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Thread: Battery connections

  1. #1
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    Default Battery connections

    I have a turbodiesel inboard and dual starting batteries. The batteries have two options for connection, SAE studs and threaded posts. I opted to use the threaded posts when I wired my boat.

    I've been chasing what seems to be erratic electrical connection from the battery to the ignition. Regardless of fully charged condition of the batteries, I sometimes get full connection, sometimes a stuttering connection (which causes my solenoid to click or clatter without engaging the starter?), and other times not enough juice to sound my pre-ignition buzzer. I have, of course, cleaned all terminals and tightened everything. When I fail to get ignition from one of the batteries, if I take the cables off and reseat them on the studs, I will generally get a full connection, or at least enough for ignition. Setting the battery switch to "both" has always worked to date but obviously I want to get ignition from each battery separately.

    So, I'm wondering if changing my cable ends to the lead clamps might have a positive effect. Seems like doing so would increase surface area and make a more reliable connection? But my impression is that the threaded posts are typical for marine applications so they should not be the source of my trouble. Anyone out there have any experience/opinion on this?

  2. #2
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    Default Re: Battery connections

    I've always put the high-amperage starting load on the clamp-on post with the electrical accessories on the threaded post. I assumed the clamp-ons could carry the higher load more reliably, due to the surface area. Dunno if this is standard practice or not--just what I've always done. Your symptoms sound like a typical corroded connection that can't carry the necessary amperage.

  3. #3
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    Default Re: Battery connections

    Your symptoms sound like a typical corroded connection that can't carry the necessary amperage
    I know, right? But what has driven me crazy is that I can't find the corroded connection! I swear everything is clean and tight. And until recently I never had a problem. Maybe when the batteries were fresher they masked inadequate connections?

  4. #4
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    Default Re: Battery connections

    Application of some sort of corrosion blocker is required, in my opinion.
    There is a material available for house wiring, which I use.
    I have used ordinary grease if nothing else is readily available.
    Bare copper terminals corrode quickly in the marine environment.

  5. #5
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    Default Re: Battery connections

    Did you try eliminating the 1/2/all switch, could be the contacts in there

  6. #6
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    Default Re: Battery connections

    Red, I have cleaned and applied grease. Multiple times.

    That's a good idea, Gareth. I have not tried bypassing the switch. It is only three seasons old but anything is possible.

  7. #7
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    Default Re: Battery connections

    A bad or going starter could give weird stuff as well, try disconnecting the pos to the starter and see if you can get the control to fail.
    I didn't know that about the starter. Not intuitive to me that it could make the ignition connection flutter or appear dead. The starter going bad is a real possibility, as I partially sunk my boat and the starter got dunked (fresh water). I replaced the solenoid, but only took the starter apart, cleaned/dried and put it back together. There was some corrosion on the armature (didn't move fast enough after the dunking), so may be a problem there. (The batteries, switch, and electronic connections on the motor did not get submerged, by the way).

    I'm going to test my starter and battery switch now.

  8. #8
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    Default Re: Battery connections

    Well, testing my starter by removing the pos. does not work for me. The starter is looped through the electronic brain on the motor that sends signals to the computerized instrument panel and apparently also rules the pre-ignition buzzer. Removing power from the starter results in dead silence.

    However: I had one battery this morning that was not giving enough juice for starting. I just stacked the positive from that battery on the main output of the battery switch and got full connection. But then I moved it back to its place and also got full connection. This despite the fact there is zero visible evidence of corrosion on the switch terminals.

    Something like a voltage drop from the starter motor as Jake suggests could be causing just enough trouble that a wiggle here or there "fixes" the problem...temporarily. Maybe I need to take the starter back out and give it another look, maybe just replace it. Spendy little unit, by the way.

  9. #9
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    Default Re: Battery connections

    Not being there, any advice is pretty speculative. I've found a connection on the cable heavy to accommodate the 100-amp or so starter load is pretty tough to assemble with a wiring eye, while that is pretty standard for the post-type terminal connection. If you have a diesel, which we don't, it is a higher load anyway. That said, lots of other things could be happening along the circuit. Mentioning ignition on a diesel is confusing--I assume you mean the starter solenoid. That alone could be faulty, but again, I'm just guessing. The usual test is shorting around the solenoid with a jumper, and see if the starter motor works then.

