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Discussion Starter #1 (Edited)
Hi all,

I am looking at using compression t-taps to tie into the main 300-400v battery line (from main battery to the inverter subsystem, part 68104794AI). I've seen this done with leafs to add battery capacity via secondary battery. My main question is, if I tie into this line and I use the voltage for reasons outside of the main inverter unit, will the ECU sense the load and freak out?

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Thanks,

Marius
 

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I'm not sure exactly where this tap is, in relation to the battery and contactor.

If it's before the contactor then you're probably OK pulling power from it, THOUGH you'll want your own contactor, AND you won't have the battery discharge protections that the OEM system has.

If it's after the contactor then the system might get annoyed. I believe there's a current measuring resistor in the contactor assembly. and if the system isn't trying to draw current and current is being drawn then it may do unexpected things, or throw codes.
 

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Discussion Starter #5 (Edited)
This tap would be after the main safety breaker but before the main power inverter module contactor (which feeds power to 12v subsystem and traction motor). The main safety breaker is the high voltage safety shutoff which is located below the rear passenger seat (if it gets disconnected, the entire battery is disabled. It is a 350 amp breaker), the contactor is built into the power inverter module and feeds the rest of the HV system.

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So the theory is, all of the battery safety mechanisms are still in play and the entire circuit is still limited to 350a draw max. At 300v, that's 105,000 watts, at 400v, that's 140,000 watts. Since the motor draws 82,000 watts max at WOT, I figure I have a safe room of 20,000-50,000 watts available in reserve to use. I'm looking to pull 20k-25k watts or so max.
 

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This tap would be after the main safety breaker but before the main power inverter module contactor (which feeds power to 12v subsystem and traction motor). The main safety breaker is the high voltage safety shutoff which is located below the rear passenger seat (if it gets disconnected, the entire battery is disabled. It is a 350 amp breaker), the contactor is built into the power inverter module and feeds the rest of the HV system.

View attachment 108135


So the theory is, all of the battery safety mechanisms are still in play and the entire circuit is still limited to 350a draw max. At 300v, that's 105,000 watts, at 400v, that's 140,000 watts. Since the motor draws 82,000 watts max at WOT, I figure I have a safe room of 20,000-50,000 watts available in reserve to use. I'm looking to pull 20k-25k watts or so max.
I’ve no idea how to answer your question but curious to know what you’re trying to do. Also note that neither inverter nor motor are perfectly efficient so the battery could see a larger than 83kw draw. Good luck!
 

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Discussion Starter #7
I'm dropping in a 100,000 watt amplifier for my sound system so I don't have to go down to 12v then up to 400v. Much more efficient this way.
 

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There are two main contactors. 1 positive and 1 for the negative they are both in the HV battery with the precharge relay. There are no contactors in the inverter. The 350amp fuse splits the battery in half.
 

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There are no contactors in the inverter module. There are 3 contactors in the HV battery box. 1 for the positive terminal, 1 for the negative terminal and 1 for the precharge system. The 350amp fuse splits the battery in half.
 

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Discussion Starter #13
Also, I understand that the battery is not live unless the key is in ignition and turned on. Can anyone confirm this?
 

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Also, I understand that the battery is not live unless the key is in ignition and turned on. Can anyone confirm this?
Good question. I know you hear the HV contactors when:
1) Actively charging.
2) When the driver's side door is opened.
3) When the key is in the ignition and turned on.
4) Possibly every few weeks while in storage and the EVSE is plugged in.
5) Possibly other events?
 

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Also, I understand that the battery is not live unless the key is in ignition and turned on. Can anyone confirm this?
Found ya.
Did you confirm with your setup that you only see voltage when the key is on?

I am still trying to figure this out, but the PDC I was thinking about tapping into, apparently looks like it goes to the HV Air Electric Heater. Not sure what those fuses are rated at in the PDC, but according to this breakout it looks like the PDC is fed directly off the HV battery harness. (#13)
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I would need to find a used (#12) High Voltage Air Electric Heater to PDC, PN 68105716AE
and (#14) PDC, PN 68105117AD to make a T-harness.

Thoughts?
 

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Discussion Starter #16 (Edited)
When you turn the key on you can hear the contactors connect. I can confirm they actually cut the voltage when they turn of a few seconds after the key is removed. Also, if you have alphaobd on your phone, you can force the contactors open/closed whenever you want.

Also, I am not sure what the heater line amperage capacity is, but it may work. It looks like a small line, depends how much load you want to draw. I imagine the heater doesn't pull many amps though. Also, make sure to use a thermistor or other mechanism to limit inrush current, this battery can easily do 10c- I blew the 350 amp fuse (over 140,000 watts)

For those new here, I am successfully pulling over 100,000 watts by tapping into the main harness.

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It looks like there is some sort of relay possibly in the PDC. If that is the case and it is used strictly to turn on the heater, I could just disconnect the heater(live in the South where it is warm 90% of the year) and make a spare plug and play harness to run to circuit breaker. It looks like maybe 8 gauge parallel wires. Need to find out what those PDC fuses are rated for. I have some tinkering/testing to do.

I'm only looking to use as a backup power source during emergency power outage, so 4,000-5,000 watts max.
109091
 

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I pulled the cover off the PDC. There are some nice convenient HV battery test points underneath.
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Energized when I open the driver side door. Cut off after a few minutes with no key in and door closed. Voltage remained steady in the accessory and Ready position with key inserted.
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Can confirm residual voltage remains, once HV battery contact opens. Takes about 10min to fully drain/bleed off completely.
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There is a screw and one clip it appears to pull the orange cover off to access the fuses below, but I'm not 100% sure. So I stopped there for now. Need a manual or something to confirm.
 
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