Power management videos are up

[Philpott]

In case you are that person who always reads ahead, here is the thread where you can share information BEFORE the seminar. A general outline of presentations will show up on these threads as soon as the speakers have a chance to cogitate and organize themselves. If you would like something addressed, ask here.

 

[BobJ]

The most common area of difficulty for skippers during the SHTP is power management. Some end up hand-steering for long periods of time due to insufficient power to run their autopilots, or they have a poor SSB transmission (or none) for the same reason. Some have had their engine key-switches become inoperative due to water intrusion, so they were unable to run the engine/alternator . . . well, you get the idea.

For the 2008 SHTP, Race Chair Synthia required energy budgets from the skippers. Due to power generation problems in the 2012 race, the energy budget requirement was re-instituted for the 2014 race.

Here are some of the energy budgets from 2008:
http://sfbaysss.net/archive-shtp-websites/transpac2008/electrical_budgets/electrical_budgets.html

To prepare these, you need to measure how much amperage each item on your boat uses, and this leads to my question. I used to have a Xantrex Link 20 installed, which would show the change in amps flowing out as I turned on each light or other item. This made it easy to prepare the budget. However, the Link 20 caused other problems so I removed it. I now have a (portable) digital multimeter. How/where do I connect the probes to the wires for each electrical item on my boat to measure the amperage it uses?

Thanks!
.

 

[BobJ]

Here's another question. Those energy budget spreadsheets were somewhat bogus because the alternator output (line near the bottom) wasn't realistic. My alternator only puts out 30 amps if the batteries are nearly discharged, and output drops off quickly after only a few minutes of charging. In the budget, how can we compute a realistic charging time?

 

[todd22123]

I now have a (portable) digital multimeter. How/where do I connect the probes to the wires for each electrical item on my boat to measure the amperage it uses?

Thanks!

I've never done this, but I think I know the answer. The digital multimeter is set to measure current and is put in series in the circuit. http://www.youtube.com/watch?v=7lwZkl0yBqA

It seems like the multimeter could be wired in series right after the battery circuit breaker switch and then devices turned on one at a time to measure current.

Todd

 

[hodgmo]

An ammeter in series will work but be very careful when breaking and connecting live circuits!

Another way to measure current is with a clamp-on (Hall effect) current meter. This is convenient if the + and - wires of the circuit of interest are available separately. This video gives the basic idea, though for an AC circuit: http://www.youtube.com/watch?v=z-KfZvbjyBY Here's a more in-depth (but longer) look with specific dc measurement advice: http://www.youtube.com/watch?v=1sq2WRGPABw jump to 09:30 to see the meter in use. If you go this way make sure the DC current range matches your needs.

Does anyone know if/where the power management excel file is available?

 

[BobJ]

I think Synthia got it from here: (energyplan.xls)

https://pacificcup.org/kb/energy-management

But again, I don't think it's much good without a realistic alternator output - the "biggest" number on the page.

 

[sleddog]

For SHTP, a power management budget is sound prep. However, figures should be taken with a grain of salt. For those relying on solar, the charging figures should be cut in half.

As many have learned before, it can be cloudy much of the way to Hawaii. When running downwind for the second thousand miles, the sun goes behind the spinny or wung out jib at local apparent noon, also reducing solar charge input.

If relying on an alternator for primary charging, would suggest carrying a spare and tools to change it out.

 

[brianb]

Measuring charger/alternator current

Measuring with Ammeter in series: A multimeter rarely has the range to measure an alternator, in fact you can damage the meter for the cheaper models and blow a fuse in the more expensive versions.

Measuring with a shunt: A measurement "shunt" is a calibrated piece of brass that is placed in series with the battery terminals. These are used by most of the better charge controllers. They can be purchased at WM/Svendsen's etc. If you have a charge controller you may have one installed. Once in place, in series with the main 12 v power line going to the battery bank, one simply puts the multimeter, in DC VOLT mode, across the shunt terminals. Then you measure the voltage while the alternator is charging. You should see values below a volt displayed. To convert to current you simply divide the shunt resistance into the voltage read. A 0.01 ohm shunt and a 0,3 volt reading yields a charger current of 30 amps. The shunts are made to be mounted on the engine compartment and left in place. If you have a charge controller connected in a way that the alternator current passes through, it can be used as well.

Using a DC current clamp: Great if you can get one, make sure it is DC capable. Last I looked they were a bit pricey.

Here is a shunt that would work in vessels with alternators in the less than 50 amp range. They sell a variety.
http://www.rammeter.com/ram-meter-20m30a50-30-amp-50-dcmv-dc-current-shunt.php

I think Synthia got it from here: (energyplan.xls)

https://pacificcup.org/kb/energy-management

But again, I don't think it's much good without a realistic alternator output - the "biggest" number on the page.

 

[brianb]

It sounds like your alternator regulator may be a bit too aggressive in dropping the charge as the battery warms up. Do you have a separate field control on the alternator ? Likely not unless it is something like an aftermarket alternator. You may also be suffering from more voltage drop in the wires from alternator to the battery, giving the alternator a false reading of actual battery voltage. If you have a field wire that goes to the regulator, and can get to it, you can put in a little switch and a resistor or two to give you the ability to fool the regulator into telling the alternator to operate at a higher level. On my Hawkfarm I put a switch that I could throw and get full alternator output at will. This was really slick when I added a 100 amp Balmar alternator, when in full charge mode the little Volvo diesel would nearly stall. Of course this is over riding a circuit that is there to prevent over heating the batteries leading to other spectacular results if left unattended.

 

[Ragnar]

the Link 20 caused other problems so I removed it.

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.

Or you can screw around with a DMM...

Slacker Out

 

[BobJ]

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.

 

[brianb]

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.

 

[BobJ]

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.

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.

 

[svShearwater]

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.

 

[BobJ]

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.
.

 

[svShearwater]

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?

 

[Ragnar]

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.

 

[brianb]

@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 ?

 

[BobJ]

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.

 

[Ragnar]

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.