# 08 main breaker **URL:** \ **Category:** GEM Forum\ **Created:** [June 28, 2015, 8:30pm UTC](https://community.electricforum.com/t/08-main-breaker/5111 "2015-06-28T20:30:29Z")\ **Posts on this page:** 12\ **Page:** 4
**Author:** ![Inwo](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.electricforum.com/inwo/32/1067_2.png) [@Inwo](https://community.electricforum.com/u/Inwo)\ **Post date:** [March 27, 2016, 12:52pm UTC](https://community.electricforum.com/t/08-main-breaker/5111/61 "2016-03-27T12:52:41Z")
The switching voltage is the same anywhere in the system. The 70 amp or 100 amp switch is designed to carry the full 350 amp load, or it would not be used in this application. Breaking is another story. Never switch under load. The 250 amp fuse is also designed properly for stock settings. You are correct IMHO that bigger is better for the switch. ---
**Author:** ![Inwo](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.electricforum.com/inwo/32/1067_2.png) [@Inwo](https://community.electricforum.com/u/Inwo)\ **Post date:** [March 27, 2016, 1:06pm UTC](https://community.electricforum.com/t/08-main-breaker/5111/62 "2016-03-27T13:06:16Z")
other things to look for in replacement. SW means switch only. 10,000a is interrupting capacity ie 10,000 amps. more is better 80v is volt rating. more is better Dc rated. ---
**Author:** ![IssaquahWA1979](https://avatars.discourse-cdn.com/v4/letter/i/91b2a8/32.png) [@IssaquahWA1979](https://community.electricforum.com/u/IssaquahWA1979)\ **Post date:** [March 27, 2016, 1:07pm UTC](https://community.electricforum.com/t/08-main-breaker/5111/63 "2016-03-27T13:07:35Z")
I have decided to install a 300a continuous duty battery switch under the seat, it has a 500A peak rating and will be installed at the battery 4 location to meet the 48VDC requirement. I talked it over with my electrical engineering friend and I have many years of designing Solar systems neither of us can figure out why they would install something so underrated or why this should not be a safe alternative. My one concern is the amperage through the negative shunt however since I broke the stud off I am not using it anyhow. Battery voltage is being monitored through a Batt Six and current will be monitored through the digital battery management system so I do not care if the dash meter is working or not as I don’t believe it anyhow. ---
**Author:** ![IssaquahWA1979](https://avatars.discourse-cdn.com/v4/letter/i/91b2a8/32.png) [@IssaquahWA1979](https://community.electricforum.com/u/IssaquahWA1979)\ **Post date:** [March 27, 2016, 1:11pm UTC](https://community.electricforum.com/t/08-main-breaker/5111/64 "2016-03-27T13:11:27Z")
This is the one that I am using on the 12VDC side, I am investigating to see if they have a higher rated shunt… [bayite DC 6.5-100V 0-100A LCD Display Digital Current Voltage Power Energy Meter Multimeter Ammeter Voltmeter with 100A Current Shunt - - Amazon.com](http://www.amazon.com/6-5-100V-Display-Digital-Multimeter-Voltmeter/dp/B013PKYILS?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o04_s00) [quote=OLD HOUSEBOATER;29748]Also consider adding one of these [DC 300A Analog Ammeter Panel Amp Current Meter 85C1 0 300A DC with Shunt | eBay](http://www.ebay.com/itm/171179319949?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT)[/quote] ---
**Author:** ![Old\_Houseboater](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.electricforum.com/old_houseboater/32/544_2.png) [@Old\_Houseboater](https://community.electricforum.com/u/Old_Houseboater)\ **Post date:** [March 27, 2016, 3:46pm UTC](https://community.electricforum.com/t/08-main-breaker/5111/65 "2016-03-27T15:46:16Z")
My current set up. Top display is a Tach. I like the digital although it’s a little tender. ---
**Author:** ![Old\_Houseboater](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.electricforum.com/old_houseboater/32/544_2.png) [@Old\_Houseboater](https://community.electricforum.com/u/Old_Houseboater)\ **Post date:** [March 27, 2016, 4:00pm UTC](https://community.electricforum.com/t/08-main-breaker/5111/66 "2016-03-27T16:00:45Z")
Hmmmm You might want to think about it. The PDM (Power Display Module) is a $900 dollar piece > [@IssaquahWA1979;29744](#): > > I am going to substitute but it will be for something heavier duty not lighter… I don’t understand when engineers install a electrical component that is underated for the system design, the switch itself becomes a hazard as we have seen they get insanely hot to the point of full melt down. I am investigating other switches even if they have to be installed elseware, problem I am running into is that the high quality HD battery swtiches are only good to 48vDC so I wiill have to continue investigating. I am curious why they went away from the old style in the \<05 model years, those seem to be durable. The other thought hear is to install a 300A continuous rated switch under the seat in the series like the old setup at whcih point battery voltage is still at 48VDC or below. ---
