New 48v 200ah 10kwh battery troubleshooting

[Gauranga108]

hi everyone i just purchased a meritsun 48v10kwh 200ah powerwall via alibaba to replace my old lead acid battery bank. My system is as follows;
3.1 kw array, Prebuilt Magnum System 4,400 Watts 48 VDC 120/240VAC
Off-Grid with Magnum MMP-175-30D panel, Classic 150,
ME-ARC50, AGS-N Module, Midnite Surge Protection Devices
The new lifepo4 battery for the most part has been running good for most loads except for one that I really need, my 1.5hp submersible well pump. For some reason when the pump kicks on the new lifepo4 battery bms shuts down and sends out a SC or short circuit protect code and then everything else including Magnum inverter and classic 150 shut down till I reset the battery. Please help if you have any suggestions or tips. The battery is rated for 100 amps continuous discharge.

 

[Steve_S]

The Pump Specs are very important here....
Make, Model, Voltage, Amps & Watt ratings. Link to Pump Spec sheet is best.
Age of Pump as well.

The Meritsun can handle 300A Surge, 120A continuous (5760W)
Designed & Intended to work in concert with their AIO Systems.

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[JoeHam]

Step 1 is to double check ALL connections and crimps to be sure they are up to the task of delivering high amps.

 

[Gauranga108]

here is the well pump control box link:

https://www.rcworst.com/Franklin-El...x-1-5-HP-230V-1PH-For-3-Wire-Motors-p200.html

 

[Gauranga108]

Here is thr motar:

https://www.rcworst.com/Franklin-El...or-4-1-5HP-230V-3-Wire-Single-Phase-p722.html

 

[Gauranga108]

Also the submersible well system is about a year old and has been used lightly with both my generator and my lead acid bank with this exact system and wiring set up with no problem. In terms of miss wiring, I guess maybe the new lifepo4 is more sensitive than the other two sources of power?

 

[Gauranga108]

This is just the well pump head its self
20gmp 12 stage 1.5hp
https://www.rcworst.com/A-Y-McDonald-23150P-Stainless-Steel-Pump-End-Only-20-GPM-1-5-HP-p7091.html

 

[Gauranga108]

also something to be noted that I find strange is that if my pv array is resting during night time or even after sunset hours and the system resets due to a fault or i just reset the battery the, the bms of the Meritsun also shoots a sc code when it attempts to again link with my inverter. If I turn the dc batery to inverter disconnect breaker off to the inverter the battery turns on the mppt midnight classic 150 no problem, but as soon as I hit the dc breaker to inverter again everything shuts down. In this instance I make sure there are no loads and that the output side of the magnum panel is off, but still it shuts down. Won't allow to reconnect till my solar array is pumping out energy from the sun, and even then the inverter turns I n but battery still shoots an sc code for s split second then goes to normal. Any thoughts

 

[Gauranga108]

In the above example the battery is full SOC! just seams that the battery should be able to start up inverter with no load even if panels are off or resting, my lead acid did that fine.

 

[mikeb]

any time you have to reset the breaker from the battery to the inverter you will have a surge from the capicators in the inverter powering up and the bms on the battery thinks that is an overload or short circuit and shuts off. you have to apply voltage with a resistor first.

 

[dRdoS7]

Hi,

any time you have to reset the breaker from the battery to the inverter you will have a surge from the capicators in the inverter powering up and the bms on the battery thinks that is an overload or short circuit and shuts off. you have to apply voltage with a resistor first.

That would tend to be bit of a pain considering most people would be using an inverter with batteries. Hopefully not every BMS reacts that way.

dRdoS7

 

[Gauranga108]

As I don't have grid power this system should be running all the time so ideally the inverter to battery disconnect breaker shouldn't be turned off too much. But like I mentioned everything works for normal use its just when I try to switch on that submersible well pump when it shoots thr SC protect code.

 

[mikeb]

i am not saying that all bms do this but mine does and apparently so does his. if your bms is able to handle the surge then you must have a high amp rating

 

[Steve_S]

As I don't have grid power this system should be running all the time so ideally the inverter to battery disconnect breaker shouldn't be turned off too much. But like I mentioned everything works for normal use its just when I try to switch on that submersible well pump when it shoots thr SC protect code.

