A Battery Switch Project, the SharkSwitch
05-18-2020 | 01:42 AM
#16
Electron Wrangler
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From: Phoenix AZ
Alan, let me challenge you a bit on the high speed charging in the rear. My purpose is to stimulate discussion especially to benefit those who are not electrically oriented.
You said you had a fused 12v outlet and some pigtails at the rear of the car. My question is where is the fuse and what is its purpose, are the pigtails fused? The circuit should be fused at the battery positive terminal. Fuses do no good if a short happens upstream of the fuse.Mark
My next comment relies on an assumption (tell me if I'm wrong) that your high-current charging is being done with the battery hatch closed. High-current charging a battery in an enclosed space is not recommended due to the release of hydrogen which is explosive. If the battery is overcharged then you get the release of hydrogen sulfide which is poisonous, corrosive, and flammable. It’s true that the generator charges the battery in the box, but normally the time at high-current charging is short. If someone connects an “old style” high-current charger spins the dial to some number of hours and goes away there could be a significant build-up of gas in the battery box. The odds of an explosion are low unless something creates a spark in the box but there may be some accelerated corrosion in the battery box area.
I would say that high-current charging should only be done with the battery and rear hatches open. That both the positive and negative leads of the charger be connected to the battery’s terminals (either directly or through some leads) and that the battery ground is switched off or removed from the ground bolt. As has been pointed out before removing the car’s ground protects the car's electronics, but it also has another benefit, if a positive lead comes into contact with the car frame or battery box lid nothing will happen as there is no return path to the battery negative terminal.
You said you had a fused 12v outlet and some pigtails at the rear of the car. My question is where is the fuse and what is its purpose, are the pigtails fused? The circuit should be fused at the battery positive terminal. Fuses do no good if a short happens upstream of the fuse.Mark
My next comment relies on an assumption (tell me if I'm wrong) that your high-current charging is being done with the battery hatch closed. High-current charging a battery in an enclosed space is not recommended due to the release of hydrogen which is explosive. If the battery is overcharged then you get the release of hydrogen sulfide which is poisonous, corrosive, and flammable. It’s true that the generator charges the battery in the box, but normally the time at high-current charging is short. If someone connects an “old style” high-current charger spins the dial to some number of hours and goes away there could be a significant build-up of gas in the battery box. The odds of an explosion are low unless something creates a spark in the box but there may be some accelerated corrosion in the battery box area.
I would say that high-current charging should only be done with the battery and rear hatches open. That both the positive and negative leads of the charger be connected to the battery’s terminals (either directly or through some leads) and that the battery ground is switched off or removed from the ground bolt. As has been pointed out before removing the car’s ground protects the car's electronics, but it also has another benefit, if a positive lead comes into contact with the car frame or battery box lid nothing will happen as there is no return path to the battery negative terminal.
Some previous threads on these topics:
https://rennlist.com/forums/showthre...eferrerid=6055 Battery Switch, Rear Outlet, Maintainer in Front Fender
https://rennlist.com/forums/showthre...eferrerid=6055 Battery Maintainer
https://rennlist.com/forums/showthre...eferrerid=6055 This one includes a less well developed idea like yours...
https://rennlist.com/forums/showthre...eferrerid=6055 Battery Venting
https://rennlist.com/forums/showthre...eferrerid=6055 Battery terminal degradation from battery out-gassing
https://rennlist.com/forums/showthre...eferrerid=6055 Battery box fuses & battery venting
Mark[/QUOTE]
05-18-2020 | 03:41 AM
#17
Chronic Tool Dropper
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.....
I like the idea of using a self-resetting thermal breaker. I just checked and they less than $7 dollars on Amazon. Do they reset instantly as soon as the load is removed or is there a time delay? In the case of a short, as I understand it, as long as a short exists the breaker will not reset. I would not recommend anything less than 15 amps as the ignition in the run position peaks at over 10 amps for a moment (at least in my car).
Mark
I like the idea of using a self-resetting thermal breaker. I just checked and they less than $7 dollars on Amazon. Do they reset instantly as soon as the load is removed or is there a time delay? In the case of a short, as I understand it, as long as a short exists the breaker will not reset. I would not recommend anything less than 15 amps as the ignition in the run position peaks at over 10 amps for a moment (at least in my car).
Mark
The ones I've used trip at a speed related to percentage of overload, and reset at some multiple of that. Even with a maintained overload, the breaker will try and reset, then will re-trip quickly. So "short" on time, longer off-time, re-close and repeat. These click pretty noticeably on trip and reset, so might need some sound wrap to keep it stealthy. As soon as it trips the first time, the alarm resets too and no more protection.
I wouldn't use a breaker any larger than needed for the alarm if we know that number. Undoubtedly that's greater than needed for interior lights.
05-19-2020 | 03:12 AM
#18
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From: SF Bay Area
Alan, Thanks for the great set of references, you kept me up late going through them. For high charging, I was thinking of “old-style” chargers of 12 amps or more and without the venting you’ve installed. I’m definitely going to see about adding that venting.
dr bob, Since the current required by an alarm is dominated by the sounding unit plus any driven lights, I measured my car’s horn draw. I found it was a bit over 10 amps. I would expect that most audible alarms would require at least a 15 amp fuse. Of course, easy enough to determine in any particular car by trying different fuse sizes.
