Yeah, according to Peukert you can have say a L-16 6V battery with 401ah @ the 20hr rate. And that battery has only 330ah @ the 5 hr rate. But if you discharge the battery at the 5hr rate for awhile and use up 330ah out of it the battery monitor with Peukert compensation says the battery is dead - 0% SOC. The Trimetric says it still has 71 ah left in it. What I have found is that what Ralph says, and what the TriMetric says, is 100% true. Take the load off that battery, the voltage rebounds, and if you finish discharging it at the 100hr rate you can get your last 71ah out of it.
And that is why the Bogart Engineering monitors have become almost the defacto-standard that all others are measured against, and have been for over 20 years. The TriMetric can be off sometimes on a recharge because the cycle efficiency depends on DoD and how long the battery has been cycled in the most efficient part of its charge curve up to ~80% SOC. And you plug in a fixed CEF (Charge Efficiency Factor) into the monitor so it can't always compensate for that. But it's a heck of a lot closer than most others I've worked with and it keeps a history on the last five cycles that tells you what your cycle efficiency is so you can adjust the CEF to reflect how you normally cycle the battery.
The beauty of the TriMetric is its simplicity in setup and the fact that it's "close enough" without having to mess with settings all the time. I hate tools that you constantly have to calibrate and adjust to insure their accuracy in order to be able to trust what it says. And that's what I absolutely love about the TriMetric - if it says the battery is at 60% remaining and you can discharge to 50%, you can rest assured that the battery has 10% of its usable capacity left yet without questioning it. On a sailing yacht, 9 days out to sea, that sort of information is what I call "Critical. Need To Know. Information".
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Less important at the lower discharge rates typical of off grid power systems ...
Ralph Hiesey, who is a brilliant engineer and the inventor of the Bogart Engineering battery monitors, has lived and breathed batteries and tested them for almost 30 years. He explains why Peukert compensation doesn't really work in the real world:
Reason: The higher amps drag down the volts more than a lower amp load ... So you get to the final 10.5 volt finish line faster
Technically, this effect is caused by the internal resistance of the batteries, and also by what is called “polarization” of the electrolyte in the battery, which causes the voltage to be dragged down when the load current is higher.
Terrific explanation !! Thanks for the article link !!Leave a comment:
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In theory it does. In practice, usually not so much. I got two battery monitors on our home off-grid system. One has Peukert compensation and the other (TriMetric) doesn't. On a long PSOC (Partial State of Charge) cycle with loads varying from bending the ammeter needles to trickle charging the TriMetric is usually more accurate than the fancy one.
Ralph Hiesey, who is a brilliant engineer and the inventor of the Bogart Engineering battery monitors, has lived and breathed batteries and tested them for almost 30 years. He explains why Peukert compensation doesn't really work in the real world:
And the proof is in the puddin' as they say. I'll put a TriMetric up against any other battery monitor made for accuracy in measuring SOC and remaining capacity in the battery and it will usually win. Especially on PSOC cycling which few battery monitors built, except the TriMetric, are able to track properly. The new TM2025's give you information on cycle efficiency of your battery so you can plug in the correct CEF.Leave a comment:
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Holy cow !! I can see that I'll be spending hours at the Smart Gauge website !! Thanks for an incredible resource link !!
Peukert's Equation-That will change my battery computations !! The heavier the discharge current, the less apparent battery capacity ...
The real explanation behind that 50% charge rule - Less discharge=longer battery life with 50% a good balance
Dump the split charge diodes for alternator controllers - The diodes are supposed to only allow current flow in 1 direction to allow the alternator to charge each battery bank, but current can't flow back the other way to affect other battery banks ... but ... voltage drop associated with diodes is not constant so battery sees lower voltage from alternator drastically reducing charging capacity ... wasted energy warming up the diode ... so much good info!
Always discharge a battery by more then 5% or it can shorten the battery life ... Never heard of that
Battery Isolator Switches - Always wire to the positive side !!
