Challenges with Solar on boats

[jheldatksuedu]

KISS is keep it simple STUPID, that had been used numerous times in my direction..

As for controller being so close to the battery, do you think they could measure the battery temperature that far away (1 ft) from the battery and be able to stop damage. I'm sure either the lawyers had them add that, or they think that might make people believe that their product is superior over ones that don't mention that. The only way they could measure temperature accurately is with an electric temperature probe and that could work 30 feet away without a problem. I'm pretty sure the only reason to have the controller close to the battery is to limit wire length and voltage drop in the wire due to the excessive current flow, if further away the controller might not sense a good battery voltage and try to pump too much current into an overcharged battery. I've already discussed that, my voltage drop in 30 feet of 10 gauge will be .18 volts, (6 x.03) in a 48 volt battery system that is as close to nothing as one could hope to get, in fact I could probably use 14 gauge if I wanted and still have no problem, compare that to 6 gauge in price.

As for having hands on experience, I've got tons of it, I build everything and I know what I'm doing. I designed and built gloves for the nasa space astronauts, and designed and help build and test the first fiberglass highway bridge open to the public. I've been building electronic and computer thing my entire life. I'm not afraid to look at problem in a different than normal approach and come up with a creative solution to the the problem. I repeat I am not stupid. I seek advice from people willing to understand the problem and that can do more than say that's not normal, I'm getting very little useful knowledge here.

[witzgall]

ah, but you are focusing on one issue, getting the most out of your panels into batteries, and ignoring other, much more important issues. The first one that comes to mind is how do you know the charge in each of your batteries? Guessing or estimating does not work, and voltage is a lousy indicator of state of charge. Secondly, the total energy that you can get from a battery, or a bank of batteries, is influenced to GREAT degree by the rate in which they are discharged. Read up on https://en.wikipedia.org/wiki/Peukert%27s_law. This is in relation to their capacity. So the faster you discharge in relation to their capacity, the less total power you can get from a battery. This alone will influence how much energy you get to use, way, way, way, way (get it) more than your savings by doing what you propose. Put your batteries together in a single bank, and you minimize this effect as much as possible.

I am all for trying out new things. Hell, check out my thread on LTO batteries I just started. But Physics is Physics. Trust me when I say, if you do it the way you propose, you will significantly diminish both the life expectancy and the usefulness of your energy storage system. And you will spend more $$$ in the end.

Chris

Originally Posted by jheldatksuedu

There are losses in all electrical systems, but with solar we are working with such small amounts of energy so it is important to conserve what ever we can. Sure you can solve this with bigger wires, and I understand why you want to put the controller near the battery but if you don't have the voltage loss through the wires then the controller can read the voltage of the battery acurately 30 feet away and do a good job of charging. Bigger wires ad cost and weight. We all spend a lot of time attempting to eliminate both of those.

I taught at Kansas State University for 30 years, Physics, Mechanical Engineering and Electrical enginneriing.

I have not forgot my electronics, I know exactly what I am proposing and thought it out very well. What you refuse to seem to realize is that ther might be more than one way to do the same problem. New Ideas are often scoffed at by people unwilling to challenge the staus quo.

[jheldatksuedu]

How does the amount of useful power change when you take it out of one 12 volt battery that comes from a 48 volt series connection or it is just standing by itself. Normally when you have multiple batteries on a boat they are connected so that you are just using one at a time. At least that's how all the boats I've been on are set up. Maybe they change that when they go to a parallel battery bank for solar charging and then use the parallel bank for discharging too. If so you risk having nothing when they go dead, no back up. Why can't you determine the state of charge of each individual battery, you have the ability to hook up to it all by itself?

As for insurance I have no desire or need for it.

[Kenomac]

Originally Posted by jheldatksuedu

KISS is keep it simple STUPID, that had been used numerous times in my direction..

As for controller being so close to the battery, do you think they could measure the battery temperature that far away (1 ft) from the battery and be able to stop damage. I'm sure either the lawyers had them add that, or they think that might make people believe that their product is superior over ones that don't mention that. The only way they could measure temperature accurately is with an electric temperature probe and that could work 30 feet away without a problem. I'm pretty sure the only reason to have the controller close to the battery is to limit wire length and voltage drop in the wire due to the excessive current flow, if further away the controller might not sense a good battery voltage and try to pump too much current into an overcharged battery. I've already discussed that, my voltage drop in 30 feet of 10 gauge will be .18 volts, (6 x.03) in a 48 volt battery system that is as close to nothing as one could hope to get, in fact I could probably use 14 gauge if I wanted and still have no problem, compare that to 6 gauge in price.

