Setting up BMV700

[viceroy]

So I installed my new BMV700 and the display lights up and shows all sorts of useful data.

I have followed this guide for base settings which will be adjusted over time.

However I now have a question on the battery bank capacity.

The Omni Power batteries I have are advertised as being 260Ah, but I've recently discovered that this is at 20C. At 10C the rating is 200Ah.

So in the BMV, do I put 400Ah or 520Ah as the capacity?

My gut feeling says 400Ah to be conservative.

 

What say all of you?

[Guest]

It is the 20c rate if I recall correctly.

[Chris Hobson]

Cool you found Dockarl's video. 

 

TTT is right, it the C20 rate so  your 8 batteries is 520Ah. You'll want that accurate so SOC is accurate and DOD alarms are accurate. As I said in a post last week it takes a bit of fiddling to get the BMV accurate but it is a very useful tool..

[viceroy]

Cool, I'll keep it to the C20 rate when I reconnect everything.

[viceroy]

Using this calculator, I was able to determine a C20 rate

My battery's Peukart Exponent is 1.13

From this, my C20 rating is 435Ah

[viper_za]

On 2/8/2016 at 0:06 PM, viceroy said:

The Omni Power batteries I have are advertised as being 260Ah, but I've recently discovered that this is at 20C. At 10C the rating is 200Ah.

But you already know this?

[viceroy]

21 hours ago, viper_za said:

But you already know this?

Actually no, the actual values are 260ah @ 100C (not 20C like some sites were suggesting) and 200ah @ 10C

[Weasel]

Your 20c rating won't be that high, especially not more than your 100c. It will likely be 220ah at 10a or something like that.

[Guest]

Viceroy ... do I spot a resemblance in here somewhere: Viceroy = Flash Gordon?

[Valken]

Hi All,

Can i ask a stupid question? I need to understand (In laymen terms) how the relay works on the BMV 702?

There are two contacts right? Are they like a positive and Negative? Does it put out a voltage? How much? Which one does what?

I am asking as i am trying to do two things here. Later i will use it for switching the geyser but for now i want to bring it into my home automation system.

I have a wireless module (Fibaro) that has multiple inputs and would like to know if this will work? If i can use this to get SOC Relay info from the BMV702 i can start doing all kind of wonderfull things with my Home Automation system. The manual states the following:

IN/OUT mode - 0-10V inputs, PWM outputs Fibaro RGBW Controller has 4 controllable, analog inputs I1 - I4, allowing for 0-10V analog signal interpretation. This functionality may be used in operation with analog sensors and potentiometers. What's more, in IN/OUT mode all inputs and outputs may be configured independently, e.g. I1 may be configured as 0-10V sensor input and I2-I4 may control LED strip or Halogen lamps. Another option is to configure I1 as 0-10V input and connect 0-10V potentiometer to it, and connecting Halogen lamps to R output. At the same time, other inputs may work with 0-10V sensors.

Any advise and help will be highly appreciated.

 

Thank you.

[superdiy]

3 hours ago, Valken said:

Hi All,

Can i ask a stupid question? I need to understand (In laymen terms) how the relay works on the BMV 702?

There are two contacts right? Are they like a positive and Negative? Does it put out a voltage? How much? Which one does what?

I am asking as i am trying to do two things here. Later i will use it for switching the geyser but for now i want to bring it into my home automation system.

I have a wireless module (Fibaro) that has multiple inputs and would like to know if this will work? If i can use this to get SOC Relay info from the BMV702 i can start doing all kind of wonderfull things with my Home Automation system. The manual states the following:

IN/OUT mode - 0-10V inputs, PWM outputs Fibaro RGBW Controller has 4 controllable, analog inputs I1 - I4, allowing for 0-10V analog signal interpretation. This functionality may be used in operation with analog sensors and potentiometers. What's more, in IN/OUT mode all inputs and outputs may be configured independently, e.g. I1 may be configured as 0-10V sensor input and I2-I4 may control LED strip or Halogen lamps. Another option is to configure I1 as 0-10V input and connect 0-10V potentiometer to it, and connecting Halogen lamps to R output. At the same time, other inputs may work with 0-10V sensors.

Any advise and help will be highly appreciated.

 

Thank you.

In layman's terms the relay on the BMV is like a stock standard on-off switch, similar to the light switch mounted on the wall in your house. The purpose of a switch is to either complete a circuit in order to make the current flow through the circuit or to break the circuit to stop any current from flowing in the circuit. The contacts on the BMV does exactly that. You can connect it in a circuit to switch something on or off depending on the action assigned to the relay e.g. switch on at a certain SOC.

The two terminals are not polarity sensitive, e.g. positive and negative and they are potential free - they do not output a voltage.

I am not familiar with the wireless module you are referring to, but what I can determine from the extract above is that you can control it's outputs by varying the voltage between 0 and 10V on each input - PWM outputs mean that by varying the voltage between 0 and 10V on the input, you will have a varying output - almost like a dimmer effect.

You can connect the module's input(s) to and external power source of 10V (less than 10V will result in a not full on at the output, because the output is PWM controlled) (more than 10V might damage the module) and connect the BMV's relay contacts in series with this voltage applied to the input(s) of the module. The BMV's relay will then either apply the external power source' voltage (10V) to the module or not, depending on the programming and state of the contacts (open or closed) and thus control the output(s) of the module between full off and full on (if the input voltage is equal to 10V).

Keep in mind that the BMV's relay contacts are rated at 1A 60V DC - that is perfectly fine when you are going to use it for the module's input(s), but if you are going to try to switch your geyser element with the BMV, you will fry the relay's contacts - it is however possible to add another relay etc. to the circuit to achieve that, but I'm not going into detail about that now.