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Old 09-22-2018, 09:58 PM   #11
ag4ever
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Default Re: Lithium Battery Conversion - LV & HV control relay wiring

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I did not notice that relay was not in stock, You can also get it from other sources:
https://www.newark.com/schneider-ele...30a/dp/32C2652
The one You linked would NOT work, it needs to have a N.C. contact.

Most AVR type MCU will have a very low current (much less than 1 micro amp) sleep/idle mode that detects a level change interrupt in order to to wake up, so Yes, the BMS will still detect the negative level being removed from the "sleep" pin when the K4 relay closes and wake up.

DaveTM, those diodes are oriented properly since current is flowing from each relay (positive) to the LV+HV path to the pack negative.
This is the line voltage relay, not the sleep relay. Am I mistaken in thinking the only one that needs NC is the sleep one? The rest are NO and provide closed circuits when the conditions are right?

I would not be surprised if I bought the wrong thing. Spent way too much time looking at specs while watching my aggies get beaten up. Grrrrrr Bama!
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Old 09-22-2018, 10:06 PM   #12
ag4ever
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Default Re: Lithium Battery Conversion - LV & HV control relay wiring

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Sergio, when I look at the diode placement on D3 and D4, (from the ZEVA LV) you have the diodes placed that no voltage from the LV can pass up. So....from my understanding is that the ZEVA can't do what it's suppose to do.

Since no current is going past the diodes D3 & D4, how can the BMS properly function?
I had the same thought at first, but when you trace the flow of power from + to - you can see it is all correct. Keep in mind the relays at the BMS control ground path, not necessarily power supply.

Best thing to do so you can understand how the current flows is print a copy, grab a highlighter, and trace the circuit from + to -. Be sure to only trace where the power can go, if you hit a diode, be sure you are tracing in the correct direction. After you do that it will help you understand the circuit and how they interrelate to one another. Might even use a different color for the coil activation circuits so you can “dry run simulate” it working.
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Old 09-22-2018, 10:12 PM   #13
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Default Re: Lithium Battery Conversion - LV & HV control relay wiring

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Originally Posted by ag4ever View Post
This is the line voltage relay, not the sleep relay. Am I mistaken in thinking the only one that needs NC is the sleep one? The rest are NO and provide closed circuits when the conditions are right?

I would not be surprised if I bought the wrong thing. Spent way too much time looking at specs while watching my aggies get beaten up. Grrrrrr Bama!
That is right, you just need a N.O. contact, I was thinking of another thread....
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Old 09-22-2018, 10:14 PM   #14
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Default Re: Lithium Battery Conversion - LV & HV control relay wiring

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Might even use a different color for the coil activation circuits so you can “dry run simulate” it working.
Good suggestion. I will do that.....only because I just gotta see it in a diagram. Maybe it goes back to my kindergarten days of "show me....don't tell me."
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Old 09-22-2018, 10:20 PM   #15
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Default Re: Lithium Battery Conversion - LV & HV control relay wiring

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The one You linked would NOT work.
Well, shucks (thinking stronger language, but trying to keep it PG).

Just noticed the one I bought is only rated at 30A @ 30 VDC on the contacts. Even though it is not seeing much current triggering the coil of it’s sister relay, don’t care to risk running almost 60 VDC through it.

Now I am really stumped, the 9AS5A52-120 relay is rated 30A @ 28 VDC.
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Old 09-23-2018, 07:38 AM   #16
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Default Re: Lithium Battery Conversion - LV & HV control relay wiring

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Well, shucks (thinking stronger language, but trying to keep it PG).

Just noticed the one I bought is only rated at 30A @ 30 VDC on the contacts. Even though it is not seeing much current triggering the coil of it’s sister relay, don’t care to risk running almost 60 VDC through it.

Now I am really stumped, the 9AS5A52-120 relay is rated 30A @ 28 VDC.
My original comment was a mistake, the only relay that needs to have a N.C. contact is the one connected to the sleep pin.

