Author Topic: looking for a cheap way to track watts or amp hour output  (Read 6524 times)

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Frank S

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looking for a cheap way to track watts or amp hour output
« on: October 19, 2014, 01:17:26 AM »
My system is not in any way automatic.
 nor will it be anytime soon but I would like to come up with a simple way to track the amount of amp hours & watts both consumed & generated.
 on my array I can tell how many Amp hours I am getting per day put into my bank. the bank voltage and estimate the state of charge .
 but when I switch to my generator and go off of the inverter at this time I have no way of knowing what my usage is or how many amp hours is being put into the bank from the 120 apm engine ALT or the 60 amp schumacher battery charger .
 With these shorter days the Array 1.1KW array does good to have a weekly average of 400 ah per day. It rarely ever reaches more than 40 amps charging levels as well.
 What I would like to have is a series of meters or a set up that will let me know how many Ah I am getting from the battery charger & the alternator as well as how many watts are actually being consumed either while on the generator or the inverter .
 Does anyone have any simple ideas?
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Frank S

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Re: looking for a cheap way to track watts or amp hour output
« Reply #1 on: October 19, 2014, 02:12:42 AM »
I have some thoughts about adding 2 or 3  more 60 amp PWM charge controllers 1 for the battery charger and 1 or 2 in parallel for the alternator  I could then monitor the total DC output and set them to drop out 1 by 1 if need be but that sounds like an expensive way to do what I am wanting to do and I still would need a way to monitor the total  120/240 VAC consumed .
 this is a 12v system with about a 1200 Ah bank, which one day I plan to upgrade to a higher DC volt system when I can afford to buy an inverter large enough to have 120/240v output at that time I will probably also add another 2 KW or more of solar.Then I am pretty sure I will dump the PWMs and go with a midnight classic 
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gww

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Re: looking for a cheap way to track watts or amp hour output
« Reply #2 on: October 19, 2014, 09:06:32 AM »
I just put a trimetric battery monitor on my system but it wasn't cheep.  $187. 
gww

DamonHD

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Re: looking for a cheap way to track watts or amp hour output
« Reply #3 on: October 19, 2014, 09:19:27 AM »
As part of another project I'm going to produce remote W measuring (and thereby Wh also) based on the OpenTRV sensor platform and possibly using the INA219, which should draw little enough power (microwatts if done right) do be able to deploy one with every few PV panels and have them go quiet when the sun goes down, ie have them powered direct from the panels.

I use the INA219 direct on my Raspberry Pi to track my system's live power consumption (yellow line here):



That device is bidirectional so you could measure power/energy in and out and voltage.

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gww

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Re: looking for a cheap way to track watts or amp hour output
« Reply #4 on: October 19, 2014, 09:31:53 AM »
Damon
cool
gww

Frank S

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Re: looking for a cheap way to track watts or amp hour output
« Reply #5 on: October 19, 2014, 08:07:19 PM »
I just put a trimetric battery monitor on my system but it wasn't cheep.  $187. 
gww
not as pricey as one way I was considering.
 the only other thing is when my generator starts  because of the ship to shore switch-gear the coach goes off the inverter
 It automaticly switches to the generator but there is some issue with going the other way. when I shut off the generator I have to manually reset the relay to go back on the inverter.
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phil b

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Re: looking for a cheap way to track watts or amp hour output
« Reply #6 on: October 20, 2014, 02:26:04 AM »
I bought a Trimetric 2025 a few months ago. They are nice and simple to use as a gas gauge. When mine arrived, part of the display was not lighting at all. The company took about 5 days to repair and return it, including shipping time. They were great to deal with. Here's a link to the meter on NAWS:http://www.solar-electric.com/catalogsearch/result/?q=Trimetric+2025&cat=0 My Trimetric is mounted next to Midnite's battery monitor. I can glance at the battery monitor for volts and the Trimetric for amps or % battery amps used.

The Classic charge controllers on my system have all that and more built into the software. I can check any parameters that I'm interested in and much more from my laptop. When the software starts on the laptop, first up is kWh. They aren't cheap though.

I just put a trimetric battery monitor on my system but it wasn't cheep.  $187. 
gww
not as pricey as one way I was considering.
 the only other thing is when my generator starts  because of the ship to shore switch-gear the coach goes off the inverter
 It automatically switches to the generator but there is some issue with going the other way. when I shut off the generator I have to manually reset the relay to go back on the inverter.

Sounds to me your inverter can't handle the surge. When the air conditioner just switches off and I flip the transfer switch from grid to the 3500 watt inverter, the AC unit hums but won't start. The locked rotor makes the amps go high enough to flip the breaker. I can reset the breaker and go back to grid power or wait for a few minutes until the pressure in the AC unit goes down and not blow the breaker again if I want the inverter to carry the load. Our grid power also has a about 130 VAC most of the day, while the inverter is locked on 120 VAC.
Phil

