Solar panel setup questions

[Kame_Sennin]

@The_Fat_Controller

4. Actual capacity : 5500mah I will be most dis chuffed if the ones i ordered only make 5.5ah

Did you get the batteries ? I am eager to know how many Ah they are !

[Kame_Sennin]

@The_Fat_Controller

Things to be aware of with cheap controllers , Many sellers lie about them being MPPT most are in fact PWM there are many fake Mppt modules there are also some good cheap controllers which really are MPPT here is one example Real budget MPPT

I have this controller and while i have not tested it for long yet i already have a few comments about it :

• When opening the cardboard box there was a noise inside the controller : After opening the controller i found a loose metal screw. Thanks i heard it before powering on because it might have shorted something !
• one of the TO220 components is thinner than the others and because its thermal pad is the same thickness there is a gap between the pad and the thermal drain (= not good!)
• beside that : neat and clean pcb with what looks like good quality components
• There is obviously a real buck converter that convert some of the spare voltage at the input into more current for the battery but the tracking seem to be either very slow or requires the input power to disapear totally for a new "tracking" cycle to occur
• While the specifications claim a "no load current" < 10mA i measure something that vary randomly betwwen 45mA and 65mA. From what i can see on youtube reviews other people have the same problem with a russian guy even measuring 130mA.

This last point is very bad news for me because with my low power pannel (20W) 45 to 65mA * 24h mean that i need more than one full charge hour each day just to compensate for the controller consumption plus the seemingly random variation is not very reassuring

[Barkuti]

@volchyonok

@Barkuti

The cell looks to be specified for a standard 1C charge current, 6.8A, and a 0.05C (1C/20) cut-off current which is 340mA.

The cut-off current is the current flow level at which the charge is stopped at the end of the Constant Voltage phase.

I honestly tell you that I still didn’t understand what is this “cut-off current”, especially since in his other videos about various other elements this same parameter is also mentioned. And if you yourself can explain what it is and in as much detail as possible, then this will become very useful for all of us.

…

Wellp, back in the day this somehow got lost but, exercising my english grammar, here's a definifion I've come up with:

Definition of charging cut-off current.-

Given that li-ion batteries are meant to be charged at a constant current rate, with a given maximum charging voltage (usually between 4.1 and 4.4 V, with 4.2 V typical for most cylindrical cells), this is done by progressively increasing the output voltage of the charging device to maintain a constant current rate to the battery while its voltage increases as it is filled, and monitoring and limiting the maximum voltage at the output of the charging device or at the battery terminals. Once the maximum battery voltage is reached and set (charging enters the Constant Voltage phase), current flow to the battery starts tapering off gradually but never reaches 0, like an inverse growth function (see the right graph below). What this means is that for current flow to stop the charging device must stop providing voltage to the battery at some point, at some minimum current flow rate which is the cut-off current.

https://www.sparknotes.com/math/calcab/logs/section4/

If some native english speaker thinks the above definition could be somehow enhanced, say so. Thanks.

[snakebite]

am i the only one who sees the total FAIL! soldering job in that second pic?

@maukka

Victron is surely the way to go if you just want it to work and make configuring easy. It’s very handy to monitor locally or over the internet with a Raspberry Pi running Victron’s Venus OS.

Mine is just in the testing phase, since I don’t have a good location for the panels.