# BMS current sensor placement



## frodus (Apr 12, 2008)

Current through the pack is the same wherever you take the measurement (or it should be). I worked with a guy on a project Mini Cooper with Orion. He installed it in the rear pack between cells.

The current at the positive and negative will be the same as the current in the middle. Since it's hall effect, it doesn't matter where you take the measurement. 

Other BMS's, or meters, sometimes use shunts. Sometimes an issue arrises because the meter needs the shunt to be at pack negative (common negative for shunt/voltage sense).

So, you're fine.


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## dougingraham (Jul 26, 2011)

evmetro said:


> I am wiring my Orion now, and my current sensor has a very short lead. The pdf wiring manual says it needs to be that way, leave it alone. I need to route the high voltage to it instead. My preference for location is a long way from the charger and the motor, so here is my question. Does it matter where in the high voltage circuit the sensor is? Does it make any difference if it is mid pack? One of my battery banks is close enough to route through the sensor, but it is between cells 13 and 14 out of 34.


Unless they specify it needs to be at the bottom or top it doesn't matter where you place it. The current will be the same anywhere in the series string. I am assuming this is a shunt. If it is hall effect device then it has no physical connection so it can go anywhere. The reason they want it short is because the signals are fairly low in voltage and it is easy for noise to get into it and electric cars are a somewhat noisy environment.


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## frodus (Apr 12, 2008)

TEV, that doesn't seem like a very good design IMHO....I don't recommend having the load (controller) on at the same time as the source (charger). Why would you drive away while plugged in?

Vsource and Vload shouldn't be on at the same time.

http://lithiumate.elithion.com/php/functional_descr.php#Battery_current


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## evmetro (Apr 9, 2012)

Yea, this is the hall effect sensor. No physical connection. Thanks for confirming what I suspected. It is pretty nice to bounce this kinda stuff off some of you guys. I just paid the price for ignorance by building a 108 volt car and having a 96 volt controller... yea, those are cheap.


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## frodus (Apr 12, 2008)

TEV,

I came to that conclusion because I worked for Elithion as Tech support for about a year and a half (and another year while at another company), and because I've worked with the Orion system on a customer's vehicle (and still do a little support for people now and then). I've seen tons of applications of these (including my own Elithion system). Neither the Elithion, or the Orion will scream fault if they're wired and operated correctly. 

Now, lets say you're wiring so that one sensor counts CHARGEcurrent and LOADcurrent, and the other sensor measures CHARGEcurrent. If you wire so that you DO have the load current AND source current flowing at the same time, and provide power to Vsource and Vload (or the equivalent on the Orion).... the Orion and Elithion can be made to stop the vehicle immediately (why would you want to drive away while plugged in?). Or they can choose to ignore the fault mode and incorrectly calculate current. But that's not really safe or recommended.

I just can't think of any good reason you'd be charging AND driving at the same time.... in which case, you're correct, you'd have to wire them so you don't count the current twice. Both systems have measures built-in to protect from that happening (which can be enabled or disabled). 

So let me rephrase: *In a properly wired and safe system*, you would not have Vsource triggered + current flowing from the charger at the same time you have Vload triggered + current flowing to/from the controller.


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## evmetro (Apr 9, 2012)

Wow frodus, pretty crear info. What if you are running a giant windmill on your roof?


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## frodus (Apr 12, 2008)

Well, then you're not really worried about range or cost... lol! 

Even if you DID want to do it that way, you would just run one current sensor to measure the windmill, the other in/out of the controller so you don't double count. It really doesn't change anything. 

*So if you WILL be charging while driving,* then install the traction sensor on the in/out going to the Controller (and DC-DC and any other Pack voltage load). The charger sensor goes on the charger only. This ensures you don't count current twice. You'd also have to disable "driving off while plugged in" (or equivalent) on your BMS master controller and wire such that you trigger Vsource when you're charging and Vload when you're discharging (note: in this case only, you could have both on at the same time).

*If you won't be charging while driving*, it won't really matter where in the pack you put the traction sensor. The charger sensor should still go wires that come only from the charging source. I'd wire so that Vsource and Vload can't come on at the same time (i.e. you won't fault the BMS master controller).



That being said.... not sure if it's a joke or not, so I'll respond technically.... a windmill on a roof hurts your range, and you won't get enough back to warrant running the windmill while driving. Your aero losses for having it on your roof take more to overcome than the windmill would put into the pack (efficiency of the blades, eff of the generator, eff of the inverter are going to exceed any gains you'd get.


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## evmetro (Apr 9, 2012)

Just having fun on the windmill thing...

Are you familiar with the orion connections to the controller and charger? I am on a pretty steep learning curve here... I want to hook the orion to my manzanita pfc 40. I have studied the regbus wiring and the orion wiring, but unclear on what wires connect the two. Same with the controller. The wiring book for the controller lists all kinds of golf carts, but I can't find a wiring diagram of one of thes connected to a manzanita charger or orion bms...


