Frustrated User Guide: Backup Power Project E8 - Dissimilar Battery Upgrade

[@Popeyes66]

Very well explained Lawrence. Pardon the Pun .

[@ثابت-ج6ض]

i would suggest water reservoir tank above ground surface to jump start the pump(Inrush current), water coming from up dont need a lot of power

[@LawrencePina]

I'm not familiar with that system. Here, on the northeast US coast at 41 degrees north latitude, we're subject to 100 degree Fahrenheit seasonal temperature swings. During the summer, we have "heat waves" defined as three consecutive days with temperatures above 90, occasionally hitting 100 degrees F. During the winter, we have "cold snaps" with temperatures in the single digits, occasionally hitting and dipping below 0 degrees F. To prevent them from freezing solid, especially when buildings are unoccupied, all private water tanks have to be below ground, well below the frost line. In the southern states, down south as we call it, winter time temperatures are milder (seldom dipping below 32 degrees F) and there are many videos showing jet pumps and tanks just like mine in outdoor sheds, directly above the well head. This keeps the noise down and allows wells to be used in houses without a basement. Please tell us more about conditions in your country. Are all the water tanks above ground? Wouldn't the pump have to work just as hard to pump water up into the tank?

[@AnthonyAntTony]

Lawrence, do you use a separate inverter and battery for your furnace or do you have the furnace and well pump on one?

[@LawrencePina]

In theory, either of my Harbor Freight, 2000/4000W modified sine wave inverters should be able run my 30-year old, 1990, well pump (1028 run watts) and my 52-year old, 1970, gas-fired, warm air furnace (450 run watts) at the same time. 1028 + 450 = less than 1500 run watts. In practice, neither can do it because the inrush wattage of the two induction motors is so high. According to my BSIDE ZT-QB9 inrush AC/DC clamp meter (currently $35 on AliExpress), the well pump momentarily draws 4,800 watts on startup and the furnace momentarily draws 3,400 watts on startup. If both attempted to start at the same time the total inrush would be 8,200 watts! I doubt that even a HF 3000/6000W modified sine wave inverter could handle that. So, in the past, we've just been careful not to run both the pump and the furnace at the same time. Going forward, I purchased a ridiculously cheap (currently $76 on Amazon), surprisingly good, PowerDrive 1000W pure sine wave inverter, specifically to run alternate loads off of the same battery bank, which is now up to 340Ah. With two inverters on the backup power system, my inrush problem is solved. It's also worth mentioning that my next door neighbor has a gas-fired, baseboard system which uses a circulator pump. His furnace uses so little power that two winters ago, we were able to run it off of a cheap Cen-Tech 750W inverter connected to an old car battery. So whether anyone needs to worry about running both a furnace and a well pump at the same time, depends on how energy efficient the furnace might be. Hope this helps. Thanks for commenting. Please like and subscribe as it really helps the channel.

[@AnthonyAntTony]

@@LawrencePina thanks so much for the very considered, detailed response. I have a new well pump and a heat pump mini split for heating (and cooling) so may get away with it.

[@AnthonyAntTony]

@@LawrencePina So do you effectively have a 3000W inverter now, with the HF 2000W and the new PowerDrive? Are they hooked up to each other (with the same types of cables ring terminal cables) and then to the battery bank?

[@LawrencePina]

@@AnthonyAntTony Not really. 3000W divided by 120V = 25A circuit, requiring 10-2 wire, but household 120V circuits are typically 15A, wired with 14-2 romex, and/or 20A, wired with 12-2 romex. Read the reviews on the HF 3000 watt Jupiter www.harborfreight.com/3000-watt-continuous6000-watt-peak-modified-sine-wave-power-inverter-63430.html?_br_psugg_q=3000+watt+power+inverter. People who've tried it report that it's really just a pair of 1500W inverters, and that it can't run what the 2000W model runs. I can't confirm that, but if it's true, the 3000W model would not run my well pump. So, the Jupiter 2000 and the PowerDrive 1000 are two separate inverters. For maximum power, they should be directly connected to the battery bank (not directly connected to each other) using a separate pairs of 1/0 cables. If you were to daisy chain one off of the other, think of the load that would be placed on the single pair of 1/0 battery cables when both units simultaneously operate at full power - close to 150A DC? It's not something I'd want to risk.