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  1. Member
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    #21
    Quote Originally Posted by moetorola View Post
    Yes, the both batteries voltage wise would be at some voltage since they are parallel but not necessarily capacity wise.

    Batteries of different age, manufacture date for a few examples. It is never a good idea to charge two 12volt batteries the are in parallel. They should be monitored separately.
    While the voltage may be the same one battery may reach 100% charge while the other is at 80%. Or vise versa, while one battery has reached 100% the other 80% the charger may over charge the fully charged battery. It really depends on charger being used at the end of the day. The old cheap metal style chargers with no regulation voltage based charging only, I would not trust em.

    It is frowned upon in the industry I work in. When in nearly every case the batteries are left unattended and some cases forgotten about. This method may be fine for charging up, but for float charging long term, as most of us do today, not recommended.

    Luckily with todays chargers having individual banks, each battery is monitored separately we don't have to worry about this. Except in parallel.
    Sorry but that is wrong. It is a common misconception that the charging current will divide equally between 2 batteries in parallel which creates the misunderstanding that the weaker one will be overcharged before the better one gets fully charged. However you can even charge batteries of radically different sizes because the current divides in proportion to their capacity so both charge at the same rate and reach full charge at the same time.

    When charging in series where the current is identical in each battery your argument is valid but it doesn't apply to parallel operation. Due to frequent misunderstanding of the difference between parallel and series, the rules for matching gets applied mistakenly to parallel.

    You don't say what industry is having problems in your experience but I've worked in telephone exchanges with a 2,500 sq ft room full of backup batteries in parallel on standby float. It is standard practice for off-the-grid solar systems.

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    #22
    Is this better?
    4WIRE 1224 w jumper ver 2.jpg

    I just swapped pins is all.
    Last edited by moetorola; 06-07-2018 at 11:14 AM.

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    #23
    You might want to fix your web site drawing.
    If I didn't know anything about wiring, and assumed those are pins. I just shorted out battery 2 in a 4 wire system and only have 12volts going to trolling motor if I followed the diagram if pin location is a concern.

    As in your drawing and mine , we are both assuming plug and socket is correctly, by either customer of manufacture that installed them. It is better to verify how the plug and socket is wired if unsure.


    I do not agree with this drawing. If we are considering plug pins!


    marinco-24v-receptacle-wiring-diagram-unique-12-24-volt-trolling-motor-battery-wiring-diagram-wi.jpg
    Last edited by moetorola; 06-07-2018 at 11:21 AM.

  4. Electrical/Wiring/Trolling Motors Moderator Jonestrollingmotor's Avatar
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    #24
    Quote Originally Posted by moetorola View Post
    You might want to fix your web site drawing.
    If I didn't know anything about wiring, and assumed those are pins. I just shorted out battery 2 in a 4 wire system and only have 12volts going to trolling motor if I followed the diagram if pin location is a concern.

    As in your drawing and mine , we are both assuming plug and socket is correctly, by either customer of manufacture that installed them. It is better to verify how the plug and socket is wired if unsure.


    I do not agree with this drawing. If we are considering plug pins!


    First, that drawing hasn't been on my website for over a year. If you've found it, please give me a link. Next, I don't understand your comments regarding a 4 wire system. IF you look closely, this is NOT a 4 wire system. IF you look closer, the connections are labeled as they are on the plug and receptacle. However, I will admit I have mislabeled the configuration of the receptacle. The wires are going to the correct labels, but the labels should be, going clockwise starting at battery 1 negative in the upper right corner, bat 1 neg, bat 2 neg, bat 2 positive, however, the batteries will still connect to battery 1 neg and battery 2 positive.

    Now, if it were a 4 wire system and you placed the wires from the batteries according to the labels, you would have 12V between bat 1 neg and bat 2 neg and 24V between bat 1 neg and bat 2 positive. Then should you use a charge plug with two jumpers, bat 1 net and bat 2 neg would jump and bat 2 positive and bat 1 positive would jump. This provides the parallel connection for charging both batteries with one charger.

