Anotherpower.com Forum
Project Journals => User Journals => Chris Olson => Topic started by: ChrisOlson on March 07, 2012, 08:43:10 pm
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I got this thing from MidNite Solar, and it's great:
[attachimg=1]
I got it mounted on the kitchen wall right by the cupboard. It shows bank capacity - right now we're at 90% with the wind blowing tonight. The Green LED on the left shows how the system is maintaining the bank - if it's green the bank has been fully charged on a regular basis. If it switches to yellow then the bank hasn't been fully charged for a week. If it switches to red the bank hasn't been fully charged for two weeks.
The reason I like it? It's a simple thing. You can tell at a glance from across the room where the bank is at and you don't have to get right up to it to study little digital numbers or anything.
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Chris
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I'm surprised that you would like such a thing. I assumed you would rather look at real numbers, real amps in or out, real voltage, real cumulative Ahrs etc. The Midnite Battery Meter is a nifty thing in some circumstances, but for a guy who does the nuts and bolts engineering of his own power production, I have to admit, that I'm a little shocked that you are satisfied to look at a single LED on a graduated scale, with an unknown algorithm, and feel satisfied with that information.
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I have mine mounted on the wall of my car port. When I leave and later arrive, I have an at-a-glance look also. I have caught when I had a ground fault, tripped main breaker and tripped panel breakers by that at-a-glance reference.
I have been able to get past the extremes the meter represents with a only a couple of volts swing between 100 and 60 to 70 percent of charge.
Anyway, no matter, this meter is a valued tool for my RE project. I have mine connected to 48v of the 72v array. I kinda have an idea of the condition of the other 24v group. I've been thinking about getting one more for that set but I only hold off due to returning to a 48v system may be in the near future.
(http://www.anotherpower.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=20086&g2_serialNumber=5)
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Oh, I can go out in the utility room and look at all them numbers too. What I like about the MidNite meter is that when we get up in the morning and walk out to the kitchen to make coffee and breakfast it's the first thing we see. At a glance from across the room I can tell where the bank is at.
I've been on a mission for the last year to get my system so it takes care of itself and doesn't have to be monitored all the time, and rarely requires any interaction from me. This little $69 meter fits right in with that mission because it's simple and you can see what you need to know by just walking by it. You don't have to stop and study a bunch of numbers to figure out what the frick is going on. And that's what I like about it.
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Chris
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Oh, I can go out in the utility room and look at all them numbers too. What I like about the MidNite meter is that when we get up in the morning and walk out to the kitchen to make coffee and breakfast it's the first thing we see. At a glance from across the room I can tell where the bank is at.
I've been on a mission for the last year to get my system so it takes care of itself and doesn't have to be monitored all the time, and rarely requires any interaction from me. This little $69 meter fits right in with that mission because it's simple and you can see what you need to know by just walking by it. You don't have to stop and study a bunch of numbers to figure out what the frick is going on. And that's what I like about it.
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Chris
That's exactly why I got mine. I use mine for solar panels and have gotten where I can tell, that morning, if my kids were up late playing games and watching tv. 8)
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I poked around their site and I could not figure out if I can put this 100+ feet from my battery bank? For in the house and my batteries are in the garage / office across the driveway. I have cat5 across for some metering and probably have a pair or more open for connecting this if it will do it over light wire. It claimed 12.5 Ma draw I think it was. I didn't see any connection diagram or discussion of wiring beyond a S model that you could switch off the LEDs.
Maybe one of the Midnite guys will chime in.
Tom
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I poked around their site and I could not figure out if I can put this 100+ feet from my battery bank? For in the house and my batteries are in the garage / office across the driveway. I have cat5 across for some metering and probably have a pair or more open for connecting this if it will do it over light wire. It claimed 12.5 Ma draw I think it was. I didn't see any connection diagram or discussion of wiring beyond a S model that you could switch off the LEDs.
Maybe one of the Midnite guys will chime in.
Tom
Tom, I would be glad to check the accuracy of this meter adding 100 feet of wire between it and my batteries. Could you let me know the size of wire you would like to test and I will have at it.
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Tom, I would be glad to check the accuracy of this meter adding 100 feet of wire between it and my batteries. Could you let me know the size of wire you would like to test and I will have at it.
I think Tom said he had cat5 cable. That should be 24AWG conductors.
