Ryan HH's question and help thread
- Thread starter Ryan HH
- Start date
basically i am building an ebike with specs of 150a max and 84v max 72v nominal. I plan on having a class T fuse in the main line connecting to controller. and also a littelfuse KLK fuse in line going to DCDC converter for my accessory circuit. lastly a fuse connected in line with charger on DC output side of charger. My question is Should I go with slow blow or time delay or fast acting. i just don't know because my controller is filled up with capacitors as well as my DCDC converter.
Yall I need some help I feel I am in over my head
and it's overwhelming and scary as I don't want
to mess up my dream project I am building an
Ebike/e motorcycle. Basically I am running 150a
max and 72v nominal and 84v max. 20s15p
batter. I want to have a fuse or circuit breaker in
main line off battery but don't know what rating
or fast acting. And I also want to have a
disconnect switch. Many people have told me to
use a Contactor so I was looking at them and I
found a really good one from battery hookup https://batteryhookup.com/collections/accessories/products/te-connectivity-ev200aaana-500a-0-900vdc but everyone is saying I need to precharge circuit to make sure
the Contactor doesn't get switch welded in
close position because of inrush current V n
the controllers capacitors but some people say I
don't need a precharge circuit. But that
Contactor I linked has an economizer on it and
people say it's the same as precharge some
people say it isn't and I still need precharge.
Just help please I don't know what I need or
what to do. Will this Contactor even work? do I
need precharge? Do I need fuse or circuit
breaker? So on. I have done countless hours of
research but find so many differing opinions I
would really appreciate some help.
and it's overwhelming and scary as I don't want
to mess up my dream project I am building an
Ebike/e motorcycle. Basically I am running 150a
max and 72v nominal and 84v max. 20s15p
batter. I want to have a fuse or circuit breaker in
main line off battery but don't know what rating
or fast acting. And I also want to have a
disconnect switch. Many people have told me to
use a Contactor so I was looking at them and I
found a really good one from battery hookup https://batteryhookup.com/collections/accessories/products/te-connectivity-ev200aaana-500a-0-900vdc but everyone is saying I need to precharge circuit to make sure
the Contactor doesn't get switch welded in
close position because of inrush current V n
the controllers capacitors but some people say I
don't need a precharge circuit. But that
Contactor I linked has an economizer on it and
people say it's the same as precharge some
people say it isn't and I still need precharge.
Just help please I don't know what I need or
what to do. Will this Contactor even work? do I
need precharge? Do I need fuse or circuit
breaker? So on. I have done countless hours of
research but find so many differing opinions I
would really appreciate some help.
What you need the fuse to do, and under what specific conditions, will tell you which kind to use. Each fuse manufacturer has data sheets that tell you what guaranteed conditions will blow a fuse, so that the system will operate normally under any condition below those. If you define the maximum current you need the fuse to handle, for the maximum time it must handle it, you can then select the right fuse type for that purpose.
Note that your wiring is what is primarily intended to be protected by the fuse; the fuse would be installed as close to the source of the current as possible, so that the most wiring possible would be disconnected by it in the case of a short further along the line. So the fuse would be rated to protect the wiring, and the wiring would be rated to supply more than the devices it connects to will ever need, worst case, so that it never heats up. Thus, you pick the wiring first, above the device needs, then pick the fuse rated below the wiring capability, and then nothing will have a problem, in theory.
In practice, to know if it will really work in a real failure, you'd have to simulate a real failure at the far end of the wiring where the device would connect, and see if the fuse actually blows as necessary to protect it.
If using circuit breakers, replace "fuse blows" with "breaker trips".
If you don't know what current a device requires for any specific time, and it is not specified by the device manufacturer, you'd have to test this with a wattmeter or multimeter capable of measuring the amps that device might use, to be guaranteed to rate the wiring to the device properly, and then guaranteed to get the right fuse to protect that wiring.
All fuses or breakers must be rated for *at least* the max voltage that could ever possibly be across them; in your case for DC voltage (*not* AC). If they aren't, and they blow under load, the current can continue flowing across the gap as a plasma discharge (a welding arc), which is hot enough to start a fire.
You can always use a fuse rated at a much higher voltage than you need, but never lower.
You can use a fuse rated for less current than you need, though it could blow when you don't want it to. But you don't want to use a fuse rated for more current than the wiring is rated for, or you can end up with a fire in the wiring if it heats up enough.
