What is a "cycle"

Bluetti claims that the AC200/p/max are capable of providing 100% charge for 3500 cycles i believe. What is a cycle?
Is a cycle every time you charge to 100%?
Example charging from0%- 59% to 100% =1 cycle

Or is a cycle a complete discharge?
100% to 0% and fully recharging it = 1 cycle

Or is it a combination.
100% to 0% and fully recharge = 1 cycle
Discharge to 55% recharge to 100%
Then discharge to 45% and recharge to 100% combined = 1 cycle?

The cycle capacity of 3500 cycles refers to having 80% of the battery capacity remaining after 3500 cycles.

I’m not sure what the technical definition of a cycle is but I would thing any discharge followed by a recharge. Even in the worst case of 3500 zero percent to 100% cycles that is almost 10 years of daily full cycles. But…I am still waiting for 10 years of testing to pass before I personally am confident of that theory.

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A cycle is generally counted as one full discharge and recharge cycle - even if not used all at one time. For example, my device is at 100% SOC, I use it to 60%, charge it back up to 100% the next day. I then use it to 40%, and again charge it back to 100%. This has now been 1 cycle because I’ve used 100% capacity of the battery and recharged that same capacity. Kinda weird to type out - hope that makes sense!


I understand your reasoning but reality is that no has tested any batteries in any brand for ten years. The battery is but one of many things to be concerned about when needing something to last for ghat many years. Any number of components or connections can fail and we all assume the battery is the only issue to be concerned with.

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A 3500 cycle to 80% capacity is just a rough guide. It will probably do better than one that is rated to be 80% after 500 cycles.

In practice, it is only meaningful if the manufacturer will back that up with a matching warranty. Given that the warranty is for 2 years, it is going to be hard to cycle it 3500 times to actually put the claim to the test within 2 years. I supposed perhaps if you cycles it once a day and got 600 cycles with the capacity down to say 75% before 2 years is up, then you may press a warranty claim (if capacity loss is not explicitly excluded that is…)

In practice, many thing besides cycle can cause capacity loss. Having the battery just sit there would cause capacity loss with just time. The higher the storage temp and higher state of charge, the more rapid time based degradation will be. Also, a cycle to the ends of capacity 100-0% is more harmful than 2 half cycles (2x 75-25) in the middle. That is why many EV recommends their owner to only charge to 80-90% on a daily basis, only topping up to 100% before a long trip.

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Hi @Wex,

Fully charge plus fully discharge = 1 cycle

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Oh yes, 100% agree with ya - just roughly defining a cycle. :smile:

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Thank you all for your replies.

Honestly I’m not as much worried about the warranty as I am finding someone to service this thing if it needs to be down the road after 2 years. Didn’t even consider the other components going bad which i guess is the plus to building your own system is you just swap the components out that need replaced.

@BLUETTI any chance there will be US based service technicians in the future for issues that arise post warranty?

Hi @Wex

Yes, some of our technicians will go to US and provide support after Chinese New Year. We also employ more local people for more customers service at the same time.