Coulometer blues

kenobi66

100 µW
Joined
Apr 18, 2022
Messages
9
Hi forum folks,

Knob here. I've got a terrific little customized electric Zapino. ('Vespa-ish') It's got a 72v 3000w motor driven by Li-Ion 40Ah batteries with BMS's, and a Lyen 12FET spd ctrl. It works fine, slower than desired but whatevs.
There's a problem with the new coulometer that I installed into the system. This one: (and see pics)

https://www.aliexpress.com/item/3256801686045873.html?spm=a2g0o.order_list.0.0.27f818028Mskp8&gatewayAdapt=4itemAdapt

It's listed as 72v-capable and seemed to work fine for a while. Then every week or so I'd charge up the LiIons and go for a ride, and the voltage read roughly 10% less. Then the next week it read another 10% less, and so on. These readings despite charging the LiIons with the supplied charger each week. Now here's the other mystery: eventually the voltage reading went all the way down to zero, yet the scooter has continued to run just fine regardless; same speed, same range. I've been riding it like this for a couple of months now and no deviant behavior.

Any idea what would cause these symptoms? Anyone else encountered this? My first suspect is a crappy, cheap sensor. Second suspect is that maybe it can handle only up to 72v as a firm upper limit, making any 72v system unsuitable since true full voltage will always be higher than that. Third: um, aliens?

Any help / suggestions greatly appreciated!

https://endless-sphere.com/forums/download/file.php?mode=view&id=316244

https://endless-sphere.com/forums/download/file.php?mode=view&id=316245
 

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I been using those for years and never had any problems. By voltage you mean actual voltage or the percentage? because voltage will always read the true voltage of the battery and is display on the lower left corner.
The percentage on the other hand can fluctuate, when you charge the battery, the battery needs to reach the max voltage you program at the top end otherwise it won't reach 100 percent. Everytime it reaches the max voltage it calibrates itself to 100 percent.
For instance if the max voltage of your pack fully charge is 76 volts (example) then the pack has to reach 76 volts for the coulombmeter to display 100 percent. If the charger only charges the pack to 75.9 volts, it will never reach 100 percent on the display even if the battery is fully charge.
You can try lowering the max voltage on the coulombmeter so that it reaches 100 percent at a lower voltage, maybe 75 volts or whatever you charger gets the battery to.
The coulombmeter is rated to 80 volts so as long as you don't go past that it should work on your system.
 
Anybody have the programming instructions for one of those?

I have one with a different problem. When I charge, it will go to 100%. When I start riding, the % drops at first, but if I let off the throttle and the battery voltage bounces back, it resets to 100% again. After a few times like this, the % is off by quite a bit.

The voltage dropping problem is strange. It would seem to be a bad unit or possibly a bad connection somewhere.
 
When I charge, it will go to 100%. When I start riding, the % drops at first, but if I let off the throttle and the battery voltage bounces back, it resets to 100% again
I think in your situation the top end full voltage is set too low. For example if the max voltage on the meter is 28 volts, but the battery full charge is 30 volts , during acceleration it drops to 26 volts (and percentage drops) but when you let go of the throttle voltage bounces back above 28 volts (full) it will keep doing that until the battery drops below the meters max voltage of 28 volts. Once it drops below the max voltage it will start working as intended.

directions
tk15 directions.jpg
 
Hi jonyjoe303,

First off: thank you for responding. It is wildly appreciated. Sometimes I feel lost in the woods with this vehicle and all its aliexpress-sourced devices. (probably because I am)
jonyjoe303: when I describe the voltage drop behavior, I'm referring to displayed percentage on the coulometer. The first couple of weeks of light riding, it read 100% charged, so I figured I'd set all the parameters correctly. Then a week later with the battery fully-charged, the coulometer reading was 90%ish. So I topped the batteries again, thinking maybe I was taking crazy pills. A couple days later I plugged the batteries into the scooter & the coulometer read 80%, and so on. Eventually one week it reached 0% and has stayed there ever since, yet the scooter's still running fine.
During all this time the parameter settings weren't changed.

( Wow, the TK15 instructions say "generally, the FULL V and ZERO V do not need to be set" ???? Is that for real? Does the coulometer read my mind? Do you think that's the problem? Because I did enter values for those: FULL V idle voltage reading from my voltmeter, and I decided on a few volts over 72v for ZERO V: 75v)
 
depending on your battery specs, I looked at some 72 volt ebike batteries to see what the min/max voltages are. And the full voltage is 84 volts and zero voltage is 56 volts. So it looks like the tk15 won't work on your system since it goes above the max 80 volts. But you can still use it.

Since your battery is 20s, charging each cell to 4.2 will get you 84 volts, if you don't drive that much you can charge each cell to 4 volts and it will get you 80 volts. Charging to less than max will make the pack last longer.

But you can set to the following even if you fully charge, but the percentage will remain at 100 percent until the battery goes below 80 volts then it will start counting down the percentage. You would have the same problem as fechter that the percentage will go down during acceleration and then bounce back to 100 percent.

I think the directions might have translation problems and they meant that the full V and zero V do need to be set.

You can set the full voltage to 80 volts
and the zero voltage to 56 volts


a 72 volt battery.jpg
 
jonyjoe303 you're amazing!!!
I will plug in those settings as you recommend & see what happens, and will send you a virtual beer!
 
Though the chargers included with the battery packs are simple 'plug-&-charge' sort of things, no settings to alter the charging level. Can you recommend a good one? Because I could use some education on the finer points of LiIon handling.
 
