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MPP 5048 MK is like an Online UPS ?
#1
Hi,

I want to build mostly a UPS (for computers and some home appliance) solution with EVE 3,2V 280Ah cells (16 pieces, 48V) and MPP Solar inverter (parallel 2 inverter).

I looked on the MPP Solar PIP 5048 MK model (EU):
http://www.mppsolar.com/manual/PIP-MK%20%28PF1.0%29/PIP-MK%20manual-20190717.pdf

This is the only MPP inverter where it says:

Transfer Time:

Line mode+Battery mode: 0ms
Inverter+Bypass: 4ms

Anyone uses MK series inverter? 
It is really like an online (double conversion) UPS where battery always works ?
How much is the energy loss because of this double conversion ?

The other question is about battery. It is always charging the battery? Or flooding it?
Batteries does not like to be charged after full, but because there is power needed in the load side ... so how does it do it?
Discharge 10% and the charge 10% ? Or constant charge ?
Lithium batteries will like it ?

Any info is appreciated

Thanks
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#2
Yes kind of online. 60w +15% losses rougly
.

You set Charge voltages yourself. Both bulk and float can be set.
NOTE! My links supplied in this message may be affiliated with Ebay and by clicking on them you agree on the terms.
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 100kWh LiFePo4 | 20kWh 14s 18650 |  66*260W Poly | ABB S3 and S5 Trip breakers
Upcoming: 14S 18650~30kWh
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#3
What bothers me is overcharging the battery.
3,65V /cell => 16*3,65V = 58,4V charge.  (if 80% charge then 3,5V * 16 I think)
So it will all the time charge the battery with 58V ?
If battery is full (3,2-3,3V is battery load V) even with low A (and 3,5V) it will overcharge it.
Or not ?
So I am not sure about it.


For example

Grid ->
MPP5048MK -> 
AC/DC inverter Charge (3,5V*16) -> 
Battery (3,3V * 16) ->
DC/AC inverter -> Load

The charger is always on a higher V than the battery, so that charges it (all the time ?).
If there is a load (say 2300W = 230V * 10A) then it comes from the battery, or somehow directly from the AC/DC inverter ? Does it know how much A is the load and generates only that amount ?
Or it lets the battery deplete 1-5-10% and then charges it back ?
Not clear for me yet  (sorry if stupid question, but can not find any precise info on it)
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#4
If you set charge voltage to 56V and the battery is at 56V there is 0A current going into the battery. Thats how electricity works.

As long as there is sun it will keep the battery at what you set it at. You got Bulk and float. If you set bulk to 57v it will go to 57v and then if float is at 56 it will drop down to 56v and keep it there for rest of the time

On Lithium you dont use this process but you set bulk and float to same voltage. Lithium have no problems being at set voltage. On LA you want to go bulk and then float since you need to overcharge to keep them balanced and have them in good shape. In lithium you just push them up to set voltage and thats it.

The charger can never be higher than the battery... The battery will alwasy reach the voltage you set the charger to go to. So just set it at the voltage you want the battery to be at.
NOTE! My links supplied in this message may be affiliated with Ebay and by clicking on them you agree on the terms.
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 100kWh LiFePo4 | 20kWh 14s 18650 |  66*260W Poly | ABB S3 and S5 Trip breakers
Upcoming: 14S 18650~30kWh
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#5
BTW if you plan to use this only as an UPS you are better off just buying an UPS. Also do you really need an Online UPS? Most equipment today can easily work with a normal off-line UPS with 10-20ms Switching time
NOTE! My links supplied in this message may be affiliated with Ebay and by clicking on them you agree on the terms.
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 100kWh LiFePo4 | 20kWh 14s 18650 |  66*260W Poly | ABB S3 and S5 Trip breakers
Upcoming: 14S 18650~30kWh
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#6
I read this very well thought article (Cell balance and usage, best practice):
https://files.ev-power.eu/inc/_auto88/_i...Charge.pdf


Unlike the lead acid batteries, that allow using the “equalizing voltage” or “trickling voltage” to stay at
full charge, the lithium cells are actually damaged when kept at the full voltage. This is the reason why
the LFP cell manufacturers do not recommend using the „floating voltage“ method to charge
the cells.
Simply said, when the lithium cell is charged, the charging voltage must be stopped and should not be
applied any longer.


So: charge -> full -> discharge -> low -> charge ....
But in Online UPS mode there is always a charge.

The LiFePO4 cell datasheet: http://www.dcmax.com.tw/LF280(3.2V280Ah).pdf
charge : 3,65 V (*16 = 58,4 V)
relax: 3,3 V (*16 = 52,8 V)

What I do not understand, if I use it then it will always charge battery at 3,65V (Online mode) ... does not stop charging it, and that overcharges the battery ?!?

If I set charge to 3,3V (the battery relax V, so it does not charge the "relaxed" 3,3V battery and battery is not powering load), then I have only 50% of the cells capacity if I have to go up from 10%.



"BTW if you plan to use this only as an UPS you are better off just buying an UPS. Also do you really need an Online UPS? Most equipment today can easily work with a normal off-line UPS with 10-20ms Switching time"
No thanks. I already thrown out 4+ UPS. The grid sometimes "not very stable" and they fight for 1-3 years against it, but then die (I have APC overvoltage protection before them)
So I am searching for a complete solution.

First I thought to use the bypass UPS like MPP 5048 MGX ... but it is only half the solution.
Better Online UPS, because even Line interactive UPS only smooth out the line errors (if can).
So I try to make sense of this Online battery function of the MK inverter

And I saw some post here, some use the MK inverters ... so I hope to learn from them Smile
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