Power / Watt Meter Review: RCSky, Watt's Up, Po8er and a little surprise...

[op2op2op2]

Finally an update on this I now know how to flash the new firmware into the chips so I'm ready to sell the watt meter kit I've mentioned months ago in the following post. I'll make another post later tonight in the buy/sell forum with some pictures. The kit will be priced at $14 (air mail shipping included with no tracking) for forum members.

Just wanted to give a quick update on the status of the uncased watt meter that sold out quicker than I had time to even list it on eBay. The original supplier initially told me they couldn't source the bigger LCD at the price point they had, so they had to revise the design and change to a smaller (standard sized) LCD. I've been trying to follow up with them in the past weeks to see if I can get a bunch of the new meters when they become available again but unfortunately their latest response is that they have been flooded with other orders and have decided to discontinue this product

I have since tried to find similar kits/products and am in the process of evaluating a few alternatives. I actually just assembled a kit today which is based on the same schematics (different PCB design), but has an older firmware. It uses a DIP packaged (using socket) ATTiny26L so I should be able to upgrade the firmware myself, once I've learned how to do it

I'll post another update when I have found a viable alternative that works well.

It would also be nice to hear some feedback from those who have purchased the meter from me.

I've ben talking with you, and know I'm waiting your buy/sell fórum post in order to make you an order (I will review the specs, just in case)

I think you are very responsable in your work and you show me that you are a good seller.

THANKS,

[gording]

Hi Martin
At the beginning I'd like to say hello all the way from Warsaw in Poland as I am a new fan of your videos. They are just great! Love not just what you tell an how yoy tell but allso the great neatnes and scruptulousity how you mount them. The picture quality, the appropriate lightning, all makes your videos just a pure pleasure to watch.
But let's get to the point. A few days before (a pitty) I discoverd the wideo of this thread I ordered form ebay a clone of the second meter in your film (Po8er). I,ve build DIY solar panel.Wish I had a fev pictures - maby if you'd like to see them I'll send them next time. Didn't care about the long time duration, however it is nicely encapsulated in electrotechnical sylicone. I' ve build it purely for my edycational purposes and to get my new hobby runing. It is about 6v and 2amps open circut. From your video I've discoverd that the Po8er power meter switches off without aux power just below 7v although the user manual (think it can be even seen on your video) says it don't require aux power even when supplyed with just over 4V. Now, it seems it won't work in my instalation without aux power. Sorry if it's a stupid question, but I'm totally new to electricity topics.

Can I split the wires coming from my solar panel and conect them to source and to aux?

And the second question: what type of plug is it that can be plugged into aux inlet in that meter - cause it seems I will have to buy it separately.

Just if you're interested the panel is to charge (project not finished yet) a 3,7 V battery through a small protection board (don't know yet but allso mayby through a LDO 5V voltage regulator. And then the 3,7 V battery will supply through a this step up converter :
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=141060955093
to which I will plug my mobile phone. So generally it is a mobile phone charger with some features build in like possibility to charge a phone during night time and a voltage regulation against both to high and to low voltage supply.
All the philosofy of this projest is to make it copletly standalone from any external power source. So it would really ruine my day if I had to use a simple AA or AAA batteries to supply the aux because the batteries would most probbably be charged from a grid socket. So what's the sense of making solar charger if you had to power the power meter controling it's performance with the electricity from your grid socket right? (However on the second thought the aux could allso be supplyed with the 3,7v battery wich the solar panel first charges, can't it? But then I would have to use some step up converter because I see from your video that the minimum aux input voltage is 4V)
Anyway. Thanks again for GREAT videos
Best Regards
Konrad Hanc

[MJLorton]

Hello Konrad,

Thanks for the feedback and great to hear you are having fun experimenting and building.

So to your question...don't worry about splitting the output from your solar panel to the aux....if there's enough voltage / power from the solar it will power up....and connecting to the Aux won't help.

The plugs that will fit are the JST 2 or 3 pin types:
http://www.amazon.com/Gino-Remote-Control-Servo-Extension/dp/B007SUKUXM/ref=pd_sim_sbs_hi_3
http://www.amazon.com/pairs-Plug-Connector-Battery-Female/dp/B0089RAXB2/ref=pd_sim_sbs_hi_6

I'm afraid it's going to be a challenge using that meter and keeping it powered from the battery without an AC adapter...

Are you using it to read power or just the voltage?

Martin.

[gording]

Hi Martin
Great thanks for your response. I know you're busy.
I'm still waiting for the power meter to arrive. I was hoping to use it for power reading. Do you think using a 3,7V Li-ion or Li-Polymer polymer with step up converter to lets say 7v won't work? Why? Is it because the power meter uses so much power itself that it would drain the battery fast? Or is it for some other reason? I will post my progress in Solads. Power part of your forum in birrbert's thread as we are making exactly the same project and exchanging experiences:)
Best regards.
Konrad Hanc

[MJLorton]

Hi Konrad,

It will work. My meter needs 7.8 volt at 9 mA to operate. So that means 216 mAh per day. If you need to use a DC-DC converter you'll have to more than double that figure so it'll be more like 500 mAh per day...so if left on permanently adds up fast.

Hope that helps.

Cheers,
Martin.

[Rusdy]

Hi Martin,
Thanks for the review of these in-line watt meters. I wish I bumped to your review before I bought one of them.

During your review, have you ever measured the accuracy of the actual Ah and Wh reading? I bought the 150A watt meter (I bought this from eBay, but the product is exactly like http://www.dragonrc.com.au/150A-High-Precision-Watt-Meter-and-Power-Analyser-p/sftrc-wm150a.htm), and having major problem with the Ah and Wh readings.

The problem is my Ah and Wh does not compute properly, i.e. it actually goes backwards  (instead of accumulating) when the output current drops. It also resets to '0' if the load goes to 0A. I wonder whether this problem pertinent to this model (150A), or just my batch.

Background: I was too stingy to get a proper MPPT lithium-ion charger (like the one made by Genasun), but using cheap CC-CV converter with Wh meter to monitor my e-Bike battery charging instead (using solar panel).

Your review confirms my finding of the inaccuracy of these units ('high precision' label does mean nothing). Lucky I did some test first before I start charging my Lithium pack.

Again, thanks heaps for your time.

Rusdy

[MJLorton]

Hi Rusdy,

Thanks for the feedback, I'm glad the review was helpful.
You raise a good question about measuring the actual consumption figures as a check. There are certainly ways I could do it with the equipment I have.
I would however like to find a good device that directly measures power consumption (Wh and Ah) accurately. Not too many about for DC.

Cheers,
Martin.

[WF2015]

Nice review Martin, as always!

Now: What is that, this "surprise-O-meter" and how can I get one?
really interested ... but sofar no hint where you can find it!

[iloveelectronics]

Nice review Martin, as always!

Now: What is that, this "surprise-O-meter" and how can I get one?
really interested ... but sofar no hint where you can find it!

http://mjlorton.com/forum/index.php?topic=288.0