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

[MTNestr]

Could someone kindly post a picture of jumper cables (or battery tender wire) attached to the battery? Also, if I were to use a battery tender can I have it on for a long period of time when I’m away from home? Do I need to disconnect any of the other cables attached to the LVB? When jump starting do I need to remove the cables that are normally attached to the LVB?

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[Finkerton]

yes, sorta.
everything I can find indicates dc-dc is capable of sending about 150-160 amps from traction pack to 'run stuff' and charge LBV at the same time basically as a parallel, until LVB tells HV it is full. HV->dc-dc stops sending juice, and runs off LVB until LVB asks for recharge.... or something like that.

so..... for extended external loads, if HV, dc-dc, LVB are all working correctly we *should* be able to run external loads averaging up to 150 amps (2000 watts) and the whole system should be able to keep up.

Thanks so much for posting this thread!

I assume this should apply to the 12V accessory sockets too? I've bookmarked this thread for if/when I need to gain access to the battery terminals (although the most likely reason is to jump start my other car, a 16 year old ICE).

However, I'd really like to run a load off the accessory sockets. There are two 20A fuses, one for each socket, so it suggests I can safely draw about 2A 120V AC power via an inverter on the power socket in terms of the fuses/wiring.

From what you wrote above I assume that you think that any load on the LVB, whether directly on the terminal or via accessory socket, will end up calling for the HVB to charge it if the 12V is getting low. That would be great if so...and if so, any known caveats (e.g. does the car need to have power on, or does this part of the electrical system always function so that you don't need to worry about a tender if you aren't driving for a while?)

 

[dtbaker61]

Could someone kindly post a picture of jumper cables (or battery tender wire) attached to the battery? Also, if I were to use a battery tender can I have it on for a long period of time when I’m away from home? Do I need to disconnect any of the other cables attached to the LVB? When jump starting do I need to remove the cables that are normally attached to the LVB?

you

Thanks so much for posting this thread!

I assume this should apply to the 12V accessory sockets too?

However, I'd really like to run a load off the accessory sockets. There are two 20A fuses, one for each socket, so it suggests I can safely draw about 2A 120V AC power via an inverter on the power socket in terms of the fuses/wiring.

yes, I'd guess there is about a 200watt limit drawing power from the 'cigarette' sockets if they are fused at 20a x 12vDC. This will be enough to run a laptop, or the tire air compressor.

I want to run larger loads if needed.... like 2000 watts, so I need good access to the LVB connection points, and MUCH heavier wires to potentially carry 150amps x 12vDC

From what you wrote above I assume that you think that any load on the LVB, whether directly on the terminal or via accessory socket, will end up calling for the HVB to charge it if the 12V is getting low. That would be great if so...and if so, any known caveats (e.g. does the car need to have power on, or does this part of the electrical system always function so that you don't need to worry about a tender if you aren't driving for a while?)

The hope is that if the HV->dc-dc->LVB are all working correctly, the HV will automatically charge the LVB when needed. The LVB won't 'know' that the energy is being exported rather than used by the MME for cabin heat or whatever, and should request a charge and/or 'wake up' the dc-dc from the HV if it senses a high continuous load. The dc-dc should handle up to 150-160amps from everything I've read so far...

 

[Finkerton]

The hope is that if the HV->dc-dc->LVB are all working correctly, the HV will automatically charge the LVB when needed. The LVB won't 'know' that the energy is being exported rather than used by the MME for cabin heat or whatever, and should request a charge and/or 'wake up' the dc-dc from the HV if it senses a high continuous load. The dc-dc should handle up to 150-160amps from everything I've read so far...

Hey, noticed something in the manual...