It should, however, be rated for more current than the devices the wiring supplies will need. If the device fails in a way that causes excessive current flow beyond the wiring rating, the fuse should blow and protect the wiring. Not much you can do with that fuse to protect the device itself from it's own internal failure. You can put a fuse at the input to the device itself if you like, that is rated for the max current you determine the device itself would ever need, above which you prefer the device to lose power.
Don't use cheaply-made fuse holders; they can cause fires. When they don't, they can cause power losses.
For more info, there's lots of threads and posts about fuses with varying levels of detailed info, if you poke around. For example, there's one good recent (last week or two) thread with pics of some problems. Will take some reading, however.
There are also lots of posts about precharge and contactors with great info, but it does take time and reading to find the gems. There will always be conflicting info by people using various products--to resolve this you go to the manufacturer of the product you want to use--if they can't tell you how to use it, don't use their stuff.
Basically, if you want a contactor, it's just like fuses: you need one rated for at least the maximum current of everything that is supplied by it, preferably more. Must also be rated for at least the max voltage the system would ever see, just like fuses or breakers, in DC volts, not AC. Must have a coil voltage compatible with how you intend to power it on and keep it powered on to keep your system powered on. Manufacturer sites should describe how their contactors work, including any "economizer" circuits or other add-on functions their product may have; they may be different between different models and brands.
Some things you may simply have to build and then test, to be sure they will do what you want when you want them to.
Note that your wiring is what is primarily intended to be protected by the fuse; the fuse would be installed as close to the source of the current as possible, so that the most wiring possible would be disconnected by it in the case of a short further along the line. So the fuse would be rated to protect the wiring, and the wiring would be rated to supply more than the devices it connects to will ever need, worst case, so that it never heats up. Thus, you pick the wiring first, above the device needs, then pick the fuse rated below the wiring capability, and then nothing will have a problem, in theory.
In practice, to know if it will really work in a real failure, you'd have to simulate a real failure at the far end of the wiring where the device would connect, and see if the fuse actually blows as necessary to protect it.
If using circuit breakers, replace "fuse blows" with "breaker trips".
If you don't know what current a device requires for any specific time, and it is not specified by the device manufacturer, you'd have to test this with a wattmeter or multimeter capable of measuring the amps that device might use, to be guaranteed to rate the wiring to the device properly, and then guaranteed to get the right fuse to protect that wiring.
All fuses or breakers must be rated for *at least* the max voltage that could ever possibly be across them; in your case for DC voltage (*not* AC). If they aren't, and they blow under load, the current can continue flowing across the gap as a plasma discharge (a welding arc), which is hot enough to start a fire.
You can always use a fuse rated at a much higher voltage than you need, but never lower.
You can use a fuse rated for less current than you need, though it could blow when you don't want it to. But you don't want to use a fuse rated for more current than the wiring is rated for, or you can end up with a fire in the wiring if it heats up enough.
It should, however, be rated for more current than the devices the wiring supplies will need. If the device fails in a way that causes excessive current flow beyond the wiring rating, the fuse should blow and protect the wiring. Not much you can do with that fuse to protect the device itself from it's own internal failure. You can put a fuse at the input to the device itself if you like, that is rated for the max current you determine the device itself would ever need, above which you prefer the device to lose power.
Don't use cheaply-made fuse holders; they can cause fires. When they don't, they can cause power losses.
For more info, there's lots of threads and posts about fuses with varying levels of detailed info, if you poke around. For example, there's one good recent (last week or two) thread with pics of some problems. Will take some reading, however.
There are also lots of posts about precharge and contactors with great info, but it does take time and reading to find the gems. There will always be conflicting info by people using various products--to resolve this you go to the manufacturer of the product you want to use--if they can't tell you how to use it, don't use their stuff.
Basically, if you want a contactor, it's just like fuses: you need one rated for at least the maximum current of everything that is supplied by it, preferably more. Must also be rated for at least the max voltage the system would ever see, just like fuses or breakers, in DC volts, not AC. Must have a coil voltage compatible with how you intend to power it on and keep it powered on to keep your system powered on. Manufacturer sites should describe how their contactors work, including any "economizer" circuits or other add-on functions their product may have; they may be different between different models and brands.
Some things you may simply have to build and then test, to be sure they will do what you want when you want them to.
Ryan HH said:
Ryan HH said:
amberwolf said:What you need the fuse to do, and under what specific conditions, will tell you which kind to use. Each fuse manufacturer has data sheets that tell you what guaranteed conditions will blow a fuse, so that the system will operate normally under any condition below those. If you define the maximum current you need the fuse to handle, for the maximum time it must handle it, you can then select the right fuse type for that purpose.
