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Old 01-15-2020, 01:15 AM   #11
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Default Re: Shore charging questions

Until the cell interior itself gets below freezing, it's just a matter of charging slower.

0.1C should be fine from freezing

above 10-15C go to a 0.2C rate,

25 should be fine for 0.3C
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Old 01-15-2020, 03:20 AM   #12
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Default Re: Shore charging questions

john61 ct and Shawn182 - yes, I recognize going to 50A (even 30A) from shore to charger I would need to replace the 12 awg wire and the inlet on the side of the van. Lifepo4 batteries not working so well in the cold is one of the reasons I went with AGM. However I didn't buy the separate temperature sensor for the Victron because I didn't completely understand the set up. Now I'm rethinking it and will probably order one so I have compensation and data points. Without the sensor I'd guess the batteries were around 30 degrees F when charging.

I'm going to need to do some studying of the charger manual to double check settings. I can't remember the ones I input, but I know I didn't change much from factory settings.
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Old 01-15-2020, 05:56 AM   #13
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Default Re: Shore charging questions

Set your charger to 50% rate (60A) using the dip switches. (you have 4 batteries so each should get 15A) 60A * 14.4 is 864 watts which is going to draw about 8A at 120V. Your 12 gauge wire and 15A outlet should be able to handle that just fine. Make cord to van as short as possible and monitor the AC input voltage at the charger. Definitely install the temperature compensation sensor on the batteries.

All the best,
541 490 5098
2010 MB 3500 RV conversion.

Last edited by hein; 01-15-2020 at 06:03 AM.
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Old 01-16-2020, 03:22 AM   #14
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Default Re: Shore charging questions

You should absolutely get the temperature sensor for your batteries since you are using them in cold climates. The standard charging voltages provided for batteries are for 70-80 degrees, AGM batteries need substantially different voltages in near-freezing temperatures which the controller will automatically adjust once you install the sensor.
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Old 01-16-2020, 06:13 PM   #15
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Default Re: Shore charging questions

I've reviewed the install and manuals, and found several points to address (all items that you folks have pointed out).

Settings - the charger is set at factory default settings: charging current 75% of maximum and input limit is 50A

Temperature sensor - not installed, but I found it in my parts bin. I can't say why I missed it at install, but that is now correctable.

Part of my lack of understanding was mixing up the temperature sensor (TS) for the charger and TS on the battery monitor (which is a separately ordered part). So TS on the charger adjusts the flow to compensate for batteries temp during charging. While the TS on the monitor allows you to know what the battery temperature is, but doesn't modulate temperature. I think this is why people see the TS on the BMV 712 to be optional. Is this correct?

I've only used shore power twice and both times were in cold weather, so first step in to install the TS. Then I'll charge when needed and monitor the system to see if I need to change settings. Installing a higher amp house circuit will need to wait for spring. I also need to think about versatility. What will be my potential power sources since we almost always do "urban stealth" or dispersed camping.

Last edited by russinthecascades; 01-16-2020 at 06:20 PM.
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