  10. #10
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    Default Re: Battery connections

    Right, sorry, by ignition I don't mean burning fuel, I mean turning the key one step, hearing the fuel pump run and the steady buzzer sound that signals proper juice, then turning the key the rest of the way and engaging the solenoid/starter. Once the starter turns over I have no problem.

    I understand your meaning regarding the wiring eye, and the heavier starting load for a diesel. I assembled all the cables myself, and I am no pro. Possibly my assemblies are sub par.

  11. #11
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    Default Re: Battery connections

    Well, testing my starter by removing the pos. does not work for me. The starter is looped through the electronic brain on the motor that sends signals to the computerized instrument panel and apparently also rules the pre-ignition buzzer. Removing power from the starter results in dead silence.
    Ugh. Come to think on it, I needed to bypass the starter solenoid but keep the circuit intact by nutting together the positive and the wiring to the ECU. Duh. But at the moment, after fiddling with connections, I have starting power from both batteries, so bypassing the starter isn't going to tell me anything.

  12. #12
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    Default Re: Battery connections

    Quote Originally Posted by L.W. Baxter View Post
    I know, right? But what has driven me crazy is that I can't find the corroded connection! I swear everything is clean and tight. And until recently I never had a problem. Maybe when the batteries were fresher they masked inadequate connections?
    Ive been through a frustrating experience as you are relating here.

    The chances are that all or some runs of the battery cables and/or cable extremities by the lugs have corroded partially, which does happen over time if you did not seal off the extremities at the time of initial installation by:

    Step 1, dipping the stripped cable extremities in molten solder;

    Step 2, introducing the extremitiy into the receptacle on the end-fitting (or lug) and soldering the lot;

    Step 3, covering the cable extremity / lug combination with heat-shrinkable adhesive-lined protective sleeving, which needs to be in place before Step 2 above (use a couple of sleeves, one over the other, one at a time, for good measure !)

    As for the point made by Hwyl regarding battery-switch contacts, I can attest to the rear-end of such switches coming away from the front-half due to the mass of the attached cables (bad design), which led to poor contact and considerable heating of the whole assembly, in turn leading to its detection.

    And these were switches from a reputable source, 'specially for heavy diesels, with an in-built alternator excitation cut-off on switch-off ' said the sales literature.

    I replaced these with BEP (Enzed manufacture) switches and no trouble since !

  13. #13
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    Default Re: Battery connections

    I did not dip my cable ends in solder, or use any solder after crimping on the wiring eyes.
    Frankly, I crimped the ends without a professional tool and didn't manage a particularly tight job. At the time I didn't think it mattered but it is dawning on me now that it does. I did use heat-shrink sleeves and all connections appear very tidy from the outside, but I feel certain that I should re-do them.

    Thanks for all the advice, folks. I am going to rebuild my cable ends and order a new starter. If it turns out the starter is not bad I will just have a spare on the shelf. My battery switch is a Blue Sea and I suspect it is fine but I will keep it in mind as a source of trouble.

  14. #14
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    Default Re: Battery connections

    Quote Originally Posted by L.W. Baxter View Post
    I did not dip my cable ends in solder, or use any solder after crimping on the wiring eyes.
    Frankly, I crimped the ends without a professional tool and didn't manage a particularly tight job. At the time I didn't think it mattered but it is dawning on me now that it does. I did use heat-shrink sleeves and all connections appear very tidy from the outside, but I feel certain that I should re-do them.
    If you use solder throughout, you may not need to crimp at all.

    Heat the lug (wiring eyes ?) with a butane-torch and drop in a piece of solder into the receptacle assigned for the cable extremity. The solder should melt instantly.

    Then introduce the priorly-sealed extremity of the cable in to the receptacle.

    BTW, I use a 1 1/4 inch dia, 1 1/2 inches long piece of SS tube with a 4 x 4 inches SS plate (3 mm) welded at one end, torched with butane (and molten solder inside) as my 'crucible' for sealing cable extremities.

    Cover the junction generously with adhesive-lined, heat-shrink sleeving. Two coats for good measure, which also augments the mechanical strength of the assembly, minimising entry of contaminants.


    Quote Originally Posted by L.W. Baxter View Post
    Thanks for all the advice, folks. I am going to rebuild my cable ends and order a new starter. If it turns out the starter is not bad I will just have a spare on the shelf. My battery switch is a Blue Sea and I suspect it is fine but I will keep it in mind as a source of trouble.
    I came across a cable that was partially corroded at one end, the source of intermittent contact only during cranking (heavy-current passage must knock it out) !