I’ve been looking into the resettable ATC circuit breakers and have ordered a few samples to try. There are 3 different types as described below in excerpts from the Bussman guide (bold is their emphasis). It warns that Type I is not intended to be continually cycling, a problem in case of a short. The Type II could be used but the manual Type III has one significant spec advantage. The interrupt amp rating on Bussmann's ATC Types I and II is only 225 to 450 amps, a standard ATC fuse is rated at 1000 amps, but the Type III has an interrupt rating of 2000 amps. Given that for starting the battery switch has to be manually moved back to the “Run” position anyway, resetting the manual breaker is only little extra effort.
I’ll provide more feedback after testing.
Mark
Type I (automatic reset): the circuit breaker trips and
resets in response to the overcurrent condition in a
repetitive fashion. This version should be used in
applications that provide for other self-limiting or
non-resettable means (such as after a main fuse, main
manual-reset circuit breaker, or momentary switch).
These devices, while automatic in reset function, are
not designed for long-term cycling conditions in
applications where operator awareness of circuit fault
or serviceability access is limited, leading to
unsatisfactory failure events. Refer to SAE J553 or
J1625 for additional details.
Type II (modified reset): the circuit breaker contains an
additional resistive component that enables the device to
have only brief trip and reset activity and then afterwards
maintains an open circuit condition (except for a low
milliamp draw through the resistor). Requires minimum
voltage/current to maintain open circuit - see standards for
details SAEJ553.
Type III (manual reset): the circuit breaker will trip in
response to an overcurrent condition after which a reset
button or lever extends externally to indicate that the
breaker has tripped and is in a non-conducting state. The
trip indicator button or lever must be manually activated to
return the device to normal operation.
dr bob, Since the current required by an alarm is dominated by the sounding unit plus any driven lights, I measured my car’s horn draw. I found it was a bit over 10 amps. I would expect that most audible alarms would require at least a 15 amp fuse. Of course, easy enough to determine in any particular car by trying different fuse sizes.
I’ve been looking into the resettable ATC circuit breakers and have ordered a few samples to try. There are 3 different types as described below in excerpts from the Bussman guide (bold is their emphasis). It warns that Type I is not intended to be continually cycling, a problem in case of a short. The Type II could be used but the manual Type III has one significant spec advantage. The interrupt amp rating on Bussmann's ATC Types I and II is only 225 to 450 amps, a standard ATC fuse is rated at 1000 amps, but the Type III has an interrupt rating of 2000 amps. Given that for starting the battery switch has to be manually moved back to the “Run” position anyway, resetting the manual breaker is only little extra effort.
I’ll provide more feedback after testing.
Mark
Type I (automatic reset): the circuit breaker trips and
resets in response to the overcurrent condition in a
repetitive fashion. This version should be used in
applications that provide for other self-limiting or
non-resettable means (such as after a main fuse, main
manual-reset circuit breaker, or momentary switch).
These devices, while automatic in reset function, are
not designed for long-term cycling conditions in
applications where operator awareness of circuit fault
or serviceability access is limited, leading to
unsatisfactory failure events. Refer to SAE J553 or
J1625 for additional details.
Type II (modified reset): the circuit breaker contains an
additional resistive component that enables the device to
have only brief trip and reset activity and then afterwards
maintains an open circuit condition (except for a low
milliamp draw through the resistor). Requires minimum
voltage/current to maintain open circuit - see standards for
details SAEJ553.
Type III (manual reset): the circuit breaker will trip in
response to an overcurrent condition after which a reset
button or lever extends externally to indicate that the
breaker has tripped and is in a non-conducting state. The
trip indicator button or lever must be manually activated to
return the device to normal operation.
Last edited by marknsf; 05-21-2020 at 03:10 PM. Reason: clarify
05-20-2020 | 09:55 PM
#19
Chronic Tool Dropper
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From: Bend, Oregon
The little plug-in fuse-replacers style are my first choice. If you do end up with a serious overload or fault to ground, the breaker will trip and then self-reset until it won't reset any more. At that point I'd pull out the failed breaker and pop in a new one. FWIW, I have a couple very old-skuul battery chargers that are nothing more than a 15V transformer, a rectifier block, and one of those breakers on a battery connection terminal. Charging a depleted battery lets the transformer run at overcurrent state for a bit before the breaker opens. Transformer cools off, breaker cools off, breaker auto-recloses, rinse repeat. At some point the battery terminal voltage comes up enough that the charging current is less than the breaker protection current, and the battery gets continuous charge voltage and subsequent reducing charge current as it comes closer to available charging voltage. Bottom line is that these breakers exist in continuous load, cycling protection situations all the time. These are Type I breakers by your definition. You can add a small Sonalert or other similar warning module in parallel with the circuit breaker to alert the driver that the breaker has opened. Would guide the thief to the switch if not installed remote from that switch of course.
The alarm horn (1) is separate from the regular horns (2). You'll likely want to test with 5A breaker to see if it opens with the actual alarm tripped, increase the breaker capacity only if it trips too early..
The alarm horn (1) is separate from the regular horns (2). You'll likely want to test with 5A breaker to see if it opens with the actual alarm tripped, increase the breaker capacity only if it trips too early..
