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

[erik.calco]

Is your "friend" named Erik?...

That whole scene looks like a car crash and fire. What exactly happened there? Did someone do something bad like choose the wrong charge profile for the batteries or was it just a junky PWM SCC that smoked and melted?

LOL no, that was really my friend. He decided to see if he could charge 18650s without a BMS after he toasted his BMS. We bought that same charger at the same time. But, I've only had mine hooked to AGMs and haven't had a problem. I ordered 18650s with him. But, I only used mine for vaping so far. I never got around to building a pack out of them. I've just been happy with the AGMs for my small setup, which works outdoors in the winter.

 

[efficientPV]

I don't think you would have to shunt that much current to get the overshoot under control. We'll find out because I have a controller that does that and it may be finally getting to me. Normally I don't have an inverter running and have a very small battery which is nearly always fully charged. Real easy to overshoot. Just a 150W soldering gun will do it when it is turned off. A TL431, FET and a small load resistor should do it.

 

[Mex Rider]

Thanks for testing this.

So I think what this means is I wiil be able remove the house battery and still be able to run a fan off solar power.

That is wonderful. I live in Phoenix and don't want to leave the house battery installed in the vehicle during the summer. Much better than what I was thinking I would have to do (install a sacrificial, smaller and cheaper battery just for the summer months).

Are you a Victron dealer or just a very interested hobbiest? I still haven't purchased the rest of my system yet. All I have so far is the Multiplus.

Haldor, please let me know how that actually works, I'm 4 hours south of you and have my fortune cells in the house right now but am going to pick up my solar panels in Lukeville on Thursday and would love to be able to run my two maxxair fans with the panels and my Kisae DMT 250 without the batteries...that would be awesome....

 

[Mex Rider]

Pulling in a related discussion that is on topic:





@Mex Rider @gnubie lets move the convo over here

Would the sort of surge protector often used for lightning protection potentially fit the bill? (of course this would might end up being as expensive as just buying a better controller)

So I'm really sure this is dumb....but could I connect a dead 12vdc, 8 amp motorcycle battery in parallel to my LifePo4 cells to absorb a spike in the event of a BMS high or low disconnect event?

 

[HaldorEE]

So I'm really sure this is dumb....but could I connect a dead 12vdc, 8 amp motorcycle battery in parallel to my LifePo4 cells to absorb a spike in the event of a BMS high or low disconnect event?

No idea. It might drain your LiFePo4 battery having that dead battery connected in parallel. Heck it might revive the motorcycle battery.

 

[HaldorEE]

Haldor, please let me know how that actually works, I'm 4 hours south of you and have my fortune cells in the house right now but am going to pick up my solar panels in Lukeville on Thursday and would love to be able to run my two maxxair fans with the panels and my Kisae DMT 250 without the batteries...that would be awesome....

Will do. I am waiting for some parts to get here to finish the battery. I have a lot of work before I will have solar power. I have an idea for a tiltable roof rack mount. I need to finish that design and build it. Probably going to be the end of September before I get that far (I am moving slow in this stinking heat).

 

[Mex Rider]

No idea. It might drain your LiFePo4 battery having that dead battery connected in parallel. Heck it might revive the motorcycle battery.

Had not thought about that but obviously a good possibility...like I said, dumb!

 

[Mex Rider]

Pulling in a related discussion that is on topic:





@Mex Rider @gnubie lets move the convo over here

Would the sort of surge protector often used for lightning protection potentially fit the bill? (of course this would might end up being as expensive as just buying a better controller)

So I have a Kisae DMT-50 charge controller and B2B charger combination with no reason to think it is not a quality charge controller but I am not an EE so trying to sort out good protection which probably should include a Victron 200 amp battery protect or Samlex BG 200, but while they protect the batteries I don't think they protect the rest of the system or do they? And with their voltage sensing ability are they stand alone or does some other device need to communicate with them. It looks like all the inverters have their low voltage disconnect way too low for any kind of battery, especially our LifePo4 batteries. The solar charge controller has a low and high voltage disconnect but that does nothing for the overall system, if I understand correctly. What do I need to add besides the battery protect? Is the battery protect going to disconnect the inverter before it discharges the batteries to 10-10.5 volts? Thanks, sorry I'm so thick

 

[Dzl]

So I have a Kisae DMT-50 charge controller and B2B charger combination with no reason to think it is not a quality charge controller but I am not an EE so trying to sort out good protection which probably should include a Victron 200 amp battery protect or Samlex BG 200, but while they protect the batteries I don't think they protect the rest of the system or do they? And with their voltage sensing ability are they stand alone or does some other device need to communicate with them. It looks like all the inverters have their low voltage disconnect way too low for any kind of battery, especially our LifePo4 batteries. The solar charge controller has a low and high voltage disconnect but that does nothing for the overall system, if I understand correctly. What do I need to add besides the battery protect? Is the battery protect going to disconnect the inverter before it discharges the batteries to 10-10.5 volts? Thanks, sorry I'm so thick

What I know about the Victron Battery Protect:

1. Intended to be a low Voltage cut-off for DC devices (plugs a gap in Victron's ecosystem, all their inverters have programmable LVD, and chargers have programmable HVD, needed a device to do the same for DC loads)
2. Cannot be used directly between a battery and an inverter (or other large load with big capacitors on the input side). In rush current can damage the device. If you want to use it with an inverter, it can possibly be rigged up to switch off the inverter without sitting directly in the current path. This would work with an inverter with a remote on/off function or possibly altering the inverters on/off switch.
3. Cannot be used bi-directionally, this will damage the device.
4. Beyond this, pretty damn flexible and can be used in a number of ways.

