whats the best relay for regen? mine keep melting!!!
- Thread starter monster
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vanilla ice
1 MW
A $5 junkyard starter solenoid mebbe? I'm not familiar with what kind of relay a regen setup requires. Just a regular four pin relay?
Is it the contacts or the coil that melts?
An automotive relay can handle 30 amps or so. They have 12v coils, so you'd need a dc-dc converter or a big resistor to drop the voltage to the coil.
An automotive relay can handle 30 amps or so. They have 12v coils, so you'd need a dc-dc converter or a big resistor to drop the voltage to the coil.
Rassy
1 MW
I have been using some relays from J.C.Whitney that are for automotive extra lights or sound systems. They are rated for 800 Watts at 12V DC. No problems so far, but my system is only 48V X 35Amps. For the relay between the controller and motor it is never switched while under power (i.e., throttle off then open or close the relay). For the relay between the motor and load, it is only being opened under a load of about 14V X 30Amps.
The secondary circuit to the relays uses an auxillary 12V SLA battery which is also used for some lights, etc. and is charged independently when the main batteries are being charged.
Last year these relays were about $10 each, the same as their 400 Watt ones, but I think it was a printing error and they changed the price earlier this year to about $20 each.
http://www.jcwhitney.com/autoparts/Product/Pr-p_Product.CATENTRY_ID:2001332/c-10101/Nty-1/p-2001332/Ntx-mode+matchallpartial/N-10101/tf-Browse/s-10101/Ntk-AllTextSearchGroup?Ntt=relay
These relays are normally open, so they have to be "on" when the motor is being used, so they are always drawing some current from the auxillary battery.
The secondary circuit to the relays uses an auxillary 12V SLA battery which is also used for some lights, etc. and is charged independently when the main batteries are being charged.
Last year these relays were about $10 each, the same as their 400 Watt ones, but I think it was a printing error and they changed the price earlier this year to about $20 each.
http://www.jcwhitney.com/autoparts/Product/Pr-p_Product.CATENTRY_ID:2001332/c-10101/Nty-1/p-2001332/Ntx-mode+matchallpartial/N-10101/tf-Browse/s-10101/Ntk-AllTextSearchGroup?Ntt=relay
These relays are normally open, so they have to be "on" when the motor is being used, so they are always drawing some current from the auxillary battery.
TylerDurden
100 GW
You could also parallel relays to handle the loads.
You have to use a FET, maybe two in parallel depending on the kind you use or what's cost effective.
vanilla ice
1 MW
Starter solenoids have to handle hundreds of amps, I'd be surprised if you could fry one. Most are used at 12v, but they work in 24v trucks too. I don't think 72v would hurt them.
Rassy
1 MW
I think the starter solenoids would work ok as long as they were operated through a 12V primary circuit. However, they have a strong internal mechanism, and I suspect their continuous current draw would be substantial. They also might not be happy with continous use, since they are normally only used for seconds at a time.
monster
100 kW
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- Jun 17, 2007
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- 1,411
thanks for all your reply's.
the relay i had between the controller and motor got so hot during normal riding that the solder at the contacts melted and the relay was sent out of alignment. i think it was only rated for 10A. the automotive relays will do 40A but are only rated for 12v. none of the relays in maplin have all the specs i need. are volts not important in relay selection?
i have no probs with 12v or 24v coils because i have taped my battery for lights etc. i don't use the regen brake much so there is no problem of wasting energy in the coil.
the relay i had between the controller and motor got so hot during normal riding that the solder at the contacts melted and the relay was sent out of alignment. i think it was only rated for 10A. the automotive relays will do 40A but are only rated for 12v. none of the relays in maplin have all the specs i need. are volts not important in relay selection?
i have no probs with 12v or 24v coils because i have taped my battery for lights etc. i don't use the regen brake much so there is no problem of wasting energy in the coil.
RLT
10 kW
How about a solid state relay?
Like this:
http://cgi.ebay.com/Solid-State-Relay-SSR-24-220V-DC-40A-Heat-Sink_W0QQitemZ230192110409QQihZ013QQ
Like this:
http://cgi.ebay.com/Solid-State-Relay-SSR-24-220V-DC-40A-Heat-Sink_W0QQitemZ230192110409QQihZ013QQ
vanilla ice
1 MW
Rassy said:
But since its a regen setup, isn't the the current requirements kind of irrelevant, because at those very times you have a surplus of current available? I never thought about how they only see a few seconds normally. Maybe that would be a problem. But I have held starters on for very long periods of time before, and only ever flattened the batteries, never hurt a starter or solenoid.
