Why is everything coming on when hook up charged 12v battery

[floridamiev]

I have had the car for a year, but dont use it much. As a result, the 12v battery goes dead quite often. Took it out and charged it, then put it back in car. Weirdly everything comes on, lights etc, noise, without keys in ignition. Once battery is in and i try to start the car, nothing lights up on the dash and I cannot drive.
Any assistance would be greatly appreciated.

 

[kiev]

Do you have a volt meter, aka digital multi meter DMM or volt ohm meter VOM, with probe leads to measure the battery voltage? Or one of those that plugs in to the cigarette lighter socket?

If so then measure the voltage when the car is sitting OFF, and when the key is turned to ACC and ON positions. Also try to measure when the key is turned to the START position. Let us know what you measure.

 

[floridamiev]

Ok. Will do. Dont have one but will get one.

 

[michael8554]

A 12V battery that has repeatedly been allowed to drain to "dead" may not recharge.

As soon as you connect the "charged" battery onto the car it may briefly power the car and then die.

Do the multi meter tests kiev suggests.

And look after the new battery........ :->

 

[pbui19]

I have one these cheapy solar tender on the dash with the wire running outside directly to the battery under the hood. It seems to really help with the slow drain.

 

[floridamiev]

Do you have a volt meter, aka digital multi meter DMM or volt ohm meter VOM, with probe leads to measure the battery voltage? Or one of those that plugs in to the cigarette lighter socket?

If so then measure the voltage when the car is sitting OFF, and when the key is turned to ACC and ON positions. Also try to measure when the key is turned to the START position. Let us know what you measure.

12.1 before attaching battery

Attached battery then dropped to 4.3 with key in off position. Put into acc and start mode and was 3.1. Attaching battery is draining it.

 

[kiev]

You need to replace that battery, 12.1 V open circuit when OFF indicates it is an old, weak or worn out battery, severely depleted and not able to hold up, as seen when it was connected and dropped to 3-4 V.
Get a fresh battery and fully charge it before putting into service.

The aux/starter battery must be kept fully charged all the time for best service life. If left in a discharged state it will become damaged by sulfation of the plates and degrade capacity and lifetime, as you have experienced.

 

[floridamiev]

Ok. Thank you. Just took battery in as was still under warranty. Will keep a trickle charger on it.

 

[PV1]

So, it appears that the front marker lights, high beams, fog lights, and ABS module all immediately powered up. I've had low and depleted 12 volt batteries on both of my cars numerous times, and the most I've had happen was the alarm go off when power was reconnected. This seems to be more than just a weak 12 volt (which actually looked okay given how bright the lights were despite all that stuff running).

Are there any signs of mouse-damaged wiring, and what does the inside of the fuse box under the hood look like?

 

[jray3]

I like that idea to check for rodent damage, as that certainly is wierd for all the 12V loads to come on as soon as you connect the battery.

As a side question- has anyone logged the DC-DC behavior when the MiEV is left for long periods, both plugged into an EVSE and not? I just found an EV fleet issue where they were leaving LEAFs always connected to commercial EVSE, so that EVery time the car woke up and demanded a topping charge for the 12V, the commercial EVSE would refuse to turn on without an RFID card swipe, so the 12V battery would get drained down to 8V within a week. This fleet was averaging less than two years of service on their LEAF 12V batteries, and had been since 2011! (That's jes the way it is with these dang EVs!)

 

[floridamiev]

So, it appears that the front marker lights, high beams, fog lights, and ABS module all immediately powered up. I've had low and depleted 12 volt batteries on both of my cars numerous times, and the most I've had happen was the alarm go off when power was reconnected. This seems to be more than just a weak 12 volt (which actually looked okay given how bright the lights were despite all that stuff running).

Are there any signs of mouse-damaged wiring, and what does the inside of the fuse box under the hood look like?

So i got a new battery and put it in and now car runs fine, but have these 2 lights on the dash.

 

[floridamiev]

Also, plugged in the car for over 24 hours and it doesnt seem to be charging fully like before.

 

[MickeyS70]

There isn’t much you can do without a diagnostic tool to read out the specific fault codes, see below for suggestions:

https://myimiev.com/threads/testing-and-monitoring-apps-and-tools-and-scanners.4950/

 

[floridamiev]

There isn’t much you can do without a diagnostic tool to read out the specific fault codes, see below for suggestions:

https://myimiev.com/threads/testing-and-monitoring-apps-and-tools-and-scanners.4950/

Ok. Thank you.

 

[floridamiev]

There isn’t much you can do without a diagnostic tool to read out the specific fault codes, see below for suggestions:

https://myimiev.com/threads/testing-and-monitoring-apps-and-tools-and-scanners.4950/

Ok. Thank you.

 

[PV1]

That’s likely a blown MCU fuse for the on-board charger. The red battery light means the 12 volt battery isn’t charging, so better keep a trickle charger on the 12 volt battery and not drive the car right now (or just disconnect the 12 volt).

In all likelihood, this is your original problem and all the shenanigans with the 12 volt battery were symptoms.

 

[floridamiev]

Thank you. I did disconnect the battery. Is this an easy fix or something i need to take to the dealer?

 

[MickeyS70]

… that depends on how much $$$ you want to spend, if it’s a faulty OBC the dealer will just replace it, DIY repair is way cheaper if you have the skills to do it, for guidance check out below

https://myimiev.com/threads/the-troubleshooting-and-repair-for-on-board-charger-obc-thread.4079/

 

[floridamiev]

um no..taking it to dealer. Thank you though.

 

[kiev]

Likely a closed relay with welded contacts that is supplying power to the system when the battery is attached. It should be open until the key is turned, but if the relay contacts have arced and welded together this would be the result.
OR,
some rodent chewed thru wires and created a short circuit to a battery power wire.