Time for new house batteries

[JRW-NAW]

These folks (from Nappanee) were at Rock Springs this year:

Solar Energy Systems - Solar Installers - Nappanee, IN

Solar Energy Systems is a leading solar installation company in Nappanee, Indiana, providing solar energy solutions for residential, commercial, farm, and RV's.

sesindiana.com

I looked seriously at the 120Ah Elevation LIFEPO4 they sell until I got distracted by bright, shiney new coachs...

Safe Travels.

 

[Dona40]

Look at it this way. A LIPo battery lasts 3-4 times as long, is half the weight and twice the usable rated capacity. IMO, they are worth the cost.

 

[Neal]

You're not helping!!!! My poor credit card!

 

[Dona40]

You're not helping!!!! My poor credit card!

Just think of you credit card a couple years "down the road"

 

[Neal]

When you don't know....test!!!

Last night I performed a test of my house batteries which are now going on 5 1/2 years old. I use the flow-rite watering system to keep batteries topped off and perform this quarterly. I also perform an equalization at least twice a year. As per this thread I did a Harvest Host recently and had a surprising drop in state of charge (SOC) which is a battery percentage remaining instead of a voltage reading available by upgrading to a Magnum ME-ARC50 control head and installing a Magnum ME-BMK (battery monitoring kit) which is a shunt that measures electrical flow.

To perform the test I decided to use the feature of the ME-ARC50 that allows me to tell the inverter when it should use shore power (pedestal). This feature is commonly used when you have to pay for electricity and you want to maximize your solar setup (or generator) to avoid electricity fees. You can use different methods such as a time window or by battery state of charge (SOC). I elected to use the AC IN SOC option telling the system not to connect to shore power until my SOC goes down to 65%. It would then charge up to the high end value of that setting which is 100% and then disconnect again and run on house batteries.

Figure 1. Evening check after PC and other loads turned off​

I started the test with everything running as usual. My PC was finishing up some work so I couldn't shut it down for a period of time which was a little bit of a bummer as I was seeing AMP draw on my BMV-712 upwards of 50 amps! I checked my PC power settings and it's on high performance so it's going to not be power friendly. I also have a power hungry video card in this PC (Nvidia 3080 Ti) and of course a 27 inch monitor. I was finally able to shutdown the PC and monitor and start turning off items to see what the loads were. I turned off my computer components under the dinette, the Dometic CF-80 cooler in the basement, night light on the Microwave, and that was about it. Loads came down to around 12-13A draw via the BMV-712 which was nice. If I wanted to go even further I would disconnect the Amazon Echo (Alexa) devices. My concern was the amount of power the PoE switch was pulling so I unplugged it, it was 1A so I reconnected it. If I really needed to conserve I could turn the Inverter off but I never do that, I want the refrigerator always on and never power cycling as I believe that's when things go wrong.

It seemed warm enough as I had windows open here in TN but was concerned about needing to run the furnace as it is a power draw. I did turn the OASIS burner on prior to going to bed so it would be available if I needed to turn the furnace on via my phone using the Micro-air smart thermostat via Wi-Fi or Bluetooth.

I watched TV for a bit prior to going to bed. the 32 inch TV and Apple TV connected drew 4 amps. At 1 AM I woke up due to it being cold and turned on the furnace, was happy to see the SOC was only down to 93%. The furnace with both zone 1 and 2 running I believe was pulling 12 amps. Front blower remains on high which doesn't help.

I woke up at 6:30 and checked the BMV-712 on my phone and it showed 84% (12.14V) which was great.

Figure 2. Morning check of battery SOC​

Conclusion: Batteries are perfectly fine and amazingly healthy. I attribute this to remaining on charge and in float while in storage, the battery watering system, and performing equalizations.

 

[Neal]

I forgot I also had VRM data available. Click for full screen if desired.

 

[Rich W.]

This brings up a lot of questions but for starters, why do you have both the 712 (I have a 700 and shunt on the shelf) and the ME-BMK. Don’t they do the same thing?

 

[Neal]

I removed the ME-BMK shunt and installed the one with the BMV-712 and piggy backed the wires for the ME-BMK on it.

 

[Rich W.]

So did you mount the 712 in the same cabinet with all the other power stuff? Got a pic of it?

Also since your LA batteries are still healthy (veering back on topic) are you going to just stick with them until they get weak? I’m guessing your coach is all electric with 8 batteries and a 2800w inverter?

 

[Neal]

So did you mount the 712 in the same cabinet with all the other power stuff? Got a pic of it?

The shunt is in the back of the battery bay, the BMV-712 display is in the pass through bay wired to the solar equipment with its wires going through the wall with other wires.