Cabin heater charger

 

2017 F31 320dA -drained battery

Got this famous warning one chilly morning arriving at work.

Not yet dead.

After i got the message the first time i Took a 2h drive on the countryside to recharge it a little, but SLA batterys do not charge well in -15°

The second time I got it I took a 1.5h trip and decided to do something about it instead of just aimlessly driving around

Worth noting is that the current world state has me working mostly from home resulting in a car trip or two a week or less.

 

In the garage -charge the battery

This is a day or two after the second
recharge drive

First of all, determine how empty.

25Ah~ish pushed back into battery.

 

In the garage -Can I add a charger?

Tore down the passengerside footwell glovebox panel, underneath on the firewall there is only a Termini® plug

The car does not have Schuko sockets...

I do not want to churn up $170 for a "proper" inline charger for Defa
engine/cab heater systems.

Lets do something stupid instead ; P

Step 1 - Add direct line to battery

Where to reach battery without digging out the compartment?
There are fuses conviniently located in the trunk, need to find
B+ live one.

Locked the car by tricking the latches and waited 24h, now measuring time.

Found one, lets see if it is bad to temporarily remove.

Fuse 161 -Headligt unit, ok to proceed i guess.

Lets add a blade fuse adapter

States 30A (yeah right)
Im not gonna exceed 4A

2.5mm² x2 red black 12/24V

2.5mm²-red black -crimped and shrinked

Connect the wires, not adding the fuse yet

GND, Forgot to take proper picture

B+ -Blade adapter installed, no fuse yet

 

Im gonna use XT60 connector

Looks good

Step 2 - Add outlet to car (230V AC)

Where to leech wall outlet?
There are no Termini® splitters to repurpose...
-Guess it's time to mod the cabin heater.

Lets add EU plug to DEFA 1400

PCB in unit, lets look closer

Added routings, soldered, "strain relieved"

Charger connected

Fuse installed (red 10A)

Modded car battery charger (link) can now be connected

First test, It's working : )

Charging nicely

Charger hidden under passenger seat, EU socket/cable hidden under footwell panel, cable routed to fuse hidden in trim panels. No visible installation.

 

-20220210

-20231210

Status Update, all works fine, car starts effortlessly @ -24°C or -11°F