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paulz
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# Posted: 14 May 2021 12:44pm - Edited by: paulz
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Doing a little wiring cleanup today and wondering if I should install the Drok meter I pulled out of my truck, now that my batteries are permanently at the cabin with solar charging.
The remote panel for the Epever SCC displays battery voltage, charge rate, not sure about state of charge but there a picture of a battery with bar graph that moves around. The Drok does have SOC and also amps outbound I believe.
Is there a benefit to having the Drok? No big deal to install, just more clutter.
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Steve_S
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# Posted: 15 May 2021 06:32am
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You have more than one battery so we shall call it a Bank. The Valence Software if you got that working can tell you about the battery itself but not the rest of them. I dunno anything about their software other than some folks got it and can use it... Talked about on DIYSolarForum.
If you place the DROK between your SCC & Inverter on one side & Battery Bank on the other, you will be able to monitor input from SCC & Charger to Batteries and output from batteries to Inverter. That will provide an overview of everything going in/out and the SOC of the battery Bank as a whole. This is where having a well balanced Parallel setup gets important so all battery packs in the bank stay level/even.
There are several different DROK monitors and so there are differences with installation, calibration and such. Most are pretty simple & easy to setup BUT you have got to be certain you do not exceed the amperage handling capacity, they can & do fail terribly if that happens. The ones which use a Hall Pickup sensor are safer in this regard as they won't short & melt down. A 50A shunt can pop like a fuse (scattering molten metal) when hit with 200A 
Hope it helps, Good Luck
Steve
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Brettny
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# Posted: 15 May 2021 10:38am
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The MT50 is almost useless on state of charge. Even worse if theres even a slight load. I have yet to get one but I hear a shunt meter are the way to go. I believe there about $45 on amazon.
Unless the sun is out and my batteries are above 13v the little picture on the mt50 shows 1bar of battery.
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gcrank1
Member
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# Posted: 15 May 2021 12:40pm
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Bar bat graphs: similar to Real Estate Agent photo's of your next dream property.
A good digital voltmeter: Priceless
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paulz
Member
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# Posted: 15 May 2021 08:11pm - Edited by: paulz
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Forgot, I have another meter too, here they are. I think the square one is the Drock, with Hall sensor. The other hard wires. I think they do about the same thing?
My MT50 bar graph moves up and down, not so much the cabin one with the Valence LFPs but the shop one with LAs goes way down if I have the shop lights on for awhile. The MT50s of course have a DVM.
I have hooked the Valence batteries to my PC with the Valence software and home made cable, lots of info there, cell by cell. But I don't have a dedicated Windows device to have on them full time.
Quoting: Steve_S If you place the DROK between your SCC & Inverter on one side & Battery Bank on the other, you will be able to monitor
Not sure I get this. My inverter is wired to the batteries direct, plus and minus, not to the SCC. What am I not understanding?
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Steve_S
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# Posted: 16 May 2021 03:51pm
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If you have more than one battery which are set in parallel, they connect at a busbar or something right. If a meter is between that busbar & battery, then the meter will only read what goes in/out of that battery.
The negative line beyond that busbar, the Inverter & SCC will tell you everything Solar In and Inverter out so you'll get the full picture.
Of course, all this depends on how your system is setup and wired, where the fuses, breakers etc are.
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paulz
Member
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# Posted: 16 May 2021 04:15pm
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Ah OK. I have two batteries in parallel. They connect to everything via the positive on one and negative on the other.
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Brettny
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# Posted: 16 May 2021 06:12pm
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Quoting: gcrank1 Bar bat graphs: similar to Real Estate Agent photo's of your next dream property. A good digital voltmeter: Priceless
The MT50 shows voltage and its accurate..but if the system is under load, even a small one voltage dosnt help. This is where a real battery monitor helps. It shows actual watts or ah in and out regardless of a load.
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paulz
Member
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# Posted: 17 May 2021 09:49am
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So what these meters are then, basically, are current meters, both real time and cumulative?
When is this important to know? If the voltage stays in an acceptable range (there is also that little smiley face on the MT50, changes to straight face on under voltage, frown on over discharge), is there a need, or is it more for initial sizing and testing of system changes? I've just been keeping an eye on voltage, and if it stays between 13 and 14 I figure all is well.
Somewhat analogous to my truck, which has gauges for many things, but I never look at them until the idiot light comes on telling me to get gas. 
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Steve_S
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# Posted: 17 May 2021 10:31am - Edited by: Steve_S
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Usually though, by the time the OIL Idiot Light comes on, you're already DEEP into mechanical failure. IE idiot light comes on when there is NO pressure.
LFP is one of the trickiest chemistries for gauging for SOC because the voltage curve is so tight... My battery bank will stay at 3.3 vpc for 3 days during use because it's going from 3.399 to 3.299 takes that long with my bank and the primary Voltage Curve is 3.000-3.400 VPC for LFP. VPC = Volts per cell.
The Shunt + WizBang Jr electronics (Midnite solar monitor) are using the NEG line. The solar input & inverter go thought it's Deltec 500A/50mv Shunt. That allows me to see all power going in from either the SCC or the Inverters Charger, and it also shows the power outgoing from the batteries to the Inverter. That provides an "Overview" of what & how the battery banks are doing.
I've attached a zoomed in logical diagram of my E-Panel setup which may help explain it better.
Solar panels come into a double 30A Breaker, then to SCC.
SCC output to 90A Breaker that feeds the 250A Breaker (in line).
The 250A Main Breaker IN takes the input from the SCC & BATT and the OUT line goes to Inverter.
The SHUNT has the Inverter & SCC Negative on one side with the BATT only connected to the other side.
This config is following the Midnite Solar Systems documentation & guidelines and is a fairly universal type of configuration.
Also, I'll mention, that each LFP battery Pack has an MRBF Fuse on its (+) Post.
BlueSea uses BussMan fuses (top quality only)
LINK: https://www.bluesea.com/products/5191/MRBF_Terminal_Fuse_Block_-_30_to_300A
Hope it Helps, GL.
Steve
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paulz
Member
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# Posted: 29 Sep 2021 04:50pm
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Finally hooked up my Aila meter to the cabin electrical system. I connected it directly to the battery bank per the instructions.
So the up arrow indicates the batteries are currently charging. The 0.645 amps I'm guessing is the difference between what the solar is giving me, 4.1 amps according to the monitor connected to the SCC, and what is being consumed by the cabin.
Sound right?
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