Help in setting up multiple Opus BT-C3100 powered by a computer power supply

Solloh

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May 26, 2020
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Hi all,

I have been creating my own charging station using a mix of Opus BT-C3100, pictures below.

I have 4 Opus and 1 Liitokala, all needing 12V, 2A - 3A. I want to power them using a computer PSU.

Since I am notusing the supplied adapters I cut the individual power supplies, connected all the positives and then all the negatives together. I soldered them to a switch (rated for 240 or 120V, since I couldn't find for 12V).

I am getting strange results with my setup. The Opus are causing a short when plugged in and they trip the power supply. When I measure connectivity between the -ve and +ve going to the Opus, I get a closed circuit for an initial ~5seconds which then clears. When I plug them in, they computer PSU justtrips.

When I connect only 1, it works fine and if I plug in the other 3 without (using the jack at the top of the OPus), they are all registerfine and they can be used. However, when I switch off using my switch, the PSU trips again.

Have anyone experienced this issue?

The TP4056 are working fine with no issues.

Any help will be appreciated



image_nicjmy.jpg

image_gehodg.jpg
 
I haven't experienced this but sounds like the switch has a short in it when switched off. if the power supply has a switch use that. or install a switch on the ac cord. The switch is designed for ac my guess is that it arcs when switched off and the arc trips the power supply.
later floyd
 
floydR said:
I haven't experienced this but sounds like the switch has a short in it when switched off. if the power supply has a switch use that. or install a switch on the ac cord. The switch is designed for ac my guess is that it arcs when switched off and the arc trips the power supply.
later floyd

Thanks floydR. You were spot on. The switch was the problem. The PSU doesn't have a switch, so I connected directly. I will look for a DC switch.
 
Likely you are experiencing "nuisance tripping" due to high inrush current as the charger's caps charge up when you plug it into the PC power supply. To work around that don't hot-plug the chargers. Instead, switch them on/off using the switch on the PC power supply.

Just how sensitive an SMPS is to such tripping depends on its design, e.g. I recall many such complaints about the Dell DA2 12V/16A brick which many hobbyists sought to repurpose. But its smaller brother, the 150W DA1 brick, doesn't have that problem(about $10 on eBay), i.e. you can hot-plug devices into it as you like.


To add to the above, PC power supplies aren't typically designed to expect such high-current hot-plugging. Rather, devices that are hot-plugged into a PC are designed using (inrush) current-limiting plugs to avoid such, e.g. an (e)SATA plug mates first via longer current-limited pins that limit the precharge current. The same idea is used in various "anti-spark" cables used in RC hobbies. See here for further discussion.
 
The Opus dont have large caps and initial current to Them is basically 0 compare to larger chargers. A computer have larger inrush then Turned in than 10 opus chargers have. Im pretty sure thats not the issue unless you have a PSU that is Brooken.

Though note that some older psus need both the 5v rail and the 12vrail loaded.
 
daromer said:
The Opus dont have large caps and initial current to Them is basically 0 compare to larger chargers [...]

"Large" is relative. Facts are better than guesses, and I know for a fact(firsthand experience) that the inrush current onthe BT-C3100 is large/quick enough to trip protection on the Dell DA2 220W SMPS, and I've heard that it also trips some other PC SMPS when hot plugged (but I don't recall which ones off the top of my head - it was many years ago).
 
gauss163 said:
daromer said:
The Opus dont have large caps and initial current to Them is basically 0 compare to larger chargers [...]

"Large" is relative. Facts are better than guesses, and I know for a fact(firsthand experience) that the inrush current onthe BT-C3100 is large/quick enough to trip protection on the Dell DA2 220W SMPS, and I've heard that it also trips some other PC SMPS when hot plugged (but I don't recall which ones off the top of my head - it was many years ago).

I am new to this stuff about inrush current. I am using a HP PSU as in the attached image. Maybe it will help in this topic.


image_irpyjg.jpg
 
^^^ It's simplest to just test hot-plugging devices to your power supply. To deduce it from the specs would be difficult, you'd need to know the actual inrush current, and also how the power supply handles overcurrent (e.g. foldback, or momentary boost, hiccup, etc).

Most PC power supplies will not have problems with small devices like a charger, but those from smaller PCs (e.g. "bricks" for SFF PCs like Dell DA2) are more likely to trip off. It is these much more compact bricks (supersize laptoppower bricks) which are often preferred by hobbyists, and they are usually quite surprised to learn that some of these power supplies trip off when a device is hot-plugged into them. That's one reason why I thought it worth mention above.
 
The best course of action is NOT to hot plug equipment in, especially items not designed for hot plugging.
Just put the switch on the ac side ie the power cord of the ps.
Build GIGANTIC Opus based charging station

Later floyd
 
floydR said:
The best course of action is NOT to hot plug equipment in, especially items not designed for hot plugging.
Just put the switch on the ac side ie the power cord of the ps.