As for having hands on experience, I've got tons of it, I build everything and I know what I'm doing. I designed and built gloves for the nasa space astronauts, and designed and help build and test the first fiberglass highway bridge open to the public. I've been building electronic and computer thing my entire life. I'm not afraid to look at problem in a different than normal approach and come up with a creative solution to the the problem. I repeat I am not stupid. I seek advice from people willing to understand the problem and that can do more than say that's not normal, I'm getting very little useful knowledge here.

And I attended Harvard University where I received a Phd in Hematology prior to becoming Lance Armstrong's personal phlebotomist. If you don't believe me... just check out my Facebook page.

[witzgall]

Did you read the link I provided?

Yes, connecting them in parallel helps to increase the usable total power you can get from a bank, by diminishing the Puekert's effect.
If you are so worried about line losses from the panels to the batteries, just wire them in series to get the voltage as high as you can, select an appropriate MPPT solar controller, and then connect that to a SINGLE 12v source (on or multiple batteries in parallel.) Done, easier and it works. Oh, and put the controller as close as you can to the batteries.

I did not mention insurance???

Chris

Originally Posted by jheldatksuedu

How does the amount of useful power change when you take it out of one 12 volt battery that comes from a 48 volt series connection or it is just standing by itself. Normally when you have multiple batteries on a boat they are connected so that you are just using one at a time. At least that's how all the boats I've been on are set up. Maybe they change that when they go to a parallel battery bank for solar charging and then use the parallel bank for discharging too. If so you risk having nothing when they go dead, no back up. Why can't you determine the state of charge of each individual battery, you have the ability to hook up to it all by itself?

As for insurance I have no desire or need for it.

[newhaul]

I am sorry if anyone ever takes the K.I.S.S. acronym personally it is not personal. Ask any of your dock mates. They all will im 90%sure tell you the same thing. It is a moto with no personal connection.
Let us know how big the arc's are when you have an unintended contact with your 12volt house ground and your 48 volt bank floating ground.

[socaldmax]

This has been pretty entertaining!

You guys have pretty thoroughly covered every aspect why nobody in their right mind would ever want to charge a 4S bank while discharging only 1 battery out of the bank at a time.

somebody isn't listening, and probably never will.

[john61ct]

KISS is not meant to imply anyone's calling you stoopid, stop being so sensitive.

Originally Posted by jheldatksuedu

How does the amount of useful power change when you take it out of one 12 volt battery that comes from a 48 volt series connection or it is just standing by itself. Normally when you have multiple batteries on a boat they are connected so that you are just using one at a time. At least that's how all the boats I've been on are set up.

Wow, just wow. Out of hundreds of boats with a house bank every SINGLE one of them put all the batteries together into a single bank!

You've been told about Peukert's Law several times right here in this thread, guess your professor qualifications means you no longer need to look stuff up you never heard of?

And the very few times I've ever heard of anyone discharging at a different rate from charging they were charging at 12V, and sometimes using 24V for example a trolling motor: see ​http://www.yandina.com/troll24info.htm

And the temperature issue isn't about safety, temperature COMPENSATION is required to charge the batt properly, and only expensive SCs have dedicated remote temp sensors.

Regarding currents, obviously after the controller's lower than from the panels!

Really, study up on the basics first, you may be smart maybe but you're sure not displaying it here.

An no insurance OK, but the safety codes are there from the industry's long experience, and it's pretty silly to ignore them when the vast majority of fires aboard are from electrics.

[john61ct]

Here you go on why a single bank is better: http://www.smartgauge.co.uk/splitting.html

Longer bank life due to shallower draw down, and actually get more AH's out of a larger bank than the sum of the member batts.

[jheldatksuedu]

Originally Posted by john61ct

Here you go on why a single bank is better: SmartGauge Electronics - Splitting battery banks

Longer bank life due to shallower draw down, and actually get more AH's out of a larger bank than the sum of the member batts.

Finally somebody was polite enough to get me to actually take them serious, I did read about this Peukert's effect and I'll have to take that into account and do some thinking, I did learn something here that does affect the design of a system.

I still don't think I am interested in putting all my eggs in one basket kind of thing. Maybe 2 banks.


replying to the others

As for temperature compensation on a device a foot away from the battery that's mostly ********.

I already mentioned why you don't want he panels in series, you can go back and read that, also that's common knowledge.

When someone uses the language that they did when they said KISS I do take it personally, it's the rest of the message that sets the tone.

If voltage is a lousy indicator of state of charge, how do you propose to do it?

As for floating ground, if you read, nothing is actually floating, I will be the only one ever doing anything on my boat, in addition the only way somebody would get to the battery system ground is to connect to a battery terminal. Anybody doing that better know ahead of time and most likely check voltages so they know what they are dealing with or they get exactly what they deserve. In a series battery bank of course there are all kind of voltages on the battery terminals.

As for insurance I always carry the minimum required by law.

[barnakiel]

Sure 100 by 12 makes 8 except when someone cares to educate themselves on how a panel rating is established. Read on. Google your friend.

