# Schematics (final??)



## Guest (Nov 14, 2010)

Its a mess but functional. Put your shunt on the Neg side as well as your voltage and amperage meter. Run your charger connected through the far side of the shunt on the Neg side. On the positive side run your charger on the far side of the breaker so if you throw the breaker it shuts off the charger. Be sure you fuse the charger cables. The main HV fuse will not blow the circuit if the charger goes wonky. So fuse the charger. 

If you can run those wires through a block to clean things up you will be a happy camper. 

Pete 

Final Update Revision is in order.


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## Anaerin (Feb 4, 2009)

If I'm reading that diagram right, you're shorting out your breaker with your volt meter.

Here's a cleaner version that looks pretty much the same without that mistake.


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## omonoid (Aug 30, 2009)

I made a HUGE update to my schematics



Anaerin said:


> If I'm reading that diagram right, you're shorting out your breaker with your volt meter.
> 
> Here's a cleaner version that looks pretty much the same without that mistake.


Thanks you inspired me to make a more organized version. I incorporated what gotti said into my new updated version (posted at the top)

Is my volt meter wired ok now?



Gotti said:


> Put your shunt on the Neg side as well as your voltage and amperage meter. Run your charger connected through the far side of the shunt on the Neg side. On the positive side run your charger on the far side of the breaker so if you throw the breaker it shuts off the charger.


Did i do that correctly?



Gotti said:


> Be sure you fuse the charger cables.


Would I use another 400a fuse or can i get away with a smaller one?


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## Guest (Nov 14, 2010)

Use a small fuse rated for the charger for that fuse. Your charger may already be fused. Have you checked into that? Looks way cleaner. That way when you go to wire things up you will clearly see each component. When you actually go to wire it up be sure you have the power off and be sure to bundle and zip tie your wires where you can to make a clean and tidy wire harness. 

Pete 

Before putting full power to the amp/volt meter you might try charging up the pack to see how they work. PS. If I am not wrong you don't run the volt meter to the shunt. Only the amp meter. Volt meter will be connected to the HV pos and neg and will need to be fused with a small amp fuse. Not sure what to use. If there is a way to isolate that from the pack but still read from the pack then you will want to do that. My SOC meter is just a volt meter and it was connected to my main HV pack. I really don't like HV on or near my dash.


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## EVfun (Mar 14, 2010)

I see some problems (or I don't understand it.) 

1. The charger fuse should be some value reasonable for the charger. Pick something about 10 amps greater than the max charger output current. Make sure the chosen fuse is rated for at least 120 volts DC (that DC part is important, it is much easier to break and AC short.) 

2. The volt meter needs to go between pack negative and pack positive. You are connected to the pack negative put not the pack positive. There is almost no voltage difference between the sides of the shunt (0.05 volts at 500 amps typically.) I would fuse the volt meters pack positive connection with a 1 amp or smaller fuse.

3. The circuit breaker needs to be rated for about 400 amps to be in that location. The circuit breaker is optional but functions as a handy way to switch the battery pack out of the system.

4. The heater traction pack power is poorly protected. I would move the heater negative connection from the pack negative to the charger side of the charger fuse (after replacing it with a lower value as noted above.) This will put a fuse of a more reasonable value in the heater circuit. The relay switching the heater positive connection must be rated for the pack DC voltage. A P&B KUEP relay is commonly used.

5. The heater relay connection to pack positive needs to be on the other side of the contactor. The output from the main contactor should only go to the controller and the controller precharge system. There is no controller precharge system shown, but that is not necessarily an issue since I don't know what controller you are using. Precharge is built into some controllers.

6. I don't see any connection from the controller to the battery pack positive. There should be a connection from the output of the contactor (where you currently have the heater relay connected) to the input of the controller. 

Hopefully this helps, sorry for dumping such a list on you. If you have any more questions feel free to ask. Thanks for the attaching a drawn out schematic, it makes your design much easier to follow.


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## omonoid (Aug 30, 2009)

*Updated to Version 3*

*Version 3*



EVfun said:


> The charger fuse should be some value reasonable for the charger. Pick something about 10 amps greater than the max charger output current. Make sure the chosen fuse is rated for at least 120 volts DC (that DC part is important, it is much easier to break and AC short.)


I looked up my charger. It looks like it is 120vdc at 10 amps. Will this fuse work for that? it is 10a and 125vdc



EVfun said:


> The volt meter needs to go between pack negative and pack positive. You are connected to the pack negative put not the pack positive. There is almost no voltage difference between the sides of the shunt (0.05 volts at 500 amps typically.) I would fuse the volt meters pack positive connection with a 1 amp or smaller fuse.


I fixed the Voltmeter. For the fuse do you mean 1 amp and at least 120vdc such as this?

Also the way i have the voltmeter set up will kepp it on 24/7 isn't that a waste of my precious battery life?



EVfun said:


> The circuit breaker needs to be rated for about 400 amps to be in that location. The circuit breaker is optional but functions as a handy way to switch the battery pack out of the system.


Mines only 250 vdc is there a place i can put it still. I was told that would be ok to shutoff everything



EVfun said:


> The heater traction pack power is poorly protected. I would move the heater negative connection from the pack negative to the charger side of the charger fuse (after replacing it with a lower value as noted above.) This will put a fuse of a more reasonable value in the heater circuit. The relay switching the heater positive connection must be rated for the pack DC voltage. A P&B KUEP relay is commonly used.