    Best way out of this maze, is to not cut corners, right from the start.

  15. #15
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    Default Re: Battery connections

    adhesive-lined, heat-shrink sleeving
    Okay, I didn't stumble across this when I did my wiring, the heat shrink I found was not adhesive lined. I will look for that.

    Best way out of this maze, is to not cut corners, right from the start.
    Absolutely true. I'm more than a little chagrined; I didn't know I was cutting corners by not soldering! I don't know how or where I got the impression that it wasn't necessary. Ignorance and inexperience on my part, thankfully not too hard or expensive to rectify.

  16. #16
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    Default Re: Battery connections

    Well, thanks for the helpful suggestions.

    I rebuilt all my cables with new ends and solder. I found it worked best to step up a size in the wiring eye. Solder on the wire, molten solder in the wiring eye, plus a tight fit was a recipe for frustration.

    But the real news is that, when I pulled all the cables out and removed the battery switch, I thought to give it a little shake next to my ear, and I heard sloshing water! Impossible, I thought, how could water have gotten in there? I was absolutely certain that the switch had never been submerged. But finally I figured out that the position of the switch directly below a deck hatch meant that every time I hosed down the self-bailing deck, the switch was getting dripped on. Blindingly obvious mistake, in retrospect.

    Anyway, with a new switch and better built cables I am back in business.

    Here is a picture of the insides of the old switch. "Mystery" solved:


  17. #17
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    Default Re: Battery connections

    Quote Originally Posted by Hwyl View Post
    Did you try eliminating the 1/2/all switch, could be the contacts in there
    Quote Originally Posted by L.W. Baxter View Post
    Well, thanks for the helpful suggestions.

    I rebuilt all my cables with new ends and solder. I found it worked best to step up a size in the wiring eye. Solder on the wire, molten solder in the wiring eye, plus a tight fit was a recipe for frustration.

    But the real news is that, when I pulled all the cables out and removed the battery switch, I thought to give it a little shake next to my ear, and I heard sloshing water! Impossible, I thought, how could water have gotten in there? I was absolutely certain that the switch had never been submerged. But finally I figured out that the position of the switch directly below a deck hatch meant that every time I hosed down the self-bailing deck, the switch was getting dripped on. Blindingly obvious mistake, in retrospect.

    Anyway, with a new switch and better built cables I am back in business.

    Here is a picture of the insides of the old switch. "Mystery" solved:


    Ahem!!!!

  18. #18
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    Default Re: Battery connections

    Quote Originally Posted by Hwyl View Post
    Ahem!!!!
    Go ahead, rub it in. Another lesson in not assuming things, though I should not have needed it.

  19. #19
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    Default Re: Battery connections

    I just finished a ten minute conversation with the shop who put a new fuel pump in on of my outboards at work, I could not get it to run, the conversation ended with "where did you get the as when you filled the tank" Me "uh o I did not check the gas"

  20. #20
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    Default Re: Battery connections

    Now that is just sad. I assume that would never happen to me!

  21. #21
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    Default Re: Battery connections

    Quote Originally Posted by L.W. Baxter View Post
    Well, thanks for the helpful suggestions.

    I rebuilt all my cables with new ends and solder. I found it worked best to step up a size in the wiring eye. Solder on the wire, molten solder in the wiring eye, plus a tight fit was a recipe for frustration.

    But the real news is that, when I pulled all the cables out and removed the battery switch, I thought to give it a little shake next to my ear, and I heard sloshing water! Impossible, I thought, how could water have gotten in there? I was absolutely certain that the switch had never been submerged. But finally I figured out that the position of the switch directly below a deck hatch meant that every time I hosed down the self-bailing deck, the switch was getting dripped on. Blindingly obvious mistake, in retrospect.

    Anyway, with a new switch and better built cables I am back in business. .......
    Congratulations for ending up with a clean slate !

    Should keep you out of trouble for another 3- 5 years !

  22. #22
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    Default Re: Battery connections

    Forgive me for not reading all the way through, and I in advance appologize if I am repeating someone else. That sed, do you have a cracked post?