Some chargers have internal adjustments; most are not marked as such, so posting pics of the insides might help us help you find them if there are any, if you're interested in trying that (if you're replacing them anyway because of this, it can't hurt even if you break them, right? ;) ).

Otherwise there are adjustable chargers out there like the Cycle Satiator from http://ebikes.ca. (and other more basic ones, but I don't know which are any good)

There are also LED PSUs, like the various Meanwell LED PSUs, such as the HLG-600H-54A I use, which is potted, sealed, and adjsutable current and voltage (it's mounted on the bottom of my trike, and has survived complete submersion in flash flood waters at least twice). (I also use a 12v version up on a pole to run a large bright LED panel for a backyard light).


BTW, you should make a thread for your scooter itself, with pics, build notes, etc., if you have time; it would be interesting to see. :)

We may also be able to help with other issues you have with it there.
 
Thanks again for posting the instructions. It's been a long time since I installed mine.

I typically charge my pack to 58v and had the "full" voltage set to 58v. But over time, the voltage reading had drifted upward so when it was 58v, the TK15 was reading 59v. I didn't see a way to calibrate the voltage reading, so I increased the full voltage by a volt and that seems to have solved the problem. Mine is an older one and apparently does not have a calibration for zero drift, just the full and empty voltages.
 
jonyjoe303, you are wizard-caliber amazing. I input the parameters you recommended into the coulometer's settings and got full functionality back! Naturally I have to repeat the same driving/charging regime over the next week before I can say empirically that everything works now, but I'm delighted regardless. Kudos to you, sir/ma'am!
I'm still mystified as to why the coulometer's readings behaved the way they had. Despite having topped them off (since the chargers will only do just that) after every test drive, the behavior ought to have been identical each day. :confused:
Anyway, will apprise. and will take amberwolf's advice to get my mitts on an adjustable charger in the future. And yeah, a couple of YouTube vids describing the whole adventure are a likely future project.
 
Hi amberwolf, unfortunately, looks like ebikes.ca's Cycle Satiator only goes up to 52v. I need something for big 72v blocks. But I'm sending them an email to make sure they don't have an alternative. Thank you for the suggestion though! I might get my next battery packs from these guys.
jonyjoe33: yup, your settings work perfectly! I actually prefer the extra voltage headroom that your settings provide, displaying 100% for a while before beginning to descend in readings. It's running great. A million thanks!

I took the scooter out on several errands this morning before the heatwave set it, awesome breeze, awesome ride, didn't burn a drop of gas. :mrgreen:
 
kenobi66 said:
Hi amberwolf, unfortunately, looks like ebikes.ca's Cycle Satiator only goes up to 52v. I need something for big 72v blocks.

:?:

https://ebikes.ca/product-info/grin-products/cycle-satiator.html
Download PDF Brochure
Design Features
Universal Compatibility
The Cycle Satiator is not limited to charging a specific battery type. Instead this one charger model can be configured for virtually any lithium, nickle metal hydride, or lead acid battery pack. Our standard 48V 8A model will charge packs with up to a 63V max charge voltage (15s for lithium), while the 72V 5A model will work all the way to to 103V max (24s lithium).

Informative Display
A large and bright OLED display screen shows all your realtime charging statistics; you can see the total amp-hours and voltage along with a clear graphic indicating the approximate charge in the pack.

Impressive Power Density
At almost 0.5 watts / cm3, the Cycle Satiator packs 2-3 times more power per volume than most other chargers available. This translates into big league charging currents in a portable size device.

Fan Free Efficiency
The power electronics were carefully designed to reach 95% efficiency at full load, eliminating the need for a fan to get rid of waste heat and keep things cool. no more buzzing fan noise and no risk of charger meltdowns if the fan fails.

Sealed and Watertight
A gasketted enclosure and connector design strategy keeps the charger electronics protected in the face of rain, road spray, dust storms etc.

Compact and Narrow Size
The charger is less than 5cm high and 8cm wide, allowing it to fit easily in a saddle bag, under the rear rack, inside a frame triangle, or screwed to a chassis.

Power Factor Corrected
AC input runs from 100-240v, allowing for worldwide operation without any voltage selection switch, and features a 0.99 power factor which will please your utility grid too.
 

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My Satiator notes:

3 models: All are limited to ~360W, overrides the max current spec

#2415 "12-24V" max output 36V @15A

for 48V

#4808 "24V-52V" output range 24-63V @8A (manual states 12-63V)

#7205 "36V-84V" outputs 36-103V but best for over 52V (manual states 20-103V), 4-5A (360W)



https://endless-sphere.com/forums/viewtopic.php?p=1532669#p1532669

voltage and current adjustable, isolated

360W output, 72V model: 20-103V 0-5A

48V version 12-63V, 0-6A (8A below 40V)

63V perfect for pack charging 18S LFP

360W, 6A at 48V, so bank size 15Ah (.4C) - 60Ah (.1C)

fanless and vibration & waterproof
very good galvanic isolation from input

can put in series, requires a mid-point tap on the pack. So if your 96V setup is made of two 48V packs in series, then each pack just has its own charging port and it will work fine

works OK off at 120+V DC

flashing profiles via USB

 
I need help. Can you tell me if the shunt resistor /sensor board have any IC on it?
 
What shunt resistor / sensor board, in what device?

I ask because you've posted this question in multiple unrelated threads. (this is the other one
Can I shorten external shunt wire? )


And what device do *you* have, and what are you needing to do with it?

I ask this because it will help us help you figure out whatever it is you need to know / do to use your device as you need to use it.
 
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