Frank S

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Re: looking for a cheap way to track watts or amp hour output
« Reply #7 on: October 20, 2014, 09:13:16 PM »
the Ac units draw about 45 amps @ start up  roof mounted Dou-therm 15 amps run. my inverter can handle the  1500w heater at least 1 of them but we hardly use the heaters unless the generator is already running and we are cooking
 the cook top is 220v so the inverter cannot even think about it.
   if the bank has as much as 12.3 v and receiving "0" charge the inverter can handle the 21cf side by side Roper fridge freezer + the coffee maker + the 32" tv and a toaster at the same time .
 the inverter was removed from service out of an AT&T vehicle  the brand actually says AT&T but it is identical to an AIMS
 it is 1800w 3600w 2 minute surge PSW and weight about 40 lbs .
 as long as I am getting at least 30 amps from solar and if the bank is @ 12.8v it will even handle my 12" Chraftsmen metal lathe & a 3/4 hp 8" bench grinder with 6  60w equivalent CFL lamps  as long as the wife doesn't decide to make toast with everything else running .
 My 3000 plus MSW Xantrex  just barely runs the lathe & the grinder with the lights any additional and it falls flat on its face but it only weighs about 20 lbs 
 Since I want to eventually upgrade to a 48v system any monitoring or meters I buy should be able to be used after the upgrade I don't want to buy something 2 or 3 times
 the Trimetric 2030 looks like it can do just that.
 I also need a way to monitor how many watts are being used while on the generator as well.   
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ChrisOlson

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Re: looking for a cheap way to track watts or amp hour output
« Reply #8 on: October 20, 2014, 11:59:29 PM »
Since I want to eventually upgrade to a 48v system any monitoring or meters I buy should be able to be used after the upgrade I don't want to buy something 2 or 3 times

Frank, I would hesitate to buy too many things if you plan on upgrading your system.  All that you want is integral in most high-end off-grid power systems.  We have complete system monitoring and controls on our kitchen wall that tells us everything we need to know about everything - and it's all integrated with the system and comes with it without using a bunch of hacked together meters:





We have a TriMetric there and the only reason we have it is because it has large easy to read numbers that can be seen from clear across the kitchen and we can see at a glance that our batteries are at 77% SOC tonight.

We also have a much more sophisticated Battery Monitor in the power room:



The Conext monitor is considerably more expensive than the TriMetric but it integrates with the XW and SW power systems over Xanbus.  It keeps track of the number of lifetime cycles on your batteries, the lifetime average depth of discharge of your battery bank, tracks two midpoints on your battery bank to tell you if your bank is balanced or not, and even tells the AGS to start or stop the generator based on battery SOC.  And it logs all your battery bank's operating parameters, including for the midpoints, once a minute for over 10 years.

My wife and I have been where you are right now and I pieced things together.  When we first built here it was new and exciting and I had a blast designing new things, trying new things, and coming up with ways to make it work better.  It took us 7 or 8 years, it started getting old and too much maintenance and too much work, and we decided we're going to be off-grid for the long term.  We decided that it has to be easier and more automatic because we don't want to baby sit it all the time - we had gone NO PLACE in 7 or 8 years because we had built a system that had to be constantly attended to.  NOTHING we bought for our original system was able to be used when we finally decided that we had to do something different if we're going to be in this for the long term.

Frank S

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Re: looking for a cheap way to track watts or amp hour output
« Reply #9 on: October 21, 2014, 01:18:50 AM »
Chris' I agree with you 100% about not wanting to spend much on a system that I hope to completely replace one day, do so with a system that will pretty much take care of itself.
  My wife has learned that she shouldn't attempt to make coffee and toast at the same time while the fridge is running especially early in the morning. At the risk of having to start the generator. I like to get up early and will usually fix myself some breakfast so the generator gets fired up anyway so it doesn't matter how much is in the bank.
 I mainly am thinking of adding a few hacked in meters so to speak so she can learn a little more about conservation of energy LOL
  also it will afford me a better idea of how much is being produced/ stored & consumed.
  BTW I know the feeling about having to cive constant child care to our system since it is small it is like chasing and picking up after a 2 year old child.
 We have to plan a long while in advance if we are going to be gone for a few days. to make sure 1 the bank gets a few top off & absorb charges just before we are going to be gone , but more importantly to deplete the food suply in the fridge & the freezer in case the inverter kicks off while we are gone.
  The last time we left we took 2 months to eat every thing in the freezer and empty out the fridge. I made sure the bank was topped off the array facing south and everything but the fridge was either switched off or unplugged. We were gone for 5 days most of the time while we were gone it was heavy clouds during the day but on the day we returned @4 Am somehow the bank was at 12.6v and the inverter light was still green.

 
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ChrisOlson

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Re: looking for a cheap way to track watts or amp hour output
« Reply #10 on: October 21, 2014, 08:29:31 AM »
Frank, those are the things that start getting old after 7 or 8 years.  When you can't leave for fear something is going to quit or fail, it gets to be a hassle.  That's what made us finally decide crap or get off the pot.  We ended up married to our house and couldn't leave it for fear something would happen.  That's not a good way to live.

Frank S

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Re: looking for a cheap way to track watts or amp hour output
« Reply #11 on: October 21, 2014, 02:37:17 PM »
Chris; When we returned from Q8  and made the decision to temporary live in this old motor coach it was supposed  to have been only long enough to locate the land we wanted to settle on and build. However I bought it from a friend while we were still out of country knowing that it and and most of my other acquisitions were going to require some work to get things in shape . We set up at another life long friends shop that needed to be either rebuilt to get up to code or torn down I made the decision to put life on hold to do this for him now a year & a half later we are still about as far away from making our final move as we were the day we landed in the US.
 The good thing is I have had time to learn much about how I want to design and set up our home-owned power company with many similarities to the system you have ended up with.
 At this point I can ill afford to spend much more from our original budget before we actually start to build my shop & our house out in west Texas.
 I do however feel that I still have some learning or familiarity curve before I will be comfortable with what I want to accomplish.
       
I live so far outside of the box, when I die they will stretch my carcass over the coffin