DIY ammeter - dead cool

  • Thread starter Thread starter GHA
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GHA said:
Oh that's lovely!! :cool:

Played with esp8266's yet?
You should be able to just use the same arduino code but they can do so much more! With built in wifi you can create you own web page on board, send data to the web if you have access, lots of fun :)
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I haven't looked at these yet. I was thinking of fetching data from a cheapo eBay Bluetooth enabled device I already use. It also displays V, Ah & Wh measured at the batteries. The standard Jeanneau fitting is rubbish for most readings. Voltage is lower than actual and current draw ignores heating, winch, windlass, inverter etc. I was thinking of piping the total A via Bluetooth and ignoring the measurement via existing shunt. I could also graph V & A over time as the display will handle graphics easily. Might be easier to add Bluetooth to existing unit than replace eBay unit with something Wifi enabled.

I'll certainly look at the esp8266's anyway, thanks for the tip.
 
Mistroma said:
I haven't looked at these yet. I was thinking of fetching data from a cheapo eBay Bluetooth enabled device I already use. It also displays V, Ah & Wh measured at the batteries. The standard Jeanneau fitting is rubbish for most readings. Voltage is lower than actual and current draw ignores heating, winch, windlass, inverter etc. I was thinking of piping the total A via Bluetooth and ignoring the measurement via existing shunt. I could also graph V & A over time as the display will handle graphics easily. Might be easier to add Bluetooth to existing unit than replace eBay unit with something Wifi enabled.

I'll certainly look at the esp8266's anyway, thanks for the tip.
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The esp8266 has a big brother, esp32 which has wifi and bluetooth, never tried the bluetooth but you might be able to get at the data that way. Still dead cheap :cool:
 
I think pvb is being a bit unfair. Arduino , raspberry pi and coding mean nothing to me but a lot of sailors are into this sort of stuff. My only concern is that basic seamanship is forgotten and absolute reliance on electronics takes over without a reality check.
 
ghostlymoron said:
I think pvb is being a bit unfair. Arduino , raspberry pi and coding mean nothing to me but a lot of sailors are into this sort of stuff. My only concern is that basic seamanship is forgotten and absolute reliance on electronics takes over without a reality check.
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If that's a worry then it isn't really down to the device, makes little difference if you are relying on a chart plotter or a tablet. Anyway, having accurate knowledge of the state of charge and health of your battery bank isn't going to put you on the rocks.. :)
 
ghostlymoron said:
My only concern is that basic seamanship is forgotten and absolute reliance on electronics takes over without a reality check.
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Isn't "basic seamanship" about ensuring the navigability of your vessel and the safety of its crew? If the boat you sail has an alternator and batteries, nav lights powered by electricity and/or electronic nav instruments (sounder, log, never mind plotters) then why on earth would the fashioning of a tool to monitor health of and diagnose problems with your electrical system be anything other than good seamanship?
 
ghostlymoron said:
I think pvb is being a bit unfair. Arduino , raspberry pi and coding mean nothing to me but a lot of sailors are into this sort of stuff. My only concern is that basic seamanship is forgotten and absolute reliance on electronics takes over without a reality check.
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Certainly a risk with people fairly new to sailing. At least I needed the basics when I started but am forgetting more and more at my age whether or not I use new kit.

I started with a home made log, lead line (with hollow for tallow) and compass. Several longer trips were made with only trailing log, compass and sextant. To be honest, the sextant mainly confirmed that I was somewhere in the North sea and I already knew landfall was >100mn away and I just needed to turn left at that point. :D:D

I had never seen an Arduino before but enjoyed spending a couple of days getting up to speed with hardware and programming. I suspect others wishing to dabble would not have a great problem picking up basic sailing either.

I will admit to not having used the sextant in several years. The lead line is still around, I wonder if I could fit a wireless camera to the base. Much better than tallow to determine type of bottom and power cable could have moisture sensors at regular intervals. Nah, better not and would need help with NMEA interface for the plotter.
 
pvb said:
Isn't this rather sad? Is this what boating has become?
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Surely, the thing that unites all of us is our desire to mess around in boats. It takes us to many places that we never expected to go to, it gives us many experiences (both good and bad) that we never imagined we would have and develops many skills and talents that we never thought we could manage. Surely that is something to be applauded, not regretted.
 
