New Wattmeter

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Deleted member 4366

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I just found this on Ebay. I'm not sure what it does yet. It's not very clear from the description, but looks very interesting, so I ordered one to see what it does. When it arrives, I'll let you know. Shame it doesn't do 12S.
Multi-function Wattmeter FD-WM | eBay
 

jerrysimon

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Aug 27, 2009
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Interesting.

I guess it would do 12s * A123s i.e. 39.6v nominal 43.2v fully charged ?

Regards

Jerry
 

jerrysimon

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Aug 27, 2009
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Same here looked interesting.

Jerry
 
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Deleted member 4366

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You've just reminded me. It arrived before xmas and I put it away. It looks pretty good in that it can hold peak values, which would be good for shunt mod testing. I'll get it out again and do some tests - I hope I didn't lose the instructions because it has lots of different modes.
 
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Right, just tested it. It has Deans connectors soldered to the edge of the board, which is handy for me because all my bikes and batteries have Deans. I lost the instructions, so I don't know how to set the alarms, but they can be set for max current and min voltage - handy for lipos as long as the wind noise doesn't drown it out (high pitched). It should be possible to unsolder it and replace it with a bright LED on wires positioned in your line of sight if you want to use it for lipo pack monitorin, or put an LED in parallel. It's a piezo buzzer rated at 1.5v.

When plugged in it switches itself on and then scrolls through: battery voltage; current; watts; temperature. It waits about 2 secs on each reading.
Press the first button and it shows what I guess is minimum voltage for about 5 seconds and then it reverts back to normal scrolling display. Press it a second time and you get peak current. press again and you get peak watts and again for peak temp.
Press the second button and it gives continuous battery volts only. Press again and it locks onto amps, then watts, then temp.

The display is soldered on with with 12 legs. It should be possible to unsolder it and remote mount it on the handlebars joined by wires with a bit of jiggery pokery, or it might be possible to mount another 4 digit display in parallel because the 12 pads, though small, are easily accessible.

Summary: Not as good as a Cycle Analyst, which costs 12 times the price, but very useful if you need data on how your bike is performing particularly if you want to check the results of your shunt mod. I shouldn't think that it's very accurate, but is easily good enough for what most of us want

Edit: It uses a ACS758 current sensor, which looks like it could also easily be unsoldered and mounted remotely once you've figured out the wiring.
 
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jerrysimon

Esteemed Pedelecer
Aug 27, 2009
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Cambridge, UK
Thanks for the review and update Dave,

So it would work on my 12s1p A123 packs each cell being nominal 3.3V, (39.6v nom 43.2v charged) ?

My bag and battery are all up front on my Brompton so I could mount it where it was visable.

All that said it probably does not offer much more than my Turnigy watt meter which is also lit.

Regards

Jerry