charging a cranking battery

[sean0920]

i have a marine cranking battery for my motor, livewell, lights, etc.  can i charge this battery with my charger?  someone told me these batteries arent like the deep cycle and shouldnt be recharged over and over again.

[sneaker]

All lead acid batterys have a limited number of discharge-charge cycles they can tolerate. The number of cycles depend on how discharged the battery was when charging began. So a battery will tolerate fewer cycles from %50 discharged to full charge than %30 discharged to full charge. Cranking batterys have thin plates with lots of surface area to allow them to deliver lots of amps to the load. Deep discharge batterys have fewer but thicker plates that deliver less current to the load, but tolerate more discharge/charge cycles. And there are some batteries in between. A typical deep discharge battery will give 100-300 discharge/charge cycles in its lifetime.

On the other hand if you are using a cranking battery to operate your trolling motor, you can expect a shorter battery life bacause of the greater depth of its discharge/charge cycles.

If you are just 'topping off' your cranking battery with a trickle charger so it will be in top shape when you want to fish, you are probably doing it no harm. In fact some of the battery 'life extenders' continuously take a small ammount of power from the battery, and pump it back into the battery again in endless cycles, and claim this process extends the life of the battery.

You did not mention why you want to put a charger on the battery. Usually the alternator on the motor quickley replaces the energy needed to start the engine. If your battery is losing its charge when the boat is stored, you need to find the responsible unit causing the power drain and fix it. If your alternator is not recharging the battery after starting the motor you need to find the cause. If the battery just won't hold a charge, it should be replaced.

Good luck...

[XcoM274]

The answer is yes. Cranking batteries aren't designed to run small current objects like lights and pumps, but, is that really going to prevent you from doing so? No. There is a chemical reaction occouring inside the battery to produce electricity, usually between a silicon compound and the led plates spoken of above. When you charge the battery, you reverse the reaction and it can start again when you put load back on it. Unfortunately, a small amount of lead is lost every time the reaction occours, and eventually you will eat a hole in one of your plates, at which point the battery isn't going to work anymore. Use the thing for a year and buy another one next year. Perhaps you want to consider an AGM battery. They're expensive, but will do what you want and are pretty invincible.

[tennwalkinghorse]

Recharge at low amps and make sure there is water coving the plates and the battery will be fine B and D makes a auto trickle charge that adjusts it self so you can not over charge the battery thats the killer to much heat check it out at Wal - Mart   JMHO

[Wayne P.]

Sean, if your engine alternator did not charge your starting battery over and over again, you wouldn't be doing any starting.

For the longest life the battery needs to be completely charged immediately after any discharge. Most fishermen do not run their outboard long enough for the engine alternator to completely recharge the starting battery from the act of starting plus the other drain put on it from sonar, pumps, and lights. I top mine off after every fishing trip with a 10A automatic charger. Most outboard engine alternators are 10A or higher.

A marine starting battery and an auto starting battery are the same except for the terminals. Your tow vehicle has an alternator of 50A-65A or larger. Some upgrade to 100A or larger if they run powerful steros or lights. Police vehicles have larger than 100A alternators.

Each charging system has a regulator to control the charging rate to match the battery's need. Your portable charger should have the same.

The 2A maintainer chargers some of you advocate are to keep a charged, unused vehicle battery topped off from voltage loss that naturally occurs and from the slight drain some vehicles have from clocks and security systems.

[sean0920]

thanks folks!! the battery is in fine shape, what i didnt want to run into was draining the battery while using the lights, livewell, etc which is all hooked to the cranking battery.  i didnt figure i would run the engine long enough to get it back up to full charge being that we usually run and gun on the friday night tourneys so the engine isnt running for long amounts of time.  i put the tester on it and it said it w as at 65%.  i got one of those  schumaker speed chargers with the trickle, medium and fast settings.

so based on what you all said it would be okay to top it off with a trickle charge?

thanks again for your help

sean