  23. #23
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    Default Re: Battery connections

    I agree with Dan McCosh's comments above about using clamp-on tapered lugs on the battery terminal posts. A LOT more surface area. It's worth it to spend the money to buy a battery terminal reamer, instead of one of those wire-brush terminal cleaners. The reamer gets rid of corroded metal and corrosion, and it also cuts away metal so you have a better surface contact.
    On large engines this is critical. The largest electrically-started engines I worked on as engineer had a pair of V16-92 Detroits (That's a 1,400 cubic inch engine). Tending the battery cables was a common pastime. Usually an engine this size would have air starters...
    When trouble-shooting a starting circuit looking for high-resistance connections, the best way I've discovered is to remember that bad connections get hot when you pass a lot of current through them. (It's why toasters get hot). So I operate the cranking circuit, and then run my fingers over the wires and devices, looking for something that's hot. These days I have a remote-sensing thermometer with a laser pointer, which makes this go faster. They can be bought pretty cheap at AutoZone.
    As far as switches go, if the contacts inside the switch (not the terminals on the outside) get corroded, you might not feel the heat. But switches are kind of self-cleaning: operate the switch a dozen times, and it MIGHT start working. You can use an ohmeter to measure resistance through a switch, but I find it quicker to use a test light with a fairly big bright bulb. I make my own by soldering wires (with alligator clamps) onto a brake light bulb, the kind with two filament wires, with both terminals soldered to one lead (positive, or +], and the second (-, or ground) lead soldered to the brass base of the bulb. This is cheap, draws a fair amount of current, and indicates pretty well. Check the test light by connecting from + to - of the battery, and get an idea of how bright the light is. Then touch the test light to the hot terminal of the switch (to make sure the light works and the switch is getting power, then clamp the + wire to the switched terminal of the switch, and then operate the switch. If the test light doesn't come on, the switch is bad. If the light comes on, but is dimmer than when connected on the hot side, there's resistance in the switch. Work it a dozen times, and the light might get progressively brighter, indicating that the switch is self-cleaning itself.
    In any event, do something about the switch.
    When I was young I used to take apart switches, apply little dabs of silver-solder onto the contacts, carefully shape and burnish the contacts.
    These days, I get a new switch, and put the old one in a box where I keep old switches that I'm going to (someday) carefully take apart, apply little dabs of silver-solder onto the contacts, carefully shape and burnish the contacts. Someday. This box is on a shelf in my shop, next to the box labeled "string too short to save."
    Last edited by seo; 06-26-2011 at 12:36 PM.

  24. #24
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    Default Re: Battery connections

    Quote Originally Posted by seo View Post
    .... When I was young I used to take apart switches, apply little dabs of silver-solder onto the contacts, carefully shape and burnish the contacts.
    These days, I but a new switch, and put the old one in a box where I keep old switches that I'm going to carefully take apart, apply little dabs of silver-solder onto the contacts, carefully shape and burnish the contacts. Someday. This box is on a shelf in my shop, next to the box labeled "string too short to save."...
    It occurred to me that I could just clean and polish the plates in my switch and put it back in service. But it is made in such a way that the plate and post will not come out of the body of the switch and therefore one cannot clean corrosion off the back side of the plate or the base of the post, or even see how plate and post are joined. So I bought a new switch, and put the old one in a box on the shelf, you know, just in case...

  25. #25
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    Default Re: Battery connections

    Definitely use the big post type clamps and large wires directly to the solenoid. Also, don't forget to check the grounding on the engine. Remember that current needs to flow all the way from the positive terminal of the battery to the starter and then back through the engine ground to the battery negative terminal. A bad or corroded ground strap or negative return wire may be the issue.
    Now is a good time!


    Steward of MAKOTO [WB Magazine #232], and Honored Member of the LPBC

  26. #26
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    Default Re: Battery connections

    Good point in #28. Check for a hot terminal on the ground cable where it bolts to the engine, and the battery. Ground (-) connections are at least as critical as + connections. If the + connections are weak, nothing happens. But if the main - are weak, then it's possible for current to flow by some alternate route. The most unusual example I ever saw was of ground current from one engine's generator running up the Morse Control cable to the engine control in the wheelhouse, then down the other engine's Morse cable, and thence to ground. The fault first noticed by a smell of melting plastic (the cable sheathing) followed by the first engine's controls seizing up.
    Last edited by seo; 06-27-2011 at 05:53 AM.

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