Ping me over the next several months....
I'm doing much of the same - buiding up a homebrew arduino based BMS.
It turns out that the Victron 600 series BMS looks really good. It's about $150 for a single bank system. Considering all the Arduino stuff you'd have to buy, and the wiring, etc... It's not a bad price.
The Victron allows you to completely program all the monitoring parameters, and even has a switched relay output, that you could use to connect voltage sources, start a generator, connect a "dumb" charger, etc...
Victron also offers monitor for TWO battery banks - but BEWARE!!! This one provides full monitoring ONLY for the MAIN battery (intended to be used for the "house system"), and provides VOLTAGE ONLY monitoring of the second battery (intended to be the "starter battery", such that it's only used for a moment to start the motor).
The system I want to build will have the following features:
1) voltage monitoring of the shunt, to monitor power consumed by the motor when running. (it would be nice to have monitoring of a second shunt from the charger to know how much current was flowing in to the battery. My charger will be LOW current - so the shunt for the motor usage won't work well for monitoring charging.)
2) Battery voltage monitoring (I'm on a 24V system) for:
a) total voltage of the battery bank
b) voltage on the lower battery of the bank
c) reference voltage for auto-calibrartion.
Rather than wiring each voltage to a different input on the Arduino, I'm planning to switch the
item to measure to the same Arduino input, so that I can calibrate from a reference, and then
(HOPEFULLY) have a more accurate reading for the two battery voltages.
3) Voltage input from a temperature sensor (this could become multiple sensors - one for ambient conditions, and one or more at the batteries, but initially just one for ambient, so that I can shut down charging if the ambient temp is over 100F, or drops below freezing.)
4) The Arduino will have a SD Card adapter so that I can record charging and operating conditions. It'll be really cool to be able to plot charging curves as well as battery voltage under running conditions.
5) I also just got a GPS module for the Arduino. This will give me real time clock data for my SD Card data logging, AND will give me SPEED information that can be automatically logged with the power data! Unfortunately, that won't take wind or motorsailing into consideration. But it'll still be great to have speed / power data recorded automatically!
6) Finally, I'll also have an LCD display so that I can easily monitor battery voltage and current as I'm out running around.
I've downloaded the "ExpressPCB" design software, and am toying with the idea of using that for at least generating schematics, and possibly going as far as building prototype circuit boards for this. But we'll see how it goes.
If I get that far, and achieve anything worthy of posting, I will.
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As for YOUR system - I'm having enough of a challenge trying to work out the detailed implementation of a simple shore power based charge.
It would be easy enough to have the Arduino monitor the wind, solar, and alternator outputs, and switch a relay or POWER FET to connect those to the batteries.
But, what would be REALLY cool would be to have smart micro-inverters or mppt boost chargers that could take your various inputs as "12V" sources, step them up to the 48V system, and merge them together automatically!
Unfortunately, that's way beyond my experience and expertise...
John
From: "white74@telus.net" <white74@telus.net>
To: electricboats@yahoogroups.com
Sent: Saturday, December 21, 2013 5:57 PM
Subject: [Electric Boats] help with bms
To: electricboats@yahoogroups.com
Sent: Saturday, December 21, 2013 5:57 PM
Subject: [Electric Boats] help with bms
Looking to build a battery management system and charge controller to work with multiple sources dc generator wind solar and shorepower when available.
The batteries are L16 used in series and parallel to get 800ah of 12vdc switchable to 200 ah 48vdc for propulsion.
The sources are:
700w air-x wind
200w solar
4 100amp alternator with external regulation
The only ac on board is the shore power converted to dc
Will be building the system from scratch so considering many option
Have moderate skill level with electronics
Can use arduino for programmable control
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