Safe or unsafe to run car with shorted batt cell?

[berniedd]

2012 CRV was fine till this afternoon, when it barely cranked up the motor. But engine finally caught, and we made it home after almost 45 minutes of driving. I took my multimeter and measured 10.5 volts across the battery with the engine shut off. Obviously one of the cells is dead or shorted. My vehicle is not among those that have had battery charging issues that could be fixed by reprogramming the engine computer. Battery is still under warranty but I'm afraid I might ruin the alternator if I jump the battery to get the engine started and drive to the battery store which is an hour's drive from my house. What do you guys think? Safe or unsafe?

 

[HerrStig]

Does the manual SAY not to jump it? Jump it, and check the running voltage. If the alternator is producing 12.5 or better it can be driven. Just don't stall it. If I were nearby I'd lend you a battery. Perhaps you can borrow one for the trip.

 

[TallPaul]

Ah for the good old days of breaker points and no computer. You could remove the battery and drive all day and park on a slope and use the clutch to start the engine from a roll. But nowadays, I bet the heavy use of electronic would preclude running without good battery power.

 

[4wheeldog]

Originally Posted By: TallPaul
Ah for the good old days of breaker points and no computer. You could remove the battery and drive all day and park on a slope and use the clutch to start the engine from a roll. But nowadays, I bet the heavy use of electronic would preclude running without good battery power.


That was only true in the bad old days of generators. Alternators need to be excited by a battery to work, at least intially. Bad things happen to voltage, when you disconnect a battery in a running, alternator equipped car.

The OP should be fine, driving to the dealer after a jump. I would feel better if I had a jumper box with me, but with 10.5 volts with the engine off, the battery should work OK except for starting.

 

[NHGUY]

Originally Posted By: 4wheeldog
Originally Posted By: TallPaul
Ah for the good old days of breaker points and no computer. You could remove the battery and drive all day and park on a slope and use the clutch to start the engine from a roll. But nowadays, I bet the heavy use of electronic would preclude running without good battery power.


That was only true in the bad old days of generators. Alternators need to be excited by a battery to work, at least intially. Bad things happen to voltage, when you disconnect a battery in a running, alternator equipped car.

The OP should be fine, driving to the dealer after a jump. I would feel better if I had a jumper box with me, but with 10.5 volts with the engine off, the battery should work OK except for starting.


Exactly.Old advice that dates back to 1964 for GM and Ford and 1960 for Chrysler (except Valiant).And 1972 for VW.

 

[kb27]

A shorted cell battery gets very hot after being charged by the alternator, since 14V is now shared by 5 cells instead of 6.

At the next jump or crank, there's a possibility of the case exploding.

I've known a couple of cases.

 

[Dan55]

I make it a habit to check the electrolyte level in my batteries. In the past a couple of my batteries went south due to low water levels.

 

[MolaKule]

A shorted battery cell puts an extra load on the alternator.

 

[JHZR2]

Sometimes you don't have a choice. Once on my way to Chicago I stopped for gas, next startup NOTHING would work. Even another car jumping did nothing. It took a tow truck connected and shorting the starter solenoid with a screwdriver to work.

So what choice did I have?

A hard short can dissipate energy and of course the battery voltage will drop, but if it's reasonably conductive, it's just going to force the alternator to work harder.

I'd replace it ASAP but not sweat it.

 

[wrcsixeight]

The extra load on an alternator by a battery with a shorted/dead cell is minimal, If the other 5 cells are still within 20% of being at full charge, but the one dead cell will discharge them. It is a matter of time of how long the dead cell is allowed to suck down the other 5 cells. Any well depleted battery can ask for huge charging currents from the available charging source.

The extra stress on the other 5 still functioning cells is greater when the alternator is holding the battery in the mid 14's. They will heat up and offgass significantly more than a 12v healthy battery with 6 functioning cells.

If you do drive the vehicle to the battery store, I would open the hood, feel how hot the battery is, and sniff for any sulfur smells.

If the battery is hot and stinky, I'd wait a while before disconnecting the cables and possibly causing a spark.

The 5 still good cells will have been bubbling vigorously and the tops of the cells filled with oxygen and hydrogen still trying to escape.

The shorted cell could be bubbling even when no charging current is applied to the battery.

A battery with a shorted cell can be dangerous. I'd remove it from the vehicle, rather than make it more dangerous by force feeding the 5 other cells at what will be rather extreme voltages for an hour drive to the battery store.

The chances of explosion are not profound, but the consequences should it happen can certainly be.

If you make it there, and they install the battery for you, inform the the installer the shorted cell before they open your hood.

 

[gathermewool]

Do you have a second car you could drive to buy a new battery?

 

[TFB1]

So the battery is in warranty but the alternator is not???

Originally Posted By: wrcsixeight
The extra load on an alternator by a battery with a shorted/dead cell is minimal, If the other 5 cells are still within 20% of being at full charge, but the one dead cell will discharge them. It is a matter of time of how long the dead cell is allowed to suck down the other 5 cells. Any well depleted battery can ask for huge charging currents from the available charging source.

Could you enlighten the masses how a dead/shorted cells discharges the other good cells??? Each cell is separate and no current flows until something is turned on... Don't tell me the KAM for PCM or radio will do so cause I'm not gonna believe it...

 

[Scout1]

When the battery shorted on my 95 T-bird, I couldn't even jump it. When I tried it just sparked when I tried to attach the jumper cables. I ended up removing the battery cable, jumping to the cable directly, she started right up and I drove home with no battery connected. Ran fine but the alternator needle jumped around a LOT! Nothing seemed to be hurt by the drive (about 15 miles) and a new battery fixed the problem. Not sure today's electronics would tolerate that, but that 95 Ford did just fine!

 

[berniedd]

Well, I weighed the options, and I chose to remove the battery and borrow my daughter's car to return to the dealer. No sense risking some alternator damage and/or battery pyrotechnics needlessly.

 

[The_Jeff]

I drove a clunker home with a shorted cell. Made it. At idle, the headlights dimmed a LOT but otherwise you'd never know.

It was venting acid slowly. I wouldn't do it voluntarily just because acid in the engine compartment, dripping onto the subframe, corrodes a lot of collateral damage.

 

[SwampSurvivor]

I drove the Cherokee for a while with a bad cell. Couldn't figure out why it wouldn't start without being jumped (seemed to crank normally) and wouldn't idle right.