Hooking alternator to charge both engine and house battery banks-Minimize connections to reduce resistance and always keep a load on the alternator so watch that battery isolators are set to "on" before charging ... other wiring options ...
Hours and hours to be spent on the website
Interconnecting Batteries - Terrific article !! Using diagonally opposite posts from positive (or neg) of last battery in bank to negative (or pos) of first battery in bank makes a tremendous difference in balancing the load across the batteries in the bank both for discharge and charging !! I would think this would be even more important in AGM batteries with lower internal resistance.
Great stuff - Thanks again !!Leave a comment:
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Take a close look at the SmartGauge website. http://www.smartgauge.co.uk/technical1.html.
I always refer people to his page on interconnecting batteries for some good advice and sample numbers. But there is a lot more information in the other pages concerning all the different way of using a single charger for multiple battery systems (the main application of his products) as well information on battery systems for canal boats ("longboats"), some of which may transfer to the sailboat environment too.
Spend some time there!Leave a comment:
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inetdog - Heavy considerations. I'll have to get with the US dealer for the wind generators before hooking them up to better understand what would happen if the wind gens went into "dump" mode with the power going to the main bus.
I was counting on the ACR and MPPT controller to regulate charge, but didn't think about them opening up for bulk stage charging and having so much charging power that I could drive excess Bulk Stage current into the battery banks attached. That's a huge consideration. I'll have to search around for the mathematical formulas to make this determination. Thanks for the terrific feedback !!
Chris - I had reservations (pardon the pun) about not having a reserve bank because electrical problems will happen ... just a matter of time. Thanks for identifying this need. You are spot on about my thoughts to add as much reliable automation as possible, not to get out of monitoring things (you do that with all systems on a sailboat), but to help maintain consistent charging, improve safety and provide alerts to problems.
That's a very interesting thought to add a second ACR for the reserve bank. That seems like a nice safety feature. I could manually shut off the reserve bank when topped off and have an ACR in place when a charge is needed to help protect those batteries in between becoming fully charged and my coming down below to recognize this fact.
It seems that having too large of a battery bank is much safer than having too small of a battery bank with charging sources potentially overpowering them. I'll have to figure out what calculations to make to try to find a good balance as that is what I'm striving to achieve. I'd love to have excess charging power if I can safely implement it, but I doubt that will truly happen in practice. Still, I need to know the safety concerns and figure out the configuration to use to help improve safety.
I know the A/C power is 30-amp service, but I'm not sure what my D/C bus is ... Right now, a pair of 8D batteries hook directly into the house power switch and I bet you are right on the money with it having some old electronic diode battery isolator (at best). I definitely want to replace these old electronics with upgraded equipment like the ACR - Thanks for pointing all of this out too !!
It sounds like I should run the high output alternator to the bus as well so that it charges all batteries at the same time. I make an assumption here, which may be errant, that with all the attached battery banks that the charge will distribute reasonably evenly to all attached batteries. Adding ACR's should help "sense" charging, but I wonder if they regulate the charging current to the bank once the batteries are down in charge for a Bulk charge? Perhaps I should add some device to regulate charging voltage. Preferably, I'd love to have some type of step charging that puts higher voltage during Bulk and lowers voltage at 80%-85% charge. Perhaps the ACR does this, but just thinking out loud here.
Thanks again for the thoughtful responses - There is golden knowledge here !!Leave a comment:
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Dennis I quoted this whole thing above and had to think about what to say. If it was me I would split your house bank. For a coastal cruiser or a few hours out to sea where the USCG can come and rescue you, probably not a big deal. But we typically have a primary and reserve bank for off-shore cruising because things can happen like a battery develops a dead internal short that gets it hotter than hell and sucks your whole bank dead and leaves you high and dry (pardon the pun) with no power.
Managing the batteries and power is a daily chore for the captain and there's not a lot of reliable automation you can put on it. I suppose it would be possible to install a second ACR to charge your reserve battery in the event there is sufficient voltage on the primary battery to do it. But what will happen is that the battery bank is too big for the charge source unless you're motoring and using the alternator, at which time you switch to BOTH anyway to charge them up.
