Clivevan Posted April 26, 2022 Posted April 26, 2022 It may be recalled that I am planning a bare bones quality system that can survive unattended (12v and USB only; for rural use without any maintenance possible) as follows: 150 W panel ---- Victron BlueSolar PWM-Charge Controller 12/24V-10A -----Blue Nova 13V 104Wh -------- 4 port USB adaptor and Power Socket 12v But a PROBLEM HAS BEEN ENCOUNTERED. I enquired from Blue Nova and received this: Charger connected to our MPS range of batteries should adhere to these requirements: Bulk Charge Voltage: 14.0V Float Voltage: 13.8V Minimum Discharge Voltage: 11.7V (This is the voltage where the inverter should disconnect the load from the battery. If the inverter/device connected to the battery is allowed to drain the battery further past this voltage point you risk damage to the cells. Under voltage cut-out: 10.0V This safety feature of our batteries should not be seen as a regulatory function, but rather the battery tripping due to extremely low voltage. You would have to monitor your setup to ascertain your load profile, to prevent your batteries from being discharged to this point. (my emphasis) That is catastrophic for my plan. How do I protect the battery against low discharge?? I am NOT using an inverter (too expensive and inefficient for such a small system). Now what? If someone has any suggestion? Quote
PowerUser Posted April 26, 2022 Posted April 26, 2022 Doesn't Blue Nova have build-in BMS to protect for low discharge? Quote
Clivevan Posted April 27, 2022 Author Posted April 27, 2022 14 hours ago, PowerUser said: Doesn't Blue Nova have build-in BMS to protect for low discharge? No. They say: Minimum Discharge Voltage: 11.7V (This is the voltage where the inverter should disconnect the load from the battery. If the inverter/device connected to the battery is allowed to drain the battery further past this voltage point you risk damage to the cells. Under voltage cut-out: 10.0V This safety feature of our batteries should not be seen as a regulatory function, but rather the battery tripping due to extremely low voltage. You would have to monitor your setup to ascertain your load profile, to prevent your batteries from being discharged to this point. Quote
0012 Posted April 28, 2022 Posted April 28, 2022 https://www.victronenergy.com/solar-charge-controllers/bluesolar-pwm-charge-controller-lcd-usb Something like this, the charge controller can be programmed to disconnect load from the battery at 11.7V ? Quote
iiznh Posted April 28, 2022 Posted April 28, 2022 (edited) On 2022/04/27 at 1:21 PM, Clivevan said: Under voltage cut-out: 10.0V This safety feature of our batteries should not be seen as a regulatory function, but rather the battery tripping due to extremely low voltage. You would have to monitor your setup to ascertain your load profile, to prevent your batteries from being discharged to this point. The BMS disconnects the battery at 10V. If you apply a voltage of 13.6V it will enable the BMS again so the battery can be charged again. Some charge controllers will not supply a charge if they do not detect a voltage. You first need to activate the battery before the charge controller will charge it. You could consider a battery protection circuit eg https://www.robofactory.co.za/voltage-convertors/359-xy-l30a-6-60v-30a-battery-charge-control-display.html Edited April 28, 2022 by iiznh Quote
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