Not all tenders are created equal. Perhaps a different/better battery tender? It shouldn't be telling you that it's fully charged when it is not, right? My original tender failed on me and overcharged my race battery to the point of the case bulging to a scarier than $hit proportion! I now have a more expensive tender that is electronically suitable for AGM batteries. I thought the other one was too, but apparently not.

 

I do not trust these tenders too much myself, I put it on rather than use my fancy battery charger, thinking a slow recharge was better than a quicker charge. Long ago a friend had a battery explode from a spark inside when he was charging it. He did not get burnt but his clothes were full of holes the next day. It was on the floor of his garage at the time and not in his car.

 

Hi Dave, you may want to have the battery load tested. Terminal voltage test of 7 (or so) volts is NOT GOOD for any period of time. If it 'sulfated' the capacity would be diminished. A load test would answer this question very quickly. If it went south because of it self discharging too long, you might have to replace it. Hope the load test comes out OK!


A battery 'exploding' can be a number of reasons. An internal short, a charger incorrectly hooked up (have seen this happen way too often), a 'short' across the terminal posts (dropping a wrench/screwdriver, happens a lot as well). Sometimes, while high current charging, too much hydrogen gas is present and if a slight spark (checking the chargers clamps on the battery being charged) and 'BOOM'. I reference a wiki article for the prior sentence " Car batteries are most likely to explode when a short-circuit generates very large currents. Car batteries produce hydrogen, which is very explosive, when they are overcharged (because of electrolysis of the water in the electrolyte). The amount of overcharging is usually very small and generates little hydrogen, which dissipates quickly. However, when "jumping" a car battery, the high current can cause the rapid release of large volumes of hydrogen, which can be ignited explosively by a nearby spark, for example, when disconnecting a jumper cable. When a battery is recharged at an excessive rate, an explosive gas mixture of hydrogen and oxygen may be produced faster than it can escape from within the battery, leading to pressure build-up and eventual bursting of the battery case. In extreme cases, battery acid may spray violently from the casing and cause injury. Overcharging—that is, attempting to charge a battery beyond its electrical capacity—can also lead to a battery explosion, in addition to leakage or irreversible damage. It may also cause damage to the charger or device in which the overcharged battery is later used."


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I reinstalled my old eleven + year old Varta this morning, it has kept going for all this time. It was in my car until two years ago when I thought that it was too old to rely on. My two year and 4 day old battery has left the building, as usual had a battery tender on it for a few times this year, for a couple of days at a time.
I put it on a charger and within 30 minutes it went from 30% charged to 80% charged according to the meter on the charger, I think not.

Tomorrow I'll see how good the Canadian Tire warranty is, I have found them OK in the past. Maybe I'll take the opportunity to step up to an AGM battery.

 

I studied the warranty and found out it promised free replacement for 4 years, sadly by the time I got to the store it was 4 years and ten days after purchase.
The tech at the Crappy Tire in Bolton put the battery on the test rig and promptly declared it dead.
Not to worry, I upgraded the new battery to a AGM battery.

 

I curently have a 2010 , C Tire Battery on my XF and did not check with their stock of AGM at CT ,to see if it is a an excact replacement or an alternative only . . . is the AGM from CT is an excact replacement ?

I bougth an AGM for Wife's car last year and noticed that the full replacement warranty on the AGM is longer than on the regular Battery.

Thanks

Daniel

 

I purchased the MotoMaster Ultra AGM battery (10-4820) and it is a bit less powerful than the regular MotoMaster Eliminator (10-4885) in cranking amps at 0°F. and more powerful than the MotoMaster (10-4800) not really that you'll notice though. They are all 48(H6/L3) size batteries and are exactly the same size. See attached PDF file.