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buckeyemike · 03-05-2016, 08:29 PM

I have a question for all you battery bank gurus. I have a magnum monitor with my 2000 watt inverter and when it registers 12.1 volts my blue sky solar monitor is measuring my battery bank at 40% not 50% I have 400 amp hours so 200 usable which is more accurate?

vsheetz · 03-05-2016, 08:43 PM

Are both set to the same/correct battery type? Some other configuration difference?

**CountryFit** · 03-05-2016, 11:22 PM

Quote:

Originally Posted by buckeyemike

I have a question for all you battery bank gurus. I have a magnum monitor with my 2000 watt inverter and when it registers 12.1 volts my blue sky solar monitor is measuring my battery bank at 40% not 50% I have 400 amp hours so 200 usable which is more accurate?

how far is your blue sky monitor away from the battery? normally that data wiring is very thin. if the distance is more than 15 feet, there will be a noticeable voltage drop at the terminals of blue sky monitor vs what is on that of battery (the same logic why where is a voltage loss on the solar panel cables down to the controller). when the blue sky senses a voltage being 11.90v, for example, it would consider your battery is at 40%.

on my coach, i measured the battery voltage at 13.40v (verified by multiple voltimeters) but my remote xantrex monitor always shows 13.33v.

twinboat · 03-06-2016, 04:33 AM

This is from Blue Sky,

A high accuracy calculation of remaining battery capacity compensates for a variety of factors including charge/discharge current, battery size, type, temperature and how the battery was brought back to full charge. It even learns from past battery behavior to continuously improve accuracy!

The age of your bank effects capacity. You started with 400 AH. How old are they ?

I believe the "monitor magic" takes that into consideration.

**CountryFit** · 03-06-2016, 05:47 AM

addition to my post #3:

op - could you check what the voltage on blue sky says? one time i called xantrex to ask how to recaliberate it, they said no way to do it.

on my xantrex, the capacity is one of about a dozen parameters i entered. it calculates based on these parameters. i suspect the blue sky might be the same. if you have or you can find a copy of the operation manual, you can look it up.

Smitty77 · 03-06-2016, 10:51 AM

You mentioned Magnum monitor, is this the BMK-Meter monitor? It too, if properly configured with the balance of your components, has a sophisticated Auto monitoring that adapts based upon usage.

One simple method to see what is what, is to observe readings from both. Turn off all charging sources (Magnum and Controller), turn off all 12V demands (Salesman switch, and main 12V power supply, if you have both.). Let the battery rest for a good period of time, say 30-60 mins. Then take multi meter readings at the battery.

Power 12V back on, but do not turn on the charging of the Magnum and the Controller yet. But then observe the readings again from these two sources.

This will give you a good ballpark to which one is reading closest to the actual at resting battery readings. Just note that the readings will probably be a bit lower, due to the 12V demands being back on again.

I know when we first installed out Magnum MS2812, with the BMK-Meter and other components. As well as our MidNite Classic 150 controller, we too would have different values. Overtime, we have come to rely on the Magnum BMK-Meter, using that as our health of battery. This is after about 6K of AH in/out, and the Magnum Auto setting learning our battery and usage. (And note, nothing wrong with the MidNite, just that the led panel with all of the values are in the bedroom. I usually am up a few hours earlier then the DW, and have just used the remote led panel with the Magnum until the DW gets up. So more used to those values, and have learned what they mean in relation to our battery bank.

Best of luck to you,
Smitty

buckeyemike · 03-06-2016, 11:43 AM

The blue sky monitor is within 15 feet of the batteries the Magnum is reading 13.1 right now and the blue sky is reading 13.2 volts so they have always been very close the only thing that is inaccurate is the percentage of battery use on the blue sky. I was looking at my settings on the blue sky and the minimum it can go is 440 amp hours in my bank is only 400 that might be a problem