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  1. M

    LiFePO4 battery heater project (makes sure battery doesn't freeze)

    I have a 700watt array now. I get about 8 hours of sun a day(this time of year), often overcast The BMS on the battery will not let the charge start if the battery is under 0. So a heater is required.
  2. M

    LiFePO4 battery heater project (makes sure battery doesn't freeze)

    and if i leave my camper parked for 2 weeks on its own in my backyard? This is part of what im trying to solve also. But great outside of the box thinking with the water though! It just wont last long enough.
  3. M

    LiFePO4 battery heater project (makes sure battery doesn't freeze)

    While freezing is a concern, charging below zero is a totally different concern. In this battery chemistry it creates dendrites and overtime these can severely reduce the capacity of the battery.
  4. M

    LiFePO4 battery heater project (makes sure battery doesn't freeze)

    I think PID is overkill (but would consider it). I am thinking of setting up an array of thermistors around the battery to make sure that they are all above T? Maybe two on top, two on the sides. The battery is about 8"x20". I am building an r10 insulation box around the battery, which will...
  5. M

    How can you determine if a fan is better at blowing or sucking?

    wow checking back on this thread months after posting it. I really like where it went :D
  6. M

    How can you determine if a fan is better at blowing or sucking?

    I see so the main consideration is just contamination effecting performance, and that all fans perform equally well sucking/blowing if their position is reversed in the same system, lets say a long tube. I tested this out with a 7' pipe and i got different results for CFM measurement from...
  7. M

    How can you determine if a fan is better at blowing or sucking?

    I am being vague because its not specific to any one system, I am working on many, and so just looking for a general rule on determining if a fan is better for pulling or pushing air.
  8. M

    How can you determine if a fan is better at blowing or sucking?

    I am trying to determine if they are better placed in positions where they suck or blow. Is there a rule to determining this?
  9. M

    Calculating air flow through a tube

    I understand the Friction Head Loss in Air Ducts - Online Calculator provided .0979 with those parameters, and so i see how you got 0.1, but i dont understand where you got the 0.9 from. I dont understand the size reduction at the begging part you mentioned. I also tried looking up velocity...
  10. M

    Calculating air flow through a tube

    Thats very helpful thank you! so seems i will have to go with a centrifugal fan to get that pressure up. I will be placing a barometric pressure sensor in the tube after the van so that i can get an idea of the flow rate
  11. M

    Calculating air flow through a tube

    It means that the air which the diesel heater intakes for heating (not combustion) is being mixed with the air im pulling from the outside through a vent :) And nope, exhaust gases are all outside the van. CO2 is coming from my breathing.
  12. M

    Calculating air flow through a tube

    I have several fans ranging between 20-150cfm, some with the computer fan design but higher power, and some centrifuge fans from vacuums that do create a good deal of pressure. but I also need it to be quiet that's why i need to find the best fit. The calculations from another post say i need...
  13. M

    Calculating air flow through a tube

    This is for a campervan project I am working on, I am trying to take outside air that is cold (Canadian winter) and mix it into the return air in my diesel heater. I need to hit a specific minimal CFM to maintain proper Co2 levels inside and I would like to be able to calculate this. The axial...
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