The 'bot says:
<RossBot> 24 AWG wire is 0.000317 square inches (0.204731 square mm, 0.510560mm dia), 81.961293 ohms per km
40 metres (130 feet - well, Tom did say "over 100 feet") = 80 metres total (40 out + 40 back) = 6.56 ohms.
Do you have a 10 ohm resistor handy? Sticking that in series with one lead would be the equivalent of close to 220 odd feet of cat5 cable (resistance wise anyway). If it works like that, it should be fine with anything less!
Oh, and:
<RossW> !ohmslaw 10r 12.5ma
<RossBot> 125.000 millivolts at 12.500 milliamps through 10.000 ohms for 1.562 milliwatts
So you won't need a power resistor. It should indicate about 0.125V low. Not sure if thats enough to worry about or not.
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Tom, I would be glad to check the accuracy of this meter adding 100 feet of wire between it and my batteries. Could you let me know the size of wire you would like to test and I will have at it.
I think Tom said he had cat5 cable. That should be 24AWG conductors.
The 'bot says:
<RossBot> 24 AWG wire is 0.000317 square inches (0.204731 square mm, 0.510560mm dia), 81.961293 ohms per km
40 metres (130 feet - well, Tom did say "over 100 feet") = 80 metres total (40 out + 40 back) = 6.56 ohms.
Do you have a 10 ohm resistor handy? Sticking that in series with one lead would be the equivalent of close to 220 odd feet of cat5 cable (resistance wise anyway). If it works like that, it should be fine with anything less!
Oh, and:
<RossW> !ohmslaw 10r 12.5ma
<RossBot> 125.000 millivolts at 12.500 milliamps through 10.000 ohms for 1.562 milliwatts
So you won't need a power resistor. It should indicate about 0.125V low. Not sure if thats enough to worry about or not.
Yes, I missed that about Cat5 cable. Thanks Ross. Getting the egg off as I type. ;D I think I was thinking " Light " wire. I don't know either. :-[
Yes, I do have a 10ohm resistor. Which end goes where? ??? Just kidding.
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I was looking for the propaganda that came with that meter but can't find it. IIRC, it said that when the meter says 50% on a 24 volt system with lead/acid batteries (you have to set a jumper in there for the battery type), that the voltage at the bank will be about 24.25 volts. And it shows 100% when the bank is at 25.5 or above.
The wire going to the meter is about the size of the wire used in ethernet Cat 5 so I see no reason why it wouldn't work with a long run of Cat 5 wire on it. It'll have some voltage drop in the long wire, but it's no big deal if it shows 40% instead of 50%. After you get used to it and you know the meter is showing 50% when the bank is at 24.3 volts, or whatever, it still serves the same purpose - it's a simple glance at it and know right away where the bank is at.
If you get up in the morning and see it there on the kitchen wall and one of the red LED's is on, then you're getting low on power. If it's yellow or green life is good and might as well brew up a pot of java and worry about the power system later. And that's the idea of the meter, to my way of thinking. It's purpose is not to know that the bank voltage is 24.38547274648 volts and it's at exactly 53.57583% SOC. It's purpose is a simple device to show "yup, the system is working normally" or "damn - we got a problem" without having to go out to the utility room to ascertain that.
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Chris
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I put a Trimetric and Mate right in the dining room. The Trimetric is set on amps. So when I see the batteries are at 23.6V a half hour before the sun comes up, and I look right next to it and see minus 58 amps, I know the wife is using the hair dryer and that 23.6V is nothing to worry about. The thing I don't like about the Midnite is that that green light will swing down, showing a low state of charge when actually, there might just be a temporary heavy load on the system.
I still think it's a useful device in some circumstances, and the price is certainly right, it just doesn't give enough information for my liking.
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The thing I don't like about the Midnite is that that green light will swing down, showing a low state of charge when actually, there might just be a temporary heavy load on the system.
Oh sure, it will do that if there's a heavy load on someplace. But it comes right back up when the load goes off. I don't need that close of monitoring because my generator will start under Peak Load Management Mode if there's a big load for more than two minutes. It takes more than my wife's hair dryer - it usually takes both the range and the water heater to kick in at the same time, plus other normal loads, to get the gen to start for Peak Load. If we're pulling 7-8 kW off the inverters with the bank fully charged and no incoming power it'll dip down to into the yellow. But as soon as the gen starts and comes online it goes right back up into the green.