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## frodus (Apr 12, 2008)

Orion Manzanita wiring to Regbus:
http://www.orionbms.com/charger-integration/manzanita-micro/

Here's how Elithion does it, for reference:
http://lithiumate.elithion.com/php/manzanita_micro.php

What controller are you using?? You've talked about several. Is this for the Curtis 1238?

There may not be a wiring diagram for controller, as they're all different and it depends on what you want to integrate.


What I'm doing with my Elithion Pro, Curtis 1238 and DeltaQ charger:
something like this:
http://lithiumate.elithion.com/php/curtis_inverter.php

- The Controller has control of the contactor directly.
- I have a DC-DC that is always on and powering the BMS.
- The ignition is 12V from the DC-DC, and triggers the V+load input to the elithion and the K1 coil positive.
- The LLIM output (sinking) connects the K1 coil negative.
- When the BMS decides that everything is A-OK, it grounds the K1 coil and the K1 relay engages, enabling the controller.
- Once the controller enables, the main contactor closes and you're now in Drive.

The DCL and CCL are connected to the throttle and braking pot, respectively. Once I hit discharge current limit, the Elithion/H11F1 basically cause the throttle to reduce automatically, which slows you down so you don't overdischarge cells (a bit like a rev limiter). Once I hit charge current limit (full pack), the Elithion/H11F1 will do the same to the regen braking pot..... which keeps me from overcharging the fully charged cells if I go down a hill. 

So I am protected from Overdischarge, Overcharge and any BMS faults that might occur.

Here's a little cheat sheet:
Orion requires an always on 12V supply, always on (pin 1).

Source (charger) is on:
Orion: Charge Power, pin 3, input, from a 12V source.
Elithion: V+Source, pin 4, input, from a 12V source

Load (controller) is on:
Orion: Ready Power, pin 2, input, from a 12V source.
Elithion: V+Load, pin 3, input, from a 12V source

Discharge Current Limit:
Orion: Discharge Current Limit, pin 16, output, sourcing a 0-5V
Elithion: DCL, pin 14, output, sourcing a 0-5V

Charge current Limit:
Orion: Charge Current Limit, pin 5, output, sourcing a 0-5V
Elithion: CCL, pin 15, output, sourcing a 0-5V

Discharge Enable:
Orion: Discharge Enable, pin 7, output, sinking (open drain)
Elithion: LLIM, pin 10, output, sinking (open drain)

Charge enable:
Orion: Charge Enable, pin 8, output, sinking (open drain)
Elithion: HLIM, pin 11, output, sinking (open drain)

The Orion also has Charge Safety, which can enable/disable regen (as opposed to using an anlog solution and an H11F1 device). It's your choice.

Both also have an Ignition input. Called Ignition Signal on Orion, and Contactor Request on the Elithion.


Hope that helps a little..... maybe not, but if you have questions, ask here. I've helped a few people with these systems (via forums, email, or paying customers).

Good luck!


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## evmetro (Apr 9, 2012)

Frodus, this info is gold. The 7601 controller should be here next week, but I am wiring up the harness that came with the 6501 controller that I am not using. There are some wires that I am not sure of... I see the wires in the diagram for pot high, pot wiper and pot low, and it sounds like I do not use pot high for my two wire throttle. That leaves pot wiper and pot low for my choices, but I can't tell from the diagram what wire to hook to the white on my throttle and what wire to hook to the black on my throttle... also not sure what to do with the forward and reverse wires- I have a manual tranny that has reverse in it already...


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## frodus (Apr 12, 2008)

evmetro said:


> Frodus, this info is gold. The 7601 controller should be here next week, but I am wiring up the harness that came with the 6501 controller that I am not using. There are some wires that I am not sure of... I see the wires in the diagram for pot high, pot wiper and pot low, and it sounds like I do not use pot high for my two wire throttle. That leaves pot wiper and pot low for my choices, but I can't tell from the diagram what wire to hook to the white on my throttle and what wire to hook to the black on my throttle... also not sure what to do with the forward and reverse wires- I have a manual tranny that has reverse in it already...


The harness for the 6501 and 7601 are the same. Same pinout, so you're good.

For your controller, you have a 2-wire pot. I don't recall what the default setting for the controllers are (I've seen some programmed as 2-wire default, some are programmed as 3 wire). It doesn't matter which way you hook up the 2 wires on your pot to the 2 wires on the controller. One wire from the pot goes to Pot Low, the other wire goes to Pot Wiper. For a 2 wire throttle, you don't use pot high.

You really need to get a Curtis Manual.... it really helps.
I uploaded one for you:
http://www.evfr.net/uploads/curtis1238manual.pdf

Page 14, type 1 throttle. 


If it doesn't work, you'll need to check to see what they're programmed with (Call Evolve). If you can't reprogram it, then you may need to bring out a third wire from your throttle potentiometer (You didn't mention what kind it is) and wire it as a throttle type 2.

Also, you have to tell the controller a direction. Either wire it for FWD, or REV.... just wire it permanently.


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