    In your "redraw" where you swapped "pins" it is correct if you're looking at the face of the plug. If you're looking at the back side of the plug where the connections are made, then you have a mirror image of the plug. On my drawing that you posted, the "pins" as you put it -- I prefer "connections" are labeled as to what wire goes where and corresponds to the receptacle / plug, but as long as it's clear which wires go to what connections, it will work.
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    #25
    Quote Originally Posted by Jonestrollingmotor View Post
    First, that drawing hasn't been on my website for over a year. If you've found it, please give me a link. Next, I don't understand your comments regarding a 4 wire system. IF you look closely, this is NOT a 4 wire system. IF you look closer, the connections are labeled as they are on the plug and receptacle. However, I will admit I have mislabeled the configuration of the receptacle. The wires are going to the correct labels, but the labels should be, going clockwise starting at battery 1 negative in the upper right corner, bat 1 neg, bat 2 neg, bat 2 positive, however, the batteries will still connect to battery 1 neg and battery 2 positive.

    Now, if it were a 4 wire system and you placed the wires from the batteries according to the labels, you would have 12V between bat 1 neg and bat 2 neg and 24V between bat 1 neg and bat 2 positive. Then should you use a charge plug with two jumpers, bat 1 net and bat 2 neg would jump and bat 2 positive and bat 1 positive would jump. This provides the parallel connection for charging both batteries with one charger.

    In your "redraw" where you swapped "pins" it is correct if you're looking at the face of the plug. If you're looking at the back side of the plug where the connections are made, then you have a mirror image of the plug. On my drawing that you posted, the "pins" as you put it -- I prefer "connections" are labeled as to what wire goes where and corresponds to the receptacle / plug, but as long as it's clear which wires go to what connections, it will work.


    I digress!

    It was just a google search for wiring Marinco plugs, and your image came up. I am guessing it is cashed on google servers.
    Last edited by moetorola; 06-07-2018 at 12:22 PM.

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    #26
    Quote Originally Posted by Ann-Marie View Post
    Sorry but that is wrong. It is a common misconception that the charging current will divide equally between 2 batteries in parallel which creates the misunderstanding that the weaker one will be overcharged before the better one gets fully charged. However you can even charge batteries of radically different sizes because the current divides in proportion to their capacity so both charge at the same rate and reach full charge at the same time.

    When charging in series where the current is identical in each battery your argument is valid but it doesn't apply to parallel operation. Due to frequent misunderstanding of the difference between parallel and series, the rules for matching gets applied mistakenly to parallel.

    You don't say what industry is having problems in your experience but I've worked in telephone exchanges with a 2,500 sq ft room full of backup batteries in parallel on standby float. It is standard practice for off-the-grid solar systems.
    I agree, however keeping I was keeping with the theme of this post as in old style 80's early 90's.

    Back then some chargers that may have been used were less than intelligent.

    And being in a 12/24 volt setup. depending on speed setting with the old style 12/24 trolling motors. The batteries will be drawn from unequally.

    Completely different scenario in most cell site backup, (and I would guess exchanges also) where typically the parallel battery strings are pulled from equally.

    In my industry (back in the 80/90s) is more like the trolling motor, where the equipment in the past (not so today with advent of switching supply's) the equipment would pull unequally from the string needing 12, 24 and in some cases even 48 volts for operation. A somewhat intelligent charger would monitor the individual batteries for current, voltage and temperature.

    Today, series is used -48 volts and the switching supply's take care of distributing the different voltages needed.