Note that your wiring is what is primarily intended to be protected by the fuse; the fuse would be installed as close to the source of the current as possible, so that the most wiring possible would be disconnected by it in the case of a short further along the line. So the fuse would be rated to protect the wiring, and the wiring would be rated to supply more than the devices it connects to will ever need, worst case, so that it never heats up. Thus, you pick the wiring first, above the device needs, then pick the fuse rated below the wiring capability, and then nothing will have a problem, in theory.
In practice, to know if it will really work in a real failure, you'd have to simulate a real failure at the far end of the wiring where the device would connect, and see if the fuse actually blows as necessary to protect it.
If using circuit breakers, replace "fuse blows" with "breaker trips".
If you don't know what current a device requires for any specific time, and it is not specified by the device manufacturer, you'd have to test this with a wattmeter or multimeter capable of measuring the amps that device might use, to be guaranteed to rate the wiring to the device properly, and then guaranteed to get the right fuse to protect that wiring.
All fuses or breakers must be rated for *at least* the max voltage that could ever possibly be across them; in your case for DC voltage (*not* AC). If they aren't, and they blow under load, the current can continue flowing across the gap as a plasma discharge (a welding arc), which is hot enough to start a fire.
You can always use a fuse rated at a much higher voltage than you need, but never lower.
You can use a fuse rated for less current than you need, though it could blow when you don't want it to. But you don't want to use a fuse rated for more current than the wiring is rated for, or you can end up with a fire in the wiring if it heats up enough.
It should, however, be rated for more current than the devices the wiring supplies will need. If the device fails in a way that causes excessive current flow beyond the wiring rating, the fuse should blow and protect the wiring. Not much you can do with that fuse to protect the device itself from it's own internal failure. You can put a fuse at the input to the device itself if you like, that is rated for the max current you determine the device itself would ever need, above which you prefer the device to lose power.
Don't use cheaply-made fuse holders; they can cause fires. When they don't, they can cause power losses.
For more info, there's lots of threads and posts about fuses with varying levels of detailed info, if you poke around. For example, there's one good recent (last week or two) thread with pics of some problems. Will take some reading, however.
There are also lots of posts about precharge and contactors with great info, but it does take time and reading to find the gems. There will always be conflicting info by people using various products--to resolve this you go to the manufacturer of the product you want to use--if they can't tell you how to use it, don't use their stuff.
Basically, if you want a contactor, it's just like fuses: you need one rated for at least the maximum current of everything that is supplied by it, preferably more. Must also be rated for at least the max voltage the system would ever see, just like fuses or breakers, in DC volts, not AC. Must have a coil voltage compatible with how you intend to power it on and keep it powered on to keep your system powered on. Manufacturer sites should describe how their contactors work, including any "economizer" circuits or other add-on functions their product may have; they may be different between different models and brands.
Some things you may simply have to build and then test, to be sure they will do what you want when you want them to.
Ryan HH said:
Ryan HH said:
Thanks so much amberwolf you have been so much help. helping me accomplish my dream truly thanks.
I have been working on my custom ebike for 4 months, and now i have the final 4 questions. I would appreciate so much if you could give your take or answer any of these questions if possible. Thankyou
1 - is a 2k resistor for precharge enough? I did the math and ohms law I=V/R, so 84V/2000R = 0.042A which is good because i wanna trickle charge out the controller caps. but it seems like .042a is so little is that enough to charge my caps? Like in 10-30seconds.
2 - I have read something online about EMF current current in mechanical relays. Apparently when a coil stops getting power the magnetic field of a coil and push lots of voltage through a line which is why I heard something about flywheel diodes to prevent this. But do you know if they are built into the relay or if I need to add one or if this isn’t even important.
3 - on my main wires going from battery to controller I have a EV200AAANA contactor and a JLLN class t fuse and an branch off wire going to a dcdc converter. Do I need to worry about regen current messing anything up in-line because the current is flowing backwards during regen.
4 - do I need to really worry about water damage to motor like rusting the motor. I have heard some people varnish their motor and say it’s a must do where some say it doesn’t matter. I would be riding is mostly dry conditions with some light rain sometimes.
Specs - 72v nominal 84v Max 150amp Max. sabvoton 72150 controller. qs205 v3 5t motor.
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