If we didn't have the inverters set up for Peak Load with the gen then I might like an ammeter to see what's going on. But for me, the idea for the whole last year is to build a system that takes care of itself. I spent over 8 years babysitting a half-a$$ed power system. I decided I'm going to spend the next 8 years fishing and doing stuff I want to do, and not even look at my power system unless some red light or alarm goes off that says there's a problem. So for me, this meter fit in very nicely because if she's all green the system is working. If it goes yellow or red and stays there, there's a problem that needs my attention.
I do have a door bell hooked up to the ALM on the master inverter and it triggers that door bell if the bank ever gets down to LBCO and the inverter is about to shut down because of low bank voltage. But that better never go off because that means the generator had a massive failure like a rod hanging out the side of the block or something.
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Chris
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I do have a door bell hooked up to the ALM on the master inverter and it triggers that door bell if the bank ever gets down to LBCO and the inverter is about to shut down because of low bank voltage. But that better never go off because that means the generator had a massive failure like a rod hanging out the side of the block or something.
<smirk> Or someone left the isolator off while changing oil, or something :)
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<smirk> Or someone left the isolator off while changing oil, or something :)
Ross, I'm a thick headed Norwegian. But by gully, I learned my lesson on that one ;D
I guess the other "monitoring tool" I like in the kitchen is our little weather station that's hanging on the wall
[attachimg=1]
The wind is blowing at 21 and it must be gusting up to 30. That means the turbines are putting out at least 150, maybe 200 amps. My wife is using at least 4 kW in the kitchen. When I came in to clean up for supper she's got a big pot of chilli on the induction range and some garlic bread in the oven. And she's got a big slow cooker thing plugged in with some homemade beef stew in it that'll cook overnight for dinner tomorrow. The little MidNite meter is ALL GREEN baby.
[attachimg=2]
Life is good 8)
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Chris
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The little meter was intended to be a very simple at a glance health check of the battery's. As has been pointed out it will only be dead accurate when there is not as big load or charge current. I think its most valuable tool is just as Chris has pointed out that at a glance status. It also lets you know the last time the bank was fully charged.
As for wire length I think that was hit right on the head it is a simple voltage drop issue. If 130ft of Cat5 has a drop of .12vdc I would say that is acceptable and if there where 2 pairs available that would cut that number down. The meter basically hooks to battery + and - with a 1-2 amp fuse/breaker.
Ryan
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The little meter was intended to be a very simple at a glance health check of the battery's. As has been pointed out it will only be dead accurate when there is not as big load or charge current. I think its most valuable tool is just as Chris has pointed out that at a glance status. It also lets you know the last time the bank was fully charged.
As for wire length I think that was hit right on the head it is a simple voltage drop issue. If 130ft of Cat5 has a drop of .12vdc I would say that is acceptable and if there where 2 pairs available that would cut that number down. The meter basically hooks to battery + and - with a 1-2 amp fuse/breaker.
Ryan
Sounds perfect for my plan to get the system status at a glance for Amy to be able to see if things can go on the inverter. I spend time where the system lives so I am usually aware of what is going on. As soon as I start talking about watts, amps and volts VS wind power and PV the poor woman just gets lost. ;D
I also discovered a full unused Cat5 cable so I can run it over pairs of 4 #24 to the house and pull something heavier from there.
Sorry to divert the original post.
Thanks for the info, Ryan. Now, where is the best place to buy one? Saw one on Amazon for list price but by the time I got it would be $85 after tax and shipping I think.
Tom
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So, I did a bit of looking around and got a much better price than the one on Amazon. Northern Arizona Wind and Sun (http://www.solar-electric.com/mnbcm.html) is shipping one to me Monday. $63.84 delivered compared to $69 list plus tax and delivery for $85 through Amazon from Northern Tool.
Hope it helps simplify things for Amy.
Tom
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Hope it helps simplify things for Amy.
Yep, it will. My wife likes it. She looks at it when she's using a lot of power and as long as nothing red comes on she knows everything is fine. She doesn't really care about the details of what keeps the green LED's on. It just gives her peace of mind that as long as it stays yellow or green that what she's doing is not killing our power system.
