What Wattmeter to choose?

[Bikes4two]

• I've played around with a couple of watt/power meters (pics below)
• One of them I've 'built in' to a battery discharge tester and the other I temporarily mounted on the bike's handlebars so I could better understand battery behaviour vs pedal assist and so on
• What I found most useful was knowing from the discharge tester, the capacity of my battery (in Wh and Ah) and then on the handlebar mounted meter, I was able to more accurately gauge battery assist range by noting Wh/Ah usage vs mileage ridden - a much better way than the usual 'fuel gauge' LED things!
• I sealed the handlebar mounted one with hot-melt glue (the black one in the pic) and didn't get any problems in a couple of downpours.
• However, the handlebar meter is a bit bulky and so I'm wondering what other meters might be available?
• Basic functionality is
  > not be bulky
  > ideally weatherproof or could be made so fairly easily (although I might consider an 'indoor' version and keep it in a saddle or frame bag).
  > must be able to measure up to 42v and record consumption in Wh and Ah
  > must NOT require an external shunt ie, the shunt to be internal to the meter and capable of upto 20A although 10A would be OK
• Any suggestions/recommendations please (with links if possible)?

Thanks, B4t

 

[matthewslack]

For the price, unlikely to be bettered.

DIY arduino type solution is about the only alternative.

 

[StuartsProjects]

For the price, unlikely to be bettered.

DIY arduino type solution is about the only alternative.

I was thinking the same, DIY approach.

The PCB inside one of the shown meters is about 56mm x 36mm and has a hd44780 display header. So most of the size is down to the display itself.

You could use an Arduino (Pro Mini for instance) to read the LCD signals and drive a much smaller OLED.

 

[saneagle]

Google is a wonderful tool.

The Best Value Wattmeter

The problems with cheap wattmeters is that they require fairly heavy wiring, and they're not very waterproof. Luckily there's a solution that costs virtually nothing to solve those problems. You need one of this type...

www.pedelecs.co.uk

 

[Bikes4two]

• Thanks for all of your replies
• I'll give the Arduino option a miss for the moment (I last played around with an Arduino about 4 years ago and I've forgotten most of what I learnt, so a steep re-learning curve ) but remoting the data to a smaller screen is worth a thought?
• And although I spec'd an internal shunt resistor, if I could determine a suitable location for a remote shunt then the wires back to the meter unit can be much thinner making a handlebar mounted unit simpler -
• Having used the two types of meter shown in the pics above, I'm going to give the KWS - DC200 a go. I'll try the 10A version (internal shunt) first as on my TSDZ2 in ECO mode, I rarely go above 4A. The DCS200 in it's native form is a panel mounted device intended for internal use, but maybe with a suitable size 'project box' I could overcome that limitation (have I now found a 'reason' for getting a 3D printer )
• 

 

[StuartsProjects]

The DC200 does look more colourful, but by the time you put it in a case (the waterproof requirement) it may end up a fair bit bigger than the ones in your first post, which you said were bulky.

I would take the Blue alluminium one to bits, it may not be too much work to modify it to be 'waterproof'.

 

[WheezyRider]

I like this one. Up to 20A without a shunt, or they do another version up to 100A with a shunt.

Personally, I would prefer one with a shunt so you don't have to have fat cables going from your battery to your handle bars and then to your controller.