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

[MJLorton]

Hi Martin,

it will be nice if you can teardown these watt meter's, based on MCU ADC it easy to calculate real resolution. For example one with attiny26l have 10bit ADC so maximal resolution is only about 58mV for 60V range (Vrange/2^Nbits). So 3 or more digit after decimal point it's just impractical, unnecessary gadget.

Accuracy is basis on quality of parts used in voltage divider and quality of shunt resistor, cheap parts have significant temperature drift etc. Even if all resistors will be measured used 6.5 digit DMM and these values will be placed in EEPROM to increase measurements accuracy it's not possible to omit ADC resolution and variability under the influence of time and temperature.

Thanks for the input...let me try make some time for a look inside in the near future.
Cheers, Martin.

[Wyreless]

I am also ready to go ahead and get the $14 Uncased Meter. If Franky is ready to sell Im ready to buy. My Email for PayPal address to send me is wyreless@gmail.com
Thanks Franky.

BTW, Hobby King has the TURNIGY 130 Amp Watt Meter equivalent to the WATTS UP for $23.95 and I was quoted at $5.99 for their International Airmail. So if you can get a hold of these and can match (or beat) that pricepoint, I know I'd rather give my money to one of Martins Preferred Vendors.

[iloveelectronics]

I am also ready to go ahead and get the $14 Uncased Meter. If Franky is ready to sell Im ready to buy. My Email for PayPal address to send me is wyreless@gmail.com
Thanks Franky.

Yes, I'm always ready to sell The only thing is the meter doesn't come with any documentation or instructions and I was going to write something up, but I haven't got around doing that yet. If you don't mind referring back to Martin's video and also the calibration instructions on page 1 of this thread you are more than welcome to buy one. I'll send you a paypal money request shortly.

BTW, Hobby King has the TURNIGY 130 Amp Watt Meter equivalent to the WATTS UP for $23.95 and I was quoted at $5.99 for their International Airmail. So if you can get a hold of these and can match (or beat) that pricepoint, I know I'd rather give my money to one of Martins Preferred Vendors.

Unfortunately I don't have low cost access to the Turnigy meters, and that is one really low price to beat! However, I have found something that looks almost identical to it and I have ordered one and I will see if it offers the accuracy and resolution it claims. It is called the "G.T.Power 130A Watt Meter" http://www.youtube.com/watch?v=y7-iaxjqyOk. I must admit the $23.95 price is really hard to beat though even with this "clone"!

[Fennec]

For example one with attiny26l have 10bit ADC so maximal resolution is only about 58mV for 60V range (Vrange/2^Nbits). So 3 or more digit after decimal point it's just impractical, unnecessary gadget.

Not really. You can calculate with "fixed point arithmetic" and simple diplay, with a 10Bit ADC , maybe 10µV resulution.

[iloveelectronics]

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.

[Majes]

Hi everyone, just reviving this old thread. Was wondering if Martin ever replaced the lcd in the uncased watt meter

I have just ordered one from Franky and a Watts Up from Martin's Amazon store. Franky is sending me an extra back-lit lcd and I am going to try and flash the firmware myself. Does any one know if PonyProg is compatible with the ATtiny26L ?  I would assume it would be since it is with the ATtiny26, but I'm unsure what the L designates.

Would be interested in hearing from any one who has dabbled around with these kits, I see a lot of potential once we get things sused out in English

Thanks Franky!!!!

[iloveelectronics]

Does any one know if PonyProg is compatible with the ATtiny26L ?  I would assume it would be since it is with the ATtiny26, but I'm unsure what the L designates.

I think the L and non L versions only differ in the operating voltage: http://www.atmel.com/Images/doc1477.pdf

I don't know much about flashing firmware yet but I believe PonyPorg would work fine as the watt meter's designer's website has screenshot of the program: http://blog.21ic.com/user1/4577/archives/2007/43308.html#47474

[Majes]

Thanks Franky,

Hopefully in a few weeks I'll be able to explain how to do it, but don't hold your breath

Thanks Franky, enjoy the holidays!!

[TimothyS]

Does anyone know which of the three pins at the input side of the  Po8er housing to use for plus and minus auxillary power?
I bought one of these on eBay, and it lacks the little connection cable for that.

[iloveelectronics]

Does anyone know which of the three pins at the input side of the  Po8er housing to use for plus and minus auxillary power?
I bought one of these on eBay, and it lacks the little connection cable for that.

What I found with mine was that the top pin is ground. Middle pin is for any positive voltage above about 7V, a 9V battery works well. I have no idea what the 3rd pin does.

[MJLorton]

I had someone email and ask the same question. I sent this to him with the pictures.:

"The attached two photos show the auxiliary power is the top two pins (1st negative and 2nd positive). I believe if the 3rd pin is connected to negative (push button) it will reset the meter without having to disconnect the power. The voltage range is 4-60v DC."

[TimothyS]

Hi all,
Does anyone know if there is a dialect of the Po8er design family (or any of the others in this video) , allowing it to measure and display not only OUTGOING Ampere, but also INCOMING.
Thus, the Ah readout would not only increase at consumption, but also decrease at charging.
This situation is common both for boats where Amps from solar charger and to gadgets is an ever changing battle. Another example is electric vehicles where electric regenerating braking is applied.
 

[MJLorton]

Hi Timothy,

I have an in line power meter called the Medusa Power Analyzer Pro which does bi-directional measurements and I think does what you are asking...it even data logs with an added module. However...it is no longer produced...a pity.

You next best option unless someone else knows of another meter is a battery monitor...like the one I did a tutorial on for Victron: https://www.youtube.com/watch?v=JO8AGV4Z7K0

Cheers,
Martin.

[TimothyS]

The victron typically sells for about 140 USD/pcs
The meters I look for are priced 15-30 USD/pcs

The closest found so far is this family of gadgets:
http://www.ebay.com/itm/90V-30A-Volt-Amp-Battery-Capacity-Power-Combo-Meter-Charge-Discharge-Indicator-/180956352800?pt=LH_DefaultDomain_0&hash=item2a21d6d120

Admittedly, these simpler meters do not take the Peukert effect into account, but for i.e. use cases where it is frequently known when the battery bank is fully charged,  the charge and discharge currents are low compared to the bank capacity, frequent resetting will do fine.

As you certainly know, the golden rule for good engineering is: Better reasonably right than exactly wrong.

Fiddling with battery aging and Peukert effect coefficients without resetting frequently is not better.....

[iloveelectronics]

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.