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Seeking Advice: Use of Model 3 as Trickle Charger for LEAF

SageBrush

REJECT Fascism
May 7, 2015
12,227
15,138
New Mexico
Our LEAF is just sitting around since its normal routine is on hold during Covid and when my wife and I go out we take the Model 3. The LEAF 12v is known to auto discharge without routine driving and I do not have a trickle charger. I could get one, but then I wondered if I could simply connect the Model 3 and LEAF together for a trickle charge overnight. I'm under the impression that my Model 3 (June 2018) will monitor its own 12v and add charge as needed.

Opinions ? Advice ?
 

cypho

Member
Dec 20, 2018
761
897
USA
For a second I thought you are planning to hook an inverter to the 12-volt battery and connect that to the leafs 120v AC charging cable.

It might take a few months but eventually you'd fill the leaf up. ;-)
 

one2many

Member
Aug 16, 2019
572
744
germany
Well my leaf 12v bat died. It was not helped by trickle charge or
any other thing I could do and I do know some tricks.
New battery and it OK for now. Power it up and that should help.
I do not think it is a great idea to use the model 3. buy a trickle charger,
they are cheap.
 
  • Helpful
Reactions: SSedan

cypho

Member
Dec 20, 2018
761
897
USA
Well a charger is about $25 , well lets use a $50k car to do that ?
Agreed.

And by the same logic, a subway ticket will get you to work for $3 so it is not a great idea to use $50k car to get to work either.

You also shouldn't plug your phone into the car to charge either. It would be silly to use a $50k car to charge your phone when you can buy a phone charging battery pack for $25.
 
Last edited:
  • Disagree
Reactions: smatthew

Morhydro

Member
Mar 26, 2020
140
78
Scotland
Set the LEAF to 80% charge maximum and leave it plugged in. It will charge its 12V battery when needed. That is what we are currently doing. The M3 gets charged about once every two weeks (that is enough mileage during lockdown) and the LEAF remains plugged in.
 
  • Helpful
Reactions: SSedan

SageBrush

REJECT Fascism
May 7, 2015
12,227
15,138
New Mexico
Set the LEAF to 80% charge maximum and leave it plugged in. It will charge its 12V battery when needed. That is what we are currently doing. The M3 gets charged about once every two weeks (that is enough mileage during lockdown) and the LEAF remains plugged in.
Perhaps I remember wrong, I thought this is what not to do.

Here is one thread discussing the problem
The 12V battery charging algorithms - My Nissan Leaf Forum
 

Morhydro

Member
Mar 26, 2020
140
78
Scotland
Hi SageBrush - I had not seen that post. But there is something in it; Our Leaf always has the timer set so it is actually only charging at night (usually 2am) as that is the lowest energy cost. This is now our second Leaf and we have never had 12V battery problems. Have been away for up to 7 weeks leaving the Leaf plugged like this.
 

wws

Member
Aug 11, 2014
926
947
Northern California
Could you buy one of those spoilers with the solar cells built in from a wrecked Leaf, and retrofit it to your car? (Of course buying a cheap solar battery tender from Harbor Freight would be a lot less hassle...)
 

JPWhite

Member
Jun 2, 2012
170
161
Hendersonville TN
Our LEAF is just sitting around since its normal routine is on hold during Covid and when my wife and I go out we take the Model 3. The LEAF 12v is known to auto discharge without routine driving and I do not have a trickle charger. I could get one, but then I wondered if I could simply connect the Model 3 and LEAF together for a trickle charge overnight. I'm under the impression that my Model 3 (June 2018) will monitor its own 12v and add charge as needed.

Opinions ? Advice ?
The LEAF 12v battery will not self discharge as long as the LEAF is *not* plugged in. Its a known defect of the LEAF BMS that it won't top off the 12v battery if the car is left plugged in. Simply unplug the LEAF and it will maintain the 12v battery just fine. The LEAF has almost non existent vampire drain, so it can be left unplugged for extended periods of time.
 
  • Informative
Reactions: SageBrush

SageBrush

REJECT Fascism
May 7, 2015
12,227
15,138
New Mexico
Hi SageBrush - I had not seen that post. But there is something in it; Our Leaf always has the timer set so it is actually only charging at night (usually 2am) as that is the lowest energy cost. This is now our second Leaf and we have never had 12V battery problems. Have been away for up to 7 weeks leaving the Leaf plugged like this.
See JP White's post below
 

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