  7. Electrical/Wiring/Trolling Motors Moderator Jonestrollingmotor's Avatar
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    #27
    Even on todays systems, there is no need to charge batteries individually in a parallel system. In fact, if you have batteries in parallel and one is drawn to apx 12V and the other is at 12.5, you will get a reading of axp 12.25 since the lower battery will pull or "load" the higher battery til they equalize. That is the voltage the charger sees. To make it more extreme, if one is 8V and the other is 12v, the charger will see apx 10V and charge accordingly. Even if the better battery reached 14 before the lesser is charged, the better will not over charge since the charger will still see the average between the two and the lesser will load or pull the higher down to a average voltage.. The only way a problem comes up is "if" the lessor will not take a charger, then the charger, in the old days, would continue to charge possibly creating enough heat in the better battery to evaporate electrolyte. Todays chargers will charge at a bulk rate for a limited time, then cut themselves off if the battery(s) are not taking a charge.
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    #28
    Sorry, I don't agree John. Using your example, you may have had one battery at 8 volts and one at 12 but within seconds of connecting together you have 2 batteries at 10 volts (or thereabouts depending on differences in actual capacity). Current will flow very rapidly from the 12 volt and discharge it to 10 while charging the 8 to 10. From then on you have a 10 volt battery. You cannot have a battery at 12 volts that is only reading 10 volts on the terminals. If that could be the case current would flow from the 12 volts "internal" source to the 10 volt terminal and since the internal resistance is less than 1/1000 ohm the maximum CCA of the battery flows until the voltage is equal.

    It doesn't matter what voltage they were before you put them in parallel, you now have a single battery (bank) at a common voltage and the charging source will respond accordingly. You cannot overcharge one battery more than the other because they are at the same voltage.

  9. Electrical/Wiring/Trolling Motors Moderator Jonestrollingmotor's Avatar
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    #29
    Quote Originally Posted by Jonestrollingmotor View Post
    To make it more extreme, if one is 8V and the other is 12v, the charger will see apx 10V and charge accordingly. Even if the better battery reached 14 before the lesser is charged, the battery will not over charge since the charger will still see the average between the two and the lesser will load or pull the higher down to a average voltage..
    Ann-Marie --- That's what I said and you're disagreeing????
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    #30
    All that I am simply saying and mentioned in one of my posts.

    Can you charger in parallel=yes!

    But I would only do this if the batteries were purchased at the same time and same make and model. And even then I would separate them and check them periodically individually. As usually they fail or loose capacity at different times, in my experience.

    Is it the best solution if the batteries are different make, model, chemistry and/or manufacturing date= I would not.

    We have to assume the person using this type of setup has little knowledge.

    In fact just had friend come over yesterday saying his engine would not start. I said, did you check your battery? He said, the battery charger went green and is charged, and it is showing 12volts.
    Well, he was right 12.0 volts on the dot..LOL
    All is well with a new battery.
    Side note: He had a 24volt TM, with two different sizes/styles, A old tractor battery and new AGM for his 24v series string. ( i did mention it to him) doubt he will change it, knowing him. lol! He did have a multibank charger , that's a plus.



    The days of 12/24 Trolling motors are nearly gone. However many people are now running or want to run 2 batteries for engine and accessories. So it is still applicable still today. But that may be for a different thread.
    Last edited by moetorola; 06-11-2018 at 12:45 PM.

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    #31
    John, we are in agreement, I just wanted to dispel the impression that a charger will charge an 8 volt battery and a 12 volt battery in parallel at 10 volts, it is the batteries that arrive at 10 volts after being put in parallel, with or without the charger. From then on you just have a 10 volt battery (bank).

    moetorola, you say you would only charge matched batteries in parallel and I believe you but you are unable to back the claim up with any logical or scientific reason other than you had some batteries go bad, which happens just as often when charged individually.

    We have to assume the person using this type of setup has little knowledge.
    AND YOU HAVE lol? A limited personal experience is not a substitute for scientific fact. At least your misinformation won't do any harm other than unnecessary expen$e.

    When using a Trollbridge on a 12/24 volt trolling motor BOTH batteries are used equally. When running on 12 volts it automatically puts the batteries in parallel so both share the load. When running on 24 volts it automatically puts the batteries in series.

