|
I'd like to put a contactor or solid state relay between my battery and motor so that I can use a simple toggle switch to turn on/off the battery.? ?Longer term, the bms could disable the battery, or I could even select between battery banks.
But for now, starting simple with an electrically controlled switch for the battery.
I'm using a 48V system. Typical max operating current may be as low as 20A, but could get spikes up to 50A.
I've looked at DC solid state relays.? And even found some rated up to 48V.? The problem is that when you read the fine print and reviews - even the 100A? SSR's are not rated for anywhere near that amount of current for constant usage.? ?(arrrgh!!)
I then started looking at "contactors", and eventually ended up looking at 48V golf cart solenoids. I've always thought of a "solenoid" in this case as being a really big relay.? It looks like the 48V golf cart solenoids should work for this application:
(Note - I'm on fresh water, and the solenoid would be in a plastic case - so I'm not worried about corrosion.)
Is that what I'm looking for, or do I need something that's more "heavy duty"? I saw references to using a flyback diode on the control contacts - and that seemed like a good idea.? Anything else I need to know?
Thanks! John
|
John, can't comment on whether that contactor is correct for your application. This is the contactor thst came with my 10KW setup. Perhaps you could cross reference it.
I'd like to put a contactor or solid state relay between my battery and motor so that I can use a simple toggle switch to turn on/off the battery.? ?Longer term, the bms could disable the battery, or I could even select between battery banks.
But for now, starting simple with an electrically controlled switch for the battery.
I'm using a 48V system. Typical max operating current may be as low as 20A, but could get spikes up to 50A.
I've looked at DC solid state relays.? And even found some rated up to 48V.? The problem is that when you read the fine print and reviews - even the 100A? SSR's are not rated for anywhere near that amount of current for constant usage.? ?(arrrgh!!)
I then started looking at "contactors", and eventually ended up looking at 48V golf cart solenoids. I've always thought of a "solenoid" in this case as being a really big relay.? It looks like the 48V golf cart solenoids should work for this application:
(Note - I'm on fresh water, and the solenoid would be in a plastic case - so I'm not worried about corrosion.)
Is that what I'm looking for, or do I need something that's more "heavy duty"? I saw references to using a flyback diode on the control contacts - and that seemed like a good idea.? Anything else I need to know?
Thanks! John
|
If you are using a 48v nominal bank with a max amp draw of 50a, but the golf cart contactor should work just fine as the motor that the golf cart relay was designed to potentially energize has a significantly higher amp draw. I looked up the ezgo cart motors yesterday, and the smallest 48v motor they sell is 4hp, so 4hpx750w=3000w 3000w/48v=62.5a They use the same relay on the 8.5hp motor aswell, so you should have a significant safety margin as far as what it was designed to handle.? That you intend to use it far below its rated capacity generally means you can expect an extended service life of the part, another advantage.? And in closing I will say that I feel as you are doing the right thing thinking outside of the box. I usually build all my own stuff out of components rather than buying sets, often using parts that meet the specs I need that were manufactured for another application. This is what allows me to afford my projects, because everyone here will attest that none of this stuff is inexpensive to begin with, and getting others to do the engineering or sell you a "specialty" part can make the war chest dry with a quickness.?
On Tue, Jun 9, 2020 at 8:43 AM, Bob Jennings <heatnh@...> wrote: John, can't comment on whether that contactor is correct for your application. This is the contactor thst came with my 10KW setup. Perhaps you could cross reference it.
I'd like to put a contactor or solid state relay between my battery and motor so that I can use a simple toggle switch to turn on/off the battery.? ?Longer term, the bms could disable the battery, or I could even select between battery banks.
But for now, starting simple with an electrically controlled switch for the battery.
I'm using a 48V system. Typical max operating current may be as low as 20A, but could get spikes up to 50A.
I've looked at DC solid state relays.? And even found some rated up to 48V.? The problem is that when you read the fine print and reviews - even the 100A? SSR's are not rated for anywhere near that amount of current for constant usage.? ?(arrrgh!!)
