I overcharged my xc90 and now it wont start,electrical problems

[volvochesterct]

Hi volvo people
first post
have owned volovsfor 40 years.
So I used a manual 10 amp charger to charge my 2006 2.5t xc90 battery because I left my ignition and a/c blower on which killed the battery. I hooked my charger up to the positive terminal under the hood and to the body for ground. It was late at night so I was headed inside for good so I thought I unplugged the charger because I didnt finish charging it.Well I left it charging all night by accident
Came out next morning and unhooked-it was still charging and doesnt have an automatic shutoff. The charger was pretty warm.
So I tried starting the xc90 and it wouldnt start.Just hear a click.My sunroof wont open.My interior lights wont come on.
My windows work.When I touch the brake pedal it makes a 10 second whirring noise.My headlights work and so do my guages.My check engine light starts flashing after 10 seconds of turning igniton on

So I though maybe I cooked the battery so I went and bought a new one and installed
Same issues.
I checked my fuses and all good. I dont know how to test my relays.
So do you guys think I ruined the CEM somehow or where should I begin searching?-I dont see or smell any burnt wires on the car
Thanks for you help

[volvolugnut]

First checks to troubleshoot:
Are the battery cables tight? they have to be wrench tightened.
What is the voltage at the battery terminals with engine and switch off?
What was the old battery voltage after you charged it? You may not have this battery anymore to check.
What is battery voltage with switch on? With headlights on?
Other info: Is car moderate miles? General good maintenance condition or in need of work?
When you used the charger, did you disconnect the battery cables and connect only to battery?

volvolugnut

[volvochesterct]

Battery cables are tight.
I connected my charger redcable to the positive terminal under the front hood near the fusebox.And my black cable to the fenderbody for ground and left it on over night at 10amps by accident.I did not connect straight to the battery in the trunk
I checked the old battery at advanced auto and they said it was low but were fine. I bought a new one hoping that would do it.No luck

225,000 miles maintained but it burns a little oil and were ready(married with daughter) to buy another with less miles. Just put a used turbo in it.Tires.
I'm not sure this is worth a tow to a volvo mechanic because if I fried something electrical somewhere I'm not looking to throw any serious money at it chasing an electrical gremlin I just created by accident. But if anybody has a suggestion where I should start looking
much appreciated.I'm a carpenter and have a large work truck and was hoping to have this as a backup but this car owes us nothing.Had it for 8 years.Bought it with 135k on it.Thanks

[Krons]

When swapping the batteries how long was it disconnected? I wonder is disconnecting the battery for 10 minutes (or more) could help the system reset.

[volvochesterct]

Not long,maybe a few minutes but I'm willing to try that if you think it would work.

[volvochesterct]

I'm gonna try it.I'll wait 20 minutes and hook the brand new battery up and see what happens

[volvolugnut]

With the headlights on, test the voltage at the two terminals under the hood where you connected the charger. This will tell us about voltage drop from battery to the front.
volvolugnut

[volvochesterct]

Ok-I will have to borrow a voltage tester so I cant reply on that until tomorrow.

Update I did reconnect the battery and have same symptoms-no luck starting.

I did unlock and lock the car 3 times(from what read on this forum elsewhere) and got my sunroof to work

[chitownV]

Hmm. The issue(s) could have been before charging thus why the battery died, it could have been caused by the charger, or a combination of both. Low voltage before the charger could have also caused an issue with modules.

If you can hear a click in the engine area when trying to start, if the dash lights up, if the accessories and lights are going on, then maybe verify the starting circuit.

I would start with some of these checks.
- Use a phone to take pics of the starter and the starter cables under the intake manifold
- Double check the starter relay. Unplug and inspect the terminals. Maybe bring it to the auto parts store to replace with the same one. https://www.autogenius.info/volvo-xc90- ... x-diagram/
- If you have a 2nd key, try that
- Ensure the dash is showing P when trying to start
- Double check that you see the brake lights go on when pressing the brake

I do have one question, if you jump started, or tried to jump start, the XC90 anytime recently?

Hopefully this helps narrow down the possibilities.
Good luck

[volvochesterct]

well my neighbor came over with a voltage tested and we reading 12.2 at the front of the car and 12.8 at the battery in the trunk. Starter fuse is good.
Im thinking a tow to the volvo mechanic may be in order next. Get a diagnostic and see what whats..If its a relay or some immobilizer function or something simple I will pay to fix but if its a costly CEM repairs with hours chasing gremlins I will say goodbye and use that money towards a newer used xc90. I did try to jumpstart it today no luck