shavermcspud
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Mine neither, I put my 16t back on to compare aagainst my other BMS and even on the latest firmware its way off. back on the shelf it goes.
Chargery BMS Cell Readings Inaccuracy. Should I be concerned?
- Thread starter Tony
- Start date
Exactly the same issue with mine. These things are poor quality, have many issues with installation and ongoing "product enhancements" documented here. Their primary role is to measure cell voltage and they can't get that right.
After 8 weeks I am still waiting for my unit to be returned and shipped back to me. I asked for a replacement to be supplied on exchange basis so I can get the power on. I gave up and bought a cheap Daly which arrived in 7 days. I will probably move to Batrium longer term.
After 8 weeks I am still waiting for my unit to be returned and shipped back to me. I asked for a replacement to be supplied on exchange basis so I can get the power on. I gave up and bought a cheap Daly which arrived in 7 days. I will probably move to Batrium longer term.
Hello All, I just found this thread as a result of looking for some clues to my issue with the 16T and voltage differences that don't agree with manual measurements. It's a sad state of affairs but oddly comforting to find out I'm not alone here...
My problem children are cells 11 and 16 for the most part with an 80-90mV delta. Manual measurements I've taken indicate the highest and lowest cells in the pack are no more than 20mV delta.
When I measure the cells manually, I measure from the negative side of a cell bonding strip (nickel spot welded 16p) of a particular cell group to the back side of the wire / connector that plugs into the BMS. I've done this with the connector connected and disconnected from the BMS with very little deviation (connected or disconnected to the BMS). I'd also tried with and without the external power supply.
I've also measured each individual cell (positive to negative) and see no significant difference when comparing the individual cell readings to the measurements between the negative terminal bonding strips and the cell positive connection at the back of the BMS connector (again, with the connector connected or disconnected to the BMS).
I'm convinced my wiring is good, and the cells are reasonably balanced ... I'm not using a calibrated DVM but don't care since I have no reason to think I'm not getting consistent relative measurements.
Question for anyone who's cracked one of these open ... any chance we're seeing cold solder joints on the BMS pcb monitor lead connectors? ... based on this thread it seems odd to me that we're not all seeing the same specific problem cells being out of whack. If it was a design problem or a component issue (or software?!) I'd think there would be more commonality.
FYI, I upgraded to 4.04 several days ago ... no difference....
dan
My problem children are cells 11 and 16 for the most part with an 80-90mV delta. Manual measurements I've taken indicate the highest and lowest cells in the pack are no more than 20mV delta.
When I measure the cells manually, I measure from the negative side of a cell bonding strip (nickel spot welded 16p) of a particular cell group to the back side of the wire / connector that plugs into the BMS. I've done this with the connector connected and disconnected from the BMS with very little deviation (connected or disconnected to the BMS). I'd also tried with and without the external power supply.
I've also measured each individual cell (positive to negative) and see no significant difference when comparing the individual cell readings to the measurements between the negative terminal bonding strips and the cell positive connection at the back of the BMS connector (again, with the connector connected or disconnected to the BMS).
I'm convinced my wiring is good, and the cells are reasonably balanced ... I'm not using a calibrated DVM but don't care since I have no reason to think I'm not getting consistent relative measurements.
Question for anyone who's cracked one of these open ... any chance we're seeing cold solder joints on the BMS pcb monitor lead connectors? ... based on this thread it seems odd to me that we're not all seeing the same specific problem cells being out of whack. If it was a design problem or a component issue (or software?!) I'd think there would be more commonality.
FYI, I upgraded to 4.04 several days ago ... no difference....
dan
He Dan,
Hope you bought it of ebay so you can ship it back for a refund. I got lured into getting an exchange in the hope that it was a by chance defect. The new one is slightly better but not accurate either.
I did more testing with balancing the 16 cel unit and it just does not work.
I have the second set of 8 cells disconnected and run it as a a 8 cell now.
It is a shame because the rest of the features are nice.
Attached 3 pics of unit in balancing mode. Each made a day apart.. the unit gets warm but it seems that it does not work. It does not discharge the highest cell first. It seems to more or less randomly discharge several cells..
In the first and last picture ( two days later) the delta V went from 71 mV to 81mV.. really weird.. Batteries are just sitting their being "balanced"
I think Jason overstepped the 16 cell version a bit, I mean it seems to be useless.
Johan
Hope you bought it of ebay so you can ship it back for a refund. I got lured into getting an exchange in the hope that it was a by chance defect. The new one is slightly better but not accurate either.
I did more testing with balancing the 16 cel unit and it just does not work.
I have the second set of 8 cells disconnected and run it as a a 8 cell now.
It is a shame because the rest of the features are nice.
