Boat battery question

[bigbrad123]

So here’s the situation. I have an AGM battery for my boat. It’s 2 years old. I store it at my dads place over the winter and take out the battery. I left the battery at his place over the winter. So this spring, my dad hooked up the battery to move the boat. Apparently he hooked it up backwards. I am not sure if he charged it or not when it was hooked up to the boat or before he put it in the boat. So here’s how I found out it was done wrong......I went and picked up the boat and got it home. The battery was dead. I figured maybe he just didn’t charge it that much. So, I put the charger on it only looking at the boat cables (red and black) and didn’t look at the actual battery. I then proceeded to charge it for around 18 hours. I had my son take the charger off so I didn’t look at how much it was charged, but I know it was charged somewhat as I moved the boat motor down. Today I came back to it and tried to move the motor again and it barely moved. After trying to figure out why it was drained, I noticed the cables were put on incorrectly by my dad. So now the cables were on wrong and I charged it “backwards” with the red on the negative and black on positive. So...question is whether the battery is shot? I am charging it again now outside of the boat. It appears to be charging. I don’t have a volt meter to check it though, but the battery charger meter is moving in the right direction. Thoughts?

 

[SLE]

The battery should be the least of your worries. Fried ecu’s For your engine(s) and other direct wired electrical equipment would be my bigger worry at the moment. I would pull the battery, hook it up to a regular charger and see if it’ll take a charge with nothing hooked up. If it takes a charge, great if not go get a fresh one and cross your fingers that’s the only issue. If stuff isn’t working when you know you have a good battery hooked up, start tracked down fuses.

theres a good chance your on board charger recognized the reverse polarity and didn’t try to charge it, most on board chargers now days are pretty smart.

good luck!

- - - Updated - - -

FWIW, I changed out my camper battery this year and hooked them up backwards. Luckily it blew the three 30 amp fuses and that appears to be the only issue. I noticed mine quick because it arc’d pretty hard when I connected the cables. Didn’t catch the fuse situation for a week until the battery was dead and I realized the converter wasn’t charging the battery with the camper plugged in. In my defense, the camper manufacture used black for Hot and White for negative on a 12V system. It should’ve been red & black and red is hot and black is negative! Not white and black which are 120V colors. First time in 30 years I’ve ever seen that. Still dumbfounded they have it that way on a relatively high end 2016 fifthwheel.

 

[7mmMag]

What kind of charger? SLE is correct about newer ones being smart and won't allow it to charge. But the diode in the charger could have got destroyed and caused the battery to charge backwards (Yes its possible). And if thats the case, I would be concerned about anything that got hooked up to the battery (electronics, motor, etc). I would suggest getting a volt meter and determine if it got charged backwards. Good luck, I hope everything is fine.

 

[bigbrad123]

I am worried about other issues you guys mention, but I am pretty dumb when it comes to electrical issues. For what it’s worth, after charging “backwards”, I never once turned on the key. I only moved the motor up and down briefly. The charger I have is a pretty old one. Guessing it’s at least 20 to 25 years old.

 

[Allen]

As far as the battery itself, discharge it completely and recharge it correctly and it should be OK. I've seen people do it to regular starting batteries and had to reverse it.

As far as the rest of your electronics, just cross your fingers and chase gremlins as you find them.

 

[701Rounder]

Might be a good thing you hooked it up backwards if your lucky since you cooked it 18 hours?

 

[Aucker33]

As far as the battery itself, discharge it completely and recharge it correctly and it should be OK. I've seen people do it to regular starting batteries and had to reverse it.

As far as the rest of your electronics, just cross your fingers and chase gremlins as you find them.

This

 

[shorthairsrus]

the newer it is the less issues -- if the motor starts - your good. most likely you have master switch to the electronics -- which if you are like me that thing is shut off not to drain the battery from something that was left on. I think its going to be fine.

Somebody mentioned the camper battery -- now while the hell do they have the cables on those like AC. Makes no sense and it always screws me up.

 

[bigbrad123]

Just checked on the battery in the garage on the charger. It appears to be charging according to the charger read out gauge. I’ll see how it looks tomorrow and try to hook it up. I need to take my boat in anyway and get the lower unit seals checked so I’ll have them check everything over.

 

[SDMF]

I bought some red electrical tape for and zip-tied all of the (+) side wires for my camper into one bundle. I zipped the (-) side together as well.

 

[MuskyManiac]

If it was hooked up backwards did you notice the up and down on the motor lift was reversed? You probably fried all your fuses to radio, depth finder, ect. Also on Mercury's (don't know about other engines), there is a large cable in there that is fuse protected. You can't change the fuse it's built in and the cable is around $100. You need to replace this or the engine will not charge your starting battery. It will still run, but will not charge.

 

[bigbrad123]

There was no change in the up or down on the motor lift. Up was still up and down was still down.

If it was hooked up backwards did you notice the up and down on the motor lift was reversed? You probably fried all your fuses to radio, depth finder, ect. Also on Mercury's (don't know about other engines), there is a large cable in there that is fuse protected. You can't change the fuse it's built in and the cable is around $100. You need to replace this or the engine will not charge your starting battery. It will still run, but will not charge.

- - - Updated - - -

So here are some pics. First two are how my dad hooked up the battery I only looked at the red and black wires and not the actual battery so I just charged it that way. The next three are my charger pics. The first is when I started charging. 2nd was after about 2 hours of charging and 3rd was overnight.

 

[SDMF]

Just checked on the battery in the garage on the charger. It appears to be charging according to the charger read out gauge. I’ll see how it looks tomorrow and try to hook it up. I need to take my boat in anyway and get the lower unit seals checked so I’ll have them check everything over.

Do you have a trolling battery that's been charged properly? If so, you could drop that in place for a quick check without having to buy a new battery. Many of the battery places will load-test your battery to see if it needs replacement or not. I'm not a batteryologist so I'm not sure if they can test for reversed polarity.

 

[bigbrad123]

Called Interstate Battery and I am going to take it up there this afternoon so they can run their tests. That doesn't solve the potential boat issues, but at least knowing whether it's a good or bad battery is a good place to start! Once I get a good battery that is charged properly, then I can start the other "tests" on my boat.

Do you have a trolling battery that's been charged properly? If so, you could drop that in place for a quick check without having to buy a new battery. Many of the battery places will load-test your battery to see if it needs replacement or not. I'm not a batteryologist so I'm not sure if they can test for reversed polarity.

 

[johnr]

CAT batteries are the best, or so i have found.
If you do need to replace it.

 

[SDMF]

Called Interstate Battery and I am going to take it up there this afternoon so they can run their tests. That doesn't solve the potential boat issues, but at least knowing whether it's a good or bad battery is a good place to start! Once I get a good battery that is charged properly, then I can start the other "tests" on my boat.

Run down Gremlins one thing at a time. It sucks and it mind-numbingly time consuming, but, in the end hopefully saves a person from having to flag down a 'Sconi on the water to save themselves.

 

[Allen]

Run down Gremlins one thing at a time. It sucks and it mind-numbingly time consuming, but, in the end hopefully saves a person from having to flag down a 'Sconi on the water to save themselves.

Knowing you, you'd probably rather swim through freshly chummed and shark infested waters than accept help from a sconi.

Not so sure I'd blame ya.

 

[SDMF]

Knowing you, you'd probably rather swim through freshly chummed and shark infested waters than accept help from a sconi.

Not so sure I'd blame ya.

You're 100% correct.