Cheers,
b.

[john61ct]

Originally Posted by jheldatksuedu

I still don't think I am interested in putting all my eggs in one basket kind of thing. Maybe 2 banks.

What have you got critical? Make your Starter a robust enough true deep cycle, can act as backup for just that stuff. No need to be as big as House.

Originally Posted by jheldatksuedu

As for temperature compensation on a device a foot away from the battery that's mostly ********.

Better than the ambient sensor located far away. Victron for example doesn't go sensor wire until you get up into their very pricey models, their bargain basement 75/15 (under $100) is internal sensed, and they're well respected technology.

Originally Posted by jheldatksuedu

If voltage is a lousy indicator of state of charge, how do you propose to do it?

There is no if about it. That's why people buy Battery Monitors, as I mentioned earlier. SmartGauge is most accurate and user friendly. The others count amps in and out and need some attention to get accurate, many people use both.

Search for "Battery Monitor" on this page http://www.pbase.com/mainecruising/boat_projects

I also recommend you read and absorb everything else Maine Sail writes.

Originally Posted by jheldatksuedu

In a series battery bank of course there are all kind of voltages on the battery terminals.

But that is irrelevant, you join them up into a 12V or 24V bank and treat it as one big battery, because that's what it is.

Originally Posted by jheldatksuedu

As for insurance I always carry the minimum required by law.

What law? Being on a boat it varies from place to place. No one is arguing you need to have insurance, that's not the point.

But with lives on the line, it behooves you to make sure the safety measures line up with what any insurer would look for, in order for your boat to qualify.

[StuM]

Originally Posted by jheldatksuedu

There are losses in all electrical systems, but with solar we are working with such small amounts of energy so it is important to conserve what ever we can. Sure you can solve this with bigger wires, and I understand why you want to put the controller near the battery but if you don't have the voltage loss through the wires then the controller can read the voltage of the battery acurately 30 feet away and do a good job of charging. Bigger wires ad cost and weight. We all spend a lot of time attempting to eliminate both of those.

• So 4 x 100W , "12V" panels @ say 17V = 68V and 5.9W from the panels to the controller.
• Charging voltage to a 48V battery bank should be around 56V with a correspondingly higher Amperage from the controller to the batteries.

Which side of the controller should have the thicker wires and shorter run to minimize energy loss?

[ramblinrod]

Originally Posted by jheldatksuedu

If you will look between the trees that are blocking your view you will find that I don't intend to have one battery fully discharged, even though I did ask what would happen if that was the case. I mentioned switching between batteries numerous times to have them equally discharged, but wondered what would happen if one was more discharged than the rest. I have decided that would not be a problem, the other three batteries would allow current to flow, if too much current flows they will boil, but I'm pretty sure that their voltage would increase enough that the current would be limited by the controller and not cause that damage, and the discharged battery will eventually charge back up. Worst case I foresee could be a 10 and 3 12's, the 12's would increase to something above 14.7 and total series voltage would then give a total of 54.1 plus some for the slight over voltage due to excessive charging, the 48 volt charger would be programmed to slow down before it nears 58.8 so you would basically have 4 volts pushing extra current through the series of batteries. I suspect that would be OK, but have not tested it yet.

It sure would be nice if you people would take the time to understand what I propose and not jump on the band wagon to call me stupid. I am not stupid.

I'm basically done here I'm not finding anyone that has any knowledge of this type of system that can answer my questions and I'm tired of trying to teach people who have no desire to learn. Stay with your status quo and be happy with your ignorance.

That tree is still smacking you in the forehead.

Are you listening?

Knock, knock, knock.

Kirchoff.

Choice 1 - Ensure all batteries are kept as close
as possible to 100% SOC, so you will get somewhere near to
their life expectancy, and now your charge current is limited by the fully charged batteries in series.

Choice 2 - Leave all batteries in series at a partial SOC so you can get some decent current to the loaded battery, (and kill your batteries at a fraction of life expectancy).

Your proposed system will either deliver very low charge current, or
kill your batteries prematurely, compared to a conventional system.

PS, you may not have learned anything here, some people can't, but you have certainly been schooled.

[Rorzech]

When it comes to what kind of system you want, Compromising is the last thing yo need to do. You can't mess with batteries the way you want unless you spend the big bucks on the sophisticated equipment that will allow you to program it to those parameters you are looking for.So you would be checking out equipment from Schneider/Xantrax, OutBack , Magnum, Midnite Solar. That's all high end stuff and any of them will do what you want. You're an engineer so installation will be a picnic for you. I'm only an HVAC guy and I put a big schneider system in 12 years ago to run my whole house on a forklift battery for years now. Do it right the first time and learn from other peoples mistakes rather than your own or it WILL cost you big. Cheers