I have a frozen maintenance free battery with a life of 14.5% life according to my dashboard display. I really can't afford to replace it at this point. I had it boosted and let it run for a half hour or so. I tried it the next day and it was dead again. Is there any way to fix it? I live in Calgary Alberta, Canada and we've just come out of a cold snap. Temperatures have been -32 and below at night for the last week or so.
No there is no way to bring a battery back to life after it have died,when a battery have been frozen it is not a lot you can do it will be chemicaly and mecanically degraded.
The best way to avoid a battery freezing is to keep it well charged(the freezing point of a fully charged battery is -70C and a 50% charged battery it is less than -30C).
The only thing you can do now is to replace the battery.
a maintenance free battery have not yet been invented so the marketing of this is misleading,but there is a lot of low maintenance batteries out there.
To make a lead acid battery last for a long time you need to be sure it never gets below 60-70% of the rated capasity for any lenght of time,and be sure to fully charge the battery as soon as possible if it have been low on charge.
If you top off your battery by fully charging it once a month you will extend the life significantly,the longest living car battery i have had died at 21 years two months,it was a standard lead acid battery 75AH.
It is best to remove the battery from the car or be sure it is at room temparature when you put your charger on it,the ideal temparature is about 20C for charging a battery.
As per the other answer, when a battery is toast, it's toast. Dubious claims of devices that can revive them should probably be disregarded and I any case those devices usually cost the same as a new battery. Have you tried getting a second hand battery from an auto wrecker? It should cost less and be more usable than the one you have
If you want to do anything with your existing battery you'll need to unfreeze it; remove it from the car and take it inside. Charge it with a trickle charger of less than 4 amps (preferably around 1 amp) - it will take a long time to charge. A 70ah battery would conceptually take 70h to charge at a rate of 1 amp (though they never get so low as to be at 0% capacity without getting ruined too) - if your car is saying 15% then it should take at least a couple of days to fully charge at 1a. If it charges faster than this it has a reduced capacity to hold a charge. If it charges really quickly, it's shot - massively degraded capacity
If you can get a reasonable amount of charge into it slowly (boosters and driving round doesn't do a dead battery any favors; slamming charge into them buckles the plates causing internal shorts and diminished capacity. It's also not enough to jump start it and run the engine for half an hour) it may start the car. In the cold the engine is much harder to turn and the battery (being a chemical reaction) just doesn't provide as much power when it's really cold. As such you'd do better to keep charging on the battery (put it on charge every night overnight) and keep the battery warmer by putting a blanket around it; even consider wiring up a heat mat (like toe things they use to keep lizards warm) under it overnight
As noted, if it's too far gone it won't provide enough amps to start the car. If your car is a stick shift then you might have some success in parking on a hill and bump starting instead of using the starter
But all in, for the messing around this is I think you'll pretty quickly look to source another battery!