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Question about wiring BMS to solar charge controller
#21
(02-10-2019, 06:38 PM)rhedbatt Wrote: redpacket brings up a good point about disconnecting a battery from a charge controller while charging.  that is a bad thing for sure.  im just not convinced you are going to be able to use these two things together and keep functionality from both. (refer first my two paragraphs)

FYI if the battery does not get to 4.25V / cell it is unlikely that the 'BMS' will do any balancing at all. that is, if you have the charge limit set on the controller too low ... might never get balanced by this method. 

My Answer
: this is why i swapped my EPEVER TRACER-AN Solar controller it has an Equalization Charge every 28th of the month which will balance all cells.

any corrections to what i am doing wrong is highly appreciated, it is for my safety after all. Thank You.

AFAIK, the tracer's are lead focussed.  Lithium does not need/want an 'Equalization Charge' anytime, let alone regular ... thats more for lead acid which burns (bubbles) off the excess (charge/energy, to 'balance' the cells inside the battery) ... vs a balance charger that has contact with each cell ... but I digress..

I like your post, but I'm now even more confused.  I've only got a BN tracer, so maybe I'm ... confused ... but I doubt it.


I like this thread and am keen for input, thanks all.
--    ----    ----    ----    ----    ----    ----    ----    ----    ----    --
all systems nominal... rock on.
-----------------------------------------------------------------------
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#22
(03-06-2019, 05:39 AM)DCkiwi Wrote:
(03-04-2019, 06:25 PM)Cherry67 Wrote: ...
the current measurement resistor
...


A.K.A the 'shunt'. (something that looks like a short on a multimeter, but is NOT a short...)


anyone else?

I have so much to say ... this is a great thread ... please jump in ... anyone?

So correct, it looks like a short, but is a shunt..... With the IR meter you can see that ROTFL.

I had seen that (Fets in the ground line) already before, but only the thread made me deal with that and indentify it as a nuisance for my system and plans.... So i concluded it may be important enough for others as well.
1 kWp in Test
4 kWh battery target - plus Mobile Home battery
Ultra low cost
Electronics ? No clue. Am machinery engineer.
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#23
Hey all.

Very interesting thread this, and interesting forum too as this is my first post. You project is very similar to mine. I have a Tracer as well, the 30A/100V version, connected to a 24V/205Ah battery bank using AGMs. They are getting a bit worn so I'm trying to build a battery bank with used 18650s.

I dont think you have to worry about disconnecting the charge controller from the battery. The manual states that you have to fuse the line from the controller so cutting the All PWM charge controllers I have ever seen explicitly states that you can _not_ fuse between the charge controller and the battery. I dont know if this is a PWM vs MPPT issue or if it's specific to the Tracer.

As someone said the Equalization mode is not for Li Ions it's for lead. The reason I bought mine a while back was because it can all types of lead batteries and also Li Ion. That being said, the default settings are pretty crappy. There is for instance no pre-installed mode for AGM batteries nor for Li Ion. What you need to get is the RS-485 to usb cable and download the "Solar Station Monitor" from EPever. Barring some settings that are only in Chinese you can set almost every conceivable parameter yourself. You can set the CC target voltage, the CV time, low and high cutoffs and warning as well as low and high reconnects. Not only for load but also for the battery, i.e. too high battery voltage cutoff. With the Solar Station Monitor you can also set the controller to Li Ion mode, which is what you want, and then all the parameters. The cable (Search CC-USB-RS485-150U on ebay or amazon) is a $5-10 necessity that turns an otherwise average MPPT charge controller into a nerds-dream gadget.

