Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
Forum Index : Solar : Using watt meter to measure solar charge - 12V 50A with shunt
I want to connect to my off-grid PV setup, two of the cheap little 'watt meters' offered by multiple vendors on eBay.
The system is 12V 500W. The 50A watt meters on sale come with a shunt. The diagram on the watt meter shows how to connect it between the battery and the load -- the shunt sits in between on the negative line. So that's one watt meter set up ok, to read power consumption.
The second watt meter I want to read power production. I believe that it should go between the solar charge controller and the battery (but tell me if I'm wrong). So, in this case, where would the shunt go, if anywhere? I'm guessing it also connects into the negative line, between controller and battery? Is that right?
Thanks in advance Ian
Edited 2019-09-04 14:50 by karmacoma
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 05:14am 04 Sep 2019
Copy link to clipboard
Print this post
One watt meter goes between the solar charge controller and the battery. That will tell you what is going INTO the battery.
The other watt meter goes between the battery and the load. That will tell you what is coming OUT of the battery.Cheers, Tony.
Thanks, Tony. That confirms that the 'production/input' meter does indeed go between charge controller and battery (rather than between the panels and the controller).
The next thing is, since these particular 50A watt meters come with a shunt, will I use the shunt on the negative side between the charge controller and the battery?
ian
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 07:48am 04 Sep 2019
Copy link to clipboard
Print this post
The shunt can go either side, and negative side shunt is much more common. You can use a pair of identical power meters for making both measurements.Cheers, Tony.
Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578
Posted: 10:23am 04 Sep 2019
Copy link to clipboard
Print this post
I have had a few of those meters for several years both in the AC and DC version. Haven't failed me yet and I have had one of them on my solar setup for 2 years now.
I find them quite good and nice and easy to read, set/ reset etc.
Davo, that's good to know. These eBay watt meters are quite cheap so there's always a question of quality. I first found out about them on the now sadly departed Alternative Technology Association forums that as you probably know ran for many years in Australia before having the plug pulled in 2017. So much lost knowledge. Alas.
Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578
Posted: 01:39am 05 Sep 2019
Copy link to clipboard
Print this post
At the risk of blotting my copy book and lowering the way I am perceived even further, I'm glad they are gone. I was on there for a while and found the culture to be that of a bunch of whining greenwashed pussies to be honest.
Anything that wasn't about Drinking the green Kool-aide on the alternative energy forum was scorned and lambasted. A simple question or comment always had to have the green agenda paid homage to. It was over the top, unnecessary and uncalled for. If what I do falls in with the green cause, Fine, It it does not, tough. I was interested in making Cheap, DIY power and that's what I went there for. I was and am not interested in anything to do with the hypocritical and prostituted green cause.
I found that site to be typically only one correct way to think and if it's not our way, then you are not only wrong but a blight on humanity as well. The bit that gets me is I have done and do more to aid the green agenda than most of these loud mouth virtue signalling whinges but I think the whole green culture is a complete farce. The majority are keen to make a lot of noise but when push comes to shove, they are only prepared to do what is convenient to them and fits in with their enjoyment. The hypocrisy among the green concerned is incredible and appalling.
Alternative does not mean something has to be done to suit the green agenda as they all inferred, I wanted to have some power independence and was looking for info and ideas how to do that on a DIY basis. Also does not mean everything has to be about unreliables as they also wanted to lecture about at ever opportunity.
I see a number of them from that site including one of the ring leaders, has now gone to another site and are into multi hundred page threads about what to do to save the planet and going round in endless circles on that.
I only look there now for laughs and bemusement. It's more than clear very few of them have the skills to change a light bulb let alone come up with or put any DIY ideas into practise.
The best thing they could do for their cause would be to stop wasting energy creating hot air with their endless green sooking and do one substantial thing to help the ideal they champion.
I got some great answers to technical questions I had over there, but I can't say that I browsed the opinion threads. Anyway, I've learned to keep my mouth shut just about everywhere because I make up my own mind, and so eventually I fall foul of every political tribe. I just don't seem to have a proper tribe gene. But on the technical side of the ATA forums, I'm sad that a great number of good answers are now lost.
Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578
Posted: 01:05pm 05 Sep 2019
Copy link to clipboard
Print this post
THAT I can certainly relate to.
I have seen time and time again that on many forums there is a collective mentality or viewpoint. If you are not doing something this way out of a dozen ways, you are wrong. If you have an individual opinion, you are a black sheep. If you don't repeat the same parroted advice, viewpoint or folklore, again you are some sort of trouble maker.
Always have to go with the approved way of thinking and don't dare think for yourself or go against the parroted mantra.
Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
Print this post