Switching AC current is easier since the signal crosses the 0v mark 120 times in a second so any arc formed as the relay contacts start to open quickly get extinguished.

Since DC currents stay at the same level, switching high DC currents has a tendency to wear out the contacts faster as it takes longer for any arc that is formed to extinguish.

We are talking about small loads for these applications, even for the KSI switch the current will be much less than the relay rating.

You could always have a spare relay mounted and ready to be switched, or just a spare ATO/ATC blade fuse can be used to jump the 1/4" quick terminals that used to go to a dead relay.

If the "auto sleep" relay were to go bad, You just need to unplug either 1/4" quick connect from the relay to prevent the BMS from shutting down.
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Old 09-23-2018, 02:37 PM   #17
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Default Re: Lithium Battery Conversion - LV & HV control relay wiring

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Sergio, when I look at the diode placement on D3 and D4, (from the ZEVA LV) you have the diodes placed that no voltage from the LV can pass up. So....from my understanding is that the ZEVA can't do what it's suppose to do.

Since no current is going past the diodes D3 & D4, how can the BMS properly function?
Ok....I did as AG4ever suggested, and traced the power flow on your diagram. I now understand that the HV "circuit" will only be on when the charger is doing it's re-charge thing. Once the charger is no longer "spitting out" power, the entire HV circuit will close down.

One question on the HV circuit is: Should there be one more diode on K3 coil circuit?

Two general questions: #1-Your diagram doesn't show it, but I assume the charger negative output goes to the battery pack negative pole? #2-I assume that KSI stands for Key Switch Input? This would be the "Hot" side?

And one ZEVA question: I'm a bit confused (Imagine that!) about the actual wiring on the ZEVA. ZEVA shows that section like this:

And I believe your diagram is the same.....but with the LV on the left instead of the HV. But the two that you show are wired the same as the ZEVA diagram? Then the one that you show going to B- is to both the charger neg and battery neg?

Thanks. Dave
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Old 09-23-2018, 04:16 PM   #18
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Default Re: Lithium Battery Conversion - LV & HV control relay wiring

You cannot use a diode on K3 because its coil is being powered by the same 120v AC source as the charger.

The K3 relay will come ON as soon as the AC power cord is plugged to the cart, regardless if the charger is outputting power or not.

The K2 relay will also need the BMS to satisfy both the LV and HV requirements before it will turn ON and allow the charger DC output to be connected to the battery pack.

The BMS can also tell the charger to turn OFF sooner by sending the proper CAN command to the charger.

You should unplug the AC power cord once the charging is complete so all relays turn OFF and the BMS goes to sleep.

All negatives are common and connect to pack negative.

The relay K1 should be the only thing connected to the cold side of the key switch, all other wires that used to be connected to the KSI go to the relay N.O. contact so they only get power if the BMS allows.

I am using the Zeva LV and HV relay outputs different then they used, my design has both wired in series and allows for either condition to shut down the cart and/or stop the charging.

That is definitely important on a Sepex cart where Regen brake current could possibly cause an issue on an individual cell by putting it over voltage.
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Old 09-23-2018, 04:24 PM   #19
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Default Re: Lithium Battery Conversion - LV & HV control relay wiring

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All negatives are common and connect to pack negative.
For clarification and safety, DO NOT confuse DC negative with any AC lines (Line, Neutral, Ground). They should Not be connected.

Also, on the DC side, all negatives are common, but some are routed through the BMS so it can control opening and closing the circuits.

The HV and LV relays are the switched ground paths.
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Old 09-23-2018, 04:33 PM   #20
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Default Re: Lithium Battery Conversion - LV & HV control relay wiring

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You should unplug the AC power cord once the charging is complete so all relays turn OFF and the BMS goes to sleep.
1 hour after charge completion so the BMS can finish post charge balance?

As I understand the Zeva BMS16 will balance while charging and after the charge is complete.
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