Good news is after finding another library for the current sensor it's even more accurate now, tracks the battery monitor and dc clamp meter very well - guessing around 100mA accuracy, maybe little lower but plenty good enough to show up very subtle patterns not obvious otherwise. Like the fridge pulls a bit more current when it starts up then tails a few hundred mA as it runs. .....
(13:24 - 13:32 with the old library)
jM3h229.png
 
nice,

now have you played with any of these cheap touch displays? I mean all these data should really be shown realtime on the chart table :p

My fin stabiliser project is now at a stage that I should work with possibly I2C (3m from control box to display) to connect the teensy doing the "hard" work (sensors-relays) to a due (I have it lying around) with a touch and lcd shield for reporting values and giving instructions to the teensy.

Two way comms and speed of refresh on a 7inch touch screen are new areas and I'm lost...
For the time being I've added a pot and long wires to alter some stabilisation values, but eventually I want a lot of info to pass back and forth...

cheers

V.
 
GHA said:
How it's wired >

Ij9RANx.png
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Shouldn't the shunt be in series with tither the positive of negative battery connection not parallel as indicated.

Is there a hall effect current sensor that can be used in stead of a series shunt that can introduce a volt drop if high currents flow as when using a windlass or bow thruster.
 
Rogershaw said:
Shouldn't the shunt be in series with tither the positive of negative battery connection not parallel as indicated.
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Not the way it's working here. The INA219 has it's own shunt resister, normally the current goes through that but the way it's wired here the INA is measuring the voltage drop across the main battery monitor shunt resister (down to micro volts) then the current is calculated from that. I thought it was 50mV/100A but the voltage drop * 10,000 is giving accurate amps so must be a 50mV/500A. The INA shunt resister is in parallel with the main one so will be intruding a tiny error, it's a massive value compared to the main shunt resistance so error will be tiny but I'll unsolder it at some point. Surface mount's a bit fiddly!

Is there a hall effect current sensor that can be used in stead of a series shunt that can introduce a volt drop if high currents flow as when using a windlass or bow thruster.
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The INA is configured for max 40mV at the moment, so should be good up to 400A, plenty I reckon :)
Not played with hall effects but there are various available on ebay.
 
GHA said:
Got a nice touch display, called a samsung android tablet :)
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Oi, that's shifting the goalposts. :p
Im sure you have a bt device to view them, I want a fixed one for this. I want it to double as generator start stop and safety stop when temp goes up, add timers etc.

Does look like the most difficult task I've come across as yet
V
 
Yes that how my shunts work.

On your diagram it looks like one terminal of the external shunt is connected to the positive terminal of the battery via the pirate ship and the other terminal of the shunt is connected to the negative of the battery or am I missing what the pirate ship is doing.
 
Rogershaw said:
Yes that how my shunts work.

On your diagram it looks like one terminal of the external shunt is connected to the positive terminal of the battery via the pirate ship and the other terminal of the shunt is connected to the negative of the battery or am I missing what the pirate ship is doing.
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Not the greatest schematic.. ;)

The pirate ship is the boat, the external shunt is the battery monitor shunt connected in series between the bat neg and everything else- domestic, solar, charger etc, everything goes through there, so any current going in or out of the batteries goes through that shunt. Then the INA219 measures the tiny voltage drop across that shunt and turns it into current. Works surprisingly well.
 
Is the shunt just for this, or for another battery monitor system? If the latter does it affect the other systems readings?

Wondering if i can piggy back off my victron bm-702 shunt, without affectinng it?
 
gregcope said:
Is the shunt just for this, or for another battery monitor system? If the latter does it affect the other systems readings?

Wondering if i can piggy back off my victron bm-702 shunt, without affectinng it?
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This is piggy backed on a BEP battery monitor shunt. There is a sense resister on the ina219 which should get removed but that should only skew the readings maybe 1% otherwise the 2 seem to work just fine together on the same shunt. Amazing a tiny little cheap sensor from eBay can measure down to microvolts so accurately :cool:
Should be possible to get the esp to serve a Web page with the data either on an existing network or on a network it runs.
 
I have a similar shunt setup for my solar charging setups with shunts 100mV per 100 A feeding a 1999 DVM. My 2 main batteries banks and engine start battery also used to have shunts but changed it to a hall effect setup due to the high current drawn by my bow thruster. The shunts caused a larger then acceptable volt drop across the shunt.

Your system is great as it allows the current flow to be recorded over time for greater info and control.
 
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