Battery Disconnect method.

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PlanetDad

100 mW
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Mar 22, 2019
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48
Hello everyone,

Doing a rebuild of my current e-bike, and am stuck on a way to disconnect the battery. This topic has been brought up before, but most post's are up to 5 years old. Hoping someone has come up with a better solution to what I've found so far.

New build will be a 48v - AWD 1500W DD hub on the rear 1200W DD Hub on the front. Each kit will be independent with identical 1800W 48V 20AH packs. Pack attached to the 1200W system will have a voltage reducer for some 12v gadgets.

Issue is a proper battery disconnect, the new packs do not have there own disconnect switch. And finding a switch rated for 60 volts up to 50 amps is difficult ( in an aesthetic size ),

This came up in my search and really liked the idea but its only for 40amp... To weak???

https://www.amazon.com/YETOR-Anti-Theft-Security-Barriers-Controls/dp/B07P4DZ2JT/ref=sr_1_19?keywords=12v%2Bkey%2Bswitch&qid=1583866789&sr=8-19&th=1

Thanks in advance, wish you all well.
 
I , and many other people , are now using XT 90 Anti - Spark Connectors .

I use them with 14s and 16s and 18s packs , even connected a 20s pack up to the controller with my wiring harness with XT90 anti-spark connectors . ( make your own wiring harness , use 10 awg wire . Hobbyking or Amazon or E-Bay , 10 awg silicone wire)

https://hobbyking.com/en_us/xt90-s-anti-spark-connector-2pairs-bag.html

( if Hobbyking is out of stock then ) ...

https://www.amazon.com/Amass-Connector-Anti-Spark-Battery-Charger/dp/B074PTHZ3M/ref=asc_df_B074PTHZ3M/?tag=hyprod-20&linkCode=df0&hvadid=241976201237&hvpos=&hvnetw=g&hvrand=3587162167514676906&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9032145&hvtargid=pla-454617925652&psc=1
 
Is it turning into a sales pitch, I could not recommend luna and neither should anyone, but there again if your a paid shill you will.

Plenty of evidence to avoid these folk, and do t use an xt90 anti spark above 12s the above working voltage will still allow a spark in capacitive circuits, ive had an issue with sparks at 16s so 20s is a no no.

Use a resistor switched and calaclute it to give a slow ramp up of the needed time then switch it out of circuit.
 
Ianhill said:
Is it turning into a sales pitch, I could not recommend luna and neither should anyone, but there again if your a paid shill you will.

Plenty of evidence to avoid these folk, and do t use an xt90 anti spark above 12s the above working voltage will still allow a spark in capacitive circuits, ive had an issue with sparks at 16s so 20s is a no no.

Use a resistor switched and calaclute it to give a slow ramp up of the needed time then switch it out of circuit.
Click to expand...

I will do some homework on them. by 20s you me the ah?
 
20S is twenty cells in series, 4.2V x 20S = 84.0V when fully charged. Ianhill, I have mentioned products from EM3EV and also Grin Tech in the past.

Ianhill, if you know of anyone who sells a solid-state semi-conductor on/off switch, please add the link.

Switches that connect physical contacts can sometimes weld themselves permanently in the "on" position, so when I found this, I made a note about it.
 
spinningmagnets said:
Here's one option, $47

https://lunacycle.com/remote-on-off-solid-state-switch/
Click to expand...


Junk, from the RC hobby, and no longevity or good reliable components usually.. and identical thing can be found elsewhere for much less. MUCH MUCH LESS $.

I personally use a Helly 2834. Very well known and used worldwide.... daily... lets "hope" it dont weld shut... lol. These tiny systems?... and no, have a precharge and the arc wont happen. Breaking the arc is what this sw is designed for. I also have a few older 75A switches from fire trucks that are smaller than a pack of cigs.



https://www.google.com/search?q=hel...VbknIEHTCkCboQ_AUoA3oECAwQBQ&biw=1218&bih=950

https://www.google.com/search?q=CRY...XDknIEHQ7KDfAQ_AUoAnoECAkQBA&biw=1218&bih=950

If you want a ssr get a CRYDOM. I wont trust an SSR, if there are gas filled or sprung latching, and good traditional reliable GIGAVAC solenoids available in the rated currents small enough. One thing about solenoids is that they are very H2O resistant. ( read, long lasting)

I also bet 1$ that the transistor in that RC sw is junk and not name brand.... ... ( read, short lasting). ( for that junk little hobby grade sw above) Just relay the big current. Duh.
 

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FYI this is NOT what I am looking for :lol:

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DogDipstick said:
spinningmagnets said:
Here's one option, $47

https://lunacycle.com/remote-on-off-solid-state-switch/
Click to expand...


Junk, from the RC hobby, and no longevity or good reliable components usually.. and identical thing can be found elsewhere for much less. MUCH MUCH LESS $.

I personally use a Helly 2834. Very well known and used worldwide.... daily... lets "hope" it dont weld shut... lol. These tiny systems?... and no, have a precharge and the arc wont happen. Breaking the arc is what this sw is designed for. I also have a few older 75A switches from fire trucks that are smaller than a pack of cigs.



https://www.google.com/search?q=hel...VbknIEHTCkCboQ_AUoA3oECAwQBQ&biw=1218&bih=950

https://www.google.com/search?q=CRY...XDknIEHQ7KDfAQ_AUoAnoECAkQBA&biw=1218&bih=950

If you want a ssr get a CRYDOM. I wont trust an SSR, if there are gas filled or sprung latching, and good traditional reliable GIGAVAC solenoids available in the rated currents small enough. One thing about solenoids is that they are very H2O resistant. ( read, long lasting)

I also bet 1$ that the transistor in that RC sw is junk and not name brand.... ... ( read, short lasting). ( for that junk little hobby grade sw above) Just relay the big current. Duh.
Click to expand...