Attached 3 pics of unit in balancing mode. Each made a day apart.. the unit gets warm but it seems that it does not work. It does not discharge the highest cell first. It seems to more or less randomly discharge several cells..
In the first and last picture ( two days later) the delta V went from 71 mV to 81mV.. really weird.. Batteries are just sitting their being "balanced"
I think Jason overstepped the 16 cell version a bit, I mean it seems to be useless.
Johan
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maharzan
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I have 2 units and both have issues reading pin 9 and 10. I think this inut needs a on/off switch. I figured there is one with ext power or batt power. It was on batt power by default and when I connected my 16s, the first 8 pin (or 9) connects normally but when I connect next 8pin, i see a spark or the sound. I think this is the reason why most people might have faulty reading on the 2nd half of the cells. I have told Jason about this too. Just my experience.
Just found this thread which discussed exactly the same problem I encountered that the 16s Chargery BMS gave inaccurate and unstable voltages (up/down for 30mV). It seems that Chargery BMS are good for the 8s model (with a lot of good comments in this forum) but not the case for the 16s model. Anyway, I returned mine last month and @Chargery gave me full refund. It is a good design and hope that the voltage reading problem for the 16s model can be solved soon.
Bob B
Emperor Of Solar
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Did you do the software updates and try using external power?
The new version they are developing is way overdue ..... hope they release it soon.
I bought it directly from Jason last month and it came with the latest firmware. I used external power source for the BMS.
shavermcspud
Solar Enthusiast
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there is a barrel connector on the side of the unit, I used a filtered 12v DC adapter on mine, it never cured the voltage issues though.
During the testing, I simply used an adjustable DC power supply to feed power to the BMS. I planned to use an old laptop PC power supply in the final setup.
For the voltage issue you encountered, was it a BMS8T or BMS16T?
I suggest using an isolated dc/dc converter to get power from the battery. You do not want to connect battery ground to the 12V BMS plug.
https://www.ebay.com/itm/323920064446?hash=item4b6b23efbe:g:s0wAAOSwj0deDvM4
shavermcspud
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BMS 16T
Bob B
Emperor Of Solar
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There is a write up about how to do it in the manual using a Schottky diode.
maharzan
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I ordered 3 Chargery 16T and all of them had voltage inaccuracy. when measuring by DMM, all cells have exact voltage or 1mV difference but chargery showed at least 20mV and it increased as discharge increased so slowly it would rise to 40mv, 60mv, etc. I just got a daly bms and JBD bms. I have connected JBD bms and it shows 3mV difference which is more accurate and I am happy with it albeit have to test other things too. Way cheaper and better it seems.
I posted another thread, assuming Chargery BMS was reporting correctly and my cells falling.
After pulling the lid on my battery and measuring with DVM, I see all 4 cells @ 3.322V and 3.321V. (Take a look at what chargery is reporting for my voltages, only -3Ah from full (I use 520Ah as full for 560Ah max capacity bank). This was after the battery had sat for 10 hours @ 14.10V to let the balancer do its thing. Since the reported voltage dropped so fast and voltage differential went wonky, I had assumed my battery was on death's door.
For 18 months, I've been powering the pack through the voltage taps. (my camper sits hibernating most of the time).
External power will come from this battery. I don't have another battery to power.
Anyhow what does the conventional wisdom say I should do? Is there another low-draw BMS which energizes heavy contactor?
Thank you!
Doug
After pulling the lid on my battery and measuring with DVM, I see all 4 cells @ 3.322V and 3.321V. (Take a look at what chargery is reporting for my voltages, only -3Ah from full (I use 520Ah as full for 560Ah max capacity bank). This was after the battery had sat for 10 hours @ 14.10V to let the balancer do its thing. Since the reported voltage dropped so fast and voltage differential went wonky, I had assumed my battery was on death's door.
For 18 months, I've been powering the pack through the voltage taps. (my camper sits hibernating most of the time).
External power will come from this battery. I don't have another battery to power.
Anyhow what does the conventional wisdom say I should do? Is there another low-draw BMS which energizes heavy contactor?
Thank you!
Doug
grizzzman
Photon Vampire
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I had the BMS8T Cell #1 was under-reporting by 10mv. #2 and #3 were close and #4 was under-reporting by 30mv. I would re-balance the pack only to have it go out of balance. My fix was to replace the BMS. good luck with your project.
Grizz - with what did you replace?
Thanks for this info. It seems consistent with my recent experience.
Interestingly, rebooted the BMS yesterday and it immediately read differently. It had been on for at least 6 months.
It powers from the battery and the unit is behind a screwed together lid, so not easy to turn on and off. Maybe I'll extend that switch and turn it on every time I take the camper out of storage.
Doug
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