diy solar

diy solar

Trying to destory my SCC's: I can't do it!

joterrence said:
test.....70 v into 12 v battery...pull battery wire out put back in.....repeat till it blows
Click to expand...
WHY are you polluting our threads with this nonsense ?
IF you have anything of value to post, post it.
IF you need to have another Puffy, have it and find a game to play.
IF you actually have anything you own, that you blew up take photo's and post it with an explanation of what you did and how to blow the stuff up.

Have you ever heard of IRC (Internet Relay Chat) you might try that, then you can find people to "chat" with and occupy yourself with.
 
joterrence said:
test.....70 v into 12 v battery...pull battery wire out put back in.....repeat till it blows
Click to expand...
That makes no sense unless you're trying to blow up your battery with a direct connection to the panels or some other higher voltage source. Where is the 70V coming from? Maybe that's the input to your SCC, but the output wouldn't be.
 
I was thinking about something to protect the SCC in case the BMS disconnect the battery: why not connect a big capacitor (10000 µF for example) directly on the output of the SCC?

It should be able to act as a big enough buffer so the SCC as time to cut the output and not destroy itself (I suspect it's a voltage spike created by the main inductor suddenly going open circuit who destroys the SCC).

Of course all of this is just educated guessing so it can be all wrong.
 
currently have a damaged EPEVER 4012an the load os fried, the last one i had did the same too u had a 24 to 12 convereter fry and dead short the load at full PV power to the controller
 
I don't see it any differently than hooking up jumper cables backwards or hooking up the panels or battery backwards.
Then there is an issue of doing it repeatedly knowing it killed the first charger...
 
Will Prowse said:
Reverse polarity SCC destruction is not what we were talking about. We are talking about leaving SCC connected to array, but disconnected to the battery.
Click to expand...

Correct but I wanted to document my stupidity in the hopes it would remind others to take the time to check the basics before looking for something more complicated.

More an indictment of human error than charge controllers for sure!
 
I'm pretty sure this is all about the peak voltage seen because of the lack of a load and how panel open circuit voltages skyrocket on no load.

It's a bit nebulous because frying or not frying depends on several things that may not be lining up to put on a successful fry.

The SCC will have a designed maximum input voltage allowed in from the array. This will be set by the semiconductors confronted by the input voltage.

Does the array wiring actually deliver more than the allowed maximum?

The actual semiconductors while specified with a maximum allowed voltage often will take a little more. So if your array is just slightly above the max you may still get away with it.

There can be protection across the array input. That protection could be shunting or loading the array enough to prevent damage to the semiconductors. If your array is not so big it could be the protection can sustain long abuse where with a larger array (more current) it would actually fail the protection quickly leading immediately to toasting the semiconductors.

To understand why you're not frying your SCCs you need to see the maximum input voltage (NOT! the maximum number of panels or other flaky values) and measure the actual input terminal voltage being seen during the attempted murder.
 
you have to understand basic of electricity to find what could be wrong with sparks.
by nature, air is not a good conductor (30 kV/cm ) but can be if the distance is short or the voltage is high.
Since when we connect the battery to the inverter, the voltage is not high (12 or 24V) , there would be no reason to have sparks due to voltage.
So the reason for Spark is probably due to contact between the two conductor, so we create at some moment a tiny contact surface with a big current that is vaporizing the metal and create the big spark.
this should not create elevation of voltage, so no danger for the device.
but... all devices have a load that can be splitted into purely resistive (like a tungsten bulb) but also into capacitive (condensator) and inductive (coil) load.
Resistive load is very dumb so we can ignore it.
Capacitive load is usually not significant alone unless you get parallel wire running on long distance.
and if you have big capacitor in the device, if they are empty, they will just absorb the inrush power.
The problem comes from Inductive load.
an inductive load reacts to voltage and current by resisting to it and creating reverse force.
when you switch on and off the coil of a relay, even a when the powering voltage is low (12V) the reaction force can produce high voltage (over 100V).
unfortunately , inverter principle is based on the use of coils to elevate the voltage, so we can say that inverters have probably a fair load of inductance in the circuit.
if you sum all of this, capacitor, inductance, power, and circuit almost open closed by a spark, you have by design a nice Spark-gap transmitter.
The phenomenon will not last long, but if you are unlucky, i suspect this could puts some problem in the device.

