diy solar

diy solar

Recent content by brum

  1. B

    Seplos CAN BUS RS485 48v 200A 8S-16S BMS

    These would be very close. Battery voltage is the cell pack voltage. Bus voltage is the voltage on the BMS output to the inverter. If low current is flowing these are extremely close. If large current is flowing the difference is caused by the resistance introduced from the wires, pack and the...
  2. B

    Seplos CAN BUS RS485 48v 200A 8S-16S BMS

    Provide pictures of the battery, not picture of the BMS UI :) .
  3. B

    Seplos CAN BUS RS485 48v 200A 8S-16S BMS

    The BMS can not handle situation with totally unbalanced cells. You are supposed to balance them before assembling the pack. Easiest solution to do it without disassembling the pack is to turn off the BMS and charge each cell up to 3.65V with power supply. Stop charging once current drops below...
  4. B

    Seplos CAN BUS RS485 48v 200A 8S-16S BMS

    Did you balancer your cells before assembling? Can you post a few pictures of your battery?
  5. B

    Seplos CAN BUS RS485 48v 200A 8S-16S BMS

    Yes. But since it is like 100mA discharge you'll need 10 hours for each Ah difference. It will take forever :) .
  6. B

    Storing heat in sand?

    Here is an example for MPPT heater controller - https://projecthub.arduino.cc/stevetearle/loadmaster-xp-a-smart-pv-mppt-solar-hot-water-controller-5264c7 . Details are pretty well explained.
  7. B

    can i wall-mount eg4-48v server rack batteries?

    As long as you have a suitable wall (concrete) and proper stand there is no issue. I have a 280Ah 16S battery mounted this way and it is over 200lbs. 4 concrete anchors + an iron stand made of 20mm square profiles with 2mm thick wall.
  8. B

    Seplos CAN BUS RS485 48v 200A 8S-16S BMS

    The process should be automatic, not you manually doing anything. The SOC will drift with the time and the BMS will compensate for that drift every time when the cells are fully charged (preferably) or discharged. So make sure that you reach fully charged state (like 3.45+V per cell) on regular...
  9. B

    Seplos CAN BUS RS485 48v 200A 8S-16S BMS

    Voltage will go over 3.4V only while charging. Then it will settle down to around and below 3.4V. Having a cell at 3.5V while charging means that it is fully charged. No point in going above that. Having wrong SOC Ah will only lie the inverter about the remaining capacity. I can't think of...
  10. B

    Storing heat in sand?

    For AC - yes. But the OP is considering DC as source. Fixed load works in fixed conditions, but the power you produce is not a constant. That's why there are MPPT trackers. Even such with DC output for heating elements. They use PWM to reduce the power on load side and dynamically control the...
  11. B

    Storing heat in sand?

    Induction heater has lower efficiency (~80%) compared to resistive heater. There are even OOB MPPT devices for resistive loads like water tank heaters. I don't see benefits in considering inductive heating here.
  12. B

    Storing heat in sand?

    And you are slowly coming to my solution. Instead of storing heat energy, I store electrical energy in the battery. And when heat is needed I start the heat pump. The pros - no heat energy losses and close to constant round trip energy losses (~20%). And electricity can do a lot more than heat...
  13. B

    Storing heat in sand?

    Did you calculated the losses? 500C with heat insulation will lose a lot more energy than 100C with the same heat insulation. Roughly 5 times more.
  14. B

    Storing heat in sand?

    I can share what people do here when we are talking about a storage tank for a lot of energy - they use water tanks from trucks with decent heat insulation. With some math and 16m3 tank you'll get close to 18kWh of stored energy for each degree Celsius of temperature rise for the water inside...
  15. B

    Slow SMA AC coupled system charging ramp up rate.

    So I think I found a solution. Still testing it, but the initial run for several hours shows very promising results. How it works - constantly monitor the PV inverter. Use some greedy logic to determine if more power can be produced and if yes - force the battery inverter to increase the...
Back
Top