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Thread: Power management videos are up

  1. #11
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    Thanks for the great input - I admit some of these are "leading questions" for the group.

    Brian yes, the stock Hitachi 35A alternator had an internal regulator. Since the little one-lung Yanmar can't spin a larger alternator, I bought a second 35A Hitachi and had it rebuilt with the field wire outside the case, then installed an ARS-5 regulator. Maybe it's ramping down too quickly. It drops from 30A to around 12-15A after a few minutes and down to 7-8A after a few more minutes. (@Skip - yes, I carry the stock alternator as a backup both for the alternator and the external regulator.)

    Slack, I've been looking at that Victron monitor - Fisher Panda (I think) is selling a bunch of them off via E-Bay at $148. Like most of the other "two bank" monitors, Victron's two-bank version just measures voltage on the second battery. Do I need two of them for full data on each battery? I still have the shunt from the Link 20 - fancy thing and heavy, but maybe I could use that the way Brian suggests. I get system voltage through my ST-60's so I really just want to measure amps in (to verify the solar panels are working) and amps out (to monitor usage). An installed in-line ammeter would do it. I suppose those come with their own shunt? Where would you install it?

    Here's another issue. For better weight distribution I moved my batteries forward. This required about 10' longer battery cables. Now I'm seeing about a .3 -.4 voltage drop at the instruments and autopilot. Do I need to worry about this? If so, it means a second switch/fuse panel up near the batteries, and I don't really want to do that.

  2. #12
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    Quote Originally Posted by BobJ View Post
    Thanks for the great input - I admit some of these are "leading questions" for the group.

    Brian yes, the stock Hitachi 35A alternator had an internal regulator. Since the little one-lung Yanmar can't spin a larger alternator, I bought a second 35A Hitachi and had it rebuilt with the field wire outside the case, then installed an ARS-5 regulator. Maybe it's ramping down too quickly. It drops from 30A to around 12-15A after a few minutes and down to 7-8A after a few more minutes. (@Skip - yes, I carry the stock alternator as a backup both for the alternator and the external regulator.)

    Slack, I've been looking at that Victron monitor - Fisher Panda (I think) is selling a bunch of them off via E-Bay at $148. Like most of the other "two bank" monitors, Victron's two-bank version just measures voltage on the second battery. Do I need two of them for full data on each battery? I still have the shunt from the Link 20 - fancy thing and heavy, but maybe I could use that the way Brian suggests. I get system voltage through my ST-60's so I really just want to measure amps in (to verify the solar panels are working) and amps out (to monitor usage). An installed in-line ammeter would do it. I suppose those come with their own shunt? Where would you install it?

    Here's another issue. For better weight distribution I moved my batteries forward. This required about 10' longer battery cables. Now I'm seeing about a .3 -.4 voltage drop at the instruments and autopilot. Do I need to worry about this? If so, it means a second switch/fuse panel up near the batteries, and I don't really want to do that.
    @Bob, you likely don't need to worry about the .3 to .4 volts drop at the instruments, they are designed to work over a very broad range, unless you see that much drop with only the instruments on and not charging with engine. If the drop exists with just instruments it means you have relatively high resistance in your power run from instuments to battery, and maybe other items are seeing that drop as well. If your alternator regulator is also seeing the drop, and it is likely it is, as it as far away from the batteries as anything, this could explain your regulator dropping off quickly while charging. If the autopilot is sharing some of these same feed wires you may have big drops momentarily as the AP battles the NW swell on your way to Hawaii. This could cause an AP shut down [on Red Sky the AP has a dedicated power run direct to batteries with a breaker next to drive motors]. You can also get some drop in breakers, I have seen as much as 0.2 volts across some older breakers. SSB transmission could also suffer as at 100W output the SSB will see spikes of 20 amps, if the voltage drops momentarily below about 11.8 volts the SSB will "FM"/distort, a big deal if you are using sail mail, and making for really lousy voice comm.

    I would suggest you do a simple analysis. Put a load at the ends of your wiring runs, like at the AP power terminals, SSB terminals, etc. A simple load device is a 12 volt turn signal bulb. It should pull a couple amps. Now measure voltage at the lamp and at the battery. If you see big drops start working your way along the wiring checking breaker, all crimp connections, etc. If you see anything in the range of 0.1 volts drop across any connection point consider replacing and/or improving the connection/breaker, etc. Sometimes just cleaning and tightening will work. If you see a large drop of the entire path but the connections look good, start considering changing to a larger wire size.

    Alternator: You added a standalone regulator ! Great ! Does it happen to have a pair of "sense" wires broken out ? They would be two small size wires connecting to the alternator output. If these exist you could disconnect from the alternator output and extend them all the way to the battery being charged, or the large power battery switch. This then allows the regulator to see the actual battery voltage and not suffer from the drops seen in the large wires going to the battery (known as a four wire measurement). THis is the best solution as it completely rules out drops due to high current and connections that can degrade with age and/or vibration.

    You may be suffering from a poor connection somewhere. As current passes through while charging, it heats up and the voltage drop rises slowly over time. As the drop rises the alternator current falls. MY main perko switch did this. I finally noticed a large drop and the thing would get a bit warmish.

    I hope this helps.
    Last edited by brianb; 10-27-2013 at 08:21 PM. Reason: Just seemed like the right thing to do.

  3. #13
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    Thanks Brian. The alternator drop-off was happening before I moved the batteries. Also, the cables are over-spec'd so there's probably not much loss from resistance (if I understand that correctly). The ARS-5 has various sensing options (battery temperature for example) so your suggestion should work. Maybe we should get together so you can look at the whole setup. I've also thought about bringing the boat to OYC for the seminar so people can look at the components - everything on my boat is pretty accessible/visible - not hidden behind lockers or bulkheads.