Thanks will look into it
 
do you need to actually disconnect the battery?

or is simply turning the controller off an option? (this will reduce the power drain to nearly nothing, and does not require anything better than the keyswitch you would've used to replace the button on that other thing with, because it does not disconnect the main battery wire, just the thin positive wire that feeds the controller brain, usually marked as keyswitch, ignition, door lock, or similar).


the input to the dc-dc for your 12v stuff will also probably have a low enough input current it could also be switched off the same way.


alternately, some bmses have pads on the inside for a switch that will disable the output. or you can add one that grounds the gate signal to the output fets, preventing it from turning on, so preventing discharge.
 
This is about the power of controllers and battery C-rate. At some point, there are no good solutions. I mean, who would want a 500A circuit breaker or switch on his bike?

I use big Andersons, no fuse, no switch, not even any sort of anti-spark methods. I just replace the Andersons when they are worn out with pitting. :wink:
 
Is a dc automatic fuse an option? I use two 100A fuses in paralell, but I usually only turn on one. They seem to be able to take short bursts of 300A. I had a pre charge circuit, but the button broke. So lately I have turned them on without pre charge. I have not heard any arcing. (20s)

They have also been put to the test when I have blown mosfets in controllers. They have worked as they should.
 
amberwolf said:
do you need to actually disconnect the battery?

or is simply turning the controller off an option? (this will reduce the power drain to nearly nothing, and does not require anything better than the keyswitch you would've used to replace the button on that other thing with, because it does not disconnect the main battery wire, just the thin positive wire that feeds the controller brain, usually marked as keyswitch, ignition, door lock, or similar).


the input to the dc-dc for your 12v stuff will also probably have a low enough input current it could also be switched off the same way.


alternately, some bmses have pads on the inside for a switch that will disable the output. or you can add one that grounds the gate signal to the output fets, preventing it from turning on, so preventing discharge.
Click to expand...

I suppose I do not 'need' to disconnect the battery. But wanted a key option for theft and convenience, as well as the aesthetically satisfying manner of a key switch that would allow power to battery disconnect switch and DC-DC, and then lighted led switch's for all the other stuff.

I've nearly given up on the idea,
 
DogDipstick said:
...I wont trust an SSR,...
Click to expand...

Any particular reason why? Reliability I presume, but in a worst case scenario is there a concern aside from it welding itself shut and failing to shut off when requested? Or is there a concern of something more... dramatic happening?
 
HK12K said:
DogDipstick said:
...I wont trust an SSR,...
Click to expand...

Any particular reason why? Reliability I presume, but in a worst case scenario is there a concern aside from it welding itself shut and failing to shut off when requested? Or is there a concern of something more... dramatic happening?
Click to expand...

Yeah It is a fail point that fails closed and is addressed by good mechanical solenoids if you can find them. I always like to overbuild and under trust. So many junk parts out there. That or I just haven't found one that I like.. but ye good ol CRYDOM have been around for a while... But anyway you should have two failsafes like a fuse TOO so the protection is doubled in case of catastrophe.. like a fuse AND a a breaker..Right?

Also, the whole getting transistors wet, muddy, hot, cold, and shaking them like they are on dirt bikes thing. Lol. Durability.
 
DogDipstick said:
HK12K said:
DogDipstick said:
...I wont trust an SSR,...
Click to expand...

Any particular reason why? Reliability I presume, but in a worst case scenario is there a concern aside from it welding itself shut and failing to shut off when requested? Or is there a concern of something more... dramatic happening?
Click to expand...

Yeah It is a fail point that fails closed and is addressed by good mechanical solenoids if you can find them. I always like to overbuild and under trust.
Click to expand...
As I suspected. Just wanted to confirm. :thumb:
 
DogDipstick said:
addressed by good mechanical solenoids if you can find them. I always like to overbuild and under trust.
Click to expand...
Sorry dude, they aren't rated for the voltages you use. The little one is rated to 30v. The big one doesn't say, but being for a truck, it's probably similar voltage rating. Same deal with the Hella 2834. It's only rated for 24v.

They aren't rated to break an arc above that voltage.

Try solar panel isolators. They are rated for higher DC voltages.
 
Before I had XT90 Anti-spark connectors on my bike, I used 3 IRFB3077s in parallel to switch off current from the battery. The whole circuit was in an aluminum enclosure filled with silicone for waterproofing, similar to the Luna Cycle product.

I was a bit wary of using XT90s at first, but now that I have used them, I am never going back. It serves two jobs (switch and battery connector), is good for WELL OVER 90 amps in my experience, and doesn't spark when plugged in. And they are cheap too, even the genuine ones are less than $3 a connector (make sure to get the genuine AMASS ones, not $1.00 a pop fakes).
 
serious_sam said:
They aren't rated to break an arc above that voltage.
Click to expand...

Like I care. I been running the Hella at 8Kw. 85.9v. Bahahha.

Sorry dude.
 
DogDipstick said:
serious_sam said:
They aren't rated to break an arc above that voltage.
Click to expand...
Like I care. I been running the Hella at 8Kw. 85.9v. Bahahha.
Sorry dude.
Click to expand...
I was just highlighting that the switches you are recommending aren't fit for purpose. It wasn't a personal attack on you. But you're response does make you seem like a bit of a fuckwit, tbh.

Running a higher than rated voltage through a switch during normal operation is a completely different situation than needing to break that voltage when high current is already flowing. I don't think you understand that.

Voltage ratings on switches are there for a purpose, and even 84VDC can make a spectacular arc, especially at the current levels that our battery packs are capable of producing.

It would be a shame if someone followed your flawed advice and reasoning, and got hurt because of it.
 
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