**Author:** ![Inwo](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.electricforum.com/inwo/32/1067_2.png) [@Inwo](https://community.electricforum.com/u/Inwo)\ **Post date:** [March 27, 2016, 8:14pm UTC](https://community.electricforum.com/t/08-main-breaker/5111/67 "2016-03-27T20:14:50Z")
> [@Gwest;29749](#): > > ^^^^ Rodney that’s a pretty slick set up. I wish the display was more modern or updated but You have pointed out very clearly how a Amp meter can Act as a guide to the driver in extending range. For that reason I think I am intrested in adding one Should have a 200amp wireless power meter in this week. It’s as far as Chcago. Wireless will take care of any power supply isolation and wiring problems. Nobody will make me a 500a model, unless I order 200 pcs. So. I guess another hack is in order.😃 ---
**Author:** ![Inwo](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.electricforum.com/inwo/32/1067_2.png) [@Inwo](https://community.electricforum.com/u/Inwo)\ **Post date:** [March 28, 2016, 9:05am UTC](https://community.electricforum.com/t/08-main-breaker/5111/68 "2016-03-28T09:05:20Z")
Got it today. Hack in progress. ---
**Author:** ![IssaquahWA1979](https://avatars.discourse-cdn.com/v4/letter/i/91b2a8/32.png) [@IssaquahWA1979](https://community.electricforum.com/u/IssaquahWA1979)\ **Post date:** [March 28, 2016, 10:14am UTC](https://community.electricforum.com/t/08-main-breaker/5111/69 "2016-03-28T10:14:20Z")
[quote=OLD HOUSEBOATER;29761]Hmmmm You might want to think about it. The PDM (Power Display Module) is a $900 dollar piece[/quote] from what I can see the only reason power is flowing through the PDM is for current monitoring for battery state of charge, the Motor controller has its own current sensing for control and protection. What my plan is to do is move the main power connections to the motor controller and then come off of it with a lower rated fuse to the PDM to protect it. I have a spare PDM board that was bad, one of my EE friends reworked for me as a spare I am going to see if the shunt circuit is a standard resistance, because if it is then I will run an external shunt on the battery feeds into the motor controller just so that the gauge works. If there is something I am not seeing here please feel free to say so, I am looking at this from a pure electrical engineering standpoint rather than a NEV application. I still do not see how having a rating of 1/3 the protected capacity makes sense in any application. I am engaging the conversation because if this works out then it means that we can utilize the current capabilities needed for the bigger motors under load safely. One of the other thoughts I had is that if this switch has been getting hot under load the internal resistance is obviously high therefore reducing performance. Let’s think through the entire system and not just one piece of it. ---
**Author:** ![IssaquahWA1979](https://avatars.discourse-cdn.com/v4/letter/i/91b2a8/32.png) [@IssaquahWA1979](https://community.electricforum.com/u/IssaquahWA1979)\ **Post date:** [March 28, 2016, 10:17am UTC](https://community.electricforum.com/t/08-main-breaker/5111/70 "2016-03-28T10:17:07Z")
[quote=Inwo;29799]Got it today. Hack in progress.[/quote] I just want to say thank you as a hacker myself to resolve issues that dealers want insane amounts of money to fix, with other folks on here like Rodney this has become a fun challenge and I think we will end up with some pretty solid solutions for those who want to fix things so they stop breaking. I don’t know much about motors but when it comes to electrical system design I can hold my own. I would be very eager to have the wireless HD shunt setup if you end up with it working properly. ---
**Author:** ![IssaquahWA1979](https://avatars.discourse-cdn.com/v4/letter/i/91b2a8/32.png) [@IssaquahWA1979](https://community.electricforum.com/u/IssaquahWA1979)\ **Post date:** [April 4, 2016, 10:26am UTC](https://community.electricforum.com/t/08-main-breaker/5111/71 "2016-04-04T10:26:29Z")
so I got to run the car this weekend with the new disconnect switch installed, absolutely ZERO heat build up in the switch so everything seems good there, now I have a hot cable going from the fuse to the #4 battery, there looks to be some corrosion in the cable so today I will stop by West Marine and pick up some cable and crimps to get that fixed up. I am also going to change the style of fuse as the one installed is a bit gunked up looking even after I cleaned it up. ---
**Author:** ![Ironpumper](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.electricforum.com/ironpumper/32/6705_2.png) [@Ironpumper](https://community.electricforum.com/u/Ironpumper)\ **Post date:** [June 19, 2020, 8:42pm UTC](https://community.electricforum.com/t/08-main-breaker/5111/72 "2020-06-19T20:42:24Z")
Hello my friend. I bought a GEM with the same problem. Make sure that ALL YOUR LUGS are tight. Usually when you take out a breaker it’s due to a " heated surge ". I put a main Albright disconnect and mounted securely. That breaker set up is the cheesiest piece of poop. ZERO issues. \*\*\*\*\* MAKE SURE YOU DISCONNECT THE MAIN POSITIVE AND NEGATIVE TO YOUR BATTERY PACK \*\*\*\* reason being your breaker will be bypassed for checking. Mine surged so bad it actually took out the contactor. The solenoid was engaging but the main lugs were toast. Best of luck ! [Previous page](https://community.electricforum.com/t/08-main-breaker/5111.md?page=3)