Battery disconnect switch.
- Thread starter Ceec
- Start date
putz
Member
They should be installed on the negative side less sparks if switching and have some thing on.If you look at all the install directions they also say negative.
http://www.pplmotorhomes.com/parts/rv-converters/55-9025.htm
http://www.pplmotorhomes.com/parts/rv-converters/55-9025.htm
rooster57
Member
Positive is the place to be FO-SHO .BUT BUT if you install it in the cable and their is NO other grounds of any kind between the disconnect and the battery. Some times the cable connector will have a #2-4 and a # 10 aux ground frome the same battery connector. If you only have 1 large cable. It wont matter. As far as any load on the battery disconnect these cars use such a small amount current it wont matter . Personaly ive been wiring for 30 years i would put it in the positive.
rooster57
Member
Putz i looked at your link and the reason for the installation of that knife switch in the neg side is because of all the exposed surface area if the switch itself. Putz is looking at a perticular type of switch and for that application it is correct. BUT that switch doesnt have enough current carring capicity for the application here. The rotery or mechanical isolation switch is what i would use on a car. This would be my choice.
http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_21064_21064
http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_21064_21064
FastEddie59
New Member
I agree with RPM, put it on the positive side. Think about how many components have metal to metal contact and if your car is fiberglass it probably has several ground straps throughout the car, if you use the negative side there is always the possiblity that it will find a ground source elsewhere and if it does it stands a real good chance in frying some electronics. Thats my two cents worth and for what it's worth I've had several cars, race and street that were wired this way, and I would not own a fiberglass or self wired car without a master cutoff switch, Eddie 
Wild Mango
Member
Always put the battery isolator on the live side, i.e. the other side from ground. As close to the live battery terminal as you can get it. A fundamental piece of the system.
Beacuse the switch has to be man enough to carry starter current look for 200A rating at least.
If your ride has an ECU and you want to avoid re booting the computer every time you switch the battery on and off, put a 2A circuit breaker across (paralelling) the switch. This will pass enough energy to keep the computer booted up but still trip on even a very low level fault. Or a "hotwire" attempt.
Beacuse the switch has to be man enough to carry starter current look for 200A rating at least.
If your ride has an ECU and you want to avoid re booting the computer every time you switch the battery on and off, put a 2A circuit breaker across (paralelling) the switch. This will pass enough energy to keep the computer booted up but still trip on even a very low level fault. Or a "hotwire" attempt.
Ted Brown
Member
If the battery itself is not grounded at the battery, no matter if you have a hundred other groung straps, they do nothing without the battery, and as far as the real late model stuff that requires an always on need, a small tender (12 volt) battery will keep your radio alive. If you can not ground the battery, you can not use anything and thats what I like.. You all do what you like, that is what makes the World turn...FastEddie59 said:I agree with RPM, put it on the positive side. Think about how many components have metal to metal contact and if your car is fiberglass it probably has several ground straps throughout the car, if you use the negative side there is always the possiblity that it will find a ground source elsewhere and if it does it stands a real good chance in frying some electronics. Thats my two cents worth and for what it's worth I've had several cars, race and street that were wired this way, and I would not own a fiberglass or self wired car without a master cutoff switch, Eddie
bentbaggerlen
Member
Working on large trucks and motor homes, if they are equipped with a battery disconnect they are on the positive side of the battery.
About the best switch to use is a Cole Hersee #75908. I have installed hundreds of them with out any failures. It is capable of carrying 2000 amps for 30 seconds if needed. I would stay away from the light duty plastic disconnect switches, and open knife switches as well. Even if its installed on the negitive side of the battery there will be a spark when the switch is opened or closed.
When changing a battery you always disconnect the negative lead first and connect it last. Doing this if you happen to contact some part of the battery box, chassis or body taking off the positive cable you will not create a direct short. A small 12 volt car battery used in a bucket can deliver well over 100 times its rated amp capacity when shorted, but only for a very short time.
But, just try pulling that wrench off the battery and frame when its red hot
About the best switch to use is a Cole Hersee #75908. I have installed hundreds of them with out any failures. It is capable of carrying 2000 amps for 30 seconds if needed. I would stay away from the light duty plastic disconnect switches, and open knife switches as well. Even if its installed on the negitive side of the battery there will be a spark when the switch is opened or closed.
When changing a battery you always disconnect the negative lead first and connect it last. Doing this if you happen to contact some part of the battery box, chassis or body taking off the positive cable you will not create a direct short. A small 12 volt car battery used in a bucket can deliver well over 100 times its rated amp capacity when shorted, but only for a very short time.
But, just try pulling that wrench off the battery and frame when its red hot
Similar threads
