A Forum run by Enthusiasts of MidNite Solar

Other MidNite Electronics => WBjr => Topic started by: smanners on November 12, 2015, 04:30:44 PM

Title: WBJr and Diversion Loads
Post by: smanners on November 12, 2015, 04:30:44 PM
Hi,

Please forgive my ignorance if this seems like a silly question but I am scratching my head a little.

At the moment I have a WBJr hooked up to the standard shunt with battery -ve terminal on one end and all other load/supply -ve terminals hooked up to the other end of the shunt. The purple wire tail is pointing back towards the battery -ve terminal as per the installation diagrams. I should mention I have a Classic 150 hooked up to 4 x 280Ah AGM Batteries in parallel.

I have in my setup an Intervolt programmable voltage sensing relay. The purpose of this relay is pretty much similar to the AUX1 output on the Solar Classic in that it has a sensing wire +/- going to battery (+) and shunt (-). The relay is set to pass power to a pure since wave inverter thus turning it on and supplying energy to various devices around my house when the voltage hits around 14.1V (playing with this a little). It will do the opposite and disconnect power once it drops to about 12.5V.

So here comes the question:

When observing the WBJr data in the local application I can see the SOC climb up 100% and then around this time the relay engages (this was setup by trial/error/observation). The amps coming out of the Classic 150 jump as expected to deal with the extra load. Usual continuous draw is around 8-10 amps and then when relay engages around 30 amps . At the time the relay engages the SOC starts to drop with a reading around -30amps. So my confusion lies around why would it show a -ve 30 amp draw when the Classic is feeding more amps into the system to compensate (I think). Will this type of scenario actually give me a an incorrect SOC overall. At the end of the day the resting battery voltage tells me one thing about SOC and the WBJr tells me another (usually a lot less SOC than voltage tells me). I know none of this is entirely 100% accurate given the nature of the beast.

I hope someone can interpret my ramblings and shed some light on the subject. I'm probably over thinking it or just being dopey.

Cheers!
Title: Re: WBJr and Diversion Loads
Post by: dgd on November 12, 2015, 08:07:54 PM

So it appears that your inverter is actually consuming about 50amps in total, its getting about 20 of those amps from the Classic and the other 30 amps from the battery.
The reason the Classic is only increasing to 30 amps output, from the normal base load of about 10 to 12 amps, is because that is all the power its getting from solar panels (o whatever input it has).
If you want to stop the battery discharging, ie the SOC% reducing, then turn off some of the loads the inverter is supplying power to.

dgd
Title: Re: WBJr and Diversion Loads
Post by: smanners on November 12, 2015, 08:55:06 PM
Hi,

Thanks for your response. Funny thing is in the evening when the inverter is resting the draw is still showing about 30 amps not 50. That is why it was puzzling me a bit.

Cheers
Title: Re: WBJr and Diversion Loads
Post by: Westbranch on November 12, 2015, 09:25:20 PM
What is the make and size of the inverter?  that is a fair no-load draw...
does it have a sleep mode?
Title: Re: WBJr and Diversion Loads
Post by: smanners on November 12, 2015, 09:56:28 PM
Sorry my mistake in the previous post. What I mean't was when the "Classic 150" is resting not the inverter. Apologies for the confusion.
Title: Re: WBJr and Diversion Loads
Post by: smanners on November 13, 2015, 05:01:38 PM
So here is what doesn't make sense. I did a simple experiment.

I turned off my solar input to the classic (isolated) so all the WBJr should be reading is Amps being drawn. It was reading "System: -5.6A" (on average). That is about what I would expect.

I then turned my solar back on and being a bit of a cloudy day the battery amps reading on the local app was around 16.0A yet the system was still reading around -5.6A.

Either I have done something wrong or I'm interpreting it incorrectly.

I would have thought as the battery amps exceeded the draw that the "System" value shown by the WBJr would move into the positive amps? Is this an incorrect assumption?

Title: Re: WBJr and Diversion Loads
Post by: dgd on November 13, 2015, 06:25:21 PM
SO the only cable connecting to the -ve terminal of the battery bank is the one that goes to one side of the shunt?
The negative from the inverter AND the negative from the Classic both go to the other side of the shunt?

dgd
Title: Re: WBJr and Diversion Loads
Post by: smanners on November 13, 2015, 06:34:42 PM
So having analysed what was going on I went back up and had a good hard look at all the wiring.

1. Battery negative on one end of shunt - CHECK
2. All other negative connections on other side of shunt - CHECK

No wait, what is that negative lead? A fair bit of cursing followed! Of all the negative leads to miss it was the one from the Classic....$%^^#@!

Thanks for your input. I will notch than one up on my dopey stuff I have done belt (its getting full).
Title: Re: WBJr and Diversion Loads
Post by: zoneblue on November 14, 2015, 04:43:59 PM
And just as a btw, if you can use the Aux1 for your load relay, you might get some more flexibility. Also note that relays that switch inverters dont tend to last very long, unless they are 200 buck argon filled versions. Mighty big arcs from caps charge up.
Title: Re: WBJr and Diversion Loads
Post by: smanners on November 15, 2015, 07:08:39 PM
I did actually end up connect AUX1 to the over-ride input on the Intervolt Relay. Works a treat using SOC% High. Much more precise than a voltage based regulation. I can also then use it as an override in the event of power outage to allow SOC drop lower than my normal preset.