That's actually the main reason I put it in the kitchen instead of the utility room - for her :)
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Chris
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This is the second time I have heard you refer to the colors of the LEDs changing to yellow and red.
The way I read the manual, it takes a full week of not reaching full charge to turn the LED yellow, and two weeks of not receiving a full charge to turn it red. I don't know exactly what the definition of "full charge" is, but wouldn't it be possible to see a green light down at 10% after six days of no wind, and wouldn't that be something to be concerned about?
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There are 2 different sets of LED's there are 3 LED's vertically in the little window to the left of the 10-100% scale for the last time the battery's where full. Red, Yellow and Green. Red means the battery's have not been full in 2 weeks, Yellow means they have not been full in a week and Green means they have been full recently (Within a Week). The other set indicate the voltage of the battery at the moment in 10-100% increments.
In the picture below it is a little hard to see but you will notice a red LED on in the yellow circle. The MNBCM or battery meter has 10-100% LED's and the first 2 or 3 are red then there is 2 or 3 Yellow (I think it is 3) and the rest are green. I should know the correct numbers and will go look in a bit. The 10% red LED will also blink when you go below 10% ask me how I know ::)
[attach=1]
Anyhow sorry about the bozo in the picture I did not take time to crop myself out or take the Kimber off either apparently ::)
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but wouldn't it be possible to see a green light down at 10% after six days of no wind, and wouldn't that be something to be concerned about?
VF - maybe a closeup picture would help - this is the meter when I first installed it:
[attachimg=1]
You see the red LED on the left. That means the bank hasn't been fully charged for two weeks. It took it until the next day to figure out that the bank was fully charged and that one went green. The 10, 20, and 30 are red. The 40 and 50 are yellow. 60-100% show green.
So if the meter is showing All Green, it means the bank has been fully charged in the last week and it's above 60% SOC. If there's anything showing yellow on the meter you're not treating your bank as nice as you could. If there's anything showing red on the meter you're a very bad boy and you should give your batteries away to somebody who will treat them nicer. :)
The three LED's on the left seem to require the bank to receive a full absorb cycle before it will go green.
Here's an example of why I find the little thing useful. When we got up this morning the the SOC showed 100%. The wind blew all night. But now it's down to 60%:
[attachimg=2]
The reason? My wife is cooking breakfast. She's got toast in the toaster (about 1,200 watts). She's got eggs and ham cooking on the induction cooktop (about 3 kW). I'm brewing a pot of coffee (about 1,200 watts). Plus the 'fridge is going, furnace blower is going, my computer, we got a couple lights on because the sun isn't up yet. The load on our bank is probably about 5.5-6 Kw as I write this.
I look around me and see what's on and the meter is still showing Full Green. That tells me immediately that my bank is right up to snuff. I don't need an ammeter to know that we're pulling some decent power off the bank right now. The bank is probably delivering 250 amps to the inverters. If the meter had dipped down into the yellow with the breakfast cooking loads on then I know my bank is down slightly from 100%. But there's not a cloud in the sky and the wind is blowing at about 10 mph. So basically, all my system has to do is rebulk the bank and it will float all day.
That's how I find the thing useful.
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Chris
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I think it just went from the want list to the needed list.
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Anyhow sorry about the bozo in the picture I did not take time to crop myself out or take the Kimber off either apparently ::)
If that is a "work" photo, I am impressed that there are still American businesses that do not see armed employees as a threat!
Seriously.
Thanks for the share.
Tom
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Tom
That is my garage but it was a work related photo. My wife pointed out that if the photo was going in Home Power I should not be packing :o
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The Kimber may be good for a work related photo? May make for more polite customers!
Taking this down a notch for a guy with a much smaller system, I sometimes put a "Battery / Alternator Tester" hardwired into the battery cables at the controller.
It would take a few days for the person to understand it (14V at noon, 12.6V after dark), but they all loved it.
6 LEDs, $3 on sale.
http://www.harborfreight.com/alternator-battery-tester-46972.html
Can only find one pic, and its not a good pic, or the standard way I did it (unusual situation... obviously), but its just to the left of the 2 light oak boards with the controllers/fuses/etc.
G-
(http://ghurd.info/images/Amish/buggyshop.jpg)
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That is my garage but it was a work related photo. My wife pointed out that if the photo was going in Home Power I should not be packing :o
Damn. We're hangin' out with some rough company here. 8)
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Chris