Interest in Charge Doctor-like device?

[smarty]

This is my latest incarnation.  Module from ali express.  The voltage and wh reading is most interesting to me.  You can also set a voltage alarm with it.  The box is quite big as there is a shunt inside and also I have fat fingers.  Feeling pretty pleased.

BTW the wh interest is because this is for my wife's KS-N1-B, and I'm a bit suss on the battery wh rating...

[smarty]

This is the module if you are wondering...

DC 6.5-100V 50A/100A Digital DC Voltmeter Ammeter LCD 4 in 1 DC Voltage Current Power Energy Meter
https://s.click.aliexpress.com/e/Cvfwepuy

[Inductores]

Ready to layout!

[Inductores]

[cdoe]

Just wondering - what's the com port for?

[The Fat Unicyclist]

18 hours ago, cdoe said:

Just wondering - what's the com port for?

Comms...   

[Inductores]

23 hours ago, cdoe said:

Just wondering - what's the com port for?

Power input and output (instead of GX ports, but I was also thinking about MOLEX connectors...). I chose D-Sub because they're very easy to solder and make custom cables

[cdoe]

If this is not a balance charger probably an xt60/xt90 are even easier to solder...

[Inductores]

18 hours ago, cdoe said:

If this is not a balance charger probably an xt60/xt90 are even easier to solder...

Well yes, but they should be able to be soldered to the PCB, and I guess they're not robust enough if soldered directly on two copper pads...

Anyway it's NOT a charger, it's just a charge monitor

Edited October 10, 2019 by Inductores

[esaj]

On 10/10/2019 at 3:44 PM, Inductores said:

Well yes, but they should be able to be soldered to the PCB, and I guess they're not robust enough if soldered directly on two copper pads...

Anyway it's NOT a charger, it's just a charge monitor

There are PCB-mounted XT60's/90's available, for example:

https://www.tme.eu/fi/en/katalog/dc-power-connectors_112990/?visible_params=2%2C6%2C613%2C422%2C7%2C9%2C1247%2C1322%2C18%2C2555%2C5%2C416%2C77%2C11%2C412%2C2671%2C413%2C419%2C2546%2C424%2C177%2C1427%2C1428%2C68%2C13%2C2467%2C32%2C205%2C1424%2C516%2C646%2C426%2C909%2C82%2C511%2C21%2C1182%2C1335%2C536%2C328%2C329%2C138%2C1323%2C247%2C527%2C49%2C69%2C35%2C1382%2C117%2C10%2C20%2C635%2C1605%2C418&mapped_params=2%3A1260%3B416%3A1641369%2C1641370%2C1641371%3B1322%3A1436472%3B

(Filtered by AMASS, XT30+60+90+150, mechanical mounting on PCB)

I haven't really worked on this apart from doing basic calculations for the step-down circuitry. Maybe one day, but lately I've been too busy to even think much about this... If the monitor is separately powered, it's relatively simple and cheap to make, but "proper" step-down for the entire voltage range (still about 40-45V to about 105V to account for all 15-24S battery systems at full and empty voltages) seems to add too much to the cost, unless someone has found a good & cheap SMPS-controller?  Of course, if limiting to max. 84V systems (20S batteries), there a lot more options.

[Inductores]

On 10/12/2019 at 5:22 PM, esaj said:

There are PCB-mounted XT60's/90's available, for example:

https://www.tme.eu/fi/en/katalog/dc-power-connectors_112990/?visible_params=2%2C6%2C613%2C422%2C7%2C9%2C1247%2C1322%2C18%2C2555%2C5%2C416%2C77%2C11%2C412%2C2671%2C413%2C419%2C2546%2C424%2C177%2C1427%2C1428%2C68%2C13%2C2467%2C32%2C205%2C1424%2C516%2C646%2C426%2C909%2C82%2C511%2C21%2C1182%2C1335%2C536%2C328%2C329%2C138%2C1323%2C247%2C527%2C49%2C69%2C35%2C1382%2C117%2C10%2C20%2C635%2C1605%2C418&mapped_params=2%3A1260%3B416%3A1641369%2C1641370%2C1641371%3B1322%3A1436472%3B

