Car wont start even though battery charger says it is fully charged

Question

I have a 2010 ford focus ran and drove just fine 2 days ago, i went out to start it today and nothing. There were no dash or internal lights on at all when i turned the key still nothing no noise at all even. I jump started it and it started just fine let it run for about 30minutes and shut it off can out an hour later to go to work and nothing again same as earlier. I put it on the charger for a few hours, said it was fully charged and still got nothing when i tried to start it. I've checked the cables and they seem fine, i checked the water and filled it with distilled. Im not sure what else would cause it, I've never had this problem before.

Answer 1

If you connected the jump leads directly to the battery terminal connectors on the dead vehicle, then there are really only 2 possibilities -

• The battery is totally dead and needs replacing
• There is a bad connection between the battery connectors and the battery terminals

If you connected the negative jump lead to the engine, then this adds an additional possible fault of a bad earth strap from the battery to the vehicle body work.

The first thing to do is check the battery. Remove it from the vehicle, put it on charge for a few hours, maybe all day, then take it somewhere that can test it. A totally dead battery seems the most likely fault to me, based on these symptoms.

If the battery is OK, then thoroughly clean the battery terminal connectors and either end of the earth strap.

Answer 2

I would remove the battery cables, clean the terminals and the inside of the cable clamps, and put it back together. Watch for any foreign matter or corrosion.

Also check the age of the battery. A 2010 is about at the end of its second battery, given 4-7 year life of a car battery. If you see a 2015-2018 date, it's probably time.

If you're having to add water that's not a good sign. 1990s and onward alternators charge very precisely and do not overcharge the battery, so batteries rarely lose water. If you have a hygrometer you might check the specific gravity after charging... if it won't go above 1/3 charged the battery is done.

Lead-acid batteries are dirt cheap, and uniquely well-suited to starting engines. So annoying though it may be, it's still cheaper to replace a lead-acid 3-4 times in a car's lifespan than it would be to use a better technology of battery. In the future lithium may drop in price enough to be a player. We'll see.