 

[Mex Rider]

What I know about the Victron Battery Protect:

1. Intended to be a low Voltage cut-off for DC devices (plugs a gap in Victron's ecosystem, all their inverters have programmable LVD, and chargers have programmable HVD, needed a device to do the same for DC loads)
2. Cannot be used directly between a battery and an inverter (or other large load with big capacitors on the input side). In rush current can damage the device. If you want to use it with an inverter, it can possibly be rigged up to switch off the inverter without sitting directly in the current path. This would work with an inverter with a remote on/off function or possibly altering the inverters on/off switch.
3. Cannot be used bi-directionally, this will damage the device.
4. Beyond this, pretty damn flexible and can be used in a number of ways.

So, the Samlex inverter is also programable for low voltage disconnect so that covers the inverter base. Do you install the battery protect between the positive bus and the DC fuse block and then the other loads are protected from a disconnect, both high and low voltage?

 

[Dzl]

Do you install the battery protect between the positive bus

This is a very common place to install it. There are some examples of how the BP/SBP can be used in the manual, its pretty flexible so long as you know its purpose and limitations. Victron Battery Protect Manual

I'm not sure I understand what you mean by:

then the other loads are protected from a disconnect, both high and low voltage?

As I understand it, the Victron battery protect, is a disconnect device, not protection from disconnects.

 

[Mex Rider]

This is a very common place to install it. There are some examples of how the BP/SBP can be used in the manual, its pretty flexible so long as you know its purpose and limitations. Victron Battery Protect Manual

I'm not sure I understand what you mean by:

As I understand it, the Victron battery protect, is a disconnect device, not protection from disconnects.

I guess I am asking if it disconnects in a way to prevent transient voltage spikes to the dc load when it is between the positive bus and the dc fuse block.

 

[Dzl]

I guess I am asking if it disconnects in a way to prevent transient voltage spikes to the dc load when it is between the positive bus and the dc fuse block.

I am not sure, but I don't believe this is within the scope of what it is designed for. As I understand it (not an expert) the Victron BP & SBP are essentially sophisticated solid state relays.

Maybe you want to consider something like a surge protector / lightning arrestor. This is not an area I have any knowledge or experience.

 

[Mex Rider]

I am not sure, but I don't believe this is within the scope of what it is designed for. As I understand it (not an expert) the Victron BP & SBP are essentially sophisticated solid state relays.

Maybe you want to consider something like a surge protector / lightning arrestor. This is not an area I have any knowledge or experience.

Thanks for your input, will check out the links.

 

[adriansantos]

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

doesnt the controller have its own fuse to prevent it from damaging if the load output short circuited. Am also using a 24v to 12v stepdown on my loadput to power my water pump, luckily its still functioning.

 

[adriansantos]

Tested the 100/20 with a lab power supply on the PV input for convenience of control. A single 12V 18AH AGM battery with a lightly loaded 1000 watt inverter (approx 40 watts) was used to drag the battery down. The battery was connected to the device to allow it to detect and store the voltage before tests were started.

With no battery connected to the controller at 'sun up', and a meter on the load output terminals and PV input being slowly raised to simulate normal conditions the load output stayed low until PV exceeded the +5v requirement for the Victron to start outputting current and then it went to regulated float, regulated 13.8

With a battery connected, and PV at a low level the battery was disconnected with almost no current flowing to the battery and the voltage rose up to 17.9 before dropping back down as capacitors discharged to 13.8. This only happened once, I could not repeat the result, even with various voltage and current limits from the lab power supply to the Victron. Even going to 5 amps into the battery and disconnecting it, the output resolutely stayed within limits, never exceeding absorption stage voltage. It may have been the cheapie lab power supply having its own issues and briefly yanking the PV input quite high, with the Victron doing its best to contain it.

This is very informative. I plan to Setup my Victron 100/20 with LiFePo4 w/ BMS for my aquaponic system. My concern really was what if the BMS cut off the power while my pump is connected to the Load Output of the SCC with the Full Sun, you gave me an answer. I will still add an additional fuse to protect my pump. Thanks

 

[Scph9002]

use 100v panels and 12v battery. Disconnect battery and you get a supprise for 12v equipments connected to the ssc load output...

 

[adriansantos]

use 100v panels and 12v battery. Disconnect battery and you get a supprise for 12v equipments connected to the ssc load output...

power surge i guess

 

[sunshine]

power surge i guess

Probably not to the 12v equipment already hooked up to it.
The surprise will come if you go to connect some other gear and the only grounding point was through that removed batterys negative terminal!
.

 

[HaldorEE]

Fun vid, I have replaced quad flat packs, but never the leadless ICs. I didn't expect the heat pad on the IC to release so easily without heating the back side of the PCB. The guy in the vid has balls of steel doing this while boondocking.

I think that was the BMS that burnt up though, not the solar charge controller. It also looks like the Electrodacus needs more protective circuitry if you can blow it up this way.

I would add TVS and series termination resistors to each input if this was my design.

I am very impressed by what a neat job, the Electrodacus designer did of packaging the electronics. Very clever to build the entire package out of stacked PCBs. And laminating a flex circuit to a plate of aluminum is an inspired way to provide enhanced thermal management on the cheap. I am going to borrow both of these ideas. I need to contact the Electrodacus designer and let him know how he has inspired me.

I work for a smaller company now and most of what I do is low volumn production (hundreds of units per year instead of hundreds of thousands per year I used to do). And electronics packaging consumes a bigger percentage of the BOM cost than I am satisfied with. The way the Electrodacus is put together looks like it would be great for low volumn manufacturing that can't afford injection molded enclosures. You could even add shielding to the enclosure by bonding copper layers in the outer PCBs.