TylerDurden
100 GW
monster said:
Volts matter for the coil, but not so much for the contacts.
You could also surf around for a cheap contactor.
http://en.wikipedia.org/wiki/Contactor
Rassy
1 MW
Vanilla Ice wrote:
Matthew will have to answer this, but I think he is just using the regen for braking purposes, and the problem he mentioned was between the controller and the motor, so all the juice necessary to run the relay would come from a battery.
Matthew, If I was starting over, I would try to find a relay (by whatever name, mechanical or electronic) that was in a closed state at rest and thus would only require power to open the circuit during regen. In truth, I'm not even sure this relay is required, but my "consultant" (neighbor, fishing buddy, retired KODAK EE that designed, programmed, built, tested, etc. this kind of stuff) could not answer all my questions without a schematic or tearing into the controller. So my mechanical solution (made him cringe) guarantees that nothing bad will happen, even if I accidently hit the throttle during regen braking.
Matthew will have to answer this, but I think he is just using the regen for braking purposes, and the problem he mentioned was between the controller and the motor, so all the juice necessary to run the relay would come from a battery.
Matthew, If I was starting over, I would try to find a relay (by whatever name, mechanical or electronic) that was in a closed state at rest and thus would only require power to open the circuit during regen. In truth, I'm not even sure this relay is required, but my "consultant" (neighbor, fishing buddy, retired KODAK EE that designed, programmed, built, tested, etc. this kind of stuff) could not answer all my questions without a schematic or tearing into the controller. So my mechanical solution (made him cringe) guarantees that nothing bad will happen, even if I accidently hit the throttle during regen braking.
Nimbuzz
1 kW
What's the scoop here -- Is this "regen" circuit a relay that would connect the motor directly to the battery and bypass the controller so the BEMF would be routed to charge the battery and create mechanical/rolling resistace to provide braking?
ort5
1 W
Anything from here will be just fine:
http://www.robotcombat.com/marketplace_solenoids.html
http://www.robotcombat.com/marketplace_solenoids.html
xyster
10 MW
Depending on the circuit, seems to me that parallel relays risks a short if one closes before the other. For a main power switch, I use a 24v80a relay I picked up from allelectronics.com.
Rassy
1 MW
xyster wrote:
You're right. In my case I use a double throw toggle switch that goes from having the power relays activated, to no relalys activated, to having the regen relays activated. Of course, if a relay fails, who knows!
Nimbuzz wrote:
In my case I don't try to save any juice, just hook the motor to a load to provide braking. I'm not sure what Matthew is currently doing with regen.
ort5, that robotcombat looks like a great source for some good relays. Thanks.
You're right. In my case I use a double throw toggle switch that goes from having the power relays activated, to no relalys activated, to having the regen relays activated. Of course, if a relay fails, who knows!
Nimbuzz wrote:
In my case I don't try to save any juice, just hook the motor to a load to provide braking. I'm not sure what Matthew is currently doing with regen.
ort5, that robotcombat looks like a great source for some good relays. Thanks.
monster
100 kW
- Joined
- Jun 17, 2007
- Messages
- 1,411
yer i was just using the current to slow the bike down, no real regen.
the mode of operation is in normal riding the current goes from battery to controller through relay to motor. the relay is in the circuit when riding normally but the coil is not energized. therefore the relay has to take current .
the only time the coil is energized is when the regen brake is needed.
cheers for all your help i have bought three 40A automotive relays so ill let you know how it goes. shame they dont do them in DPTT (double pole triple throw) then i would only need one of them.
the mode of operation is in normal riding the current goes from battery to controller through relay to motor. the relay is in the circuit when riding normally but the coil is not energized. therefore the relay has to take current .
the only time the coil is energized is when the regen brake is needed.
cheers for all your help i have bought three 40A automotive relays so ill let you know how it goes. shame they dont do them in DPTT (double pole triple throw) then i would only need one of them.
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