@ggw perhaps I missed that in the manual.

What page do they say that ? 

@misterb Yes.  In the case, compressed, with a capacitive active balancer.   I think balancing should not be done uncompressed.

I top balance mine outside of the case,
again fully compressed, but I don't use an active balancer, I just use a 'charger' (featured on youtube Offgrid Power Solutions) seems to work perfectly well.

@misterb 

I'd originally intended to top balance in parallel.  When I thought it through, it just seemed a lot of faff - how to compress the cells?  How to actually wire them up?  And then you need an enormous current to keep the total balance time reasonable.  In contrast an active balancer while cells are in series means you install the cells in the case, compressed, and wire up with the intended busbars.  The significant difference is the use of an active balancer - higher current so faster than the seplos passive thing which would take ages to balance the cells.

It was Andy from Off grid garage that said you should compress while top balancing; he thinks the first few cycles are the important ones that require compression; once the battery is old it doesn't matter - the damage is either done :-(, or not :-).  

its not that difficult - i lay mine out in two rows side by side, two pieces of 3/4 inch ply at each end and 4 threaded rods,, one in each corner, nuts on the rods tightened up to clamp all the cells together. Roger Ivy from offgrid power solutions demonstrated that you can just use the L and N wires from a length of 2.5mm cable, just remove the insulation at the point that a connection to a cell is needed. takes about 30 mins to make them up, easier than it sounds !! although i clamp all the 16 cells together i only top balance 8 at a time, then when both banks are done, then i link both banks together and do it again, though of course it only takes about an hour or so to 'equalise' them. 

i agree though on the time it takes to top balance - its a couple of days using the method i use, to do one bank of eight, so overall its around 5 days. a bigger charger would prob do it a lot quicker, but i am happy with it charging slowly. i set my charger to around 30A initially and the power gradually reduces as the cells charge, so when they reach 3.65v the charger shows 0A ! i didnt realise that at first as no one seems to show that on their top balancing videos !

PS its not just off grid andy who says you should compress the cells, i think will prowse did a video of charging without compression, but i dont know what long term effects that had on the cells. i think one reason cells are compressed before top balancing, is so that they fit into the ready made cases that are commercially available!!! 

its not the journey, its the destination ..... so long as we are all happy with our end result, then it doesnt matter how we get there !!! As i stated previously, given the choice at the time, it would have been the ready assembled Fogstar 'special' without a doubt! 

So close.....

@robl 

My battery discharged all day lovely got to 20:30 before it ran out - 20%SOC

once it hit 20% - the Sunsynk immediately started charging the battery (ignoring the USE TIMER i had set)

time 1 00:00 20%SOC

time 2 01:00 100%SOC USE GRID charge

time 3 08:00 20%SOC

time 4 13:00 20%SOC

time 5 08:00 20%SOC

time 6 00:00 20%SOC

Any idea how this occurred? only ay i got it to stop was to disable "use grid" in the battery settings. 

This morning, it stopped charging @08:00 - so it is reacting to the USE TIMER function 

Posted by: @adrianmc

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@ggw perhaps I missed that in the manual.

What page do they say that ? 

The manual says 80%DOD - for 3500 cycles

My interpretation of that is 10%~90%.

On other forums, the common consensus is 20%~100% = 80%DOD

This is my first week - i'm being conservative. if more info comes out saying I can go to 5%, that would be great as i will use it. 

@ggw can you take a photo of what is showing on the screen? i have added a photo of mine so you can compare

Posted by: @ggw

↑

time 1 00:00 20%SOC

time 2 01:00 100%SOC USE GRID charge

time 3 08:00 20%SOC

time 4 13:00 20%SOC

time 5 08:00 20%SOC

time 6 00:00 20%SOC

You need these to be sequential, Time 5 looks out?

So for example:

time 1 00:00 20%SOC

time 2 01:00 100%SOC USE GRID charge

time 3 08:00 20%SOC

time 4 13:00 20%SOC

time 5 16:00 20%SOC

time 6 00:00 20%SOC

Time 2 means it would charge from grid between 01:00-08:00, and discharge all the rest of the time down to 20%.  Any solar would charge it up though.

i agree with @vaugi - it may have been solar that was charging it as opposed to the grid, at the time you didnt have 'charge from grid' ticked, my experience has been that it will always charge from solar if there is excess from what the house is using. 

i have mine in the following order

solar to house, then if any excess

solar to battery, then if any excess

solar to immersion heater 

Seems the timer was the issue, I had time 1 set wrong. Worked @08:00 and all day so far.

Screenshots from our Sunsynk.  We have an old independent 4kWp FIT install, and our elec is Octopus Go.  The sunsynk charges from night elec and PV, runs the house from 4:30am till 12:30am.  It took a lot of messing around with settings to get it to work, didn’t seem at all intuitive to me.  Settings below work perfectly for us.