[Caps18]

With the fuses in the middle of the battery, is 500A the right size? Are they slow-blow fuses? The controller can handle 650A, although I'm not sure how often I would ever get up to 500+Amps.

I also don't know about the 3 packs in parallel getting to 500A over one fuse. Would it be divided by 1/3rd because the power could go over the other two 'packs' (16 batteries in the row)?

 

[dougingraham]

But, please say something if I missed something. Well, I still need to connect the gauges with their proper wiring, but that is also something I don't know for sure.

I added the inertia switch to where I think it goes. Will it get mounted someplace in the cabin or under the hood though?

Thanks

The inertia switch can be physically mounted anywhere in the car. I would place it right next to the main contactor and wire it such that when it opens it opens the main contactor. In other words it needs to go in series with the low voltage side of the main contactor wiring. The inertia switch only purpose is to stop the motor from running away should you have an accident. Where you have it now it has to carry all the 12v DC power and I am pretty sure it was not designed for that. Also you would still want to be able to operate the hazard flashers in the event of an accident and current placement has all your 12V disabled I believe.

The three 500 amp fuses in the middle of the pack can go away. They will do nothing for youin that placement. They might as well be bus bars. You already have a fuse between the pack and the motor controller and one between the battery and the charger. Both of those will protect the wiring to their respective devices.

I am sure there is more but that was what jumped out at me in the time I have to write this reply.

 

[Caps18]

I have updated it with what I believe is where you said to place the inertia switch. It would disable to Main Contactor in it's current position I believe. You were right in suggesting that it was in a bad position previously.

I just found out that there was a big discussion over to have the DC-DC converter always on or after the ignition key. I will have to figure out that still, but I am leaning towards this.

And for a normal battery pack, the fuse in the middle probably would work to break half of the pack and try and save some cells if something goes wrong, but with the three of them wired in parallel, I agree that I don't think that they would do much. I also wonder how often that fuse is actually useful preventing a real situation.

I placed the wires to the gauges that I think are right. I haven't seen any diagrams or pictures of the wiring of those yet (or it has been months). Does the HV shunt work in this way?

 

[evmetro]

With the fuses in the middle of the battery, is 500A the right size? Are they slow-blow fuses? The controller can handle 650A, although I'm not sure how often I would ever get up to 500+Amps.

I also don't know about the 3 packs in parallel getting to 500A over one fuse. Would it be divided by 1/3rd because the power could go over the other two 'packs' (16 batteries in the row)?

I often see more than 500 amps with my AC 74 and 7601 controller. My pack is only 108 volts, so my amps will be a little higher, but I do see all 650 amps pretty often, even though it is only a metro. 6% grades at freeway speeds, 100 mph+ speeds on flat ground, taking off from red lights, spirited driving on country roads. Most freeway driving is around 150 amps. My pack fuse is a shawmut 300 volt 500 amp

 

[evmetro]

I probably would have made groups of 3 cells in parallel and then wired the 16 groups into series, but there are a lot of things that I don't know... If you had 16 "585 ah" cells, your bms could be a little simpler. Why the 3 groups of 16?

 

[palmer_md]

I probably would have made groups of 3 cells in parallel and then wired the 16 groups into series, but there are a lot of things that I don't know... If you had 16 "585 ah" cells, your bms could be a little simpler. Why the 3 groups of 16?

Parallel first then series is the preferred method. He's working with an existing pack that has 48 modules in series that has 3 blocks of 16 modules. Its pretty easy to just separate the three blocks and put them in parallel instead of series, but probably not the preferred way to parallel the cells. It could be done parallel first, but it would require a lot of reconnections of the individual modules, and they already have a very nice interconnection system on top of the blocks. It would be a shame to see that go to waste in order to parallel them first.

 

[dougingraham]

I just found out that there was a big discussion over to have the DC-DC converter always on or after the ignition key. I will have to figure out that still, but I am leaning towards this.

My preference is to have a buffer battery and only turn the DC-DC on when the car is running. You leave it on all the time if you don't have a buffer battery.

You may have an issue with the pack voltage and the 1238 controller. My understanding is that 36 LiFe cells is the typical max number. I have heard of 38 causing occasional issues (129.2 volts.) At full charge voltage 36 cells would be 122.4 volts (36 cells * 3.4 volts). Your pack is comprised of 16 cells each of which is 8.4 volts when fully charged giving a pack voltage of 134.4 volts. It seems like it might be on the edge of working which is why I mention it. I would talk to Brian Seymore about max acceptable voltage on that controller. I would hate for you to have an issue like this. If that turned out to be a problem a less desirable solution would be to drop back to 15 cells. Another solution would be the 1239 controller which tolerates a higher voltage but the downside is less current so less torque. And I could be all wrong about what is acceptable on the 1238 controller.