Good suggestion about using the charger fuse with heater. 

I have a Magnecraft & Struthers-Dunn 10A/150 VDC relay which i verified works for my application



EVfun said:


> The heater relay connection to pack positive needs to be on the other side of the contactor. The output from the main contactor should only go to the controller and the controller precharge system. There is no controller precharge system shown, but that is not necessarily an issue since I don't know what controller you are using. Precharge is built into some controllers.


I fixed the heater relay connection i understand why that was wrong. 

I plan to have a precharge resister i just dont know what rating for the resister. I have a diy controller from Paul and Sabrina's shop.



EVfun said:


> I don't see any connection from the controller to the battery pack positive. There should be a connection from the output of the contactor (where you currently have the heater relay connected) to the input of the controller.


That was a typo. It's there now 



EVfun said:


> Hopefully this helps, sorry for dumping such a list on you. If you have any more questions feel free to ask. Thanks for the attaching a drawn out schematic, it makes your design much easier to follow.


Very helpful!!!


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## EVfun (Mar 14, 2010)

*Re: Updated to Version 3*



omonoid said:


> *Version 3*
> I looked up my charger. It looks like it is 120vdc at 10 amps. Will this fuse work for that? it is 10a and 125vdc


I would suggest a 15 amp version so it is not right on the edge of blowing when you are charging. Also, a common ceramic heater will peak at more than 10 amps. That fuse type is a good choice as they are longstanding form for DC protection. It should be available in the future.



> I fixed the Voltmeter. For the fuse do you mean 1 amp and at least 120vdc such as this?


Good choice. In the smaller current ratings it is possible to use the ceramic versions of the standard 1/4 by 1-1/4 fuse. One line with a DC rating is the ABC line. I usually use these because the fuses and holders cost less (still, use quality fuse holders.) If you use this type of fuse it is very important not to take a short cut or "cheap out" in the future and stick a regular glass fuse in them, they explode with a shower of glass shards and a small plamsa ball.



> Also the way i have the voltmeter set up will kepp it on 24/7 isn't that a waste of my precious battery life?


You should figure out how much current it draws. Most analog volt meters are remarkably stingy with battery power, usually 1 or 2 milliamps at full scale. If it is low like that it shouldn't be a problem (100 amp hours would take over 5 years, self discharge would be much faster.) If you want the breaker to also shut off the volt meter you can move the fuse connection to the other side of the circuit breaker (I would recommend that so the breaker stops all traction pack draw.)



> Mines only 250 vdc is there a place i can put it still. I was told that would be ok to shutoff everything


It is quite O.K. to include a breaker and your chosen location is good. It isn't required but extra layers of safety can only help.



> Good suggestion about using the charger fuse with heater.
> 
> I have a Magnecraft & Struthers-Dunn 10A/150 VDC relay which i verified works for my application
> 
> ...


I would recommend consulting with them on the choice of precharge setup. The requirements vary with the chosen controller. At around 120 volts it may be possible to use a household edison base light bulb. I use a 7.5 watt night light bulb as the precharge resistor for my Curtis 1221B controller. Oh, don't use the miniature base screw in bulbs for this, the small contact spacing isn't really suitable for DC operation.



> That was a typo. It's there now
> 
> Very helpful!!!


Thanks for the kind words. Seeing the revised diagram I see one more potential change that may better suit your needs. With the current setup the charger and heater current will not show up on your ammeter. The charger current not showing up is the usual setup with an analog ammeter because most don't read both directions. The heater not showing up may be undesirable. If you want charging current and heater draw to be reflected on the ammeter you can just move the ammeter side of the charger fuse to the other side of the shunt. If you want one and not the other that will require one more fuse.


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## omonoid (Aug 30, 2009)

*EVfun*

When i said my breaker was 250 vdc i ment 250 amps. You had said at one point it needed to be at least 400. So mine wont work or what?

I think i fixed the amperage meter to read the heater and charging amps. Is that right?


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## EVfun (Mar 14, 2010)

Most circuit breakers are very slow blowing. The use of a 250 amp breaker is quite common for controllers set up so the peak current is 600 amps or less. The breaker should be rated for the DC voltage required and that is what makes suitable breakers kinda expensive.

Here is an example of a breaker commonly used in EVs. If you do manage to blow the breaker that was quite a hill climb, and you can fix it with a flick of the switch. 

I like the schematic now. I think I would make one small change, I would move the negative side of the volt meter to the other side of the shunt too. It is not really important but I like the idea that the pop of a breaker can completely disconnect the pack positive from the rest of the vehicle and pulling the big cable off the shunt can completely disconnect pack negative from the rest of the vehicle. This helps if you have a battery management system. With one of those if there is any load (even 1 milliamp) on the pack when you connect or disconnect the last cell it is possible for that cell monitor to see full pack voltage across it, usually destroying the unit. 

I'm using a Thundersky Lithium pack with EVworks cell regs so that is a consideration, and hindsight is 20/20. I pull the negative just by pulling the big cable off of the pack side of the shunt, but I have to pull the big cable and 2 small wires off of the main contactor to isolate the positive side. I just put the 2 smaller wires back on the contactor but I have to fumble around with them when it could have been avoided. (I put the positive and negative pack cables inside seperate pieces of plastic conduit and lock them in with zip ties so they will not make any stray connections to anything)


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## omonoid (Aug 30, 2009)

Thanks for your help EVfun i made that small change with the neg voltmeter wire

Anyone else see any issues or have advice?


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