I think there is very few chanced to create such circuit when you switch on/off trough a MOSFET like a BMS does, but you they are pretty high when you manually connect the cable into the terminals. They are probably higher if you connect the battery into the inverter, than if you make the sparks at hte battery's terminals
 
It would be crazy if no battery caused it to blow up think about if a breaker trips on the battery side from over current.
Ive Never had a problem on any battery based system with this.
 
Carly said:
Click to expand...
That will only happen with Electrodacus's earlier SBMS modules that have PV and LOAD connections at the SBMS (e.g. SBMS40, 120, 100, etc). Not a problem with latest SBMS0 since it sits outside the Load and Charging circuit. Much better design. Also results in the fact that no heat sinks are required since the shunts are now external to the SCC too.
 
Last edited:
Will Prowse said:
So I took every EPEver/Victron/PWM/Renogy solar charge controller, and tried to fry it by connecting it only to solar panels, and not to a battery... guess which one survived?

EVERY SINGLE ONE! I couldn't destroy any of them, and I left them connected to a high voltage array (80 volts) for 4+ hours each.

I connected each one to a lifepo4 bank after the test, and they functioned perfectly. Tested output with a watt meter before and after as well, no change.

I read in the manuals that you must NEVER connect an SCC to an array without connecting it to a battery first, because the potential that it can fry. I know that having improper gauge wires on an SCC can cause overheating around the terminals (dedicated voltage sensing leads would probably fix this problem, but many SCC use the charging lines as voltage sensing, which makes it wise to over gauge them most times. The voltage drop of a long run of hot wire can be horrible). But to actually connect an array to an SCC, and not to a battery, in my experiments, no issue.

I am thinking that the feedback signal in the converter circuit needs a reference voltage at the output to work. Then it can track the power point between the panels resistance and internal resistance of the battery, then push current to the max. If you only have the input powered up but no current is flowing, what would it stress? The panel would be in an open circuit voltage, and possibly use some power to charge up caps on that side of the circuit, but thats about it. Should be fine to leave connected.

Am I wrong? I know some MPPT's circuit designs are pretty complex, but they are still a simple converter circuit with inductor and capacitor and basic logic system to modulate it. I know some current limited converters can handle amp sources at input/output, and others can't. but because the solar panel is open circuit in this instance, and the output is also voltage sensing of the battery, I don't think any damage can occur.

What do you guys think? How can I destroy one?
Click to expand...

I cannot find any advice caution, instruction or mention whatsoever in regards to a no battery connected situation with my SCC. http://www.ultisolar.com/Ultisolar-Tracer1215BN-Tracer2215BN-Tracer3215BN-Tracer4215BN-Manual.pdf
 
Sandman said:
On page 6 it tells you to connect in exactly the sequence pictured, which is battery first.
Click to expand...

THANK YOU first and foremost for taking the time to review the manual with me.

Great idea to follow recommended connection sequence, though, I think that sequences 2 and 3 could be exchanged and all would be ok.

While there are precautionary statements and warnings in the manual, I still see nothing mentioned about equipment damage due to no battery connected.

Notes:
A) If the fuse that I have installed on the positive lead at the battery terminal blew, gasp, which would precisely be the same as disconnecting the battery load from my beloved Epever whilst panels were connected, heaven have mercy, would that spell game over for my SCC? Nyet.

B) Side note, Isn't it interesting how the sequence shows the inverter being hooked up directly to the battery instead of through the SCC's load terminals? Luckily I hooked it up correctly without even looking at the connection sequence!
Maybe the direct to battery inverter connection is because the SCC's load terminals are not meant for heavy current applications and/or the additional heat that would be produced within the Epever is not desired?

Have a great day, OG.
 
Last edited:
I have a Tracer 4215BN, and due to some crappy breaker that tripped multiple times at 30 amps i got disconnected from the battery! Nothing happened!!!

I just re set the breaker and everything was ok! This happened with about 1000 Watts of solar and at full sun in 3 different occasions.
 