(Filtered by AMASS, XT30+60+90+150, mechanical mounting on PCB)

I haven't really worked on this apart from doing basic calculations for the step-down circuitry. Maybe one day, but lately I've been too busy to even think much about this... If the monitor is separately powered, it's relatively simple and cheap to make, but "proper" step-down for the entire voltage range (still about 40-45V to about 105V to account for all 15-24S battery systems at full and empty voltages) seems to add too much to the cost, unless someone has found a good & cheap SMPS-controller?  Of course, if limiting to max. 84V systems (20S batteries), there a lot more options.

Thanks for the link! I didn't even know if it existed...

According to the step-down regulator, I found (and bought) this:

https://www.mouser.de/ProductDetail/946-MP157GS

[esaj]

5 hours ago, Inductores said:

Thanks for the link! I didn't even know if it existed...

According to the step-down regulator, I found (and bought) this:

https://www.mouser.de/ProductDetail/946-MP157GS

Nice, I looked at some of the MPS-regulators earlier, but all the suitable models were out of stock and no information when they might become available again (but that was 3-4 months ago ). That's a huge price reduction vs. the Linear Tech-devices.

EDIT: Oh wait, that's an AC/DC -regulator, the datasheet suggest rectified 85-265V AC input, what's the lowest DC voltage it still works with? The device would need to work on a 16S or 15S with depleted batteries, so the charger output might be <50V, thus why I was looking for input ranges from about 40...45V (empty 15/16S) or less up to 105V or more (full 24S). I've never seen anything other than 85V AC mentioned as the lowest input on the AC/DC-models, and never tried anything but DC/DC-switchers, if the AC/DC's can work down to 45V DC or so, then there's a lot of options. Although if the minimum RMS AC voltage is 85V, it would mean min. 120V DC, but apparently you're already using it on lower voltages. A quick glance on Electronics Stack Exchange advises against using less than the minimum voltage though, apparently the device can overheat due to undervoltage lockout -problems even if it seems to work fine for a while.

This was the MPS-model I was looking at earlier, out of stock and lead-time of 19 weeks:  https://www.mouser.fi/ProductDetail/Monolithic-Power-Systems-MPS/MP9488GS-P Works from 7.5V up to 450V DC input.

Edited October 14, 2019 by esaj

[Inductores]

Actually take a look to the schematic on the last page of the MP157 datasheet:

Even though the input is from an AC source, the input to the IC is rectified, so it should be the same if a DC input is used (from the charger). I asked to the company for stock of the MP9488 and they recommended me to buy the MP157 model, according to them it's the same device but different name (?)

Edited October 15, 2019 by Inductores

[esaj]

17 hours ago, Inductores said:

Actually take a look to the schematic on the last page of the MP157 datasheet:

Even though the input is from an AC source, the input to the IC is rectified, so it should be the same if a DC input is used (from the charger). I asked to the company for stock of the MP9488 and they recommended me to buy the MP157 model, according to them it's the same device but different name (?)

If it's indeed the same device, then it's a good deal. But the datasheet for MP157 does say that:

"Avoid the minimum DC voltage below 70V. Low DC input voltage will bring the problem of thermal shutdown."

So I don't think they're actually the same device. MP9488 could probably be used without issue in place of MP157 with rectified AC (it can handle the high input voltages), but likely not the other way around, when the input is lower DC voltage. But, of course if it works without issue down to minimum voltages needed in charging, then why not. Can you try to run it for several hours straight at low voltage and see whether it overheats / goes to thermal shutdown? Say, 50V DC?

Edited October 15, 2019 by esaj

[Inductores]

19 hours ago, esaj said:

Can you try to run it for several hours straight at low voltage and see whether it overheats / goes to thermal shutdown? Say, 50V DC?

Yes sure, I need to buy some more components but I'll test it.

I contacted the MPS Area Sales Manager to confirm if the MP157GS is capable of working with a 7.5V-to-450V Wide Input Range. I understand it is (according to the fact that it's "exactly the same device"), but I want to be sure...