How many amps is the main bus in your power panel? That boat should have a 100A bus. The only thing it might not handle is a big alternator, in which case you'd have to bypass the bus with the alternator wiring and go direct to the primary battery with it. I'll bet you a dollar bill your boat has one of those old electronic diode type battery isolators in it and if it does you may as well toss that overboard and replace it with a ACR.
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Dennis, I will add that your original alternator wiring in the boat probably went to the starting battery. Once you put in a Big Time alternator that has to be revamped. Your poor little starting battery can put out 160A with no problem with huge voltage sag to 9.5V during cranking. But shove 150A into it @ 14.7V and it'll toss its cookies on the spot.Leave a comment:
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If the stage voltage settings on the different charging means are compatible (not necessarily identical) and neither charger uses a "dump" mode regulation, then no harm will come to the batteries with one critical exception:
If you are counting on the charger or CC output limit to avoid putting too much current into the batteries during the Bulk stage, then make sure that the two charging sources together cannot drive excess Bulk current into the battery bank.Leave a comment:
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It's amazing the depth of knowledge lurking here
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OK, so hook the panels in parallel ...
1. Wire 2 solar panels on arch in parallel to MPPT controller near main bus
2. Wire MPPT controller to main bus
3. Wire High Output alternator on engine to main bus
4. Wire engine starter batteries to Blue Sea ACR
5. Wire this ACR to main bus
6. Insert "make before break" (1,2,Both,Off) Blue Sea battery selector between 2 house battery banks & main bus
7. Hook pair of DuoGen wind generators to bus
Question from #6 above - Should something else be used to accomodate charging two banks of batteries at a dissimilar state of charge if "Both" is selected?
Would it be best to instead leave both house banks of batteries hooked into the main bus, constantly being charged? The more detailed question here is whether charging a battery bank that is at 50% state of charge any more efficient than charging a battery bank that is at 90% charge? If not, then by always having both banks of batteries tied to the main bus, they remain at the same state of charge and are always being charged since it's doubtful they will ever reach 100% SOC while powering devices onboard. If by chance the do reach 100% SOC, the MPPT controller will stop charging them and the wind generators should dump to the diversion loads. If I'm running the engine altermator, I'm onboard, awake and watching things to turn it off. The ACR should isolate the additional pair of engine starting batteries so they should be fine, right?
Question from #7 above - I believe that the NCHC 60 regulator for each of the DuoGen wind generators has an isolating relay that controls two large contactors; one contactor is connected to the batteries and the other to the diversion load. Should I connect the large connector designated for the batteries to the main panel instead and if I do, will it still isolate the wind generator from other charging sources and would it still be able to properly "sense" no load (a rare event) and change the path to the 600 watt diversion load for each DuoGen to prevent overcharging?
The controller with isolating circuitry that comes with each DuoGen D400 Industrial wind generator can be found here: http://www.flexcharge.com/NCHC-High-...ontroller.html
I'm starting to see how everything will come together. By having all batteries connected all the time to all charging sources, I can adjust use of electronics to manage drain and make sure I can maintain power. If while I'm testing things out before setting sail for destinations afar, I find I don't have enough charging power, I can add a water generator or two to help with the mix. With all charging sources running into the main bus, I'll have to make sure all devices (switches, ACR, cabling of sufficient size, etc.) can handle the huge amperage and charge connected through the main bus !!Leave a comment:
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Parallel is correct, but for the wrong reasons. If in series the shaded PV will not block the output of the other PVs due to bypass diodes within the PVs. This will function, but the diodes present a voltage drop of about 1/2 volt to 1 volt for each bypass diode and that is the reason for parallel to be better.Leave a comment:
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Chris - Awesome, thank you sir !!
Sorry, I got carried away with the research notes.