About your shunt and the JLD 404. The JLD will sense current flow in both directions so it will sort of keep track of your regen with it wired this way. What it wont do is keep track of the charge current so you will need to manually reset it after a charge. (I suspect you probably have to do this anyway as errors will accumulate in the coulomb counting.) To get it to count the charge current you will want to move the point where the charger connects to the battery to encompass the shunt. In my car I have the shunt directly connected to the negative of the battery and the charger negative is tied to the car side of the shunt so the shunt will see the charger current. Also your current placement of the shunt does not count the energy taken out of the pack by the DC-DC converter.

 

[evmetro]

I know that I am known as the j plug troll, but have you considered adding any other inlets for more charging opportunities?

 

[evmetro]

I really admire your schematic. What would I need to get to be able to make schematics like that? Right now all I have is paper out of my printer tray and a pen....

 

[Caps18]

Sorry, I have been away from my computer for the past few days.

I used Apple Keynote to make the schematic, but Powerpoint works too And is better in some line length instances...why does Keynote not let me make the wires the correct length sometimes?

I have a 120V AC Level 1 J1772 charger that I am borrowing for a few months right now. And all the places around town would be J1772 Level 2. I don't believe that will be an issue finding charging stations to plug into. I'm just surprised that the chargers don't come wired up like this already.


I am concerned about the high voltage as well. I was told 120V is no problem. 15 in a row wouldn't be a big deal if I had to do it that way.

I doubt I will be going higher than 70mph, so I should be fine on the amps side of things I hope.

 

[Caps18]

My preference is to have a buffer battery and only turn the DC-DC on when the car is running. You leave it on all the time if you don't have a buffer battery.

You may have an issue with the pack voltage and the 1238 controller. My understanding is that 36 LiFe cells is the typical max number. I have heard of 38 causing occasional issues (129.2 volts.) At full charge voltage 36 cells would be 122.4 volts (36 cells * 3.4 volts). Your pack is comprised of 16 cells each of which is 8.4 volts when fully charged giving a pack voltage of 134.4 volts. It seems like it might be on the edge of working which is why I mention it. I would talk to Brian Seymore about max acceptable voltage on that controller. I would hate for you to have an issue like this. If that turned out to be a problem a less desirable solution would be to drop back to 15 cells. Another solution would be the 1239 controller which tolerates a higher voltage but the downside is less current so less torque. And I could be all wrong about what is acceptable on the 1238 controller.

About your shunt and the JLD 404. The JLD will sense current flow in both directions so it will sort of keep track of your regen with it wired this way. What it wont do is keep track of the charge current so you will need to manually reset it after a charge. (I suspect you probably have to do this anyway as errors will accumulate in the coulomb counting.) To get it to count the charge current you will want to move the point where the charger connects to the battery to encompass the shunt. In my car I have the shunt directly connected to the negative of the battery and the charger negative is tied to the car side of the shunt so the shunt will see the charger current. Also your current placement of the shunt does not count the energy taken out of the pack by the DC-DC converter.

I am re-working it to move the shunt around. But I am worried about how the charging will work, and if I should tie into the HV battery cables and have a SSR relay that would open to prevent the power from going to the main contactor. Then again, maybe there would be something in the controller that would prevent the motor from working when it is being charged, even if the throttle was pressed.

 

[Caps18]

I have moved the charger cables around. Do I have to worry about the three packs evenly charging in this setup?

 

[dougingraham]

I have moved the charger cables around. Do I have to worry about the three packs evenly charging in this setup?

The packs will charge just fine. An optimum arrangement would be to parallel the cells in the strings but it will work fine without doing this.

In a previous note you were concerned about the possibility of turning on the motor while charging. There is a normally closed relay contact on the AVC2 which is the device used to enable the EVSE. You can loop the main contactor signal through this normally closed contact. If the J1772 is plugged in the main contactor won't close because the normally closed contacts will be open.

I was trying to figure out what the extra shunt to the right of the charger is for since you don't show it connected to anything. Also there should be a fuse in one of the high voltage lines running to the charger sized for the wire used there. It should be at the battery end of the wire. You should fuse every circuit that leaves a battery with a fuse sized for the current capacity of the wire or device, whichever is lower.

 

[palmer_md]

Here is the same controller with the suggested wiring diagram.

http://hpevs.com/Site/images/jpeg/Schematics/513-up/1239/auto1239_513-up_revb.pdf

 

[sabahtom]

Your wiring diagram is better than mine so I will comment quietly...Wondering about using a single fuse for the power steering, vacuum brakes and DC-DC output? I also would think its good to put a fuse rating for your traction fuse, and maybe you need another fuse for your DC to DC input.

 

[Caps18]

Here is the same controller with the suggested wiring diagram.

http://hpevs.com/Site/images/jpeg/Schematics/513-up/1239/auto1239_513-up_revb.pdf

Yes I had seen that and there is some good information there, but it doesn't cover everything, and is missing a lot of the details that people have helped me with here.

