How to DIY - add access holes for LVB 12v battery connection points & HV Disconnect Relay for Safety

[generaltso]

Does anyone know what amperage a jump start requires? Since your not "starting" anything, wouldn't it be just a few amps to trigger a relay?

Good question. I'm not sure anyone has measured it.

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[dtbaker61]

Does anyone know what amperage a jump start requires? Since your not "starting" anything, wouldn't it be just a few amps to trigger a relay?

if the LVB drops to the point you need a 'jump start'.... remember that it is not like a 'jump' where you need high current to turn over a starter motor, and then expecting the alternator to continue to supply 12v once the car is 'running'.

With our vehicles, if the LVB is 'dead' to the point the car won't run.... it could be the module that maintains the LVB charge is not sending HV energy to maintain the LVB. Meaning that a few amps for a minute might give you enough energy to pop the hood and/or start the MME..... but unless you have the charge on for long enough to get a fair bit of energy into the LVB, it would likely just die again unless the HV module wakes up to maintain the LVB.

This is why a tiny 'jump' battery hidden in the frunk or whatever is not a great solution. It might pop the trunk, but not have enough energy to transfer to the LVB to run for very long if the dc-dc module is bad and not sending energy from the HV. Presumably, if you are 'getting a jump', it's from an external vehicle that can run jumpers to the external port to pop the hood, and then hook up to the connection points for a good 20-30 minutes to get a fair amount of energy into the LVB.

If you are getting a 'jump' from an external vehicle.... you should probably plan on wiring capable of carrying 40-60amps to the LVB connectin points.... which is about what you'll gt thru jumper cables connected to an external vehicle running at 14-15 volts.

 

[New2EV]

if the LVB drops to the point you need a 'jump start'.... remember that it is not like a 'jump' where you need high current to turn over a starter motor, and then expecting the alternator to continue to supply 12v once the car is 'running'.

With our vehicles, if the LVB is 'dead' to the point the car won't run.... it could be the module that maintains the LVB charge is not sending HV energy to maintain the LVB. Meaning that a few amps for a minute might give you enough energy to pop the hood and/or start the MME..... but unless you have the charge on for long enough to get a fair bit of energy into the LVB, it would likely just die again unless the HV module wakes up to maintain the LVB.

This is why a tiny 'jump' battery hidden in the frunk or whatever is not a great solution. It might pop the trunk, but not have enough energy to transfer to the LVB to run for very long if the dc-dc module is bad and not sending energy from the HV. Presumably, if you are 'getting a jump', it's from an external vehicle that can run jumpers to the external port to pop the hood, and then hook up to the connection points for a good 20-30 minutes to get a fair amount of energy into the LVB.

If you are getting a 'jump' from an external vehicle.... you should probably plan on wiring capable of carrying 40-60amps to the LVB connectin points.... which is about what you'll gt thru jumper cables connected to an external vehicle running at 14-15 volts.

I guess I was assuming just a bad battery...not a bad dc-dc module. The FL sun has a way of destroying batteries. But I see your point that the reason why the LVB is low would potentially impact the amperage needed to jump start the car.

 

[dtbaker61]

I guess I was assuming just a bad battery...not a bad dc-dc module. The FL sun has a way of destroying batteries. But I see your point that the reason why the LVB is low would potentially impact the amperage needed to jump start the car.

....exactly....
not just 'start' the car, but to keep it running until you figure out whether its a bad battery, or bad charging....

 

[kennethjk]

All this is hurting my head, I just want it to work, how many electrical engineers does ford have

please Ford get the little battery to work all the time

 

[louibluey]

if the LVB drops to the point you need a 'jump start'.... remember that it is not like a 'jump' where you need high current to turn over a starter motor, and then expecting the alternator to continue to supply 12v once the car is 'running'.

With our vehicles, if the LVB is 'dead' to the point the car won't run.... it could be the module that maintains the LVB charge is not sending HV energy to maintain the LVB. Meaning that a few amps for a minute might give you enough energy to pop the hood and/or start the MME..... but unless you have the charge on for long enough to get a fair bit of energy into the LVB, it would likely just die again unless the HV module wakes up to maintain the LVB.