I then started looking at "contactors", and eventually ended up looking at 48V golf cart solenoids. I've always thought of a "solenoid" in this case as being a really big relay.? It looks like the 48V golf cart solenoids should work for this application:
(Note - I'm on fresh water, and the solenoid would be in a plastic case - so I'm not worried about corrosion.)
Is that what I'm looking for, or do I need something that's more "heavy duty"? I saw references to using a flyback diode on the control contacts - and that seemed like a good idea.? Anything else I need to know?
Thanks! John
|
Here's another more affordable option than thunderstrucks offering: Looks like yours is still lighter on the coffer though.? I know that there are some that fortunate enough for see "money as no object", and am happy for them. But personally, I spend a chunk of my time looking for the ways I can do what I am trying to do affordably, and using a $40 or $50 cart/industrial relay instead of a specialty $125 relay that does the same job is a perfect example of the kind of though that makes these projects even possible on my budget.?
On Tue, Jun 9, 2020 at 9:37 AM, ryanwestbrookcary1@... <ryanwestbrookcary1@...> wrote: If you are using a 48v nominal bank with a max amp draw of 50a, but the golf cart contactor should work just fine as the motor that the golf cart relay was designed to potentially energize has a significantly higher amp draw. I looked up the ezgo cart motors yesterday, and the smallest 48v motor they sell is 4hp, so 4hpx750w=3000w 3000w/48v=62.5a They use the same relay on the 8.5hp motor aswell, so you should have a significant safety margin as far as what it was designed to handle.? That you intend to use it far below its rated capacity generally means you can expect an extended service life of the part, another advantage.? And in closing I will say that I feel as you are doing the right thing thinking outside of the box. I usually build all my own stuff out of components rather than buying sets, often using parts that meet the specs I need that were manufactured for another application. This is what allows me to afford my projects, because everyone here will attest that none of this stuff is inexpensive to begin with, and getting others to do the engineering or sell you a "specialty" part can make the war chest dry with a quickness.?
Hope this helps! On Tue, Jun 9, 2020 at 8:43 AM, Bob Jennings <heatnh@...> wrote: John, can't comment on whether that contactor is correct for your application. This is the contactor thst came with my 10KW setup. Perhaps you could cross reference it.
I'd like to put a contactor or solid state relay between my battery and motor so that I can use a simple toggle switch to turn on/off the battery.? ?Longer term, the bms could disable the battery, or I could even select between battery banks.
But for now, starting simple with an electrically controlled switch for the battery.
I'm using a 48V system. Typical max operating current may be as low as 20A, but could get spikes up to 50A.
I've looked at DC solid state relays.? And even found some rated up to 48V.? The problem is that when you read the fine print and reviews - even the 100A? SSR's are not rated for anywhere near that amount of current for constant usage.? ?(arrrgh!!)
I then started looking at "contactors", and eventually ended up looking at 48V golf cart solenoids. I've always thought of a "solenoid" in this case as being a really big relay.? It looks like the 48V golf cart solenoids should work for this application:
(Note - I'm on fresh water, and the solenoid would be in a plastic case - so I'm not worried about corrosion.)
Is that what I'm looking for, or do I need something that's more "heavy duty"? I saw references to using a flyback diode on the control contacts - and that seemed like a good idea.? Anything else I need to know?
Thanks! John
|
I don¡¯t work for a company that has anything to do with electric conversion etc. ?but I would like to say here that having a resource that has the knowledge to make these systems work reliably and safely has value. ?Not only do they provide the knowledge that can help people through these projects but they also set up a distribution path that motivates suppliers to make changes to products to meet our needs and address shortcomings we could use. ?As individuals looking to DIY with the least out of pocket costs we have next to zero buying power and are stuck with whatever we can find. ?Keeping specialized companies for what we need has value and it employs people that we want to see employed. ?Just saying there is an argument to be made to pay people for their expertise. ?I know you guys don¡¯t want to be providing support in years to come. ?By all means we should help one another and for those that really can¡¯t afford it I think it¡¯s great you are able to do it. ?I just don¡¯t think telling the readers of our threads that it¡¯s the smart way to do it is all that accurate.