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    #32
    Quote Originally Posted by Ann-Marie View Post
    John, we are in agreement, I just wanted to dispel the impression that a charger will charge an 8 volt battery and a 12 volt battery in parallel at 10 volts, it is the batteries that arrive at 10 volts after being put in parallel, with or without the charger. From then on you just have a 10 volt battery (bank).

    moetorola, you say you would only charge matched batteries in parallel and I believe you but you are unable to back the claim up with any logical or scientific reason other than you had some batteries go bad, which happens just as often when charged individually.

    AND YOU HAVE lol? A limited personal experience is not a substitute for scientific fact. At least your misinformation won't do any harm other than unnecessary expen$e.

    When using a Trollbridge on a 12/24 volt trolling motor BOTH batteries are used equally. When running on 12 volts it automatically puts the batteries in parallel so both share the load. When running on 24 volts it automatically puts the batteries in series.
    Nothing I have said is untrue! And I did say it is possible to charge in parallel. But there are circumstances that may cause issues with this method.


    Nothing I have said is misinformation! There IS a correct and wrong way to charge in Parallel.


    https://www.impactbattery.com/blog/t...s-in-parallel/

    http://www.batterytender.com/connecting-chargers
    Last edited by moetorola; 06-13-2018 at 12:38 PM.

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    #33
    Have you seen what happens when a battery in a parallel setup fails? (there are different failure modes of batteries). Again, can you charge in parallel yes, is it optimum, NO

    My point is (in bass boats) it is battery to separate the batteries and charge individually with todays smart chargers!

    And with Jones drawing of the parallel connection in the plug for charging.
    It is better to install a multibank charger to charge the batteries.Than to charge the batteries in parallel from the trolling motor plug, as they did back then. Remember this post was (I thought) about how things back in the 80/90s were done.

  14. Electrical/Wiring/Trolling Motors Moderator Jonestrollingmotor's Avatar
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    #34
    Quote Originally Posted by moetorola View Post

    It is better to install a multibank charger to charge the batteries.Than to charge the batteries in parallel from the trolling motor plug, as they did back then.
    I have to disagree with this statement. Todays chargers are too smart and monitor the voltage. If you try to charge two paralleled batteries with a two bank charger (Instead of a single bank) the charger could "read itself" and "think" the battery is charged and go into a maintenance mode. If you're going to leave the batteries connected, it is best to charge with a single bank charger --- that's how it was done back in the late 70's and 80's.
    John
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    #35
    Quote Originally Posted by Jonestrollingmotor View Post
    I have to disagree with this statement. Todays chargers are too smart and monitor the voltage. If you try to charge two paralleled batteries with a two bank charger (Instead of a single bank) the charger could "read itself" and "think" the battery is charged and go into a maintenance mode. If you're going to leave the batteries connected, it is best to charge with a single bank charger --- that's how it was done back in the late 70's and 80's.
    John
    keeping with the original post (80s/90's),,,,,I am talking about an older boat, that has the parallel jumper in plug end of a 12volt charger, then charging from trolling motor socket.

    By installing a multi bank on board charger the batteries would be isolated in this scenario. Because they would not need to charge from the front trolling motor port with a charger that has the parallel jumper, correct, or am I missing something?.

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    #36
    Quote Originally Posted by moetorola View Post
    keeping with the original post (80s/90's),,,,,I am talking about an older boat, that has the parallel jumper in plug end of a 12volt charger, then charging from trolling motor socket.

    By installing a multi bank on board charger the batteries would be isolated in this scenario. Because they would not need to charge from the front trolling motor port with a charger that has the parallel jumper, correct, or am I missing something?.
    If you have a boat that was of that vintage, and it has the 4 wire system, there is nothing wrong with charging using the same charge plug as we did back in those days. However, if a person with that type boat would like to have an onboard charger, it is OK to charge the batteries with it also. In that case, the charge plug would not be used and the batteries would never be put in parallel but charged individually by a dedicated bank to that battery. The trolling motor would need to be unplugged to keep the charger from feeding the trollingmotor control board if it's a PWM trolling motor. Either way will keep the batteries charged.
    John
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