Fishfinder Battery Charging Question

[tuber]

This is probably a dumb question, but do I use a regular 12 volt charger to charge a 12v 7amp battery? And if so, do I put my charger on Maintenance free or conventional? Any advice? Thanks

tuber
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[Theekillerbee]

You can, but you have to be real careful. I've heard of some of them getting melted if left on for too long. They just throw too many amps for the little gel cells. If you only plan on leaving it on for 2-4 hours, you would be fine.
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[IceFishingGod]

If your charger has a "trickle function" you can use it. But it must be less than 2 amps per hour, or (2AHC) 2 amp hours per cycle. I wouldn't keep it on more then 2 hours. You can use a a battery charger with more but you risk blowing it up. Like TKB said, those little gel cells aren't made to handle a lot of amps at once. My charger works at .42AHC, it takes about 8 hours from 0 to full.

IFG

[Troll]

Charging a battery to fast can cause it to melt or even worse explode. Lead acid batteries can also boil dry if charged to fast.
Look at your charger, what is the charging amp rate? If it is 6 amps or so it will be ok for a couple of hours. If it is a 20 amp model thats risky.
It is best to use a trickle charger or 2 or 3 amps for the smapp batteries. You can buy them for $10 at harbor freight. These will charge the battery slowly overnite and won't boil or melt the battery. They are also the ticket for keeping big batteries charges up while not in use for long periods. I keep one on the RV all winter.
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[IceFishingGod]

I forgot to add, maintenance free, if you use a regular one. It won't throw as much current.

IFG

[tuber]

Thanks everyone for the info. Mine does not have the trickle function, so it only will do 10 amp. I don't think I am going to chance it. I bought the battery at sportsmans a week ago, and used it for about 4 hours last time, so hopefully it still has enough charge for one more trip. cross my fingers.

tuber
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[TubeDude]

[cool][#0000ff]As others have advised, use the little "trickle chargers", with the stepdown transformer plug. It is difficult to harm a gel cell battery with those, even if you leave it on past full charge.[/#0000ff]
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[#0000ff]It sounds like you are planning to run the battery until it runs out of juice. It also sounds like you used it straight out of the store without charging it. NOT GOOD.[/#0000ff]
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[#0000ff]Gel cells are not designed to be "deep cycle" batteries. Do not drain them before recharging. Keep them charged between uses and top them off before each trip. Put them on the charger as soon as you walk in the door after using them.[/#0000ff]
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[#0000ff]If you are serious about getting good use from your battery, pick up a small voltage testor that will test 12 volt batteries. Use it to check the voltage output before and after charging. Your sonar will run on voltage down to about 10 volts or so. But, your battery will be putting out about 13.5 at full charge, and will drop to about 11 - 11.5 after a day's use. The battery should be charged then, not taken out for another trip and run until it runs out of juice.[/#0000ff]
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[#0000ff]If you take care of the SLA batteries, they will last for years of regular use. If you treat them like deep cycle batteries they will fail quickly.[/#0000ff]
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[tuber]

Thanks TubeDude, I appreciate the info. I asked the guy at sportsmans if I needed it charge it before I used it and he said no, so I didn't even think about it. Now I understand better after your post. I am heading out to buy a charger tomorrow. Thanks again.

tuber
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