Just my opinion and I know they are like a holes. ?We all have them and most stink ? Larry
toggle quoted message
Show quoted text
On Jun 9, 2020, at 10:02 AM, Ryan G via groups.io <ryanwestbrookcary1@...> wrote:
?Here's another more affordable option than thunderstrucks offering: Looks like yours is still lighter on the coffer though.? I know that there are some that fortunate enough for see "money as no object", and am happy for them. But personally, I spend a chunk of my time looking for the ways I can do what I am trying to do affordably, and using a $40 or $50 cart/industrial relay instead of a specialty $125 relay that does the same job is a perfect example of the kind of though that makes these projects even possible on my budget.? On Tue, Jun 9, 2020 at 9:37 AM, ryanwestbrookcary1@... <ryanwestbrookcary1@...> wrote: If you are using a 48v nominal bank with a max amp draw of 50a, but the golf cart contactor should work just fine as the motor that the golf cart relay was designed to potentially energize has a significantly higher amp draw. I looked up the ezgo cart motors yesterday, and the smallest 48v motor they sell is 4hp, so 4hpx750w=3000w 3000w/48v=62.5a They use the same relay on the 8.5hp motor aswell, so you should have a significant safety margin as far as what it was designed to handle.? That you intend to use it far below its rated capacity generally means you can expect an extended service life of the part, another advantage.? And in closing I will say that I feel as you are doing the right thing thinking outside of the box. I usually build all my own stuff out of components rather than buying sets, often using parts that meet the specs I need that were manufactured for another application. This is what allows me to afford my projects, because everyone here will attest that none of this stuff is inexpensive to begin with, and getting others to do the engineering or sell you a "specialty" part can make the war chest dry with a quickness.?
Hope this helps! On Tue, Jun 9, 2020 at 8:43 AM, Bob Jennings <heatnh@...> wrote: John, can't comment on whether that contactor is correct for your application. This is the contactor thst came with my 10KW setup. Perhaps you could cross reference it.
I'd like to put a contactor or solid state relay between my battery and motor so that I can use a simple toggle switch to turn on/off the battery.? ?Longer term, the bms could disable the battery, or I could even select between battery banks.
But for now, starting simple with an electrically controlled switch for the battery.
I'm using a 48V system. Typical max operating current may be as low as 20A, but could get spikes up to 50A.
I've looked at DC solid state relays.? And even found some rated up to 48V.? The problem is that when you read the fine print and reviews - even the 100A? SSR's are not rated for anywhere near that amount of current for constant usage.? ?(arrrgh!!)
I then started looking at "contactors", and eventually ended up looking at 48V golf cart solenoids. I've always thought of a "solenoid" in this case as being a really big relay.? It looks like the 48V golf cart solenoids should work for this application:
(Note - I'm on fresh water, and the solenoid would be in a plastic case - so I'm not worried about corrosion.)
Is that what I'm looking for, or do I need something that's more "heavy duty"? I saw references to using a flyback diode on the control contacts - and that seemed like a good idea.? Anything else I need to know?
Thanks! John
|
Don't get me wrong, if someone lacks sufficient knowledge to safely and effectively engineer and build their own system, they should absolutely go with a turn-key offering and pay someone else the big bucks necessary or not mess with it at all.... But this from is really representative of a niche market of, from what I can tell, mostly passionate diy-ers that have an interest in understanding what they are trying to build or re-fit. Some here look for advice on turn-key systems, but many seem to be more interested in the technical aspect of how to make it work, and come here to ask those with the knowledge and experience for advise, a wise move if they themself lack it. Once someone has a basic understanding of electrical theory, it is not hard to figure out what components will work together. And sometimes, in researching alternative options, great innovations are made (keep in mind that the guys at thunderstrck and similar companies really just figured this same stuff out themselves and sometimes we find ways to improve the kits they offer by just swapping one of their components)
Even the Curtis controllers they offer can be bought at around half the price they want on places like eBay and Amazon.?
