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

[SageBrush]

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 ?

 

[jelloslug]

I don't see why it would not work.

 

[cypho]

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]

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.

 

[SageBrush]

I do not think it is a great idea to use the model 3

Why ?

 

[one2many]

Well a charger is about $25 , well lets use a $50k car to do that ?

 

[cypho]

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.

 

[Casmium]

Coleman 2 Watt, 12-Volt Solar Battery Maintainer | Walmart Canada

 

[Akikiki]

Please come back and tell us what you did.

 

[smatthew]

https://www.amazon.com/Automatic-Trickle-Battery-Charger-1000mA/dp/B074Z2NFWW

You will hurt the life of the 12v battery in your Tesla if you attempt to do what you are proposing. Teslas have a TINY 12V battery. Spend $20 and do it the right way

 

[NathanielHrnblwr]

Model 3's have been known to flag unexpected 12v draws. Buy a charger for $20.

 

[Morhydro]

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.

 

[HyperionMark]

@SageBrush Gen1 or Gen2 Leaf?

 

[SageBrush]

@SageBrush Gen1 or Gen2 Leaf?

Gen1 -- 2013 'S' Model

 

[Gumball]

You WILL kill your 12V battery in the M3 by doing that.

 

[SageBrush]

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]

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]

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]

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.

 

[SageBrush]

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