OUPES claims "Avoid charging while using." What?!?

[ooglek]

A friend of mine purchased two Oupes Solar Generators, one 2400 and one 1200.

They emailed them stating:

Avoid Charging While Using

We do not suggest discharging the power station while it is charging. Although this is possible in unavoidable circumstances, but OUPES power station is not a functional UPS system. This way might reduce the lifespan of the battery and cause the charging voltage too high or too low.

Now this flies in the face of everything I know about electricity.

Have they done a terrible job of designing their product, that charging while discharging could cause a battery over-voltage situation?!? Can anyone explain why they say this? Why would a manufacturer state this, or design a solar generator that would damage the system if you had input power to the system, as well as a load attached? Would the input power not get redirected to the load first, then charge the battery if the input power was greater than the load? Or if the load was greater than the input power, take 100% of the input power plus some of the battery toward the load?

This seems highly suspicious.

I have attached the image from the email.

 

[FilterGuy]

We would have to know more about the internal design of the system to have any hope of explaining it.

 

[ooglek]

We would have to know more about the internal design of the system to have any hope of explaining it.

Agreed. But it sure seems like if charging and discharging at the same time can cause damage to the LiFEPO4 battery pack, then the design is pretty terrible when compared to the all-in-ones and other Solar Generators on the market.

If the Charger and Inverter were both connected to the battery at its terminals, then current would flow however it needed to flow, either fully to the load, or partially to the load and partially to the battery.

You'd have to do something pretty radically different, and IMHO stupid, to have that cause damage to the battery pack. Or lack an internal BMS. Or be generally incompetent regarding how electrical current flows work. If the charger input is normalized to say 13.6 volts (4S), and the inverter runs off 10-15 volts, and the battery and inverter and charger are connected in parallel, then the charger output will be passed directly through to the inverter. If the load requirements are greater than the charger can provide, the battery will provide the remainder. If the load requirements are less than the charger is providing, then 100% of the load is fed from the charger, and the remainder from the charger will charge the battery. This is Kirchoff's Current Law.

 

[FilterGuy]

Agreed. But it sure seems like if charging and discharging at the same time can cause damage to the LiFEPO4 battery pack, then the design is pretty terrible when compared to the all-in-ones and other Solar Generators on the market.

I sure can't argue with that.

 

[ooglek]

From OUPES Sept 7, 2023:

Thank you for contacting us.

Yes, we suggest customer discharge the power station when it is fully charged.

Because the Emergency power station is not a functional UPS system, they have differences.

But you can still pass through charge, it's ok. It's not potentially harmful to you.

Just let you know that discharging the power station when it is fully charged will be a friendly cycle to the power station.


Regards
Lily
OUPES Support Team

Nowhere on their website do they mention anything about "Emergency power station," nor did I ask about a UPS.

Are they considering solar input and using the inverter simultaneously as a UPS?

This company literally makes zero sense to me. Either they are wrong and it is fine to charge and discharge at the same time, or the design of their solar generators is completely crazy. Or they used crap LFP cells and are trying to put the blame on the user when the user does not get 2000+ cycles out of the batteries.

Something is fishy.

 

[Ellcon123]

In terms of the battery you can only charge, discharge, or neither. You can't be charging and discharging at the same time. The way I interpret their response is that they don't want the battery held at a high state of charge.

 

[ooglek]

Agreed. However in a circuit, Kirchoff's Current Law states that the current flowing into a node/junction must be equal to the current flowing out of it.

Which simplified, means if the Charger is connected to the battery, and the Inverter and/or DC Loads are connected to the battery:

• When the load is less than the input, the input fulfills 100% of the load, and the remainder charges the battery. If the battery is at capacity, the input current is reduced.
• When the load is more than the input, the input provides as much to the load as possible, and the remainder comes from the battery. If the battery is dead, and the input is limited, then you simply cannot run your load.
• When the load is exactly the input, the input fulfills 100% of the load, and the battery does not get charged.

There is not an "input" and "output" side of the battery. Either current is going into the battery terminals, current is leaving through the battery terminals, or no current is flowing.

With a BMS, there should not be any way for the input (within specs) to damage the batteries or reduce the lifespan of the batteries. Nor should the load be able to damage the batteries or reduce the lifespan of the batteries.

If the BMS is terrible, or the solar input causes the BMS to get too hot when the battery is full and there is no load attached, then I suppose the heat could damage the battery, or a terrible BMS would allow individual cells to go over-voltage.

The heat thing is the only thing I can think of, and if they didn't consider airflow and heat exchange in the design, that COULD explain their advice not to charge and discharge simulatenously.

Every way that seems plausible that it would hurt the unit to literally use it normally leads to my belief that the unit has one or more design flaws that reduces the longevity of the device even when used as any other solar generator would be used.

Argh.

 

[TacomaJoe]

Could it be that the heat generated by the charging circuits, plus the heat of the inverter circuitry overwhelms the cooling ability of the unit? Or there could be some shared voltage sensing components. The inverter may not be able to read battery level if the charger is active.

 

[ooglek]

That's my hypothesis. OUPES Support either does not know, does not understand, refuses to say, or some other reason.

Why would the Inverter need to know the battery level? Use the current/voltage available until the voltage falls below a certain threshold and shuts off. If the charger is active, why should the inverter care if the voltage/current is coming from the battery or an external source such as Solar or AC adapter???

Whatever the actual reason (heat, shared voltage sensing, etc) the restriction is a stupid design flaw and if the advice is accurate, people should avoid OUPES unless the use case is charge to full, use to empty, repeat, and never charge while discharging.

 

[RobertoJJJ]

That's my hypothesis. OUPES Support either does not know, does not understand, refuses to say, or some other reason.

Why would the Inverter need to know the battery level? Use the current/voltage available until the voltage falls below a certain threshold and shuts off. If the charger is active, why should the inverter care if the voltage/current is coming from the battery or an external source such as Solar or AC adapter???

Whatever the actual reason (heat, shared voltage sensing, etc) the restriction is a stupid design flaw and if the advice is accurate, people should avoid OUPES unless the use case is charge to full, use to empty, repeat, and never charge while discharging.

Yes, their answer sounds ridiculous. I agree with this point of view. Do they seem to treat users as fools?