All that said, I just hate how the industry leaders like to make everything a "rich mans sport" ?I am reminded of the gear reviews and suggestions in rags like f&s, to see what they recommend one could get the impression that you gotta have a six figure salary to even consider deer hunting! But au contraire, I have put much venison on the table with a $70 Moisan nagant wearing gi surp bdus?
For those on a budget, a little interest and education can potentially make something possible that otherwise would not have been due to finance. It's not a coincidence that people like Edison and tesla came from meager beginnings... if they had been better off, they may never have had the ambition to develop the ideas they had into actual things.?
Like you say, just my 2 cents
On Tue, Jun 9, 2020 at 9:37 AM, ryanwestbrookcary1@... <ryanwestbrookcary1@...> wrote: If you are using a 48v nominal bank with a max amp draw of 50a, but the golf cart contactor should work just fine as the motor that the golf cart relay was designed to potentially energize has a significantly higher amp draw. I looked up the ezgo cart motors yesterday, and the smallest 48v motor they sell is 4hp, so 4hpx750w=3000w 3000w/48v=62.5a They use the same relay on the 8.5hp motor aswell, so you should have a significant safety margin as far as what it was designed to handle.? That you intend to use it far below its rated capacity generally means you can expect an extended service life of the part, another advantage.? And in closing I will say that I feel as you are doing the right thing thinking outside of the box. I usually build all my own stuff out of components rather than buying sets, often using parts that meet the specs I need that were manufactured for another application. This is what allows me to afford my projects, because everyone here will attest that none of this stuff is inexpensive to begin with, and getting others to do the engineering or sell you a "specialty" part can make the war chest dry with a quickness.?
Hope this helps! On Tue, Jun 9, 2020 at 8:43 AM, Bob Jennings <heatnh@...> wrote: John, can't comment on whether that contactor is correct for your application. This is the contactor thst came with my 10KW setup. Perhaps you could cross reference it.
I'd like to put a contactor or solid state relay between my battery and motor so that I can use a simple toggle switch to turn on/off the battery.? ?Longer term, the bms could disable the battery, or I could even select between battery banks.
But for now, starting simple with an electrically controlled switch for the battery.
I'm using a 48V system. Typical max operating current may be as low as 20A, but could get spikes up to 50A.
I've looked at DC solid state relays.? And even found some rated up to 48V.? The problem is that when you read the fine print and reviews - even the 100A? SSR's are not rated for anywhere near that amount of current for constant usage.? ?(arrrgh!!)
I then started looking at "contactors", and eventually ended up looking at 48V golf cart solenoids. I've always thought of a "solenoid" in this case as being a really big relay.? It looks like the 48V golf cart solenoids should work for this application:
(Note - I'm on fresh water, and the solenoid would be in a plastic case - so I'm not worried about corrosion.)
Is that what I'm looking for, or do I need something that's more "heavy duty"? I saw references to using a flyback diode on the control contacts - and that seemed like a good idea.? Anything else I need to know?
Thanks! John
|
One other question I had - and hope one of the experts can answer this:
I don't see a max voltage rating on the contacts for any of the contactors.? Only the voltage of the coil, and the amperage limit of the contactors.
Is it safe to use a 12V contactor (low switching voltage going to the coil) to switch a 48V battery bank?
Ryan, Thank you for the second contactor suggestion (from Amazon) - more affordable, but more importantly - that one appears to be intended for DC, whereas the original Thunderstruck suggestion was for AC.? If it's electromechancial, might work??? I'm not an expert there.? ?I know it wouldn't work to use an AC solid state relay in a DC circuit.
