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  1. Factory400

    DIY BMS design and reflection

    I have been designing power electronics for a long time and MOSFET selection seems to get a little more challenging for each design since I learn a little more about the FETs every pass. I commend you for writing a summary of decision matrix. It is a very complex topic and it very rarely ends...
  2. Factory400

    Overcharge club- new member 🙋‍♂️

    The same hardware and software is used for extremely consequential tests and experiments. GPIB has been around since the 70's. My Agilent power supplies cost around $5,500 each - mainly because of the crazy focus on reliability. A dedicated disconnect circuit can also fail - especially a...
  3. Factory400

    24v to 12v dc to dc converters, how efficient?

    The aux battery has it's own isolated charger that runs on 120VAC. It is a bit convoluted, but uses the parts I had on hand. It also keeps the little battery tended while the RV (travel trailer) is not being used.
  4. Factory400

    Overcharge club- new member 🙋‍♂️

    I ultimately decided not to make this dedicated disconnect circuit. Fortunately, I have a stack of GPIB programmable power supplies and used Python to manage the charging. I cannot imagine trusting an analog off-brand low-cost power supply with an expensive battery bank.
  5. Factory400

    24v to 12v dc to dc converters, how efficient?

    I have the 40A Victron which is enough to cover most everything. That is on a custom ideal diode in parallel with a small lead-acid battery/charger. That way, if anything goes over the limit of the converter - the battery effectively supplies a boost. This required me to trim the converter to...
  6. Factory400

    Does an AC to DC power brick need pure sine wave or will it be fine on a modified sine wave cheap inverter?

    Lol - Factory400 is not my job. If it was.....I would be crazy hungry. Factory400 is my pet project where I experiment with ideas on how to cram a full suite of design and manufacturing into my garage space at home. It is exiting, and I do sell things sometimes. But it is just a fun thing to...
  7. Factory400

    Does an AC to DC power brick need pure sine wave or will it be fine on a modified sine wave cheap inverter?

    I don't squabble over semantics and all of my successful commercial designs are still successful. :cool: As the business owner and circuit designer - I have to communicate in a way that everyone can pickup on what I am putting down. The engineers around me (that are much better and much more...
  8. Factory400

    Does an AC to DC power brick need pure sine wave or will it be fine on a modified sine wave cheap inverter?

    Fair enough....my wife says the same thing. And no - it is not a threshold. That is why I noted it is expressed in db at a certain frequency - not any fixed threshold. The load will have a certain amount of noise at various frequencies that are considered tolerable. That is different with from...
  9. Factory400

    Does an AC to DC power brick need pure sine wave or will it be fine on a modified sine wave cheap inverter?

    The price difference is indeed rather small - IMHO the modest additional cost of sine wave is worth not needing to worry.
  10. Factory400

    Does an AC to DC power brick need pure sine wave or will it be fine on a modified sine wave cheap inverter?

    The PSRR describes how a signal on the DC input voltage of the regulator system is transmitted to the regulated output. I am not making this up. How much noise on the input vs noise on the output. How much noise the power supply can reject. A power supply will attenuate noise by some...
  11. Factory400

    Does an AC to DC power brick need pure sine wave or will it be fine on a modified sine wave cheap inverter?

    That is not really true. The steps in a modified sine wave are rather difficult on the the front-end components and create a ton of noise that can go beyond the Power Supply Rejection Ratio. The high current and voltage steps along with the noise that bothers the extremely fragile control loops...
  12. Factory400

    Chargery: AH measurements

    That sounds reasonble for that part. I have been using those for many years and really like them. Once they are programmed - they do all of the hard work and just spit out the results. Now - they just started shipping the 20bit version called the INA229 which I think is a drop-in replacement...
  13. Factory400

    My first question - which BMS to choose

    This is a tough one - the BMS market is FLOODED with cheap Chinese stuff that is very difficult to predict. I have an RV system that needs to operate in the cold, be very reliable, and not malfunction in a way that can damage the pack or any individual cell. I examined the usual suspect cheap...
  14. Factory400

    Chargery: AH measurements

    STM32 internal ADC is what I believe is being used. There is a reference on the board, but I don't believe that STM32 has an external reference input - could be wrong on that.
  15. Factory400

    Chargery: AH measurements

    It sounded like a hypothetical expectation for a future product. The current one that uses a 12bit ADC is dismally implemented IMHO.
  16. Factory400

    Chargery: AH measurements

    Well.....considering the existing unit is 12bit but delivers something like an unstable 8bit ADC - his estimate may not be too far off.
  17. Factory400

    Chargery: AH measurements

    A 16bit ADC does not effectively deliver 16bit performance. Although with oversampling and other techniques that slow it down, you can get fairly close. As I have said before - the analog side of the circuit is delicate and must be carefully considered to avoid noise that will start eliminating...
  18. Factory400

