Watt/Ammeter With peak amps and watts for 72v system

[theloadedquestion]

Hey guys,
So I recently changed my system from 52v to 72v and I'm having a heck of a time replacing my old wattmeter, a basic bitch, blue 150a turnigy that worked awesome, but sadly is only good up to 60v. Searching for a replacement I was only able to find units with rather large external shunt, which I didn't like but whatever, it's something I can deal with. I pulled the trigger on this guy here
https://www.amazon.com/Multifunction-Battery-Monitor-Multimeter-Voltmeter/dp/B07T8GN61Z

Unfortunately, after wiring everything up and installing it I discoved that it is real time only, and doesnt record peak watts or amps, and that is all but useless for me.

Are there any higher voltage wattmeters out there, capable of 100a+, preferably with internal shunt but not a requirement, that also record peak battery watts and amps? I'm coming up empty handed but that doesnt make sense to me. If turnigy can put out a cheap unit good for 150a but made for lower voltage rc applications I see no good reason why a similar higher voltage unit should be any harder to produce and sell.

Thanks!

 

[amberwolf]

The Grin Tech Cycle Analyst
https://ebikes.ca/shop/electric-bicycle-parts/cycle-analysts.html
can do what you want, except that you must calculate peak watts from the Vmin and Amax; for whatever reason I don't understand, Grin has never implemented a peak watts function within it (though it does show you realtime watts). Unlike almost all other wattmeters, it also saves it's data when disconnected from power, which is very useful if diagnosing battery cutouts, etc.

However it does use an external shunt--it's designed to use the one already in your controller to monitor battery current, if it's accessible either to add wires to or already has them. If not, you can simply use a standard external shunt, which Grin Tech also sells (or use the one that came with your new wattmeter).

You only need the v2.x if it's just a wattmeter / speedometer (and some other limited control/monitoring), but if you want the advanced control and monitoring/etc options you'd use v3.x.

FWIW, an internal shunt requires you run the heavy gauge battery wires all the way to and from your wattmeter. If that's on your handlebars, that's a lot of unnecessary wire in the current path to your controller. An external shunt saves you all that wiring, because the shunt is either already in your controller or can be mounted right at it (or right at your battery, or anywhere in between). Then all the wiring to the handlebars is small-gauge signal wire. (which can also be fused more easily for protection against fires in case of a wiring fault).



FWIW, the Turnigy (and other virtually identical units) are basically clones of the WattsUp, and as such all use the same basic design, including the voltage converter from battery voltage. They *could* design a new voltage converter, and frontend for monitoring battery voltage, and rewrite the firmware to deal with the higher numbers, but so far as I know none of them have done so, most likely because most of them are just clones of a clone of a clone, and no one at those companies *can* actually redesign it (they just copied what the others did), and the successful-selling companies don't really have a need to make a new one that does anything different from the old. (There have been some posts over the years about some that claim to handle higher voltage, but they dont' display it correctly, still maxing out at the same voltage the old ones did, and watt readings that don't read correctly either because of that).

 

[theloadedquestion]

Cycle analyst is definitely on my wish list but I don't think Santa is going to hook me up so that's out of the budget range at the moment. Thanks for the thorough response though man.

 

[999zip999]

Cheap as they last have 3 one 11years old . The early ones don't like rain don't know about the v3's

 

[E-HP]

I used one of these for a while:
https://www.amazon.com/Digital-Multimeter-DROK-6-5-100V-Voltmeter/dp/B07KPXVNY5/ref=sr_1_9?dchild=1&keywords=watt+meter+100a+80v+dc&qid=1607719788&sr=8-9
I don't recall which values it stores, but I used it because the energy (Wh) value is retained even after shutting it off, which was something helpful on long rides where you might turn the bike off a few times during a trip.