Your vehicle has a high voltage to low voltage energy transfer feature that keeps the 12 volt battery charged by the high voltage battery. If the 12 volt battery level is low, the high voltage battery transfers energy to the 12 volt battery when the vehicle is off.​

I have actually not yet tried to see if the accessory sockets are active when the car is off -- they aren't on most cars. So probably for those to be active, the car needs to be powered on. But I wonder if this statement means that it _doesn't_ charge the 12V battery when the vehicle is on, or if it _also_ charges the 12V battery when the vehicle is off.

It would seem kind of insane for it to not charge the 12V battery when it's powered on if the 12V gets low. But it might also be that it simply handles the accessory sockets and other low voltage needs straight from the HV->LV converter when it's powered on and doesn't even drain the battery at all.

 

[Fat Mach]

mmmmm, crimper results better than solder. Just my opinion, but in the EV world under heavy (1000 amp loads), proper crimps hold up better and more dependable over time.

Agreed. But if you don't have a nice set of crimpers for that size cable, soldering works JUST FINE.

 

[Finkerton]

At this point I've drawn near 20A from both accessory sockets simultaneously for about 3 hours with no problem.

Curious if anyone has done the direct battery post clamp with much higher loads. I don't need that yet but would be good to understand if it's an option. Ioniq 5 V2L has me a little jealous :-D

 

[dtbaker61]

At this point I've drawn near 20A from both accessory sockets simultaneously for about 3 hours with no problem.

Curious if anyone has done the direct battery post clamp with much higher loads. I don't need that yet but would be good to understand if it's an option. Ioniq 5 V2L has me a little jealous :-D

I am pretty sure we can draw 160a at 12v = 2000 watts ish
... bit have not verified

 

[greenaero]

I did a little exploring under the panels in the Frunk, and decided to modify the panel covering the LVB terminal connection points... used for jump starting a dead, trickle charging or adding a heating blanket, or connecting an external load such as an inverter for 'external loads' when Camping or supplying (up to 2000 watts) AC power where ever needed.

The Frunk 'surround panels', are kind of a pain to snap off, and you are likely to break the connection snaps, or even the panel itself over time as it gets brittle with age, or in the cold.... I'd hate the idea of try to get access to the LVB if it dies outside some dark snowy cold night!

The simplest solution is to use a hole saw to make big enough holes to grab the approved Connection Points with jumper cables, and get some hole plugs if you really want to cover when not in use. This procedure takes literally no more than 5 minutes, and you won't have to pop the panels off to give, or get, a 12v 'jump'

View attachment 19132

https://www.amazon.com/gp/product/B00MN6GQE8/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

View attachment 20939

Great work @atbaker67! Many thanks! Grabbing my drill right now.

 

[dtbaker61]

Great work @dtbaker61! Many thanks! Grabbing my drill right now.

I'm probably going to make a larger 'hatch' when I get started on my more invasive 'Internal Inverter', but the holes are big enough for jumper cables in a pinch.

I am still hunting around for better understanding of what the current limitations of the dc-dc charger from the HV to keep the 12v running.... not timing out, re-charging from HV as needed, etc.

 

[greenaero]

I made the access holes yesterday. Thanks again @dtbaker61 for pioneering this mod and sharing it. You are the man!

 

[ProximusAl]

So I use GFDRS a reasonable amount on my Mach-E so it's a proper pain in the butt removing the panels to access the 12V to put the battery maintainer on whilst programming modules.

Seeing this article, I'm like yep, so I've done it, but I've done it slightly differently.

I made a cardboard template, based on the two plug holes to the left of each connector when the cover is removed, which allows me to exactly dead centre both +ve and -ve pins.

So my word of warnings for anyone thinking of doing this....

If you DO exactly dead centre the hole over the -ve, you will expose the crossbar, so best not to or your plug wont fit in.
I chose to drill slightly left of my pilot hole to avoid the crossbar, but did not think for one minute about the top back cover.
As you can see on my hole, it's extremely close, but luckily I can gently lift the top cover so it will sit on my hole plug.

So the key things for me on the -ve pole, find dead centre, and drill slightly left, and slightly down.