It is safe to test out hot-plugging on any decent quality power supply. They are designed to gracefully handle overloading without damage to themselves or their loads.

floydR said:
Build GIGANTIC Opus based charging station

Not clear how that video is relevant since it says nothing about the power supply (or hot-plugging). He appears to be using a dirt-cheap generic (12V/30A) SMPS like those that are all over eBay. These are power-supply analogs of "20000mAh" 18650s - typically way overspec'ed, very low quality (and some are even serious fire hazards).

I strongly recommend against using them. Instead for the same price (or often less) you can get a refurb top-tier power supply that will likely outlive you. A popular choicein the RC community are server power supplies, e.g. the 12V/47A HP DPS-600 (made by Delta). There are many such refurbs available from top-tier PC ODM/EMS/ECMs such as Delta, Flextronics, Hipro(Chicony), Seasonic etc, easily found on eBay at good prices.

Another option is to go with top-tier industrial power supplies, e.g. those from Phoenix, Puls, Siemens, Omron, Cisco Ascom, Cosell, TDK-Lambda, XP Power etc, many of which can be found for 10 to 100 times less than street price on eBay.

There is no reason to buy a generic junk power supply when great deals on high quality supplies are ubiquitous.

Note: it is possible that the power supply in the video is a MeanWell (a decent middle tier choice), since their caseslook similar.But those are often cloned so one has to be carefulbuying them. There are no such clones of said top-tier supplies, so that is one less worry.
 
side said:
floydR said:
I haven't experienced this but sounds like the switch has a short in it when switched off. if the power supply has a switch use that. or install a switch on the ac cord. The switch is designed for ac my guess is that it arcs when switched off and the arc trips the power supply.
later floyd

Thanks floydR. You were spot on. The switch was the problem. The PSU doesn't have a switch, so I connected directly. I will look for a DC switch.
Just move the ac switch from the dc side to the ac power cord and see if it helps.


No need to buy anything else, and if it works problem solved. If it doesn't work you are out nothing.
 
^^^ Of course that will work (if inrush is the problem) but it doesn't allow you to switch on/off individual chargers. So if one charger is hanging and needs a power cycle then you have a problem if others are running long programs so can't be shut down. And its much better for longevity if you only power on the devices that you actually need (vs. all of them).

Not to mention its a real PITA when you later forget that you can't hot plug, and then do so and lose all your work on other running devices. So if you go that route then construct it so that it is not easy to make that mistake. But better to get a power supply without that limitation (Dell DA10s can often be has for < $10 on eBay)
 
Agreed, That is why I use a power bar to power my Opus's and the precharger/post discharge charger. Even have an Old Computer powerbar that has individual switches for each outlet think I used it forthe C=64. although most power bars don't trip when you unplug/plugin a original ps from an opus.
I was trying to help solve the OP problem. Enjoy most of your posts, even though I might not understand fully what is posted.

Later floyd
 
Floyd and Gauss, thanks alot for these replies. I am learning something new.

floydR said:
Build GIGANTIC Opus based charging station
This video was one of my inspiration to building my charging station. If you notice, he has only one switch which is what I wanted to mimick.

gauss163 said:
I strongly recommend against using them. Instead for the same price (or often less) you can get a refurb top-tier power supply that will likely outlive you. A popular choicein the RC community are server power supplies, e.g. the 12V/47A HP DPS-600 (made by Delta).
I will look for one of these in my neck of woods

gauss163 said:
There are many such refurbs available from top-tier PC ODM/EMS/ECMs such as Delta, Flextronics, Hipro(Chicony), Seasonic etc, easily found on eBay at good prices.

There is no reason to buy a generic junk power supply when great deals on high quality supplies are ubiquitous.
In my neck of woods (Nairobi, Kenya), ebay and Amazon are not an option. To give you a sense of this, everything on that charging board, except the switches, PSU and cables, is bought from Alibaba (yes Chinese version of AliExpress) and Banggood. The minimum waiting time is 2 weeks and can be as long as 2 months. I have learnt to work with what I get. The logistics are another nightmare.

gauss163 said:
^^^ Of course that will work (if inrush is the problem) but it doesn't allow you to switch on/off individual chargers. So if one charger is hanging and needs a power cycle then you have a problem if others are running long programs so can't be shut down. And its much better for longevity if you only power on the devices that you actually need (vs. all of them).
This is a really good suggestion thanks. i will definitely put some more switches, probably on the AC side and a proper DC switch as well as suggested by Floyd also.

Just to mention, I have plugged the charging board to an Uninterruptible Power Supply (UPS) unit, since our power utility company is the definition of a joke of a utility company. Power fluctuations, load shedding, "dirty" power are the norm here and in multiple times I have lost over 6 hours of parallel testing using the Opuses before this board.

The UPS provides me a master on/off switch for now. Since it works for now, I will use it and make the improvements down the line.
 
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