Smart Chargers and Smart Fridges

[bawlmer]

I have a Sterling Pro Charge Ultra charger. It has that power saving feature that makes it go semi-comatose on occasion to save electricity. I call it “CEC” mode named after the California Energy Commission which mandates this behavior. I have caught it in the act several times. All indicators turn off and I believe power stops being applied to the batteries during that period. When the charger detects a predetermined draw from the batteries it comes back to life. I know this was discussed on this forum before.
I just purchased an Isotherm refrigerator with smart energy control. Now another power saving device is on board. The fridge can sense the input voltage and from that input the fridge can tell what is powering it. If it senses a higher voltage, it knows the batteries are charging and runs at high speed and gets the box very cold. When the voltage drops it assumes the boat is sailing or anchored. When in Auto mode at the dock the temp swing in the fridge is between 26 and 46 degrees F. When the Charger goes into “CEC” mode it fools the fridge into thinking it is sailing and puts the fridge into energy saving mode. Either the draw from the fridge or something else will snap the charger back from its sleep and cause the fridge to return to high speed again. When I take the fridge out of auto mode the swing is between 28 and 42 degrees. It does not pay attention to the input voltage in that mode.
When I was actually sailing the temp went as high as 48 degrees before the fridge snapped on again. That was the full cycle in energy saving mode without interference from the smart charger. These are just my observations and I don’t even know if this issue is worth worrying about. Unfortunately, neither one of these devices have ethernet or M2K ports. If they did I could hook them up to each other and let them figure it out for themselves

 

[Mark Maulden]

How bout taking the charger out of CEC mode? My power bill with refer running is ~2 bucks per month...

 

[Mark Maulden]

How bout taking the charger out of CEC mode? My power bill with refer running is ~2 bucks per month...

 

[Benny17441]

I think BOATUS and the marine appliances manufacturers should study the issues and present boaters needs and recommendations to the California Energy Commission. 48F is not a safe temperature to keep perishables at.

 

[kloudie1]

I remember reading a post (from Maine Sail, I think) that detailed how to turn off the CEC mode to smooth the fridge temperature out..

 

[bawlmer]

Disabling CEC mode is the plan. I just have to make sure it does not affect charger operation.

 

[Maine Sail]

Disabling CEC mode is the plan. I just have to make sure it does not affect charger operation.

If affects it by not doing the stupid CEC stuff. Turning of CEC turns it back into the charger it was before CEC...

 

[bawlmer]

That was my concern, that I would lose some smart charger functionality when I disabled CEC mode. I still can't get through the fact that Sterling calls it "PS" function. They should call it something else as "PS" is inaccurate.

 

[marchem]

I've read the manuals for both the ProMariner and Sterling smart chargers, trying to understand what they were doing. It's a little confusing, in part because the manufacturers don't use the same words for their three stages; Sterling even uses different words for the same stage. I emailed with Sterling tech support a few times and think I've finally got an understanding of what they do:

Assuming the battery starts at 50% SOC and the charger is in Flooded (Preset 1) profile.

Stage 1 (Fast, Bulk, Charging). Constant, (max) amps; voltage is based on battery resistance (low R for 50% SOC), and slowly rises (as SOC increases to 80-90% and battery resistance increases) until it reaches Absorption/Conditioning/High value of 14.8V. Now it switches to:

Stage 2 (Absorption, Condition, High). Constant V of 14.8V. Amps decrease as battery resistance continues to increase, and SOC rises. At some point the unit decides that the SOC is about 98% (based on time and amps?) and it switches to:

Stage 3 (Float, Auto Maintain). Constant V of 13.6V. Amps as required.

After some time, if in BC mode, it switches to standby, turns off charge and monitors the battery voltage. If it drops to the Maintenance voltage, 12.8 V, the unit switches back to Absorption (Stage 2).

In PS mode the unit should stay in Stage 3. If DC load goes up (frig, bilge pump, etc.) the unit will supply enough current to cover the load.

So that's why your fridge acts up when the charger is in BC (CEC) mode. PS mode should fix the problem.

In the different profiles the voltages change, but the process is the same.

 

[Mechone]

Fridge should not go above 40 degrees ,only when you restock it as it has to pull the heat out. My fridgoboat is set at 35 and goes between 33 and 36.5

 

[bawlmer]

When I installed the fridge I set the DIP switches to the factory recommended configuration. These switches determine things like threshold voltage, temperature offsets and swings. It looks like I may have to revisit the settings.

 

[NotCook]

I can’t think of a good reason a fridge should go below 33F. You really don’t want it to be a freezer, and it takes a lot of energy to get it down to 26F unnecessarily. I’d be more inclined to have it range between 33 and 42. I suspect there are settings to balance plate temp and difference between plate and fridge temp, etc.

Our boat lives on the hook, with solar providing 420 Watts (nominal). It keeps the SeaFrost refrigeration running day and night in the hook at a constant 40F.

What came as a real shock to me was how opening the fridge door and gawking for even a short while let’s the fridge temp skyrocket up to 65F. All that cold are feels good on your feet, but now the fridge has to start cooling the new warm air that rushed in to replace it! Top loading fridges have their disadvantages, but they clearly have the advantage of not letting the cold air out when you open the top!

 

[bawlmer]

To follow this up, I changed my charger to "PS" mode and took my fridge out of auto mode also. The temperature spread is now between 34 and 39 degrees. I will eventually put the fridge back in auto mode in anticipation of another voyage. When in auto mode the temp drops to 26 degrees when charging power is applied. The manufacturer says the fridge will take the box down to this temp without freezing the contents. Changing the laws of physics like that is pretty impressive. Thanks for all the input.