Does Pass-through charging add a cycle to the battery (Jackery)?

ecwashere

New Member
I've been charging my chromebook via USB-C from my Jackery (15W draw @5V) while simultaneously charging with a 60W solar panel. Most of the time the input (10-40W) exceeds the output and averages about 30W over 6-7 hrs.

Does this cycle the battery, albeit slowly, and decrease the battery longevity?

My limited understanding says the 12V-18V DC input is being buck/boosted to ~14.5V. From there, current will either flow to the battery or get bucked down to 12V for the DC output or 5V for the USB-C. When the draw from either of these exceeds the solar input, it obviously draws from the battery then. Please excuse my layman's knowledge of circuits.

So is this going to reduce the cycle capacity on the Jackery? Mine is "only" rated for 500 cycles and I'm just using the Jackery as a "buffer" because I don't have another battery or charge controller to experiment with.

I mostly want to understand how to use my batteries the least amount possible when energy from the panel is available.

I did search the forum and found a discussion about the Bluetti and EcoFlow but I was wondering if Jackerys work differently.
 

snoobler

Solar Honey Badger
Moderator
A discharge followed by a charge is cycle.

Cycles are either shallow or deep.

Cycle life is not absolute, but it is based on a given discharge depth.

Cycle life is based on 60-80% of rated capacity, i.e., after XXX cycles, the battery will still have 60-80% (different manufacturers use different standards, typically either 60 or 80%) capacity. It's not like a switch turns off and it doesn't work anymore.

For lithium, cycles centered around 50-60% tend to be the least stressful to the cells. Example: you use 20% per day. Using 40-60% or 50-70% is less stressful than using 80-100%.

For lead-acid, critical that they be recharged to full after every use.

In your situation with limited use, I would try to keep the Jackery somewhere between 40 and 80%.
 

ecwashere

New Member
Thanks for enlightening me.

In a nutshell, if I'm charging at 30W from solar and simultaneous discharging at 30W, then I'm not putting any "stress" on the battery cycles since all the input is going directly to the output? No current is flowing through the batteries?
 

snoobler

Solar Honey Badger
Moderator
If the unit is supplying loads with solar, then it's just passing through and any "cycling" is negligible.
 
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