On the +ve pole, if you hit dead centre, your hole saw will cut into the depression in the plastic where it slopes down to the screen wash.
I chose to drill up just enough to not chop into that part.
Also be wary of the slight hump over towards the bonnet (or hood) stopper.

All in all took me nearer 20 minutes to do mine, but I wanted it to be as good as it could be.

HTH

 

[dtbaker61]

So I use GFDRS a reasonable amount on my Mach-E so it's a proper pain in the butt removing the panels to access the 12V to put the battery maintainer on whilst programming modules.

Seeing this article, I'm like yep, so I've done it, but I've done it slightly differently.

I made a cardboard template, based on the two plug holes to the left of each connector when the cover is removed, which allows me to exactly dead centre both +ve and -ve pins.

So my word of warnings for anyone thinking of doing this....

If you DO exactly dead centre the hole over the -ve, you will expose the crossbar, so best not to or your plug wont fit in.
I chose to drill slightly left of my pilot hole to avoid the crossbar, but did not think for one minute about the top back cover.
As you can see on my hole, it's extremely close, but luckily I can gently lift the top cover so it will sit on my hole plug.

So the key things for me on the -ve pole, find dead centre, and drill slightly left, and slightly down.

On the +ve pole, if you hit dead centre, your hole saw will cut into the depression in the plastic where it slopes down to the screen wash.
I chose to drill up just enough to not chop into that part.
Also be wary of the slight hump over towards the bonnet (or hood) stopper.

All in all took me nearer 20 minutes to do mine, but I wanted it to be as good as it could be.

HTH

good shooting

I bought a bag of plugs, and have about 18 left over. PM me if you want me to mail you a couple for a couple bux+postage.

actually, I just noticed you are UK, so you can get them cheaper local.... just look for 50mm electrical 'plugs'

 

[dtbaker61]

Could someone kindly post a picture of jumper cables (or battery tender wire) attached to the battery?

do not attach jumpers directly to battery terminals, use the designated 'connection points' under the side cover.

Also, if I were to use a battery tender can I have it on for a long period of time when I’m away from home?

should not be needed for MANY months. The HV battery is designed to periodically wake up and maintain the LV if needed.

Do I need to disconnect any of the other cables attached to the LVB?

no

When jump starting do I need to remove the cables that are normally attached to the LVB?

no

 

[ProximusAl]

good shooting

I bought a bag of plugs, and have about 18 left over. PM me if you want me to mail you a couple for a couple bux+postage.

actually, I just noticed you are UK, so you can get them cheaper local.... just look for 50mm electrical 'plugs'

Yeah thanks. I ordered some from Amazon Uk and then found out they are coming from China….but hey ho, they are coming.

Thanks again for posting this originally. Really helpful indeed.

I’ve even label printed exactly the same as you!

 

[EELinneman]

I did a little exploring under the panels in the Frunk, and decided to modify the panel covering the LVB terminal connection points... used for jump starting a dead, trickle charging or adding a heating blanket, or connecting an external load such as an inverter for 'external loads' when Camping or supplying (up to 2000 watts) AC power where ever needed.

The Frunk 'surround panels', are kind of a pain to snap off, and you are likely to break the connection snaps, or even the panel itself over time as it gets brittle with age, or in the cold.... I'd hate the idea of try to get access to the LVB if it dies outside some dark snowy cold night!

The simplest solution is to use a hole saw to make big enough holes to grab the approved Connection Points with jumper cables, and get some hole plugs if you really want to cover when not in use. This procedure takes literally no more than 5 minutes, and you won't have to pop the panels off to give, or get, a 12v 'jump'

View attachment 19132

https://www.amazon.com/gp/product/B00MN6GQE8/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

View attachment 20939

Could you not use the wires provided in the bumper cover on the passenger side. I don't have my car yet, so am working from memory but understand that these are there to provide an external 12v option if the LVB is dead.