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Need help on a 24v starting system/charging on a 75 Striker

Discussion in 'Electronics' started by Just Fishing, Jun 8, 2022.

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  1. Just Fishing

    Just Fishing New Member

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    Background on boat
    1975 54 Striker SF with DD 12v71TI. I was told that this has a 24v starting system. Bought in Feb. 2022. The boat has two gen sets. Batt charger is a 3 bank. Looks like only one Gen-set is hooked up to the Batt Charger.

    How is this normally done? Does anyone have a typical wiring diagram?

    I think battery1 + is hooked to the starter solenoid and the - is connected to the ground. The other side of the solenoid is then hooked up to the - of battery2 and the + of battery2 is hooked to the starter.

    The battery charger + is hooked to the + of battery1 and the battery charger - is hooked to the - of battery2. Same for Port and Stbd.

    Is the Alt. a 24v Alt?

    The boat shows to have an emergency jump solenoid on the dash, how would this be tied in? I don't see one in the engine room.

    This does not seem right to me. I am thinking that this should have 2-3 bank battery chargers. One for the port and one for the stbd.
  2. Pascal

    Pascal Senior Member

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    The first question is how many batteries do you have. You said you were told it has a 24v starting system, if so it would be using banks of two 12v batteries not just one battery as you described.

    each engine and generator should have its own battery bank and plus a house battery bank for lights, pumps etc. that’s the right way to do it for reliability.

    while an electrical diagram for the boat can be helpful the first thing to realize when dealing with a almost 50 year old boat is that things are likely to have been changed and modified over the years often by less than competent owners or mechanics

    the engines are likely to be 24 volts although back then 32 volts was common on larger boats. But again, if it was 32 volts when new it may have been changed to 24 volts at some points since 32 v stuff is harder to find

    often engines are 24v but generators are 12 volts. In that case you would have a 2 bank 12 charger for the generators and a 3 bank 24v charger for the engines and house

    first step is to know exactly what voltage is each system and how many batteries you have
  3. Just Fishing

    Just Fishing New Member

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    I have 6 batteries—two 12v 8D batteries for each motor and house and one for each Gen. I have Port and Stbd House power and this comes from one of the starting batteries on each side.

    The Gen-sets are pretty straightforward. Each Gen has its own 12v battery and Alt from each. Just odd that the battery charger is only hooked up to one generator battery.

    I see no indication that this had 32v. There have been many modifications over the years and is easy to spot due to the wire type. The previous boat owner had owned this boat for 25 years.
  4. Pascal

    Pascal Senior Member

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    Ok that clarifies things. Yes the 12 volt charger should be connected to both generator batteries. Is it a two bank charger? If single bank you should replace it with a two bank charger. I really like Promariner ProNautic chargers. They’re compact and smart.

    As mentioned I m not a fan of start banks doubling up as house but it s short cut many builders use. When I repowered and rewired my 1970 53 Hatt, I went with a 4 bank system: mains, generator and house. Also went to 24v house and 12v for mains.

    as to your parallel solenoid, you should be able to find a red positive cable going from each engine bank or from each bank battery switch to the other with the solenoid along the way. Have someone hold the switch and listen in the engine room for the click.
  5. DOCKMASTER

    DOCKMASTER Senior Member

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    Agree with Pascal that bad things can happen when starting batts are also your house bank. I would strongly recommend you change this.
    I have 2x 8d in series for each engine 24v starting. The only other 24v loads I use these for are the anchor windlass and bow thruster. But I never use the windlass or BT unless engines are running first.
    I then have 6x Group 31 12v batts for house bank and gen starting. I use the group 31s because they fit well where I want them. I do not have dedicated gen starting batts but I have multiple ways I can start them from the engine batts if I have a failure in the house bank.
    For charging it is very straight forward. 1 24v dual bank charger for starting batts and 1 12v charger for house bank. Engine alternators charge the 24v banks when running. I have an emergency 24v to 12v batt to batt charger so I can charge house batts from engine alternators if my 12v charger quits or if I lose both gens.
  6. Pascal

    Pascal Senior Member

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    Ideally bow thrusters should not be on the same bank as engines especially when the engines are computer controlled and / or with electronics controls. The voltage drop can stall the engine or confuse the controls.
  7. DOCKMASTER

    DOCKMASTER Senior Member

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    I don’t use my thruster much. Even when I do, it has little effect on battery voltage with engine running. Wasn’t worth the space and weight for me to put in dedicated batteries for the little I use the thruster.
  8. mapism

    mapism Senior Member

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    Having helmed for 17 years a trawler with no b/t at all, I sympathize with your train of thought.
    Just be aware that what Pascal said applies also to your electronic 1018s and their controls.
    The risk factor here is that whenever due to wind or current you might use the b/t a bit longer than usual, sooner or later the voltage is bound to drop.
    And that would be the worst moment to stall engines or get unresponsive controls...
    I appreciate that a dedicated bank would be OTT, but in your boots, I'd consider putting the b/t under the domestic bank.
  9. rtrafford

    rtrafford Senior Member

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    Agreed, get the thruster and windlass off any DC circuit with sensitive circuitry like nav equipment, engine controls, engine ECU's and sensors, etc. Too much risk, and that risk grows as your batteries age.
  10. Just Fishing

    Just Fishing New Member

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    Thank everyone for their responses. I started the process of moving my house power off my mains. Figuring out how the mains work with the 24v starter was easy. + from battery 1 goes to the starter solenoid, and the other side of the solenoid goes to the neg. of battery 2. Battery 2 + goes to the starter. My question is about the charger. The charger has been replaced. It's a 3 bank charger with 3 positive outputs and only one common. One bank for each of the two mains and then one for the Generator. I tried tracing this out and found where the original charger was, and its wiring was intact. The new charger is wired to the original wiring at this spot. How does the single 12 v bank charger, charge up the two batteries on the main? The charger looks like the wires go into the electrical distribution panel. When I turn on the charger, the voltage on both batteries goes up to 13.8v, and 12.8 when the charger is off. How did these systems work? Even the alternator seems to be 12v, but I haven't tested this. I'm pretty good at electrical stuff, but this confused me, and since I can not trace those wires out, I'm not sure what to look for.