Edited October 16, 2019 by Inductores

[Tinkererboi]

Looking forward to seeing a replacement to the charge doctor! 

Here's my own solution, it reads and records power input and allows me to fast charge at a total of 5.5 amps using my Gt16 chargers.

However what I really need is control of charging parameters. Was led to believe it can auto cut off currents of up to 20A based on a defined voltage with a small internal shunt but really can't find the option anywhere after scrolling through all menus. Being able to understand chinese does not even help in reading the instructions as descriptions are messy and vague at most.

Oh, and its not an easy build, so much can go wrong with the badly labelled and even mis-labelled polarities on components from China. This is one project I do not want to try again. A word of caution for anyone working with low cost chinese components: Always verify EVERYTHING with a multimeter first! 

Edited October 22, 2019 by Tinkererboi
Grammar error

[Chriull]

@esaj @Inductores - just fyi  (i n case you are looking for a quickstart wo messing with the step down converters ) there is from traco the TMR 3WIR Series (3 Watt, 43-160VDC Input, 3.3,5,9,12,15V Output) for ~25 € and from cincon the EC6AW-110 Series (10W, 43-160VDC) for about ~15€

[esaj]

21 hours ago, Chriull said:

@esaj @Inductores - just fyi  (i n case you are looking for a quickstart wo messing with the step down converters ) there is from traco the TMR 3WIR Series (3 Watt, 43-160VDC Input, 3.3,5,9,12,15V Output) for ~25 € and from cincon the EC6AW-110 Series (10W, 43-160VDC) for about ~15€

RECOM also does board-mountable switching-modules with isolation and whatnot, but the issue is the price. If the end user should be able to build / buy the parts for about 25-30€ total or less, the module alone would pretty much eat the entire budget   

Edited October 27, 2019 by esaj

[Inductores]

Okay, you convinced me to use XT60 connectors...

 

[Inductores]

Time to send the Gerber files to the manufacturer!

[cdoe]

That OSHW logo looks interesting. Are you planning to sell kits?

[Inductores]

7 minutes ago, cdoe said:

That OSHW logo looks interesting. Are you planning to sell kits?

20 in Spain and Berlin, after that I'll release the design for everybody

[Rotator]

On 8/12/2019 at 1:19 PM, Rotator said:

Hello. Recently, I was looking for a CD like device on aliexpress and I have found this about usd 12: https://es.aliexpress.com/item/32990510887.html?spm=a2g0s.9042311.0.0.b1e463c0bSte1Q Only needs a relay or Mosfet to cut power. Moreover, it has a TTL-serial interface as well, easy to bridge over bluetooth. It might be a winner way...

Finally I have got this coulometer working like a charge Doctor.

I have added a small circuit to stop the output when voltage goes up or when the current goes down.

The total price is around usd 15. You will need the coulometer itself, a npn transistor, a zener diode, a N channel mosfet and a pair of resistors. Easy to build.

Currently, I am testing the device charging my KS16S. The initial tests were fine. I am going to test it at my electric bicycle (10s 36v). This must work between 10v and 200v (the selected mosfet must support the upper limit)

When the threshold parameters are reached, the coulometer activates a signal in a pin. (3.3v). This signal is connected to a NPN base transistor ground biassed, so its collector goes ground when signal is activated. This collector stops a positive biassed N Channel mosfet gate with its source connected to the negative output an its drain connected to the load.

If there is any interest, I can put the circuit diagram and some pictures.

I am thinking in to connect the serial interface of this coulometer to a ESP8266 to send the charging status parameters to a online web, so you can see the charging process in any place and at any time. Moreover, since my charger is connected to a Sonoff socket (IOT) the process it could be interrupted at any time or when a online configured parameters would be reached. This could be more functional than a bluetooth interface.

Anyway, this is another option, and a real alternative to a charge doctor v2.

[Inductores]

Ready for testing!

Edited December 18, 2019 by Inductores

[Daniel Queron]

You built that? Congratulations, I am impressed. Very clean construction Maybe you could teach a thing or two to GW?  And I would be interested in the test results.