    Quote Originally Posted by Ragnar View Post
    Slacker runs with a battery monitor, the Victron BMV 600 which I highly recommend. Best $160 I've spent on her. Great piece of mind since you know what's going on with your battery at all times - amps going out, amps going in - when you need to charge. It comes with the shunt, so it's easy to install. I've had no issues with it at all. There is also a 2 bank version.
    Slacker Out
    Slack, how did you wire up the Victron to monitor both batteries? The 2 bank version only measures voltage on the second battery, not amps, state of charge, etc.
    Last edited by BobJ; 10-27-2013 at 10:17 PM.

  4. #14
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    Bob,

    I finally got the keys to the forum so I could post something...

    Regarding alternator output and a budget. What I would do is first assume that you will only use 1/4 of your battery capacity and that you will operate with the batteries somewhere close to 50% discharged as a minimum and 75% discharged as a maximum. In that range you should get the maximum output of your alternator. While that does limit your battery capacity and may require more frequent recharging, it greatly simplifies the energy budget and maximizes the life of your batteries (by not discharging them too deeply) and minimizes overall runtime (because you aren't trying to recharge the batteries to 100% at reduced alternator output).

    Actually, above is Option 2. Option 1 would be to get a Victron and wire it to your house bank. If your "house" bank is actually two banks then wire them together. I can't imagine doing distance sailing without some type of energy monitor. We have a Victron on Shearwater. Works great and was a huge help in diagnosing an alternator problem we had. We had a Link 10 on previous boat and that worked fine too.

  5. #15
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    Welcome Justin.

    RAGTIME!'s energy budget assumes a range of 50%-85% battery use. With enough sun, the solar panels do a nice job of keeping the batteries topped up, but with alternator only I'd have to run the engine far longer than what's shown. The only time I got more than 30A out of the alternator was after intentionally running the batteries way down (by leaving the incandescent steaming light on for 2-3 days). Even then, the output dropped by half after about ten minutes.

    Your second comment gets at one of my questions. I have two group 27 AGM's (about a year old). I'd rather not have two monitors but since I isolate the batteries when in use, I think I need to be able to monitor them separately.
    .
    Last edited by BobJ; 11-28-2013 at 02:21 AM. Reason: Fix busted link

  6. #16
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    Sounds like an alternator or regulator issue then. No reason you should get (much) less than rated output out of the alternator when the batteries are 50% discharged. I had a similar issue when I upgraded our electrical system. It turned out the voltage sense for the regulator was not actually reading the battery voltage and so the regulator thought the batteries were more charged than they actually were and it would trip through the 3 stages really quickly, drop the alternator voltage down to ~13.2 volts and at that low voltage the acceptance of the batteries was really low and the alternator output was greatly reduced. Now with it sorted out, that initial alternator voltage is more like 14.4 volts and I can see 100 amps out of a 120 amp alternator for 30-60 minutes before it starts to drop off. Is it possible your alternator voltage is changing to a lower value within the first 10 minutes and that is reducing your batteries acceptance of current? Internal or external regulator?

    Is there a special reason you have the two batteries isolated? Do they both serve as your house bank or is one house and one starter?

  7. #17
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    Quote Originally Posted by BobJ View Post
    Thanks Brian. The alternator drop-off was happening before I moved the batteries. Also, the cables are over-spec'd so there's probably not much loss from resistance (if I understand that correctly). The ARS-5 has various sensing options (battery temperature for example) so your suggestion should work. Maybe we should get together so you can look at the whole setup. I've also thought about bringing the boat to OYC for the seminar so people can look at the components - everything on my boat is pretty accessible/visible - not hidden behind lockers or bulkheads.



    Slack, how did you wire up the Victron to monitor both batteries? The 2 bank version only measures voltage on the second battery, not amps, state of charge, etc.
    Hi Bob,

    Moving batteries away from the charging sources? Couldn't you just move the cooler forward? Ah, of course - priorities - the beer needs to be near the cockpit. 2 house banks? I guess I'm a simple guy. I went to Hawaii & back on one group 31 house battery & a starting battery. AGMs seem to charge a little faster. I don't bother monitoring the starting battery. If there is ever a problem with it I can interconnect to start the engine anyway.

  8. #18
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    @Bob, @Ragnar got me to thinking. Maybe your cooler is turning on as it is too close to the engines heat and then absorbs much of the current that would have been used to charge the batteries ?

  9. #19
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    You guys are kidding about the cooler, right? In 2006 I took ONE bottle of beer for my half-way party and it stayed in the bilge until consumed. Drinking that beer knocked me out enough that while asleep, I almost lost my best spinnaker in a squall. NO beer was aboard during the 2008 race.

    RE a starting battery, at sea my Yanmar is just a big battery charger. It takes very little to start it so I have two matched Group 27's to run everything and no starting battery.

    This has all been really helpful. I think the regulator is not sensing the true state of the batteries and is ramping down too quickly. I plan to focus on that area.

  10. #20
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    You sailed to Hawaii with no beer? Is that legal? Seems like there should be a rule change...

    I confess to not appreciating the logic of your 2 separate house batteries. I guess one is really your reserve/starting? But then why monitor both? Why have them both the same size? Somehow I'm sure you've kicked this around 16 times and that's why it's setup this way. Oh wait, one is for the house, the other for your cooler?

    Sorry Bob, I'm trying to be funny. Probably just coming across as lame.

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