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Cold cranking

Using AutoCraft battery charger to charge up ATV battery at 7 hours for a full charge at 1.5 amps

We had some trouble getting the ATV started.

I took the battery to an auto parts store for testing. They only measured 90 cranking amps when the minimum for this size is 190.

The voltage was over 12 volts, which has fooled me in the past before I learned that engine starting is all about cold cranking amps.



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Hi Mark,

Failure modes in Pb batteries have been well studied. That said in my experience has been that once the battery has gotten into real trouble replacement is the only thing that works.

A battery consists of many cells in series. If only one cell has a problem the whole battery has a problem. Sometimes a cell will 'leak electricity' inside. That is to say discharge itself quickly. Inside small fingers form from one plate to the other. Sometimes these can be 'fixed' by applying a large voltage transient to the battery or cell.

The other common failure mode is that a cell has high resistance. This sounds like what you describe. One cause is running out of fluid (electrolyte). Either the water component has evaporated or there are not enough ions (sulphuric acid) to conduct the electricity.

The other cause of high resistance is letting the battery stay discharged for a while particularly in hot weather. A compound of lead forms that is an insulator. This insulating effect can often be reversed by applying overvoltage pulses for a time period. You talked about this type of device in an earlier column. When it works it works well.

Wouldn't it be nice if you could just remove the bad cell or cells and 'fix' the battery. Many folks who build their own electric cars do this. They buy individual cells. Then you have to monitor them, etc. I don't know of any vehicles with this solution, but it would be the best.

Hopefully I haven't totally overloaded you with information? Let me know if you want more!!

Right now I have a pile of 'bad' batteries which of course only have 1 cell problems. Ugh!!

I have finally become enough of a consumer to just bite the bullet and buy another and vow to more faithfully remember to open the battery cutoff switch when I am done using the truck!!

The cutoff switch works well. Even a tiny drain on a Pb battery seems to discharge it sooner than later, So opening the circuit totally has a MUCH bigger effect on its life than you might suspect with your battery life calculations.

warm regards to you both, John

Comment by John Wed Oct 23 10:08:38 2013
CCA
I have a small compact loader that I had starting problems over time. I ended up always having to deal the the battery being weak. I ended up looking around and got with an online coupon a great deal on a 350 CCA battery from autozone or advanceautoparts. I keep a float charger on it when I don't use it for more than a few days. It cranks like crazy in the dead of winter.
Comment by Marco Wed Oct 23 11:05:54 2013

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