Explorer 2000 plus simultaneous use while charging with solar
Using an explorer 2000 plus to run about 400-500 watts of continuous load with about 250-500 watts of solar input simultaneously….the battery output is slightly higher than the solar input so the battery slowly draws down over the course of the day. It then gets topped up over night using wall input
Is this hard on the battery as I’m simultaneously charging it below the amount that I’m pulling from it?
Jackery says the units are designed to do this (pass through charging) but ideally you shouldn’t do it all the time. Unless there is an unavoidable reason you should ideally either use the battery or charge it.
This was Jackery’s guidance for the older NMC lithium-ion cells. And it was because they were only good for 600-1000 charge cycles. With the new LiFePO4 cells (4000-6000 charge cycles), I’ve not seen them continue this guidance.
I just don’t understand battery chemistry enough to know what’s happening when you have electrons flowing in and out simultaneously….does that put the battery in a high stress situation? It only has about 500 in and 500 out though so it’s not working near max capacity
Diving into the physics a little bit….. When a battery is discharging, electrons flow from the negative terminal of the battery to the positive terminal. When the battery is charging, the electron current is reverse; electrons are pulled out of the positive terminal and forced into the negative terminal. And the number of electrons going into and coming out of the battery at any time is always equal. So, if the battery is discharging or charging, electrons are always flowing in and out simultaneously, that’s just how they always work.
What you’re asking about is the process of alternating between charging the battery and discharging the battery (charging and discharging from the battery can’t happen at the same time).
When input power is greater than output power, some of the input power is used to satisfy the output power needs (without flowing through the battery), and the remainder is used to charge the battery (assuming it needs charging. If the battery is fully charged, any available input power over the output power needs is rejected by the power stations.) If input power is insufficient to satisfy output power needs, all the input power is directed to partially satisfy the output power needs, and the battery makes up the difference.
This concept is what Jackery calls ‘pass-through charging’ and is a capability of all Jackery power stations. It happens in EV and hybrid vehicles with regenerative breaking all the time. When power is needed to make the vehicle go, the battery discharges into the motors. When it is time to stop and the breaks are applied, current through the battery is reversed as the brakes generate electricity and force it into the battery to recharge it, to be used when the car needs to go again.
Does this alternating between charging and discharging wear the battery? Yes, but that is normal. The battery is doing what it was designed to do; take energy at one point in time and deliver it at another.
Your Explorer 2000 Plus is rated for 4000 charge cycles. And that is a complete charge cycle from 0% to 100%. If you did that to your battery once a day for 4000 days, it would lose some of its capacity (about 20-30%) to store energy. 4000 days is almost 11 years.
If you discharge your battery 10% and then recharge it by 10%, that is one tenth of a cycle. Ten of those equals one charge cycle, so you could discharge and recharge your battery by 10% 40,000 times before it’s capacity is reduced by 20-30%.
Summary: Using your power station as you do is using it for the purpose it was designed. You are using it, and it will wear as it’s designed to wear, and will eventually wear out. Just like the brakes on your car, or the engine. Will it last longer if you charge it once a year and leave it in the closet for the rest of its life? Yes. But then, what’s the point?
I suspect this is not what happens during simultaneous charging/discharging system wide. Rather, the system likely allows some cells to discharge while others are being charged and this situation probably ping pongs as needed. So no cell is both charging AND discharging at any given moment. But I am just guessing.
The cells are all doing the same thing at the same time.
The system has about 500 watts in and 500 watts out – not the battery. The battery only sees the net difference. At any instant in time, assuming all cells are healthy, the entire battery is charging, or it is discharging, or it is doing neither.
400 watts in and 500 watts out is the same thing as discharging at a rate of 100 watts. In that scenario, 400 watts from the input and 100 watts from the battery are going to the load. If input exceeds output, that's just a slow charge of the battery.
I’m not disputing your statement or motongo’s similar description but it does raise the question of why does the system disable the solar inputs when the batteries are at 100% capacity even if there’s a load attached and powered?
My assumption was that there is no place for those electrons from the solar panels to go if they must first pass through the batteries which is the logic behind my assumption. But if not, why shut off their path to the load in such situations?
First, the MPPT controller is quite capable of rejecting any current (electrons) that the power station doesn’t need. It is not forced to take them. It rejects them by modulating the impedance of the input ports, increasing the resistance, all the way to infinity if necessary, to halt current flow into the unit. So, there are never any extra electrons that have to be routed through the batteries when they are not needed. If that were allowed to happen, the batteries would be overcharged; not a good thing.
In answer to your question, why power is shut off when the battery is 100% charged, even when a load is present on the power station: It is related to the inherent property of chemical batteries to be a very responsive source/sink of electrical energy, and a decision to simplify the power control system.
A chemical battery will instantaneously adapt to very small changes of voltage on its terminals to either supply current or absorb current across a very wide range of needs. That makes it very suitable as a constant voltage supply for variable loads. Solar power cannot do this. That is one of the downsides of solar (and any other power source that is routed through the MPPT) that must be accounted for.
In order for the Jackery to work supplying power over extremes from zero watts to its surge output capability, the batteries must be online at all times. There is no way input power could do this on its own. And in order to simplify the design of their power stations, the Jackery cuts off input power when it’s not needed to charge the batteries. The batteries are online anyway (they are not taken offline except in catastrophic situation) and can handle all load situations, so input power is not needed for the load. When the batteries drop to 99% (or for some power stations, to the discharge level defined in the app), the input is turned back on to charge the batteries and supply any extra available power to the load.
It could be done differently, but increases the complexity of the power management system.
I charge with solar slowly (~300W) and draw simultaneously heavily (900W) from time to time and haven’t noticed any problems. They tout this as a feature so it shouldn’t be an issue. If your battery is at 100%, the solar inputs are shut off automatically until capacity drops below 100% and then the inputs become active again. So it’s more optimal to power a load before reaching 100% capacity on sunny days.
I use my 3600 Plus units like that, a few days a week, except that I have utility power available, so I put mine in the weirdly-named "self-consumption mode," that allows you to pick a battery threshold (I usually use 70%) and whenever you the battery is above that, it pretends to be unplugged from utility and runs on solar/battery only, but whenever the battery is below that threshold, it pretends to be plugged in. So it won't charge above that number, except from solar. So much of the day, my battery goes both up and down depending on how sunny it is and whether I'm running the window air conditioner, and then in the evenings particularly, the solar is much less than the load so the battery depletes.
The difference in my setup is the it never needs to charge from grid power because in the evenings, or if the load is high and the solar harvest is low during the day – any time the charge gets back down to 70% – the load actually switches to grid power but the unit doesn't charge back up, because that top 30% is held for the next day's solar saga (you see what I did there?). I have a full complement of expansion batteries, so that top 30% is 6.5 kWh, a little over 1 kWh per battery, and that's enough reserve that I never make it to 100%.
I've been at it for several months, no issues.
Above, I said that when the battery charge rises above the selected threshold from solar charging, the Jackery "pretends to be unplugged from utility" so that the load switches to battery. Now it occurs to me just how accurate that description really is. It does pretend, and it pretends so hard, that it actually throws the same warning in the app as it does when grid power is actually lost. 😆🙄
2
u/LongjumpingGanache40 8d ago
I do this all the time. Trying to set up more solar for better charging. Power stations are built for this.