I have done this many times accidentally and now do it fairly routinely. I do have several controllers paralleled together so to an extent they keep each other happy. Electronically there is really no reason why they should die. they see full solar voltage in normal use when batteries are full after all. That said some controllers do give a problem in that if The sun sets and comes up again or there is a solar disconnect and reconnect before battery voltage is re-applied, they can set themselves up for the wrong voltage battery bank and when you do reconnect it may think it is a 24v bank and not all are clever enough to realise they have got it wrong and will overcharge. For this reason I always advise those on my group to stick to the recommendation just in case.
 
Will Prowse said:
I read in the manuals that you must NEVER connect an SCC to an array without connecting it to a battery first, because the potential that it can fry.
Click to expand...

I've been browsing through the Victron Smartsolar 75/15 manual, I can't find any explicit statement prohibiting or even cautioning against leaving the SCC connected to the PV array but disconnected from the battery/loads.

I do see that in there install instructions, they advise connecting loads (switched off), then batteries, then PV, but they don't emphasize the point, or imply there is a risk of damage if the advice is not followed. And beyond installation there is no mention of danger/damage from leaving SCC connected to PV but disconnected from batteries (for example using a breaker or switch between batteries and SCC).

This is the only reference I can find in the manual:
Section 3.4 Cable connection sequence
  • First:connect the cables to the load, but ensure that all loads are switched off.
  • Second: connect the battery (this will allow the controller to recognize system voltage).
  • Third: connect the solar array (when connected with reverse polarity, the controller will heat up but will not charge the the battery).
The system is now ready for use.
Click to expand...

Can anyone (@Justin Laureltec maybe) clarify whether Victron specifically cautions or prohibits placing breakers or switches between the battery & SCC?
 
Can confirm that they don't actually care, and in fact require a fuse or breaker between the SCC and the battery. Technically the wording is in there because of a conceptual problem on paper that they wanted to make sure would never happen, but this was written before the days of LFP and BMS systems and all that. Their own systems now will shut off the battery when necessary, which would obviously create the very problem that they're trying to -theoretically- avoid.

I too have tried really hard to make a Victron SCC fail in this way, under various conditions including the full-bore-charging sudden disconnection event that the wording was theoretically written to avoid, and I have never managed to cause a problem by doing this.

The official word from Matthijs on this is that no one has ever heard of this condition actually causing a problem, it's just that an engineer back when his dad was originally developing these decided to include the language to cover for a theoretical problem that has never, in anyone's experience, actually occurred. With that in mind, they've been going through and slowly updating manuals accordingly... there definitely used to be some stronger language in the manuals that's now being removed (can't guarantee it's out of all the manuals yet) with only the language about connecting the battery first being left in - and that's just so the units can recognize and set the system voltage.
 
Sorry if I'm dragging up an old thread here... but I have something to add/ask...

I have a Tracer 3120AN which is going to charge a 24V battery bank.... I want to use the "load side" to connect to a 12V battery charger... Soooo
1) I'm guessing I'll need a 24-12 DC DC converter to do this right? Or can these tracer units do 24V to battery and 12V to load?
2), assuming main battery bank had a BMS disconnect event, surely the Tracer would still be putting current out to "load" terminals still... thus maybe that would prevent damage to the Tracer SCC, as current still has somewhere to go?

Cheers. Loving this forum (and Will's videos... so much positivity is infectious (forgive word choice in these trying times)... :)
 
Will Prowse said:
So I took every EPEver/Victron/PWM/Renogy solar charge controller, and tried to fry it by connecting it only to solar panels, and not to a battery... guess which one survived?

EVERY SINGLE ONE! I couldn't destroy any of them, and I left them connected to a high voltage array (80 volts) for 4+ hours each.

I connected each one to a lifepo4 bank after the test, and they functioned perfectly. Tested output with a watt meter before and after as well, no change.

I read in the manuals that you must NEVER connect an SCC to an array without connecting it to a battery first, because the potential that it can fry. I know that having improper gauge wires on an SCC can cause overheating around the terminals (dedicated voltage sensing leads would probably fix this problem, but many SCC use the charging lines as voltage sensing, which makes it wise to over gauge them most times. The voltage drop of a long run of hot wire can be horrible). But to actually connect an array to an SCC, and not to a battery, in my experiments, no issue.

