How to interpret Victron results

[mikeo16]

I have a 160 w panel with a Victron smartsolar mppt controller. A couple of question on interpretation of results:
* yield in wh - how do I convert that to AH? For example Victron will report 620 wh and I am trying to determine if that is keeping up with my frig which is drawing about 50 as mps per day
* battery minimum- how accurate is that number. For example, some days if I did not run my engine. It may report 12.18 volts. I have 2 group 31 batteries wired together for my house (220 amps total). I realize I want to keep batteries above 50% or 12.25 v

[noelex 77]

Originally Posted by mikeo16

* yield in wh - how do I convert that to AH?

You divide by the charge voltage. 14v is close enough so 620Whr equals about 44 Ahr that can withdrawn, for the same SOC, assuming a 12v battery system.

Originally Posted by mikeo16

* battery minimum- how accurate is that number. For example, some days if I did not run my engine. It may report 12.18 volts. I have 2 group 31 batteries wired together for my house (220 amps total). I realize I want to keep batteries above 50% or 12.25 v

This is a common confusion. The Victron will report the minimum battery voltage. This is quite different to the minimum resting battery voltage. The resting battery voltage is measured when there is no discharge (or charge) currents for a significant time (ideally 24 + hours).

[mikeo16]

Thanks, this is exactly what I was looking for- much of appreciated.

[Bleemus]

Without going into too much math a 160 watt panel will not keep up with a fridge that is running.

[mikeo16]

Thanks Blemus. At a high level I would agree with your assessment but I think more information about intended use may result in a different response. I live in New England and only do coastal cruises during July and August when the sun provides energy 13 plus hours per day. When coastal cruising we typically stay 1 to 3 days at one harbor. Traveling between harbors is often 70% motoring unfortunately. We have a 90 amp alternator with external Balmar 612 regulator. Temperatures in new England are typically 70 to 85 degrees F. With the 160 w panel I am probably running a 15 amp deficit daily considering all consumption which is made up each time I move to a new harbor. My summer cruising is often one 2 to 3 week trip and a couple of 2 to 3 day each year. Given the above info, would you think I still need to add more solar and if so roughly how much would you suggest?

[Bleemus]

No. With that much motoring it sounds like you are getting most of the bulk and absorption done with the alternator and the solar can get you to float a few days a week. For a few weeks a year your setup should be fine.

Double check the battery manufacturer suggested settings and make sure the Victron matches them.

[mikeo16]

Thanks Bleemus for your advise- I will follow up on your recommendation

[Pete7]

Mike, we have a similar set up with 2 x 110AH batteries and 150w + 30w of solar, though the 30w panel is under the boom. Your summer temperatures are a little higher than Southern England but not much especially this year.

In addition to the Victrons I also watch the Sterling battery monitor which normally reports 12.4 - 12.3v at dawn, certainly no lower. By early afternoon the number of AH going into the batteries has dropped to virtually nothing and the only numbers displayed probably meeting the current usage on board. Voltage settles at 13.9v.

I did have a 60w suitcase solar panel which folded up neatly and moved around the deck several times a day. This was really efficient because I could focus it directly at the sun. Unfortunately it slipped and one glass side smashed. The thought of broken glass on the deck was a real concern so it went straight to a marina skip. It disappeared in an hour so hopefully someone can make use of it.

Now whilst we have lots wiggy amps in the sunshine, a couple of days of cloudy rain, not unheard of in England, means we need to do something. So I am thinking of buying another 100w or so solar panel, perhaps semi flexible because they are light to store below when at sea and then lift out when anchored. This will give us the option of running a small slow cooker we have on board. I did a test earlier this year and whilst the draw is 10AH whilst warming up, once up to temperature after 30 mins, like a fridge it cycles on and off so overall much lower over say 5 hours.

The other thing you could look at is reducing the fridge usage. Extra foil and foam insulation, always keep it full even if its only water in bottles, we use wine and a couple of bar beer mats at the bottom changed every 48 hours to reduce condensation pooling water.

Are there any other large loads you could work on, LED for lights, turn the radar off if conditions are good etc.

This is a typical picture by late afternoon.

[mikeo16]

Thanks Pete. Your advise is spot on for next steps in reducing consumption. We really don't have much high loads as we have already switched to led lights. The frig/freezer is new and installed at same time as solar so still playing with optimal efficiency settings available with digital electronic thermostat. Insulation on a 32 year old boat can always be improved. I have done some but more work is needed. I think my winter project will be to improve the top folding doors with the piano hinge. I would really like to replace the top doors with a better seal (beyond what I h as very as already with adding a simple rubber seal from a hardware store)