Lots of differing ways and opinions on sizes to achieve the same thing.
Cant say i have the best track record with incandescent light bulbs its been 20+ years since ive used one apaet from for cars etc, but i changed to halogens and then LED because they always popped instead of just blowing the filament.
The idea of holding one whilst it potentially pops is not for me. Im sure theyve changed but, just nah!
I do like the idea of the switched circuit Al, or at least mounting the resistor to the board in a way that it can be easily used and not lost!
Pre charge resistors
Re: Pre charge resistors
3.16kw Canadian solar. roof. 3kw solis G98 mcs
12kw midea ASHP
200l hot water
3152W RE, Whitelaw Brae
Octopus agile/outgoing fixed 15p
Planned;
Hybrid system
43kwh eve batteries, 3x16 280A
6-8+kw solar, DC connected.
12kw midea ASHP
200l hot water
3152W RE, Whitelaw Brae
Octopus agile/outgoing fixed 15p
Planned;
Hybrid system
43kwh eve batteries, 3x16 280A
6-8+kw solar, DC connected.
Re: Pre charge resistors
I bought a small box and put a push button in it. This is in series with the resistor. Then that is in parallel around the main dc on off switch. Works well. I can’t remember numbers. I think about 120 ohms.
Rs online
Standard Items Ordered Reference: 173137181
Arcol, 120Ω 25W Wire Wound Chassis Mount Resistor HS25 120R J ±5%
Stock no.:160-792
Qty:1
APEM Momentary Push Button Switch, Panel Mount, SPST, 12mm Cutout, 48V ac, IP67
Stock no.:224-984
Qty:1
Rs online
Standard Items Ordered Reference: 173137181
Arcol, 120Ω 25W Wire Wound Chassis Mount Resistor HS25 120R J ±5%
Stock no.:160-792
Qty:1
APEM Momentary Push Button Switch, Panel Mount, SPST, 12mm Cutout, 48V ac, IP67
Stock no.:224-984
Qty:1
Re: Pre charge resistors
The major reason I'd use one is so I don't blow the FETs on the BMS, they can be surge sensitive. If they fail open then broken battery, if they fail short then all the battery disconnect features are inoperable. After that it's so I'm not blowing chunks of plasma into the ether off my battery cables and getting arc-flashed eyeballs.
It really doesn't have to be a big wattage impedance: it's an instantaneous load. Larger impedance (less heat because less current) for longer works fine too.
I generally prefer to build an external BMS for raw cells with a magnetic latching contactor and an ultra low consumption polarity reversible coil pulse generator driving it instead. I've one build which is a key-switched restart.
Any Albright with an M in the name are magnetic latching & fairly bombproof eg. SW200M.
Another very handy current limit is a series CC power supply...great for bench powering faulty power electronics too. Say it's a 24V inverter. Then use a centre tap on the battery 0 ->12V and series that to a 12V power supply:
-Battery 0v to Inverter Negative
- Battery 12V to PSU DC Output Ground
- PSU DC Output Positive (set to 12v now a potential difference of 24v to battery negative because the ground reference of the PSU is +12v from the battery) connected to the Inverter Positive +24V with a ~1 > 5A Current Limit set on the PSU.
Once the capacitors are charged (and the inverter is switched off) the PSU will display a near zero current output. Remove the cold-start kit and use the 24v battery to boot the inverter proper.
{EDIT: # bittova overcomplicated brain fart that one: often my first "simplest solution" is unnecessarily complicated....You can of course just dial the CC CV PSU to 24V and not bother with the series battery...sometimes I'm too McGuyver for my own good.
}
It's also a good cheat for making higher voltage PSUs. Say your PSU only goes to 36V but the inverter you're testing is 48V..series a 12volt battery to the PSU DC output. Presto 48V CC CV upgrade.
It really doesn't have to be a big wattage impedance: it's an instantaneous load. Larger impedance (less heat because less current) for longer works fine too.
I generally prefer to build an external BMS for raw cells with a magnetic latching contactor and an ultra low consumption polarity reversible coil pulse generator driving it instead. I've one build which is a key-switched restart.
Any Albright with an M in the name are magnetic latching & fairly bombproof eg. SW200M.
Another very handy current limit is a series CC power supply...great for bench powering faulty power electronics too. Say it's a 24V inverter. Then use a centre tap on the battery 0 ->12V and series that to a 12V power supply:
-Battery 0v to Inverter Negative
- Battery 12V to PSU DC Output Ground
- PSU DC Output Positive (set to 12v now a potential difference of 24v to battery negative because the ground reference of the PSU is +12v from the battery) connected to the Inverter Positive +24V with a ~1 > 5A Current Limit set on the PSU.
Once the capacitors are charged (and the inverter is switched off) the PSU will display a near zero current output. Remove the cold-start kit and use the 24v battery to boot the inverter proper.
{EDIT: # bittova overcomplicated brain fart that one: often my first "simplest solution" is unnecessarily complicated....You can of course just dial the CC CV PSU to 24V and not bother with the series battery...sometimes I'm too McGuyver for my own good.
}It's also a good cheat for making higher voltage PSUs. Say your PSU only goes to 36V but the inverter you're testing is 48V..series a 12volt battery to the PSU DC output. Presto 48V CC CV upgrade.