Hi everyone,
I recently bought a 4S Li-Ion pack for long range from the following site:
https://www.farinsframes.com/4s-3000mah-...tery-pack/

It was shipped at 3.5V.

Today I charged it with the Li-Ion program in my iMax B6 Mini and then I made my first flight, after which I landed at about 3.6V.

Then I tried to put the pack back in storage voltage using the li-ion storage program in my charger, but I noticed that it was charging the pack (I guess up to up 3.8V, like LiPos). For now I left it at 3.6V.

Which is the safest storage voltage for this Li-Ion pack? 3.5V (as it was shipped at) or 3.8V (like LiPos)?

Thanks in advice.

3.8v is good enough. Don’t loose your sleep over it.

Some charge and store them using lipo settings on their chargers.

I store mine Liions on about 3.7V per cell and LiPos about 3.8V per cell.
The Liions are good if you land on 3V or just a little below 2.8V, but don't overdo it.
When you charge the Liion, about 4.15 or 4.1 is very good. 4.2 works too, but Liions don't like it too much. Mostly because it makes the lifespan of the battery shorter.
There is an article over at Oscar Liang website where he covered this topic in much detail.

If you look at the spec sheets of several 18650 cells they are rated up to 4.2v charge. You can safely charge them to 4.2v.

only an empty battery is truly safe
3.8v is a good compromise about cycles/lifespan and usability.

I think a lot of people just use LiPo settings these days. Older LiOn cells used to not like being charged as high a voltage, but I think all the the good ones being made today can be charged and stored just like a LiPo. 4.2 max, 3.8 storage

I am NOT an experienced LiOn user, but that's what I have read about. In the past it could cause problems, but modern LiOn cells have gotten a lot better recently which allows them to be charged the same as you would a LiPo.

If I am wrong please correct me on this.

I used the charger storage program and it put it at 3.7 V.

I asked to the vendor and he told me that 3.8 could work, like a LiPo.

Since the charger automatically puts it at 3.7 V and it will be more simple, is it ok to leave the pack at that value?

anything less than than highest discharge rated liion cells arent usable for fpv, we need to buy the top cells which also provide the "abilities" lipos have.
"the old liion cells" is a quality we doesnt get benefits out of it compared to lipos.
molicel 21700c, sony vtc 18650.... there arent a lot good choices for us.