Your wiring diagram is better than mine so I will comment quietly...Wondering about using a single fuse for the power steering, vacuum brakes and DC-DC output? I also would think its good to put a fuse rating for your traction fuse, and maybe you need another fuse for your DC to DC input.

That is a good question. Maybe using one fuse is definitely wrong. I will update it here.

The question is, can I figure out the existing wires to use the fuse box built into the truck, or will I need to start over and create a new one...

With this wiring diagram, I will hopefully be able to tell what wires I need and what wires can be removed.

The packs will charge just fine. An optimum arrangement would be to parallel the cells in the strings but it will work fine without doing this.

In a previous note you were concerned about the possibility of turning on the motor while charging. There is a normally closed relay contact on the AVC2 which is the device used to enable the EVSE. You can loop the main contactor signal through this normally closed contact. If the J1772 is plugged in the main contactor won't close because the normally closed contacts will be open.

I was trying to figure out what the extra shunt to the right of the charger is for since you don't show it connected to anything. Also there should be a fuse in one of the high voltage lines running to the charger sized for the wire used there. It should be at the battery end of the wire. You should fuse every circuit that leaves a battery with a fuse sized for the current capacity of the wire or device, whichever is lower.

Thank you for pointing out the AVC2 relay. That makes a lot of sense and is correct.

I was wondering about that shunt too. The charger manual has it in there, but doesn't say where it goes to. Maybe it goes to the CANbus controller so it can read how much current is going into the battery when charging...

But, I believe the fuse on the red + HV wire coming off the left side of the battery is there already and in the right location. It would be used if it is charging or in operation. Is it not correct?

 

[dougingraham]

Your wiring diagram is better than mine so I will comment quietly...Wondering about using a single fuse for the power steering, vacuum brakes and DC-DC output? I also would think its good to put a fuse rating for your traction fuse, and maybe you need another fuse for your DC to DC input.

The primary point of the fuse is to protect the wiring from a short. A lot of people think the fuse is there to protect the device at the other end of the wire. That is not really the case. Can you protect the wire going to multiple devices with a single fuse? Yes, but you need to be careful in calculating the wire and fuse sizes and sometimes one size does not fit all. Look at it this way. The DC-DC converter will only draw a few amps at most from the traction pack and its input will track its output. The power steering pump could have large transients. The vacuum pump could have large starting currents but then tapers off as the vacuum increases. You need to wire to handle average currents and fuse for the peaks. And are you ok with losing all three systems at the same time when driving down the road?

 

[Caps18]

It isn't looking quite as neat as it once did. I would have to move around a lot of stuff to make the wires look good.

But, I hope that it is getting closer to what is correct.

(I added the individual fuses, and the existing lights, wipers and such already have fuses that aren't shown on the diagram.) I forgot to move the fuse from next to the key ignition to the key relay. I don't want to lose everything if one fuse blows.

 

[dougingraham]

I was wondering about that shunt too. The charger manual has it in there, but doesn't say where it goes to. Maybe it goes to the CANbus controller so it can read how much current is going into the battery when charging...

But, I believe the fuse on the red + HV wire coming off the left side of the battery is there already and in the right location. It would be used if it is charging or in operation. Is it not correct?

If that shunt next to the charger connects to the charger then you need it but run the shunt sense wires back into the charger. My guess is that the charger knows what the current is.

The large fuse on the HV+ line leaving the battery would be fine if you run the same size cable to the charger as you run to the motor controller. If that is a 500 amp fuse and you run 6 gauge wire to the charger then it is like no fuse at all on the wires between the charger and the traction battery because it will never open in the event of a short between those devices or if the output stage of the charger fails shorted. The charger fuse should be set just above the maximum charging current. The motor controller fuse should be selected for the draw of the motor. Very different currents and probably different cables sizes. A battery pack needs a fuse for every circuit that leaves it. Since we often use a common negative we tend to not fuse the common so you should have N-1 fuses on a battery pack where N is the number of wires connected to the pack.

In my car I have two battery packs in series so I have two huge fuses to protect the 2/0 cable leaving the batteries. One fuse is inside each pack. This protects the wiring between the packs and the wiring to the high voltage terminal strips. I don't have a separate fuse to the motor controller, it is protected by the battery fuses. I have a separate fuse for the Charger, DC-DC converter and to the heater sized appropriately for each device connected to the HV terminal strip. You can fuse these on either side but by convention we normally have a common negative and fuse the positive side.

Hope that is clear.

 

[sabahtom]

Thanks Doug. I had a question earlier today regarding this so I copied your post over to the other thread.

http://www.diyelectriccar.com/forums/showthread.php/can-charger-and-dc-dc-share-94488.html