Another thing that's come up in this thread is loads. The load port can do the rated amps, maybe not for the smaller Tracer models not sure, but the short circuit detection is super sensitive. I cant connect an inverter bigger than 120W to my load port. Any bigger and the inverter rush-in triggers the short circuit detection and disconnects it. In my current set up I have the inverter directly to the battery bank and leave the undervolt cut-off to the inverter, 22.0V as it is. It's a bit on the low side for AGMs but fine for 7S with 3.14V per cell. Connecting the inverter to a BMS I am thinking will have similar results, maybe even cause an switch back and forth between on and off. I'm thinking in a single cell undervolt situation but I suppose it applies to raw current as well. An harmonics situation I dont think is good. There are inverters with current limiters and there are separate current limiters as well. As for the BMS so far I think all I have seen are crap and their mode of operation bordering on insane, but again I'm new at this.

End of rambling, as for your original question. All I can say is you will void the warranty on your tracer as connecting the common negative version to any common positive equipment will do so.
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#24
hello, I mounted 10 3s70p batteries with cells 18650 2200, each with a BMS with balancer. When I installed in my system everything was OK until the batteries fully charge, after it seems that the bms does not let enter the load and the solar controller is 20v in the output instead of 12v. What should I change?
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#25
You most likely ran to high voltage and the BMS disconected. Did you set up the charger to NOT go above the max volvate that the BMS let through?
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#26
(04-22-2019, 05:44 PM)daromer Wrote: You most likely ran to high voltage and the BMS disconected. Did you set up the charger to NOT go above the max volvate that the BMS let through?

1+.
I guess the theme of the cooperation between Battery, BMS and charger should find its way into the faq.
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1 kWp in Test
4 kWh battery target - plus Mobile Home battery
Ultra low cost
Electronics ? No clue. Am machinery engineer.
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#27
hello, I mounted 10 3s70p batteries with cells 18650 2200, each with a BMS with balancer. When I installed in my system everything was OK until the batteries fully charge, after it seems that the bms does not let enter the load and the solar controller is 20v in the output instead of 12v. What should I change?

The 20 volt your getting is a voltage surge, when the BMS shutsoff charging, all controllers(mppt/pwm) that I have used, produce voltage surges. The BMS uses electronic relays to shutoff the power going into the battery, these relays leak voltage. When the BMS shutsoff it will still read about 11 volts, the charge controller sees this voltage and thinks the battery is empty and tries to forcibly charge the battery, the battery won't accept amps. 
The bad part is these voltage surges will destroy anything that is connected to your battery, I lost many 12 volt fans/pumps/lights that can't handle voltage surges.

I added a overvoltage protection relay to disconnect the solar panel at a lower voltage that I know won't trip the BMS, but if the battery goes out of balance it might still cause the BMS to shutoff. All my valuable 12 volt devices I run through a 12 volt voltage stabilizer as extra insurance. The overvoltage relay is too slow to prevent damage to 12 volt devices, it shutoff the panel, but the 1 or 2 seconds it takes will kill devices. I haven't lost anymore 12 volt devices with the voltage stabilizer.



12 volt voltage stabilizer. Highly recommend these for those that charge lithium from charge controller. If the bms shutsoff early for whatever reason this will protect from voltage surges to 12 volt devices.
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#28
If you have the BMS in between the charger and the battery and battery and load you dont need to add any extra devices. Thats what the BMS is made to do. Protect from over and under voltage scenarios. Of course this should only happen if there is no sun or your charger have been wrongly setup.
The Ultimate DIY Solar and build place
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 83kWh LiFePo4 | 10kWh 14s 18650 |  66*260W Poly
Upcoming: 14S 18650~30kWh | Automatic trip breakers, and alot more
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#29
(04-23-2019, 04:56 AM)daromer Wrote: If you have the BMS in between the charger and the battery and battery and load you dont need to add any extra devices. Thats what the BMS is made to do. Protect from over and under voltage scenarios. Of course this should only happen if there is no sun or your charger have been wrongly setup.

so would that be one, or two BMS's ??
--    ----    ----    ----    ----    ----    ----    ----    ----    ----    --
all systems nominal... rock on.
-----------------------------------------------------------------------
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