Mini Cooper 2001-2006: Why is Battery Not Charging?

Your battery is constantly under drain; however, when it isn't taking a charge, it can be a really annoying problem to solve.

By Jeffrey Smith - June 29, 2016

This article applies to the Mini Cooper (2001-2006).

Trying to solve a battery charging problem can be a real challenge. There are many different reasons why your battery won't charge, and getting to the bottom of the problem can be very frustrating and time consuming. Having a pro search this out for you can cost a small fortune in labor; let alone what needs to be fixed once the problem is found. If you take a methodical approach, you can save hundreds in labor finding the source of the issue yourself. The fix may very well be a fairly simple and straightforward DIY job, saving you a bunch of greenbacks to put that smile back on your face. If the fix turns out to be a bit more than you want to tackle, you'll have still saved a bundle by doing the legwork for your mechanic. Learn how to diagnose the problem and find the solution here. You may even find that you can do this on your own, so let's get started.

Mini Cooper 2001-2006: Why is Battery Not Charging?

Materials Needed

Phillips and straight edge screwdrivers
Ratchet and socket set
Multimeter
New battery (if necessary)
Battery charger (if needed)
Alternator (if needed)
Clutch pedal switch, ignition switch or starter solenoid (if needed)
Special belt removal tool (if needed)

Step 1 – Check your coolant level

There was a common issue with the fan assembly and coolant level.

The earlier models of the Mini Cooper had some common issues with the fan constantly running. If you have noticed that your fan isn't shutting off after a long time, it could be a result of this issue. The fan eventually shuts off after it completely drains the battery. This could be caused by a couple of factors.

Check your coolant level. If it is low, fill it to the proper level.
Once filled, you will want to monitor the level and the ground under your car to find any leaks.
The thermostat could be bad, but it is not a stand alone product. You would have to replace the entire fan assembly.
The fan assembly has been known to rust up and go bad, resulting in a fan that won't properly shut down until the battery is drained.
The specific culprit has most commonly been found to be a six-pin resistor pack to the right of the radiator. You can disconnect this and the fan will stop running, but obviously you can't run with this, just enough to get the assembly replaced which is the only option.

(Related Article: How to Replace Cooling Fan - NorthAmericanMotoring.com)

MINI COOPER CAR WONT START BATTERY DIED FAN STAYS ON ALTERNATOR BATTERY CABLE WIRE WIRING ELECTRical problem — Figure 1. The fan assembly connector often times goes bad and the entire unit must be replaced, but it is a fairly easy DIY fix.

If the fan isn't causing a problem, next up is the alternator.

Step 2 – Check your alternator

If the alternator isn't generating enough current, your battery will not properly charge.

When your alternator is working as it should, it will output 12.5 to 14.5 volts when your Cooper is running. Connect a multimeter to it and start your car. If you don't see this kind of output, then it is time to change that alternator. It's better to do it now than wait until it completely dies and leaves you stranded. Alternators are not too difficult to replace on your own; however, you will need to remove the bumper cover and have a special belt removal tool. If you don't want to tackle this job on your own, you can still save some money by purchasing the alternator on your own and then taking it to a reliable pro to do the replacement for you.

(Related Article: How to Replace Alternator - NorthAmericanMotoring.com)

If your fan and alternator are good, check your battery cables.

Step 3 – Check your cables and grounds

If your cables are loose or corroded, normally your car won't start, but your Mini can exhibit other weird symptoms.

If your cables are excessively corroded or are loose, clean them up with a steel wire brush and make sure they are tight. Also, check for a loose ground connection. Normally, these cars will not even start with a loose ground, but it may be just tight enough that it is intermittent and appear to be a battery charge issue. Make sure your ground strap is in good condition and tightened down all the way.

If your battery cables and grounds are fine, check other wiring.

Step 4 – Check for wiring shorts

The problem may be from rusted connections, frayed wires from a myriad of things, including critters.

Electrical problems can be a real bear to track down. Check all the wiring harnesses you can see to make sure they are solidly connected together. Check the wire that runs from the harnesses back to their starting and terminating points. If they are cracked or crumbling, you probably have a break in there. Sometimes critters can get in the engine bay on cold nights to get warmed up and they will chew through anything that gets in their way. Replacing the wiring can be a difficult task, but searching for them is the most costly part as your labor hours will skyrocket. If you can at least find the culprit, this will save you a ton of money if you need to take it to a pro to have it replaced.

If there are no obvious signs of damage on your wiring, start checking the continuity between components.

Step 5 – Check your clutch pedal switch, ignition switch and starter solenoid

If they have gone bad, your car probably won't start and seem like a battery charge issue.

Get your multimeter out and test the clutch pedal switch to start. If that is good, check the ignition switch next. If that also checks out, the start solenoid is the next obvious break in the line. The connector pins are notorious for rusting and corroding. These are all relatively simple parts to replace that you can do in your own garage, saving you a bundle from taking it to a pro to resolve.