What does the capacity display refer to?

What does the capacity display refer to? Does it refer to the total capacity or to the remainder when DoD is subtracted?

Most power station companies keep a ~10% “reserve” to protect the devices from accidentally being fully discharged. Its a safety net because if you truly ran it down to 0%, you would need to open things up, and bypass the bms to get things “jump started” to be able to accept a charge. SOO you can safely discharge your unit to “0%” as displayed on the screen and be fine. Hope this helps

I understand. But is it so by the EP500 Pro? Then 100 % are 100 % from 90 %. :slight_smile:

@Tinkerpete I don’t personally have the ep500 so can’t speak from first hand experience but believe with that unit, you can actually adjust within the app, the “percentage” you want the unit to be charged/discharged too. They do this because with lifepo4 chemistry, it’s “ideal” to keep it between 20-80% to preserve the longevity of its cycle count ratings. I don’t worry about that sort of thing tho, because I’ll probably never see any degrading of the cells. They will more then likely “calendar age” before I get anywhere near 3500+ cycles out of them. That’s a ridiculous amount of cycles. Hahaha

Well, I use the EP500 Pro as a home storage unit. It is partially discharged and fully recharged every day. For it to pay for itself, it would have to last at least 10 years. I’m already thinking about that.

I’m currently doing a capacity test. At the moment it has delivered 2874 Wh and is at 17%. If I convert that, it reaches a maximum of 3462 Wh! That’s not even close to the 5120 Wh. Nor the 5120 Wh * 90% * 90% = 4147 Wh that the manual talks about. Once 10% loss because of the inverter and again 10% because of the DoD of 90%.

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@Tinkerpete Interesting man! I’m glad you’re sharing that info and I also love seeing these numbers/figures for these units so thank you! I know they can be pretty time consuming as well! haha

& I’m curious… what type of load and “rate” are you administering for your capacity tests? I’m assuming they are getting their numbers for a “standard” .2c discharge rate? Maybe @BLUETTI can find a spec or data sheet for the ep500 pro and shoot us a link for it?

Now I have 3126 Wh and 8%. I do not use a C rate. 2C would be 5120 / 2 = 2560 W for 2 hours.

I am testing it for the typical scenario at my home. A Fritzbox and some chargers around the clock = about 90 W. About 12 hours additionally a desktop PC with about 160 watts and sometimes with a 3D game about 500 watts.

Do you think that makes that much of a difference?

It reminds me of the days when there was a dispute/false advertising when it came to Hard drive capacity. 1 TB drive is not giving you 1TB of space.

Same marketing claiming 2048 watts, but you don’t get that, more like 1600 watts or so…

When will people get tired of the sales game? They should be forced to give actual wattage available.

This difference is based on the following circumstances:

1 KByte = 1,024 byte and 1 GByte = 1,037,741,824 byte

However, calculations are often made with 1000 bytes only. Therefore, it can be calculated precisely and actually has nothing to do with the fuzzy statements of the powerbank industry, which conceals losses due to bad converters.

If I recall the issue was not what 1TB represent, but after a hard drive is formated, the storage is less then 1TB. Even apple had to do a disclaimer with the iphones, making it clear that storage is less due to formating and operating system files.

I haven’t seen an inverter that has an efficiency better than about 90 perecent. That what Victron claims for their inverters. The bigger the inverter, the more the loss. Victron inverter are smart inverters and will go into a state and wake up when a load is detected.

I have to agree if the loss is worse than 10 percents, then one has a cheap converter/inverter and/or poor firmware programming.

A disclaimer should be made by the powerbank industry, if they have not done so.

I think with the drives formatting the system also takes up and reserves space to manage the storage. Pointers, paging, errors to bypass bad tracks/storage etc. the larger the drive the higher the overhead. And it is probably true that they use 1000 to represent 1k instead of 1024. As non computer literate users don’t really understand base 2 and more towards base 10.

Hi @Tinkerpete , There is no problem with your algorithm.
DOD is the industry basically sets aside 10%. The difference 685 = (4147-3462) is the difference between the battery discharge power and the optimal discharge power. And the temperature at the time of discharge is also related.