bank (only!), in order to provide a 24V charge-current supply to the 24V bank. But this would need to also be relay controlled, perhaps via another Blue Seas #7610 ACR (this one between the House bank and the input to the DC-DC Converter), so as to not drag down the House bank when the trolling motor is running.

As you can surely glean from the above, this is not a trivial project. But it is one which IS worth doing right.



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Old 10-09-2012, 04:56 PM
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Reading that makes my head hurt. All this guy wants to do is to be able to charge his trolling motor battery while running. There is never a need for a 24v charger with 12v batteries as all banks on a onboard charger are isolated and can charge individual batteries that are in a series configuration so forget about 24 volt chargers. Here is an idea. Not sure how effecient it would be but you could put a single bank onboard charger on the 3rd battery and run it off of a power inverter when the big engine is running. Might not charge enough to make it worth the effort. Not sure how much it would charge the 3rd battery but it would charge.
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Old 10-10-2012, 07:54 AM
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yea, i mean. I don't think it's that hard of a concept... I simply don't have the resources to make the switch. I think if someone did and marketed it correctly it could work well. I could draw a simple diagram up in minutes that would make everything work in conjunction in order to switch over at the right times and do what i need. I just don't know why it hasn't been done and why people think it cant... I can manually rewire them as needed as i have been and it works well.
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Old 10-10-2012, 08:37 AM
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Simple solution. An automatic switch for the price of a manual switch. The automatic switch detects when you turn on the trolling motor and switches to series in 1/30 second. When the trolling motor is off for about 30 seconds it switches back to parallel.

Take a look at http://www.yandina.com/troll24info.htm
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Old 10-10-2012, 09:55 AM
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HOLY THANK YOU JESUS!! lol i knew there had to be something out there that could do what i am trying to do... I know damn well i'm not the smartest person in the world and have not likely thought of something new... I will be looking into this very soon!
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Old 10-10-2012, 11:05 AM
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Originally Posted by Capt. Steve Barnes View Post
Reading that makes my head hurt. All this guy wants to do is to be able to charge his trolling motor battery while running.
I understand. But while that may seem simple at first blush, appearances can be deceiving. There are a number of very important details which MUST be kept in mind, or you create the potential for disaster (or just plain create disaster).


Quote:
There is never a need for a 24v charger with 12v batteries
Sorry, but that is simply NOT true.

The thing you're overlooking is that the trolling motor bank, while physically comprised of two 12V batteries in series, is effectively a single 24V battery, and needs to be treated that way.


Quote:
as all banks on a onboard charger are isolated and can charge individual batteries that are in a series configuration
You CANNOT count on that.

To do what you describe would require "floating" the negative terminal of the 2nd battery approximately 12 volts above ground during the charging process. But many "multi-bank" chargers are designed to isolate ONLY the positive outputs for each bank, while concurrently sharing a common ground between not only the various outputs, but also the chassis itself (in part for safety reasons; but often also due to cost considerations). This still allows them to provide multiple "isolated" outputs to charge separate battery banks, as long as they really ARE separate battery banks (your "split-bank" scenario is not). I've not done an exhaustive study; but I'd wager that this is actually more common than having two or three isolated-ground outputs.

Quote:
so forget about 24 volt chargers.
So NO, do NOT "forget about 24 volt chargers."


Quote:
Here is an idea. Not sure how effecient it would be but you could put a single bank onboard charger on the 3rd battery and run it off of a power inverter when the big engine is running.
And what good would that do, presuming that "3rd battery" is a 12V type (which it near-certainly would be)? He needs to charge (and charge equally!) AT LEAST two 12V batteries in series to provide power for his trolling motor.

(And yes, it would also be horridly inefficient; but that's beside the point, really.)



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Old 10-10-2012, 12:19 PM
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Originally Posted by Dookie30 View Post
HOLY THANK YOU JESUS!! lol i knew there had to be something out there that could do what i am trying to do...
Don't get too excited; and definitely look VERY closely at that device before purchasing it or installing it on your boat. I have reason to believe that, quite beyond the fact that it is likely NOT the solution you're looking for, it could be downright dangerous.

Consider the following quotation directly from the Owner's Manual for said device:
We recommend 6 gauge wire for the motor cables and
for extending the supplied cables. The 10 gauge wire
supplied is used for current limiting protection - see
explanation under WARRANTY at end of these instructions.

Since the connections made in the battery circuits can
carry hundreds of amps, it is imperative that you have low
resistance connections. This means having clean metal to
metal contact, the right size ring terminals, properly crimped
terminals, and secure mechanical fastenings.
First, it should be laughably obvious to anyone with even elementary electrical knowledge that "10 gauge wire" and "hundreds of amps" absolutely do NOT mix well -- that combination could literally start a fire!

Second, the very idea of deliberately using undersized wiring to provide "current limiting" is an anathema to sane wiring practices and proper safety standards. The ABYC, the USCG and the NFPA ALL require that wires be protected by appropriately sized fuses or circuit breakers precisely to avoid this possibility. See http://www.acbsphl.org/Tips_and_hints/ABYC_Wiring.htm for a simplified overview of this topic.