Perhaps you meant 2 solar panels wired in series? If so, that would boil down to:
Wire 2 solar panels on arch in series to MPPT controller near main bus
Wire MPPT controller to main bus
Wire High Output alternator on engine to main bus
Wire engine starter batteries to Blue Sea ACR
Wire this ACR to main bus
Insert "make before break" (1,2,Both,Off) Blue Sea battery selector between 2 house battery banks and main bus
Perhaps some other folks are more familiar with the wind generators and can offer some advice here. I'm guessing I wire the wind generator to the main bus using the isolator and somehow wire this to the diversion load after figuring out how it senses "no load" and diverts power being made by the wind gen to the diversion load to prevent overcharging with the excess power ??
Thank you so much for this terrific information !!!
I hope it will help many others !!
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I advised against using a portable generator onboard. A certified marine generator is no problem and most larger sailing yachts have them. Our H-R 54 had a 12 kW Volvo genset in it.
I'd wire your two solar panels in parallel and use a MPPT controller of your choice wired into the main bus. Put your big alternator on the engine and wire that into the bus. I don't know much about these wind generators and how their diversion loads wire up. They're actually using some sort of diversion load on a sailboat though? Cripes the AIR-series turbines from SWWP were self-regulating without no diversion loads. Seems to me the Ampair ones are too. Anyway......
Our battery selector is make before break type. The only way the bus can be disconnected from battery power is to turn the switch to the OFF position. I think that's the best switch to get - can't remember the brand name of ours but I think it's a Blue Sea switch. Our ACR is a Blue Sea, that I know. The ACR just handles the starting battery charging.
I wouldn't hold my breath on turning sea water into jet fuel.
“We haven’t actually made it to the specifications stage yet. But we know we’re in the hydro-carbon region and it shouldn’t be very difficult to meet that specification.”
In other words, it don't work. They can get lots of media attention with their theory. And make it sound like they're really on to something. But in the mean time, better stick to regular old diesel fuel if you want your engine to run.Leave a comment:
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Wait - I thought Chris advised against using a generator because of grounding concerns if I recall correctly ... Besides, if you do the math on the fuel requirements, it is hard to maintain even stopping at ports without a huge fuel tank and a HUGE ONGOING expense. I don't mind 1-time costs, but when I retire with no income ... it's those ongoing charges that I have to avoid ... besides funds set aside for emergencies like new sails, etc.Leave a comment:
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I recall 7-8 years ago that the power generated by solar panels was so insignificant that I would have only considered wind power. Things have changed and solar power is one of the fastest changing energy technologies. Right now, diesel fuel's energy density is far superior to renewable energies. Who knows, perhaps my small fuel tank may get a boost soon ...
But for the here and now, I think there are enough sources of power, some of which I haven't even explored here, that can create a zero-net-sum daily power production and consumption. Granted, it requires modifying lifestyle choices as well as using power from a variety of sources. Doing this on a boat is a pipe dream right now, but you gotta love the creativity - and the power of these fresnel lenses that this guy also sells:
To be more realistic, using solar for heating water even onboard a boat can be readily achieved. Cooking with a solar oven is also do-able. If my main two power drains are the D/C frig and radar, I have to believe it is possible to input enough power to equate to what is used - since those high efficiency cold cathode fluorescent lights and LED nav lights require ... nothin' almost
The curvature of evacuated tubes puts them at a constant 90-degree angle to the sun for maximum energy transfer to water - or - to glycol for circulated heat. It's even possible to capture the energy of the day into salt for use at night.
With all of that said, I'm just focusing now on the safest way to hook up a couple of solar panels to a couple of wind generators to safely charge 6 AGM batteries using electronic devices such as the ACR and other linear rectifying devices that can direct energy flow and others that can manage this flow to equalize charge to prevent inaccurately sensing false loads. My concern is that I will not properly connect the wind generator to the board for charging while maintaining the ability to dump charge to a diversion load and not cause problems for my solar charging going to this same board without even introducing the additional charging source of the engine alternator.
Wow, I must be getting tired
... OK, so basic wiring 101 for hooking a pair of solar panels to the board AND a pair of wind generators so that everything plays nice and diversion loads are accessible without causing additional problems ??? How would you do it?
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