Battery voltage question
 

The car is only driven on the weekend. Just checked the battery voltage, it is showing 11.2v when parked in the garage, but when I warm up the car, the voltage goes back up to 14v. Is it the battery needs to be replaced? will I get warning light on the dash (it is a MB)?

:suspicious:

Seems like either your battery isn't holding a charge or something is draining it. A fully charged battery is theoretically 12.6V. Get the battery tested.

Voltage is one of the symptoms, not the problem. Amperage is what you need to be measuring. Also HK is more humid, clean your battery connectors with a scotch pad and apply so dielectric grease to reduce oxidation.

If the car is only driven on the weekend, get one of those solar panels that plug into the cigarette socket, put it on your dash. Problem mitigated.

Most car dealerships would have http://www.ebay.com/itm/VW-SOLAR-PANEL-BATTERY-CHARGING-UNIT-/261406629326?pt=LH_DefaultDomain_0&hash=item3cdd0c9dcewhen new cars arrive.. so never hurt to ask.

do they turn off if battery is fully charged? i was thinking more on the lines of one of these guys

MotoMaster Eliminator Intelligent Battery Charger 12/8/2A | Canadian Tire

If it goes up to 14v that means its charging. If your car starts, and the battery starts the car, its working. 13v is a fully charged battery.

drive your vehicle for for 45mins to charge up ur battery via the alternator. or buy a trickle charger to keep your battery charged when vehicle is not driven. battery lose voltage because of parasitic draw

note: because it is a MB, there is a lot of electronics on this vehicle. that may have cause a larger draw compare to average vehicles.

I don't think so but because the panels are so week. I think they rate in mA the probability of overcharging is low.

If you are looking for a battery float charger, nothing beats CTek. Those Motomaster chargers are not the greatest. In my garage I use Ctek, then if worse come to worse I have a Motomaster Boosterpack (basically a lead acid battery). Then if worse come to worse BCAA platinium.

The inspector said the battery needs to be replaced when I bought the car, but strange enough he said at this voltage the car can't be started or struggle to start. Anyway, I will get it replaced first. Thanks guys.

Inspector gadget?

Have you ever had to boost your battery? If so, the alternator will never be able to charge it back to 100%. If I were you I would go buy a battery charger, disconnect the leads (you can leave the battery in the car if you want) and give it a good, slow, low amp charge overnight and then reassess (if your battery is not a Maintenance-Free battery, then make sure the water is topped up with distilled water). If you notice the battery voltage drop again then you may have a draw. Also note that if your battery is dirty, it actually creates a bridge between the two posts (usually only a problem on top post) which will result in a small draw, so make sure it's clean. Also you can usually bring your battery in to a parts store and they will test it for you on their load tester.

If you are concerned about a parasitic draw, try this.

1) Leave your car off with key out, doors closed and everything in the normal position it would be in if you were leaving your car off in the parking stall, but with the hood popped.
2) If you have a hood light, disconnect it for the time being.
3) Disconnect the negative cable to the battery, leave the positive connected.
4) Take your multimeter, set it to DC Amps
5) Place one multimeter lead on the negative post on the battery, and take the other lead and place it on the now disconnected negative cable.
6) If you read amperage on the meter, that is a parasitic draw. Note that almost all vehicles have a small amount of draw with the vehicle off to keep the clock running, security systems and such.
7) To isolate where the draw is coming from, as you are watching the multimeter, start pulling fuses, one at a time, replacing them as you pull them. As you are pulling fuses, if you find that the amperage reading drops sharply when you remove one fuse, then you have found the circuit with the draw.
8) Once you have determined the circuit with the draw it should become fairly obvious what component is causing the draw, but if not, try and get the wiring diagram for your vehicle and again (make sure you have all the fuses back in at this point), one by one, start disconnecting components in that circuit until you find that drop in amperage again and then you have found your draw!

Sorry if this wasn't what you were looking for but more info is better than less.

Get a trickle charger, problem solved

Back in the day when i had a 1400+ watt RMS amp + Kicker L7 i was doing a motormaster warranty replacement about every year :ilied:

Kill it multiple times and it will never be the same.