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Topic: House Batteries (Read 1681 times) previous topic - next topic

Re: House Batteries

Reply #20 –
I am now in Durango, CO. Yes, you need a computerized BMS for anything more than four cells in series, IMHO.

Re: House Batteries

Reply #21 –
I will never go back to wet cell batteries, due to the maintenance issues.  When I had the Safari with Trojan batteries, I used the Pro-fill watering system which not only made the job of keeping proper levels easy, but possible (nearly impossible to see into the cells on the inside batteries.  You can get them at Camping World:  Pro-Fill RV Edition Dual 6-Volt Battery Watering System - Flow-Rite Controls...

Re: House Batteries

Reply #22 –
Quote from: Tim –
I am now in Durango, CO. Yes, you need a computerized BMS for anything more than four cells in series, IMHO.

Can A bms be made for the Volt battery at 12v? or the Ford Cmax battery? Im pretty sure it can.. just need something to tell it what to do and how?

Re: House Batteries

Reply #23 –
A BMS is a good insurance policy for any voltage battery. There was/is a fellow on eBay selling Volt batteries and BMSs, for a price.

That said, humans make good BMSs if they  monitor the cell voltages manually.

Re: House Batteries

Reply #24 –
Quote from: Tim –
A BMS is a good insurance policy for any voltage battery. There was/is a fellow on eBay selling Volt batteries and BMSs, for a price.
I have talked to him but he wants $300 for the bms in 12v
Quote from: Tim –
That said, humans make good BMSs if they  monitor the cell voltages manually.
This guy does not have time for all that... I need it VERRRRRRY simple lol .. if not I might neglect lol

Re: House Batteries

Reply #25 –
Worth it. FYI: I just saw a video from Mortons on the Move about using a 5 KWH Tesla battery at:

Overview of the Tesla Lithium Battery Module We are Installing in our RV -...

Here was my reply:

Mortons on the Move  Thanks for your video and reply. From one electrical engineer to another, I encourage you to do a service for all the RVers out there and perform a worse-cast power usage analysis. This would include:

1. Constantly running 24 Volt to 12 Volt converter and/or inverter with it's related losses
2. 30% loss of battery capacity after a certain amount of time: 3-8 years.
3. Running the battery DOD (Depth of Discharge) between 20 and 80 to maximize longevity
4. Boondocking under trees
5. Freezing temperatures and running battery and other heaters, like water pipe and waste water tank heaters.
    Keeping the pipes from freezing can use a lot of electricity.
6. Cloudy skies
7. Using high-powered appliances after dark.
8. Running a residential fridge.
9. Under-powered or dirty solar array. Use MPPT charger output power, not input power. I recommend 1200 watts minimum of input power. 1900 watts of input is preferable because there is alway loss due to sun angle, dirty panels and solar charger losses.

I have a 9.2KWH 48Volt pack with 1.9KW solar and the battery has gone flat on several occasions. I recommend that modern RV batteries have about 20KWH based on my real-world experience of one year with our system. This involved driving the rig at 55MPH at 10 degrees F and boondocking at Mammoth Cave, Big Bend and Death Valley National Parks.

That said, RVers can certainly live with 5KWH by cutting down on the power consumption, especially when the above worst-case conditions occur. This would require a compromise, which many power-hungry Americans will not be comfortable with. If an RVer "cooks on it" after dark, which to me means using a large electric appliance like an 1500 Watt electric stove or convection oven, it can take a dramatic toll on the batteries. My LiFePO4 batteries used to throw error codes in the Orion BMS because the cell voltage would drop to 2.9 Volts during heavy discharge. I resolved this by lowering the "weak cell" threshold to 2.3 Volts to account for heavy loads. So now we try to use our 1500 Watt convection oven when the sun is shining.
 

Re: House Batteries

Reply #26 –
Quote from: Tim –
Worth it. FYI: I just saw a video from Mortons on the Move about using a 5 KWH Tesla battery
Cool video!  Thanks for the link.  I will watch the rest of the series, just for general interest.  Not a conversion I would attempt...too complicated.

If you used two of the Tesla batteries and wanted to "display" them, you could make a coffee table top out of them!  Great conversation piece!