Feature request

[offgridQLD]

I have two classic 150's and was wondering if a feature request might be possible.

Lithium battery's are becoming more popular. With lithium battery's you don't really run a EQ charge but the EQ feature can be very handy with lithium's.

Every so often you need to balance the cells. A lot of the cell level balances boards are trigger to start shunting current at a set voltage allowing the runts in the pack to catch up. usually around 3.6v before they are triggered.

So with the classic charge controller you can simply set it to do a EQ charge at a voltage high enough to trigger the cell top balances and scheduled  for say every 7 days and your lithium is happy .

The issue is I would like to be able to limit the max current during EQ to say 2A max.

How hard would it be to add this feature (amp limit setting for EQ)

Kurt

[Vic]

This has come up on this Forum,  before.

It WOULD be very nice to have a current Limit setting for EQ,  even for Flooded batteries ...  was EQing a bank just yesterday,  and manually set the current limit lower than its normal setting just for the (manual) EQ,  and then (hope I0 remember(ed) to reset it back to the normal,  higher setting.

Many FLA batteries like a current limit of 5% of 20 hour Capacity max.

It would be very nice if this EQ current Limit was not the CC's output current,  but,  rather the actual current INTO the battery,  via the WBjr.

Completely agree,  that having a specific EQ current Limit,  settable by the user would be a great addition.    FWIW,   Vic

[vtmaps]

This has come up on this Forum,  before.

Indeed it has, and I'm unable (at the moment) to find links to the discussions. 

This feature is closely related to limiting battery current during bulk and absorb charging.  The ability to set a maximum battery current means that you could have a (relatively) large array with a (relatively) small battery, and power loads that are larger than the maximum safe battery charging current.

--vtMaps

[zoneblue]

....And absorb based on SOC.

This is us ganging up on Bob for a new round of firmware development. ;-)

[offgridQLD]

Yes I was hoping the amp limit for EQ wouldn't be to much to ask. It seems like a easy fix but  perhaps I am ignorant to some complexity with implementing the upgrade.

I have 8200w of PV eager to boil the living  out of a battery . Though that's not really a issue with my lead acid bank as temp compensation and manually triggering a EQ when I know the battery's are full naturally keeps the amps  to maintain EQ voltage low.

The Issue when triggering a ( lithium battery EQ) basically a short time under 1hr perhaps one a week - fortnight at high enough voltage to trigger the cell top ballancers (over 3.6v - cell).  The cell top balance boards can't shunt much current. so I want to limit the max EQ current to around 2A.

Kurt

[vtmaps]

Indeed it has, and I'm unable (at the moment) to find links to the discussions. 

Here's a good one:  http://midniteforum.com/index.php?topic=790

--vtMaps

[boB]

....And absorb based on SOC.

This is us ganging up on Bob for a new round of firmware development. ;-)

That one was planned from day one.  Ok, day two but a LONG time ago...  There WAS even
a menu item for this along with the Re-Bulk but I pulled it out because this was a long
time away from the WB Jr., which was also planned.

[dgd]

The Issue when triggering a ( lithium battery EQ) basically a short time under 1hr perhaps one a week - fortnight at high enough voltage to trigger the cell top ballancers (over 3.6v - cell).  The cell top balance boards can't shunt much current. so I want to limit the max EQ current to around 2A.

So you have sixteen 3.2volt lithium cells in series and you want to activate the balance boards at 3.6v per cell or 57.6 volts while limiting max current to about 2amps

You could, at equalise time, switch in a current limiting resistor between Classic and the battery bank   58v/2a = 29ohms
You could make up a suitable resistor using a bunch of 10watt 3 ohm  types.

But then again it would be much nicer if boB did it in firmware 

dgd

[keppelk]

+1 for the limited current EQ feature. Would be really useful for balancing lithium.

At the moment I just set the EQ voltage 0.2V below the fully charged voltage. Leave a manually started EQ running until the cells are closely balanced, then increase the EQ voltage 0.1V in steps until the pack is fully charged and balanced. My Sinopoly cells are fully charged at 3.7V (59.2V). BMS starts balancing from 3.6V (57.6V). I usually only charge to 3.625V (58V) since there is almost no capacity above this point and it gives me headroom in case the pack gets unbalanced. 6kW of array can charge far faster than the measly 1A at single cell voltage the BMS can shunt to balance! Mostly pack stays near balanced, but still top balance every so often anyway.

Keeping with the balancing/charging lithium topic. I read here that there was an Aux setting that allowed a BMS to stop charging. I'm running latest firmware and didn't see this available in the Aux settings? bOb - is this setting in the most recent firmware?