stickygreen0 avatar image
stickygreen0 asked

battery protect BP-220 low voltage disconnect but dont reconnect need help


Im new for a solar setup. I managed to do a tesla battery setup work great except for the battery protection.... i set it to 19v disconnect so its the setting 2C, it work so much that it stay disconnected when i take off the 2-1 pin it show E3 even at full battery so i have to disconnect the cable and put back them on it and it work fine... until it reach again low voltage i hope some one can help me. this week end i tought it was the inverter so i changed it.... this morning still same problem

ho yes the inverter has a low disconnect at 19.6v

Lithium BatteryBattery Protectdischarge level
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2 Answers
nebulight avatar image
nebulight answered ·

First I'm just going to say that an BP is no substitute for a BMS. You should have a BMS on that tesla pack for safety.

Second, that BP is under rated for the size of that inverter. That has the ability for 8000w which is 350 amps at 22.5v.

Third, from the first picture it looks like you may have some type of battery monitor with a shunt however you have the solar charger directly hooked up to the battery (along with something else) which will give you incorrect readings. You should hook everything up to the shunt and have the only connection to the battery be the shunt.

With all that out of the way, if you still plan on using the BP, then you need to be in Mode 2, not mode C. Mode C is for lithium ion BMS control only. If you are in Mode 2, it's possible that it didn't correctly detect your voltage. Fully charge the battery and go to program mode and detect the system voltage:

4. The BP automatically detects the system voltage one time only after connection of plus and minus to the battery. The selected voltage (12 or 24V) is stored, and further automatic detection is disabled. See d in the programming table for how to reset it when re-using the BP in a different installation.

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stickygreen0 avatar image
stickygreen0 answered ·

yes my bms cable are on the way,

the battery monitor is on the negative of the battery, i moved the cable of the mppt direct to the battery.

im on mode 2 already but at mode C for lithium that probly the problem. I will need to do a mode D i think for detect right?

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nebulight avatar image nebulight commented ·

Yes, mode D will detect the voltage. Then A2 for alarm/LED mode at low voltage of 19V (you don't need to wire an alarm or LED if you don't want, but it's on the three pin phoenix connector if you want). When in Mode C for lithium, you have the two wire loop on the two pin connector, since that circuit is never broken, it won't shut off anything.

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