    DIY BMS design and reflection

    This is the best part of the conversation so far - and the area where I have the most to learn. :cool:
  19. Factory400

    DIY BMS design and reflection

    Of course - I just remembered your project is 48v. More like $5/ea for 1.2mOhm https://www.digikey.com/en/products/detail/infineon-technologies/IPT012N08N5ATMA1/5413683 What would you say your practical dissipation budget would be for a 300A switch? 16 of these would be about 36W - a little...
  20. Factory400

    Seeking advice on a the need for a fire-resistant cabinet for Li-Ion battery

    My 2 cents..... A metal cabinet will not do a good job of containing a LiIon fire. The intense and localized heat will make quick work of sheet metal. You need a large mass (like the mentioned sand) to absorb and dissipate the heat long enough for the fuel source to be exhausted. This is...
  21. Factory400

    DIY BMS design and reflection

    Just a quick pass..... 1.04mOhm https://www.digikey.com/en/products/detail/vishay-siliconix/SIRA50ADP-T1-RE3/9462341 420uOhms https://www.digikey.com/en/products/detail/on-semiconductor/ntmts0d6n04cltxg/9829162
  22. Factory400

    DIY BMS design and reflection

    As I have mentioned on other threads - I am hardly concerned about MOSFETS or back-to-back MOSFETS as an ultimate backstop to a runaway problem. I think I will have my new system setup with remote control signals connected as my first layer of shutdown control. Most likely it will work great...
  23. Factory400

    DIY BMS design and reflection

    Do inverter/charger usually work this way though? ....currently looking at my Victron Multiplus 3k's to see how they work. If I am going to rely solely on an external device to behave a certain way - I want to make sure that device has rightfully earned my trust.
  24. Factory400

    DIY BMS design and reflection

    I am not sure I trust my inverter/charger to stop just because I said so. The biggest concern is that it requires a positive signal to stop (as far as I know). If the wiring came loose - the system would never stop charging no matter what the BMS said about it. I would rather have an active...
  25. Factory400

    Current Clamp meter that measures energy?

    It is easy if the load is perfectly constant - it is hard/impossible if the load changes a lot. Some sort of integration scheme is needed for a dynamic load. 12v/24v halogen lights are the most stable load available for low cost and would work well for capacity testing. Inverters tend to make...
  26. Factory400

    Wiring 16 cells into 24v battery???

    I have a 16 cell 24v LiFePO4 system that is currently in the 2p8s configuration with a single BMS. It works electrically just fine, but it is too heavy to move and I would like to be able to split it up for other reasons. I am planning to get 2 BMS's and two independent batteries. Either...
  27. Factory400

    DIY BMS design and reflection

    Ok - so that means the charge cutoff relies on a signal to the charger to stop charging?
  28. Factory400

    DIY BMS design and reflection

    How are you proposing to accomplish a 1 port BMS switch without back-to-back FETs?
  29. Factory400

    Can I power my 30amp RV from my truck alternator

    I run my generator while I am driving. My entire power system is in the bed of the truck - I run the genny on eco mode and it limit the charging to about 700w so it is nice and quiet. Pretty simple. If my batteries, inverter, etc have any issues - I still have a genny (and a backup genny). I...
  30. Factory400

    DIY BMS design and reflection

    the 3000VA unit still only has one high-current connection that is both charge/discharge, right? Are you talking about the remote control inputs?
  31. Factory400

    Can I power my 30amp RV from my truck alternator

    Running 12V 300+AMPS any distance in a vehicle is: 1. Dangerous 2. Difficult 3. To manage voltage drop - massive cable will be needed. 4. The inverter needs to be as close to power source as practical - which is a pain in the butt. Personally, I would never, ever even come close to considering...
  32. Factory400

    Can I power my 30amp RV from my truck alternator

    A couple of things I did with a similar size travel trailer...... I got a soft-starter for the AC. This is a device that reduced the starting current needed to get you AC compressor started up. The BIG benefit is that it can now run with no problem on a EU2200i Honda inverter genny...
  33. Factory400

    DIY BMS design and reflection

    My system has a Victron inverter/charger - making a 2 port BMS useless. There is absolutely, positively nothing wrong with back-to-back FETs. That is even more true if you absolutely need a single port BMS.
  34. Factory400

    I want to make my own BMS

    I asked the same thing early on....."For fun" was the answer. Fair enough to me even though personally it would not be fun unless I was getting something unique out of it. This project has nothing unique that I can tell. Still, some interesting conversations. I am going to guess that those...
  35. Factory400

    Best adhesive for no drill roof mounted panels?

    The roof of my Micro Minnie is smooth with no obvious signs of mechanical fasteners. I can sort of make out the ribs if I push on it while looking for the most rigid area. I do not, however have any idea what the ribs are made of, therefore no way to know what fastener to use or how strong the...
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