justint
Posts: 1
Joined: Sun Nov 15, 2020 1:33 am
Delivery Date: 15 Nov 2020

Car alarm goes off when charging timer starts

Sun Nov 15, 2020 1:38 am

I have a 2011 leaf, and frequently the car alarm goes when the charging timer starts. It doesn't happen everytime and so was replicated at the dealership, and they therefore said they couldn't fix it. Has anyone else had this problem. When it happens, i can deactivate the alarm with the fob but because i charge overnight it is very annoying and is annoying my neighbours. Thanks

LeftieBiker
Moderator
Posts: 16152
Joined: Wed May 22, 2013 3:17 am
Delivery Date: 30 Apr 2018
Location: Upstate New York, US

Re: Car alarm goes off when charging timer starts

Sun Nov 15, 2020 5:17 am

I composed a longish post, and a site error ate it. Short version: check the rest voltage (car off for 30 minutes, doors closed, hood open) of the 12 volt battery. If that is dying then the voltage drop when charging starts may be triggering a sensor in the alarm that warns if the power is cut. If it's below 12.3 volts, recharge the 12 volt battery externally. If the battery is 4+ years old, replace it, and charge the new one fully before installation. Good luck.
Scarlet Ember 2018 Leaf SL W/ Pro Pilot
2009 Vectrix VX-1 W/18 Leaf modules, & 3 EZIP E-bicycles.
BAFX OBDII Dongle
PLEASE don't PM me with Leaf questions. Just post in the topic that seems most appropriate.

GerryAZ
Gold Member
Posts: 2764
Joined: Mon Nov 22, 2010 6:47 pm
Delivery Date: 12 Jun 2011
Location: Phoenix, AZ

Re: Car alarm goes off when charging timer starts

Sun Nov 15, 2020 7:18 am

Is it the factory alarm that just flashes the lights and beeps the horn or a more elaborate aftermarket system? The factory alarm will activate when the 12V battery voltage recovers after dropping below a low-voltage threshold so it could be triggered when charging starts and the DC-DC converter starts charging the 12V battery (if 12V battery is weak). Aftermarket systems could be sensitive to electrical transients caused by the main contactor closing and charging current ramping up if their sensors, wiring, and control modules are not properly shielded.
Gerry
Silver LEAF 2011 SL rear ended (totaled) by in-attentive driver 1/4/2015 at 50,422 miles
Silver LEAF 2015 SL purchased 2/7/2015; traded 8/10/2019 at 82,436 miles
White LEAF 2019 SL Plus purchased 8/10/2019

LeftieBiker
Moderator
Posts: 16152
Joined: Wed May 22, 2013 3:17 am
Delivery Date: 30 Apr 2018
Location: Upstate New York, US

Re: Car alarm goes off when charging timer starts

Sun Nov 15, 2020 1:30 pm

If it is, as Gerry suggests, an overly-sensitive alarm (and you can't adjust the sensitivity) then an AGM or "marine" type 12 volt battery might solve the problem. Or, conversely, a starting type battery with a higher CCA rating than the OEM might experience less of a voltage drop when the contactors close. In any event, the battery size/configuration is 51R.
Scarlet Ember 2018 Leaf SL W/ Pro Pilot
2009 Vectrix VX-1 W/18 Leaf modules, & 3 EZIP E-bicycles.
BAFX OBDII Dongle
PLEASE don't PM me with Leaf questions. Just post in the topic that seems most appropriate.

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