Jump to content


  • Posts

  • Joined

  • Last visited


1 Neutral

Profile Information

  • Gender
  • Location
    Leighton Buzzard, for now
  • Occupation
  • Boat Name
  • Boat Location
    Continuous cruiser

Recent Profile Visitors

The recent visitors block is disabled and is not being shown to other users.

  1. Yes, it is a JP1, and you're about right with the revs. Also with the alternator pulley - I haven't actually measured it (I will), but probably closer to two and a half, I can't really run the engine now so I'm going back to this in the morning.
  2. They are as you described in your first comment about them. The alternator one is a bit larger than 2", the engine one 10-12". I'm tired, I got lazy in my description. I realise that doesn't help, I will be more specific.
  3. Yes, it is. Also, yes, you're right about the pulleys - they're massive, I'll abandon that train of thought. Doing so now...
  4. Sooo...lamp now coming on, but not going off. It is a very low revving engine, though - I'm limited in how much I can crank it up. No guage but it's low. I'm guessing this particular model of alternator worked at some point with this engine, though. Although that is a guess. Another oddity....there is no negative cable on the Dynastart. It's bolted to the hull, but there isn't a negative back to the starter battery, which is where it gets it's power from.
  5. Got terrible signal, thought I replied to this but can't see it. Apologies, my bad - both the starter negative and leisure negative connect to the bolt holding the alternator on, which is in turn connected to the hull. I'm sorry - my brain's getting fried!
  6. Apologies, was away from the boat for a few days. No, the negative bus bar is connected to the leisure battery negative terminal. Which is not connected to the hull...
  7. Which explains why I can eat a Chinese meal for three!!!?!
  8. You've both been awesome. Going with that, I'll report back once I've got my hands on a good leisure battery.
  9. Ooh, interesting! Never tried that, I'm going to give it a go! I love shallots. Never occured to me to try them with this. I shall!
  10. Yes, is the answer to that one. It's on a plastic fitting, mounted on a wooden board.
  11. Yes, this part makes sense. I wasn't hugely surprised it didn't work with the negative cables disconnected. Very helpful posts Tony Brooks and Nick Norman, thank you. I'll report back shortly! Appreciate your help. And yes, I'll gladly post a pic of the engine. Prewar Lister JP1.
  12. Not directly to the engine block, no, but there is the heavy negative lead running via the alternator body (not a terminal on the alternator, but the big bolt at the top of the alternator, which does ultimately go to the engine block), to the leisure battery negative (and onto that earth bar). Would this be basically the same? Ahhhh....yes. Ok, so the alternator light does not work. It is powered by the leisure batteries. I don't actually have an ignition, she's hand crank with Dyna start, but this is starting to make a bit more sense. I'm going to try with healthy leisures. Thank you, Nick Norman, very much. My brain just became a tiny bit less baffled.
  13. Fair assumption (I just double checked myself!) but no, it is indeed a Unipoint. Not heard of them before myself.
  14. Yeah, I explained the whole thing terribly in my first post. I was tired and frustrated! Regret that slightly now! Also, this is all quite new to me, so I know I don't always use the correct terms. A better attempt - alternator wasn't charging, so I checked all cables and connections, using a multimeter, either checking resistance to see if the wiring was good, or in the case of the alternator, I wanted to see if the voltage was a) the same as the leisure battery while the engine was off and b) if there was any increase in voltage when the engine was running. Used a multimeter, negative probe on negative starter terminal, positive probe on positive alternator terminal. What I discovered was that when the engine is off, the voltage at the alternator positive terminal drops to less than 1V when the negative cables between starter and leisure batteries are connected. This is the same whether they are connected at the alternator body, or bypassing the alternator. I don't have a starter motor (have Dyna start/hand crank connected directly to the starter battery, there is not a negative wire between the Dyna start and alternator). The two large, negative cables between the starter battery and leisure batteries were connected at the body of the alternator, large bolt onto the engine block. If, however I do bypass the alternator, and have the negative cable from the starter running straight to the negative leisure terminal (and onto the earth bar from there), the starter battery will not power the Dyna start. Thank you, Nick Norman! That is useful info about the Sterling unit. I will try again with a healthy leisure. Back to the other point - voltage reading at the alternator positive terminal. The thing is, it IS showing more than 12V when those negative cables are disconnected, and almost nothing when they are connected. Could this also be simply because my leisures are dead? My god. I hope so!!!!!
  15. "Where are you measuring the voltage? If the leisure negative is disconnected, there will be no voltage between leisure positive and the negative bus bar." I agree completely, this is exactly what's confusing me. I can see that the voltage from the starter battery is reaching the alternator positive terminal, but ONLY when I disconnect the negative cable between the starter and leisure batteries. Which makes no sense to me at all! "If the leisure bank is indeed dead flat, when the alternator tries to charge it, the voltage between alternator output and negative will be low." Yes, but the loss of voltage running to the alternator when negative cables are connected occurs when the engine is off. It's not the fact that the alternator isn't charging (I know it can't charge if it's not getting any voltage), it's the fact that it no longer gets voltage from the starter battery when the negative battery cables are connected. Apologies, it's difficult to explain this, because it's so damn odd!
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.