There is the Big Hint as to what is happening. Clearly, when you turn on the water pump the Start Surge is too much for the BMS' to cope with resulting in an overload trip. The pump you have is NOT a Soft-Start pump so it will start with a very large surge (typical 2X the rating for that moment) and this can be made worse, the deeper the well is, the more force is required to push the water up & out.

You did not specific WHICH Inverter Model you have: (BTW, this info should have all been provided up front. Help yourself by being MORE Informative.

MS4448PAE​

Output Power	4,400W
Peak Watts	8,500W

MS4348PE​

Output Power	4,300W
Peak Watts	7,500W

A Typical soft-start pump will start off at 500W stage up in 150/200 increments over a few seconds which puts no strain on inverters. There IS a reason the lights dim for a second when the pump kicks on.

Looking at the links you posted, it does not appear that they carry Soft-Start pumps and one thing jumped out Right Away. If anything THAT IS A RED ALERT ! There is also no info on Amps / Watts draw on that pump on their site... 1.5HP does not translate into Amps/Watts.
The Meritsun Packs says it can handle 300A surge @ 48V so that should be 14,400W.

 

[Maast]

Since the pump started fine on the lead-acid bank but is now tripping the new LFP BMSs overamp protection I'm thinking the easiest way to fix the well pump starting draw is to wire in a set of 4 automotive 3 or 4 farad supercapacitors between the battery bank and your inverter.
Treat it like it's own mini-battery pack and attach a balancer to them - NOT a BMS just a balancer. Or you can wire in a 1.3 megaohm resistor between the pos and neg posts of each capacitor.
Capacitors in a series string easily get out of balance and it'd be easy to go over the voltage limitations of one of the supercapacitors and damage it.

 

[Hedges]

Motor probably draws 1.5 to 2 kW running.
Staring surge has been 5x running for smaller motors I've tested (window A/C), haven't tested a large induction motor yet.

Is this the battery?

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"300A for 1 second" would be 15 kW.

What is the surge current for your inverter? Not listed here:

4400W 48VDC Pure Sine Inverter Charger MS-PAE | Magnum Dimensions

www.magnum-dimensions.com

But Steve_S found 8500W. That is probably insufficient to start the motor easily, so could be struggling for an extended time. Good old lead acid kept up with it. Do you have a way to measure battery voltage and AC voltage over a few seconds, like oscilloscope or a logging DMM that can store dozens of measurements per second?

Maybe a large capacitor paralleled with battery would provide the necessary current. Try 10,000W for 1 second, 1V drop. That would be 50V, 200 farad. (rated higher voltage than peak charging voltage, of course.) Maybe smaller couple of farads like Maast suggests, but I've observed 150 millisecond starting times for motors with grid behind them. I think yours is taking longer.

A different inverter with twice the rating would likely work, but that costs more. What would be ideal is a pump that starts gradually, like 3-phase with VFD, but that's expensive and I haven't found small 3-phase well pumps. Other applications like my 2-horse pool pump are readily available; that one slowly ramps up to speed over several seconds.

 

[Hedges]

Control box documentation says,

"Two-wire motors are split-phase designs with integral starting components and do not require a control box; features Franklin’s patented 2-wire BIAC starting switch, which provides reverse impact torque to aid starting in adverse environments and prevents extreme fast cycling (e.g. water-logged tank)

Three-wire motors through 1 hp use Franklin’s exclusive three-wire QD (Quick Disconnect) Control Box with the patented QD Relay. This relay provides the ultimate in operational life"

"Suitable for outdoor mounting

Capacitor start/run design (except QD boxes)"

Motor documentation says,

"Single-phase three-wire submersible motors require the use of control boxes. Operation of motors without control boxes or with incorrect boxes can result in motor failure and voids warranty. Control boxes contain starting capacitors, a starting relay, and, in some sizes, overload protectors, running capacitors, and contactors. Ratings through 1 hp may use either a Franklin Electric solid state QD or a potential (voltage) type starting relay, while larger ratings use potential relays."

His motor is 3-wire, indicating control box provides phase shift for starting. Documentation says capacitors wear out with frequent cycling or excessive temperature.

Replacing capacitor may help. Different size capacitor may work better.

 

[Gauranga108]

Mine is the MS4448PAE

 

[Gauranga108]

Please reference page 16 for exact well pump specs. Also page 18 has information on capacitors

 

[Gauranga108]

My well pump is a 4" 3 wire at 1.5 hp motor model prefix 224300