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Old 10-10-2012, 12:30 PM
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Originally Posted by Itteldoo View Post
I understand. But while that may seem simple at first blush, appearances can be deceiving. There are a number of very important details which MUST be kept in mind, or you create the potential for disaster (or just plain create disaster).




Sorry, but that is simply NOT true.

The thing you're overlooking is that the trolling motor bank, while physically comprised of two 12V batteries in series, is effectively a single 24V battery, and needs to be treated that way.




You CANNOT count on that.

To do what you describe would require "floating" the negative terminal of the 2nd battery approximately 12 volts above ground during the charging process. But many "multi-bank" chargers are designed to isolate ONLY the positive outputs for each bank, while concurrently sharing a common ground between not only the various outputs, but also the chassis itself (in part for safety reasons; but often also due to cost considerations). This still allows them to provide multiple "isolated" outputs to charge separate battery banks, as long as they really ARE separate battery banks (your "split-bank" scenario is not). I've not done an exhaustive study; but I'd wager that this is actually more common than having two or three isolated-ground outputs.



So NO, do NOT "forget about 24 volt chargers."
I don't know of any multiple bank chargers on the market today that have common negative connections. They all have 2 wires for each output and each output is regulated separately.

Actually if you want to look at it in detail, a 24 volt battery is actually 12 2 volt battereis in series. The "perfect" way to charge them would be a 12 bank charger with 2 volt isolated per output, progrmmed to charge each cell.

But since that is impractical the next best choice is 2 12 volt chargers rather than a 24 volt charger. The reason is a 12 volt charger will charge to its maximum voltage setting ASSUMING that each cell is at 1/6 the total voltage. If one cell is weak it will reach full voltage before the others. So when the charger goes into the maintenance mode one (weak) cell is fully charged and the rest have received exactly the same abount and are undercharged. Charging can continue after the weak cell is fully charged while the others gain voltage and this will overcharge the weak cell, cause gassing, and hasten its demise.

The probability of all the cells being matched in a 12 volt battery is very good, made at the same time, same chemistry, same age etc.

But with 2 12 volt batteries in series the chance they match is much less and that is why batteries in series must be matched as close as possible. There is much more probability that a weak cell in one battery will be abused significantly more while the other stronger battery is charging enough to reach the cutoff voltage for the 24 volt charger. They are no longer treated separately.

Putting them in parallel for charging at 12 volts has the added advantage that if they are not matched, current will flow from the good one to the bad one for a few seconds so they are at EXACTLY the same voltage and then both charge to exactly the same level.
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Old 10-10-2012, 01:11 PM
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UGHH.... There's always a spoiler... I'de like to see YANDINAS take on this concerne with the wire size vs. amperage.
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Old 10-10-2012, 06:22 PM
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I don't know of any multiple bank chargers on the market today that have common negative connections. They all have 2 wires for each output and each output is regulated separately.
Your premise does not follow from, and is not supported by, the stated criteria.

Just because a multi-bank charger provides separate negative leads for each bank does NOT mean -- or even imply -- that they do not share a common ground internally. It implies only that the redundant leads are provided for installation convenience.

Similarly, each output can be (and presumably is) separately regulated regardless of whether or not they share a common ground.

That you would presume that separate negative leads necessarily implies either of these things only further destroys your credibility (and in turn, that of your products).


Quote:
Actually if you want to look at it in detail, a 24 volt battery is actually 12 2 volt battereis in series. The "perfect" way to charge them would be a 12 bank charger with 2 volt isolated per output, progrmmed to charge each cell.
In theory, correct. But since in this case all 12 cells are by definition (near-)identical, and due to the physical construction must also be (near-)identically discharged, this would constitute overkill in practice.

However, the same most definitely does NOT apply to two dissimilar or dissimilarly-used 12-volt batteries which "just happen" to be put into a series configuration on a temporary basis from time to time.


Quote:
But since that is impractical the next best choice is 2 12 volt chargers rather than a 24 volt charger.
That can work if, and ONLY "if", we can be certain that those two 12-volt chargers do not share a common ground anywhere on the DC side. As previously discussed, this absolutely does not apply to many "dual bank" chargers. But it can also easily be an issue with many single-bank chargers, if they tie their 12V "-" output to chassis ground (as many do), since those chassis would presumably both be tied to the boat's common grounding/bonding system for safety and galvanic corrosion reasons.

The upshot here is, as I stated previously, the trolling motor bank is a 24-volt bank, and needs to be treated that way -- AT ALL TIMES. And that effectively means a 24-volt charger, period.



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Old 10-11-2012, 06:06 AM
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My question was how to switch 2 12v batteries from series to parallel, and back at my convenience... So charging would take place when they were in parallel. Much like they would be if you had two house batteries. People all over have two batteries ran in parallel for whatever reason. When the boat is underway both batteries are being charged in line.... This 24v bank charging crap is off topic. my goal is to not have to do such. Therefore i need a switch be it electrical or manual that will switch parallel to series and back... I'm not saying YANIDAS hardware is sufficient or not, but his product was made to do what i need done. So how about to solve this you sell me one at a much discounted rate and i will report its "productivity" lol
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