    The main reason I dove into this yesterday is that my charger was not charging. Found the common wire broke. I have fixed that.
  11. rtrafford

    rtrafford Senior Member

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    I'm assuming those chargers are 12v with a dedicated lead to each battery, 3 outputs designed to charge and monitor each battery? Be careful with the electric aboard an aluminum boat...
  12. Just Fishing

    Just Fishing New Member

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    Well, I would have assumed the same thing, but this charger is not. The charger in the boat has a single return, a ProNauticP Charger. I am looking for a wiring drawing on how they originally did something like this. I have two batteries, one alternator, and this charger. It seems that all batteries are getting a charge but it does not look right to me. I have 3 wires going somewhere from this charger. I believe it's to the electrical panel but ran out of time Sunday. Wish I knew the original design. There are still many of these DD 12v-71 out there.
  13. rtrafford

    rtrafford Senior Member

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    You have three batteries there. I'll assume two of them are in series to provide 24v to the main, and one is alone to provide 12v to the generator. You should isolate a smart charger onto the one generator battery and install a 24v smart charger to the 24v system. One charger servicing three batteries will not maintain the batteries properly long term if it isn't a three battery output. Simply sharing a single output three ways isn't a proper installation.
  14. Pascal

    Pascal Senior Member

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    0E7FC2FE-E239-4022-B299-4E06CFE6A02E.jpeg This sentence doesn’t make any sense at all:

    “Figuring out how the mains work with the 24v starter was easy. + from battery 1 goes to the starter solenoid, and the other side of the solenoid goes to the neg. of battery 2. Battery 2 + goes to the starter. ”

    Both batteries should be connected in series, pos to neg to produce 24v
    Positive terminal on the bank goes to battery switch and then to starter, negative goes to engine ground.

    mid both battery pos got to starter you ll have 12 volts at the starter with 2 batteries in parallel


    Assuming you connect both batteries in series to power the 24v starter, then your 24 charger should be connected with a single output wire to the positive of the bank, and the negative to the bank negative

    if someone used a 12 V charger, you can make it work by sending each charger output to each battery. Not ideal but it will work.
    Last edited: Jun 21, 2022
  15. Just Fishing

    Just Fishing New Member

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    both of you, thanks. Pascal, what I have is the starting solenoid between battery 1&2 so the 24v charger can not work. The two bank charger will work but not with a common - for both banks but that is what is on there. I have two mains and two Generators. The Gen batteries are one for each Gen. Only only one was connected to the charger and that was direct to the battery. I think to make this simple, I should have a 4 bank charger on the mains and then a two-bank on the Gen sets. House power comes from the Gen batteries. Right now House power is coming from battery 1 port and stbd.

    The alternator from the motor looks to be hooked up to the house battery only. 12v.
  16. rtrafford

    rtrafford Senior Member

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    No clue as to why there would be a solenoid between the two 12v batteries to your starter other than to think that it’s a parallel solenoid and that your starters are 12v. ???
  17. Pascal

    Pascal Senior Member

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    You need a marine electrician on this thing.
  18. DOCKMASTER

    DOCKMASTER Senior Member

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    Sorry but you are really not making sense and is very difficult to follow. As per Pascal, really recommend you get an electrician on board. You do not need a 4 bank charger for your 24v starting batteries. You need a 2 bank 24v charger. You have four starting batteries total. 2 per side should be connected in series which basically turns two 12v batteries into one 24v battery. So hence why you need a two bank 24v charger.
  19. rtrafford

    rtrafford Senior Member

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    Given that he apparently has a solenoid between the two main engine starter batts suggests to me that he actually has 12v starters with a parallel solenoid to use for starting. I'm not trying to be disrespectful, but I don't think he knows what it is that he actually has? Whatever the case, the setup reads wonky, and it needs quality help.
  20. Just Fishing

    Just Fishing New Member

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    All, I had figured it out yesterday. This is a 24v starting system. The solenoid between the batteries ties the positive from battery 1 to the negative of battery 2 and then over to the starter. The key is when the solenoid drops out. There is an aux. contact that makes contact, making both batteries parallel for charging. Alt. is a 12v alt. I have attached the solenoid drawing. The top half works like a normal starter solenoid. Terminal 1&2 close when starting. When de-energized Terminal 1&3 becomes closed and so does 5&2. Then the 12v alt. on terminal 2 will charge both batteries. Pretty darn interesting. BTW, I am not an electrician. I am a controls engineer. Been doing this for a long time and haven't seen anything like this in over 30 years. This stuff was done on generator protective relays that I had worked on back in the 80s. I did find those two drawings on the internet, just had to dig past pages of advertisements by Google. I really want to thank everyone here. Without these forums, jobs would be much harder and I hope I can contribute. Any more questions on this, let me know. I feel like I have a better understanding now of the starting & charging system. Now off to figure out the emergency starting system and how this ties the two banks together. I will post this on another thread.

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