Realistic Cycle life?

[houseofancients]

Not according to EG4. They state a cycle is 80%. They've posted here on the forum to that effect.

Well then their definition is different to every manufacturer, supplier, BMS or tech..

Something to think about

 

[timselectric]

Not according to EG4.

And that's worth a nickel, if you put a dime in with it.

 

[macdaman]

And that's worth a nickel, if you put a dime in with it.

Yea - I went through a whole thing with them due to the fact that my EG4 LL-S batteries increment on average 2 cycles a day. After throwing some numbers at them, they first said a cycle was 80%, not 100%. They then said cycle count didn't matter since it wasn't used for any warranty purposes. I made note of the fact that cycles were the #1 or #2 items listed on EVERY piece of marketing materials so it "must?" be important.

Last word was that they were working on a firmware fix on the cycle count issue on the LL-S batteries. One was published sometime ago for the LifePower batteries. Haven't heard anything since.

 

[timselectric]

Yea - I went through a whole thing with them due to the fact that my EG4 LL-S batteries increment on average 2 cycles a day. After throwing some numbers at them, they first said a cycle was 80%, not 100%. They then said cycle count didn't matter since it wasn't used for any warranty purposes. I made note of the fact that cycles were the #1 or #2 items listed on EVERY piece of marketing materials so it "must?" be important.

Last word was that they were working on a firmware fix on the cycle count issue on the LL-S batteries. One was published sometime ago for the LifePower batteries. Haven't heard anything since.

Cycle count is less important than the color of paint on the outside.
It means absolutely nothing.

 

[bestconcreteblock]

Higher overpotential voltage means there is a higher voltage gradient across the electrolyte which opens the electrolyte to more decomposition.

I assume this is true for power cells that are designed for high C-rates as well?

I am using high C-rate cells in an application that regularly pulls steady 2-3C. I see almost 400mV overpotential under these discharge conditions. Interesting thing is that I can still get cell Ah capacity at these rates, just lower voltage. Cell voltage always seems to bump up very slightly about 2/3 of the way through these tests. I attribute that to cell heating. I am extracting heat from the cells. Cell temps typically don't go about 86F.

 

[aussiesam]

I was going to share this video, I like it , he did use older type cells.. But I have doubts about expectations vs reality. I'm in the tropics and the people here are telling me that they are seeing way less than expected out of their batteries. Some can be explained by hot weather. So my batteries are in a temperature controlled room and I baby them (I even have apps monitoring temperature and humidity levels). But my expectations in general are low. If they make it to 10-15 years I will be very happy. My friends who have invested in some of the popular brands all seem to have issues with cells, bms , alarms etc. All within the first 5 years.

There are also different conditions that play a role. We do keep charge rates under 0.2C, but we charge them every day from 20-100% (in comparison to Tim for instance who's cycles once every 3-5 days?). So I cannot realistically expect to get the same results as Tim. When Will was talking about the battery bank being undersized if you are charging over 0.1C. I was confused and thought it conflicted with the idea that it was fine to cycle them once every day. If you live in a place where the sun shines 99% of the year your calculations will be different than if you live in cold weather. My batteries are sized to power our home for about 1.2 days, in the rare occasion that it does rain, we just turn some stuff off and in the absolute worst case I do also have a transfer switch to use grid as back up, but haven't had the need switch even once since it was installed (which was roughly 4 months ago)

 

[Rocketman]

You NEED some kind of communication with the batteries - so you can look at the cell voltages (occasionally) while charging to know if your cells are getting out of balance. (So you know if you need to work on that).

It is your choice if you want communications between the battery and the inverter/system. This is usually having the BMS control the charging.

As far as battery longevity… my opinion is the BMS is going to fail long before the cells will. Keep that in mind when deciding which ones to purchase (it will be you replacing the BMS - it will be well out of warranty and the original company will probably be long gone).

Good luck!