Trying to Power a 1/2 HP Booster Pump and already killed a battery

claywd · February 2021

I have this booster pump which fills a pressurized tank indoors with water stored in my outdoor storage tank. It only runs for a minute or so max maybe two to three times a day. My Idea was to power it with four of these batteries in parallel to create a higher throughput amperage using 4AWG wire. Charging the batteries was trivial so we won't focus on that part. I'm using this inverter for output.

Context:

Well my original calculations said that one of the batteries would power the pump for at least 10 seconds so I hooked it all up and gave it a go. The pump kicked on for about 1/2 -1 second and then it all died.... I disconnected the battery, hooked it up to a charger real fast and everything seemed fine. So I tried it again thinking maybe something came loose. This time, the pump didn't power up. The battery also doesn't take a charge anymore. That being said, I figured I must have overlooked some detail and need to provide more power. So I ordered more batteries... determined to make this work.

Problem.

I ran across a forum where someone was calculating something similar to what I needed to calculate and I think its saying I need to be able to provide 5 x 11 amps @ 230 volts = 12,650 watts for starting the booster pump at least for the first few seconds. Well, that's 12,650/12vdc= 1054A.... If all this is correct then...

I can't supply that over 4awg... at least not for long
The inverter I chose won't work for powering anything above 5k watts and I might have blown it as well.
idk if batteries can discharge that fast but I figured one battery should be able to provide 72kA/s or 1kA for a minute. So I don't fully understand why the battery died.

So at this point I'm a bit lost because I don't know what failed and I'm not entirely sure how many watts I should plan for at startup.

Any help is appreciated.

Alternative thoughts:

* Maybe I should just switch out my pump + pressure tank with a tankless system like this. or this ... since I already have an outdoor storage tank. These would use less power... although they would run more often draining the batteries faster.

BB. · February 2021

Claywd, are you trying to repost your question (the software put you post "in moderation" because it looked like a duplicate post?

Any, if you want to continue, we can... Or I can delete.

Take care,
Bill "moderator" B.

claywd · February 2021

Also, should I just abandon the plan to run this well pump and instead invest in something like this? Tankless Pressure Pump™ System - NEW 2019 – RPS Solar Pumps

I feel stupid for not looking into the above sooner... 🤦‍♂️

claywd · February 2021

BB. said:

Claywd, are you trying to repost your question (the software put you post "in moderation" because it looked like a duplicate post?

Any, if you want to continue, we can... Or I can delete.

Take care,
Bill "moderator" B.

Actually let's delete the other one. I realized after the fact I posted it in the wrong place. Sorry mod. I thought editing it and adding "disregard" would accomplish that task as well.

mcgivor · February 2021

What batteries are you using?

BB. · February 2021

No problem. I can move your post, you don't have to repost... And we are pretty easy going anyway.

-Bill

claywd · February 2021

mcgivor said:

What batteries are you using?

https://www.amazon.com/gp/product/B07X523S96/ref=ask_ql_qh_dp_hza. added to the original post as well. Not sure how the link got lost

mcgivor · February 2021

There are a few things that need to be considered, first the battery is far too small to power the pump, most likely what's happened is the internal BMS has disconnected the load on overcurrent, this will also in effect disconnect the ability to charge.

The pumps AC current demand has to be multiplied by a ratio of 20:1 for a 12V battery, roughly the run current should be ~4.6A, therefore the battery needs to supply 92A at 12V and significantly more on startup, perhaps 400Ah for a second or so. The 80Ah bank should have a maximum 80A, or 1C for each 24Ah.

Using a smaller pump is one solution, or a larger battery capacity, but 12V inverters are not user friendly and really shouldn't me made at such high wattage due to the high currents needed, moving up to 24 or 48V would be best.

claywd · February 2021

I agree on the 12v setup. The batteries are so readily available though and I was hoping to make this adaptable in case it didn't work and I went with a different setup altogether. I could at least reuse the system for something else. I'll keep the 24V/48V option around as well while considering all the options.

perhaps 400Ah for a second or so. The 80Ah bank should have a maximum 80A, or 1C for each 24Ah.

So if I were going to build the minimum system I would need another 14 batteries to make up the missing 320Ah required to turn that pump on?

mcgivor · February 2021

Having 18 batteries in parallel is not a wise idea, many connections and hard to ensure each is charging or dischargeing at equal rates. A better solution would be to have a single battery with one BMS, usually made-up from large capacity prysmatic cells something like this
https://www.amazon.com/Lifepo4-Lithium-Battery-System-battery/dp/B07TWDP8D9/ref=sr_1_32?dchild=1&keywords=200+ah+lithium+ion+battery+24v&qid=1613721973&sr=8-32
Actually works out cheaper as well, I linked a 24V 200Ah example, same cost for 12v 400Ah.

Whenever using solar it's best to have equipment like a pump working during sunlight hours, keeping it as small as practical, having a 1.5 hp pump working for a few minutes per day, or night, requires electrical support equipment to be sized accordingly. For example I recently installed a submersible 24V DC well pump with is own MPPT controller that is powered by a single 400W panel without batteries , it can fill a 1000 liter (260 gallon) holding tank in 2 hours in perfect conditions, a second 230V 150W on demand pump provides house pressure, everything including the demand pump cost ~$400.

Not knowing exactly what your particular requirements are I can't offer suggestions, other than to say, I think you need to rethink the whole exercise, there must be a better solution.

MrM1 · March 2021

mcgivor said:

Having 18 batteries in parallel is not a wise idea, many connections and hard to ensure each is charging or dischargeing at equal rates. A better solution would be to have a single battery with one BMS, usually made-up from large capacity prysmatic cells something like this
https://www.amazon.com/Lifepo4-Lithium-Battery-System-battery/dp/B07TWDP8D9/ref=sr_1_32?dchild=1&keywords=200+ah+lithium+ion+battery+24v&qid=1613721973&sr=8-32
Actually works out cheaper as well, I linked a 24V 200Ah example, same cost for 12v 400Ah.

That looks like an amazing price. And BMS too. Would you say that is a pretty good drop from when you built up your LifePo4 bank? I wounder if those are all balanced cells in that box?

Trying to Power a 1/2 HP Booster Pump and already killed a battery

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