I am thinking that the feedback signal in the converter circuit needs a reference voltage at the output to work. Then it can track the power point between the panels resistance and internal resistance of the battery, then push current to the max. If you only have the input powered up but no current is flowing, what would it stress? The panel would be in an open circuit voltage, and possibly use some power to charge up caps on that side of the circuit, but thats about it. Should be fine to leave connected.

Am I wrong? I know some MPPT's circuit designs are pretty complex, but they are still a simple converter circuit with inductor and capacitor and basic logic system to modulate it. I know some current limited converters can handle amp sources at input/output, and others can't. but because the solar panel is open circuit in this instance, and the output is also voltage sensing of the battery, I don't think any damage can occur.

What do you guys think? How can I destroy one?
Click to expand...
How about doubling the max solar panel watts Input to MPPT. Even though solar panels rarely put out rated watts, I wonder what the limits of oversizing solar input beyond ratings will do, and what is are the limits.
 
Capt Bill said:
How about doubling the max solar panel watts Input to MPPT. Even though solar panels rarely put out rated watts, I wonder what the limits of oversizing solar input beyond ratings will do, and what is are the limits.
Click to expand...
I do not think it is a problem. Think of this if your batteries are full and your SCC is in float mode it is holding back 90% if the PV power and the SCC does not even get warm in float mode. So I'm thinking you could throw 10x the rated capacity with no I'll effect. Not that I would try 10x but 3x seems reasonable
 
Craig said:
I do not think it is a problem. Think of this if your batteries are full and your SCC is in float mode it is holding back 90% if the PV power and the SCC does not even get warm in float mode. So I'm thinking you could throw 10x the rated capacity with no I'll effect. Not that I would try 10x but 3x seems reasonable
Click to expand...
my post got inserted here on page three, but flipping through threads; I was respond to beginning of thread and Will's:
Trying to destory my SCC's: I can't do it! ... How can I destroy one?
(letter got big from copy n paste/ not my intension)
 
I've been using a Blue Sky 2512i charge controller for 14 years. If battery is disconnected the controller will still output voltage. I know this when I disconnected the battery to work on electrical, and then sparks started to fly when shorting + to ground. I don't know what voltage the charge controller outputs when no battery connection, but if it's panel Voc then electronics connected to the system could fry.

Better check charge controller output voltage when battery is disconnected.
 
Capt Bill said:
How about doubling the max solar panel watts Input to MPPT. Even though solar panels rarely put out rated watts, I wonder what the limits of oversizing solar input beyond ratings will do, and what is are the limits.
Click to expand...

I have spent way too much time looking into this :). Short answer, you can do this, but it depends on the controller. Victron very clearly states (scroll down to the section on oversizing your pv array) its okay to do so long as you keep the Voc and Isc (max voltage and max current) of the array below the max input voltage and max input current of the controller--which for Victron controllers means that you can substantially 'over-panel' without risking damage to the controller or system, excess power is just not harvested. An extreme example is the Victron 100/50, at 12v it can output about ~650W, but based on the input specs 100V 60A the array could be upto 6000W.

Epever controllers (and the Renogy controllers made by whoever makes Epever controllers) have the same stipulations about keeping Voc and Isc below max scc input voltage and current, but also state that max input power (Watts) can't exceed max output power (Watts) by more than 3x. Not sure about other brands

You may be interested in this post on the topic
 
You must log in or register to reply here.

Similar threads

Kiwi2000
Victron SCC's and oversizing of PV array
Replies
5
Views
563
Samsonite801
S
L
BMS/charge controller issue
Replies
6
Views
252
littleharbor2
L
R
Export limiting
Replies
1
Views
149
SeaGal
SeaGal
RWSadler
Rick - Retired CEO of African Mission in Uganda
Replies
1
Views
121
sunshine_eggo
sunshine_eggo
Hogheavenfarm
Stalling Issue on turbine
2 3 4
Replies
86
Views
4K
brandnewb
brandnewb

diy solar

diy solar
Back
Top