As someone else mentioned, the golf cart contactors are frequently used with the flyback diode on the coil, which is probably important at these voltage levels.? ?I'm not sure about the "precharge resistor".? I agree with the implementation if you're switching the motor on and off directly.? ?However, I'm assuming that for a 48V system with a 500 ohm resistor, you're adding about a 100mA CONSTANT load this is always there.? Since I'm using the contactor to switch on and off the battery bank, I don't want that load when the contactor is turned off.? ?And, since the controller should be powered down when the battery bank is switched on/off - the resistor shouldn't be needed (there should be no load when the contactor is switched on or off).
On Tuesday, June 9, 2020, 09:02:59 AM CDT, Ryan G via groups.io <ryanwestbrookcary1@...> wrote:
Here's another more affordable option than thunderstrucks offering: Looks like yours is still lighter on the coffer though.? I know that there are some that fortunate enough for see "money as no object", and am happy for them. But personally, I spend a chunk of my time looking for the ways I can do what I am trying to do affordably, and using a $40 or $50 cart/industrial relay instead of a specialty $125 relay that does the same job is a perfect example of the kind of though that makes these projects even possible on my budget.?
On Tue, Jun 9, 2020 at 9:37 AM, ryanwestbrookcary1@... <ryanwestbrookcary1@...> wrote: If you are using a 48v nominal bank with a max amp draw of 50a, but the golf cart contactor should work just fine as the motor that the golf cart relay was designed to potentially energize has a significantly higher amp draw. I looked up the ezgo cart motors yesterday, and the smallest 48v motor they sell is 4hp, so 4hpx750w=3000w 3000w/48v=62.5a They use the same relay on the 8.5hp motor aswell, so you should have a significant safety margin as far as what it was designed to handle.? That you intend to use it far below its rated capacity generally means you can expect an extended service life of the part, another advantage.? And in closing I will say that I feel as you are doing the right thing thinking outside of the box. I usually build all my own stuff out of components rather than buying sets, often using parts that meet the specs I need that were manufactured for another application. This is what allows me to afford my projects, because everyone here will attest that none of this stuff is inexpensive to begin with, and getting others to do the engineering or sell you a "specialty" part can make the war chest dry with a quickness.?
Hope this helps! On Tue, Jun 9, 2020 at 8:43 AM, Bob Jennings <heatnh@...> wrote: John, can't comment on whether that contactor is correct for your application. This is the contactor thst came with my 10KW setup. Perhaps you could cross reference it.
I'd like to put a contactor or solid state relay between my battery and motor so that I can use a simple toggle switch to turn on/off the battery.? ?Longer term, the bms could disable the battery, or I could even select between battery banks.
But for now, starting simple with an electrically controlled switch for the battery.
I'm using a 48V system. Typical max operating current may be as low as 20A, but could get spikes up to 50A.
I've looked at DC solid state relays.? And even found some rated up to 48V.? The problem is that when you read the fine print and reviews - even the 100A? SSR's are not rated for anywhere near that amount of current for constant usage.? ?(arrrgh!!)
I then started looking at "contactors", and eventually ended up looking at 48V golf cart solenoids. I've always thought of a "solenoid" in this case as being a really big relay.? It looks like the 48V golf cart solenoids should work for this application:
(Note - I'm on fresh water, and the solenoid would be in a plastic case - so I'm not worried about corrosion.)
Is that what I'm looking for, or do I need something that's more "heavy duty"? I saw references to using a flyback diode on the control contacts - and that seemed like a good idea.? Anything else I need to know?
Thanks! John
|
I just purchased a $24 contactor from Amazon that could work for you:
WINJUN 4Pin Auto Starter Relay 12V DC 500 Amp Vehicle SPST Contactor?
I¡¯ll use it on my charge bus with max current of about 100A. I use the Tyco one for my load bus which can use over 400A. OK to use 12v to close contactor and have 48v connected to the high amp connections.?
the Tyco uses 6A of 12v to close the contact. If you have an inverter in the bus, you¡¯ll need to rig a ¡°slow start.¡±
|
Reuben Trane