This is why a tiny 'jump' battery hidden in the frunk or whatever is not a great solution. It might pop the trunk, but not have enough energy to transfer to the LVB to run for very long if the dc-dc module is bad and not sending energy from the HV. Presumably, if you are 'getting a jump', it's from an external vehicle that can run jumpers to the external port to pop the hood, and then hook up to the connection points for a good 20-30 minutes to get a fair amount of energy into the LVB.

If you are getting a 'jump' from an external vehicle.... you should probably plan on wiring capable of carrying 40-60amps to the LVB connectin points.... which is about what you'll gt thru jumper cables connected to an external vehicle running at 14-15 volts.

I doubt this is a problem unless the LVB is so low, it is really dead (we have heard a couple of GT stories like that). Otherwise, once the DC/DC converter comes on, there is a good slug of energy to the LVB which should keep MME on. My guess is, 95%+ of the time, a standard jump pack will work fine, and off you go!

 

[mmap]

iWith our vehicles, if the LVB is 'dead' to the point the car won't run.... it could be the module that maintains the LVB charge is not sending HV energy to maintain the LVB. Meaning that a few amps for a minute might give you enough energy to pop the hood and/or start the MME..... but unless you have the charge on for long enough to get a fair bit of energy into the LVB, it would likely just die again unless the HV module wakes up to maintain the LVB.

This is equivalent to saying that jumping an ICE car won't work if both the battery and alternator are dead. That might be true, but no one ever worries about that kind of ''double failure' scenario.

 

[StrWhtMME]

Great instructions. Thanks for the measurements. But you only need the positive terminal access, as it is recommended that you use other ground , not battery for negative connection. Just a thought.

 

[generaltso]

Great instructions. Thanks for the measurements. But you only need the positive terminal access, as it is recommended that you use other ground , not battery for negative connection. Just a thought.

The negative jump point below the hole is not the battery (the positive isn’t either).

 

[dtbaker61]

This is equivalent to saying that jumping an ICE car won't work if both the battery and alternator are dead. That might be true, but no one ever worries about that kind of ''double failure' scenario.

no one driving an ICE vehicle would suspect a bad alternator, but
with a BEV, you have to think about different things..... Like what's the most probably cause for the LVB going dead in the first place.

probably NOT because you left the door ajar overnight.
much more likely that the dcdc or the HV to LVB module is bad, or failed to wake up.
This is why a 'quick jump' in a BEV is unlikely to be a solution.

 

[StrWhtMME]

The negative jump point below the hole is not the battery (the positive isn’t either).

Thanks, I have not removed the shields yet. Hope to do this modification in the future. Thanks again

 

[kennethjk]

I am wondering is this would cause any issues And can be used in the MME

I have a CTEK maintainer. I also have a connector that can attach directly to the battery + and - posts, and I snap in the lead to the CTEK when I don’t drive my car for weeks at a time.

I would only have to drill one small small hole in the frunk cover and when I don’t drive the car I can just snap in the lead to maintain the battery.

As someone pointed out this doesn’t help me “jump start” the 12V battery if needed but it should help to reduce the need to jump the battery and I think eliminate the possibility of the frunk not opening.

any thoughts?

thanks

 

[ChasingCoral]

I am wondering is this would cause any issues And can be used in the MME

I have a CTEK maintainer. I also have a connector that can attach directly to the battery + and - posts, and I snap in the lead to the CTEK when I don’t drive my car for weeks at a time.

I would only have to drill one small small hole in the frunk cover and when I don’t drive the car I can just snap in the lead to maintain the battery.

As someone pointed out this doesn’t help me “jump start” the 12V battery if needed but it should help to reduce the need to jump the battery and I think eliminate the possibility of the frunk not opening.

any thoughts?

thanks

You might not even need to drill. Depending on the length you could probably pass the cord between the panels.

 

[ZuleMME]

You might not even need to drill. Depending on the length you could probably pass the cord between the panels.

Little dangerous there unless it's fused on the battery connection (it should be). Otherwise if the panels cut through and it shorts... I knew a guy that installed a subwoofer and fused near the sub instead of at the battery. It was bad. Lot's of smoke and battery acid everywhere.

 

[kennethjk]

You might not even need to drill. Depending on the length you could probably pass the cord between the panels.

True, more important I just don’t want to screw up any electronics, I don’t see why that would happen by attaching cable to the battery posts themselves but I am not an expert in this area by any means.

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