Can I charge a lawnmower battery with a car charger ?

[headgroundsman]

if a battery is very deeply discharged you can sometimes bring it back to life by connecting a good battery in parallel before charging

[skyhuck]

I have read on the web many times that dead batteries can be resurrected, but when ever I click on the link and watch the video it alway goes on and on repeating how great this method is, without actually giving the method, until I loose the will to live and no longer care, so I switch it off.

[Daniël Bos]

I'm no great expert, but here's my understanding.

 

Most modern battery charger need to detect a voltage before they start charging, when your battery is completely dead the voltage isn't sufficient to trigger the charger to turn on so connecting another battery with jump leads can start of the charging process.

My mother in law came across this after buying several new battery chargers, none of which would charge her batteries she uses on fence energizers (which use so little power they can drain a battery right down before they stop working).

 

Battery capacity reduces over time do to deposition of sulfate on the plates, covering them.

You can in some instances reverse this process by charging at a higher voltage which cracks these sulfate crystals off. This is normally achieved by charging at around 15v, with pulses up to 16v. The pulses physically crack the sulfate off, revealing the lead plates again so they can do their thing.

To do this properly you need a dedicated charger.

 

Depending on how the battery ended up being so discharged, the other thing that causes a battery to fail is the physical warping of plates, they bend under a high current load and when they touch the cell is dead, permanently. This is more common with big starter batteries. This cannot be reversed.

[NFG]

Hi again, a bit more detail:

 

Generally 12V batteries that dip below 10.5V become too sulphated to recover & the damage ireversible.

 

For a battery capacity in A/hr of C normally the max charge rate is generally C/10 so a 35Amp/hr you'd charge at 3.5Amps. Carging at rates above C/10 can help to remove sulphite so giving it a blast with your car charger should help. You need to keep an eye on battery voltage & electrolyte level & not overcharge for too long or let it get too warm though.

 

If a battery is left uncharged then the risk of sulphation incresaes & you need to try and remove the sulphate that has plated out on the lead. The problem is that the sulphate hardens with time so the effect becomes permanent. Daniels post above also refers to this.

 

The use of a CTek charger may help as they have a de-sulphation step in the charge cycle, really its a preventative measure rather than a cure as if its been left a long time without charging its probably too late.

 

The process referred on YouTube of connecting a good battery in parrallel & then reversing the polarity of the good battery is to attempt re-condition a sulphated battery. Ive tried it with both a good battery & the output of a welder I think it was 21V with limited success but there are some fairly large currents flowing so you need to take care as it could cause explosion <insert disclaimer here>

 

If a good charge dosn't work, draw stumps & buy another battery along with a CTek 3.8 or 5.0 which can charge all types of lead acid battery.

 

N

Edited March 13, 2017 by NFG

[Aaron2010star]

Hi again, a bit more detail:

 

 

 

Generally 12V batteries that dip below 10.5V become too sulphated to recover & the damage ireversible.

 

 

 

For a battery capacity in A/hr of C normally the max charge rate is generally C/10 so a 35Amp/hr you'd charge at 3.5Amps. Carging at rates above C/10 can help to remove sulphite so giving it a blast with your car charger should help. You need to keep an eye on battery voltage & electrolyte level & not overcharge for too long or let it get too warm though.

 

 

 

If a battery is left uncharged then the risk of sulphation incresaes & you need to try and remove the sulphate that has plated out on the lead. The problem is that the sulphate hardens with time so the effect becomes permanent.

 

 

 

The use of a CTek charger may help as they have a de-sulphation step in the charge cycle, really its a preventative measure rather than a cure as if its been left a long time without charging its probably too late.

 

 

 

The process referred on YouTube of connecting a good battery in parrallel & then reversing the polarity of the good battery is to attempt re-condition a sulphated battery. Ive tried it with both a good battery & the output of a welder I think it was 21V with limited success but there are some fairly large currents flowing so you need to take care as it could cause explosion <insert disclaimer here>

 

 

 

If a good charge dosn't work, draw stumps & buy another battery along with a CTek 3.8 or 5.0 which can charge all types of lead acid battery.

 

 

 

N

 

 

 

Cheers

 

 

Sent from my iPhone using Tapatalk

[Stihl123]

yes you can, i do it all the time!!!

12v is 12v!

[peatff]

One got left on the start and charge round at the bike shop while we went out and an hour later it looked like a black football and was steaming and seething. Mechanic knocked the clip off the terminal with a long cane and then left it alone for half an hour to calm down. Get an Optimate or something similar to maintain your battery.

[NFG]

yes you can, i do it all the time!!!

12v is 12v!

 

Agree, but its the capacity of the battery that determines the charge rate usually the capacity divide by 10.

 

Lawnmower bateries are in the 30-40 Amp/hr capacity which requires a 3-4 Amp charger.

 

A car battery is around 100 Amp/hr & chargers will apply more current depending on its design, some may only reach 4 or 5 Amps maximum which is sufficient if left overnight as charge current reduces as voltage increases with most constant voltage chargers - or it may have a high/low setting so selecting low would limit the current.

 

Over charging is acceptable for a short period, but can risk buckling the plates or as above in Peatifs post.

 

N

Edited March 13, 2017 by NFG