Battery Question

[jheydubya]

I have a fairly new to me boat. Its an 89. I believe the previous owner neglected the batteries. I have them on maintainers, and they test fine with the voltmeter. The starter battery is from '18, and the deep cycle is a '20.

The motor runs great, but it is slow to start, it seems like an electrical issue. I have had it out, and it starts weakly at the ramp, and doesn't want to restart later if turned off. No noise, no clicking, when I turn the ignition I see the volts drop, and no sound at all from the motor. I eventually get it to start, trailer go home to try to figure out what is going on, and at home with ear muffs it starts immediately, no issues.

I am going to load test the batteries today, and most likely replace them for a fresh start anyway. But do any of you more experienced guys have an opinion on this?

MY SECOND QUESTION: I see batteries that are marketed as a starter battery, AND a deep cycle battery, I don't understand how it can be both. Do y'all recommend them? Should I just get a regular starter battery for the starting?

Thanks for any input.

 

[Bondo]

Ayuh,.... Welcome Aboard,..... Start off by cleaning to shiny metal Clean, All of the battery connections,.....
Both ends of all the cables,.....

 

[racerone]

What motor ?-----Best to buy a new battery if it is 4 or 5 years old.

 

[mike_i]

What do you mean "the previous owner neglected the batteries"? You need to check the batteries under load not a resting voltage. The deep cycle is built with thicker plates and made to slowly discharged while powering accessories such as lights, pumps, radios and other stuff. The starter battery is built to provide high current for a short time as in starting a motor. If the batteries are on a maintainer be sure they don't run dry and the maintainer is "smart". I run two deep cycle batteries. New batteries would be a good idea since you'll know your're starting off with good batteries and able to maintain them correctly.

 

[jheydubya]

It is a 50hp force motor, runs well, seems to have been fairly well maintained.

What motor ?-----Best to buy a new battery if it is 4 or 5 years old

 

[jheydubya]

What do you mean "the previous owner neglected the batteries"? You need to check the batteries under load not a resting voltage. The deep cycle is built with thicker plates and made to slowly discharged while powering accessories such as lights, pumps, radios and other stuff. The starter battery is built to provide high current for a short time as in starting a motor. If the batteries are on a maintainer be sure they don't run dry and the maintainer is "smart". I run two deep cycle batteries. New batteries would be a good idea since you'll know your're starting off with good batteries and able to maintain them correctly.

Reading between the lines talking to the guy during the sale, I believe the batteries went dead completely at least once.

 

[jheydubya]

Thanks guys, I will get a couple new batteries, and cross my fingers I don't have to dig into the wiring too much until winter.

But have y'all heard of batteries marketed as dual purpose before? I hadn't. Any experience with these batteries, link below:

Duracell Marine Dual Purpose Battery, Group size 24 - Sam's Club

Buy Duracell Marine Dual Purpose Battery, Group size 24 : Marine Batteries at SamsClub.com

www.samsclub.com

 

[racerone]

I would get a new starting battery.-----Now you have 2 batteries to test for your other stuff.-----Replace them as needed.------If your starting battery will not crank the motor fast enuff , the motor will not start !

 

[Bondo]

Thanks guys, I will get a couple new batteries, and cross my fingers I don't have to dig into the wiring too much until winter.

But have y'all heard of batteries marketed as dual purpose before? I hadn't.

Ayuh,..... Napa has dual purpose marine batteries, that I use,.....

Had good luck with 'em,.....

 

[cptbill]

Take them to any parts store and have them load tested that will or should answer your question

 

[jheydubya]

Ok, had the batteries load tested, they tested ok. I went ahead and replaced the ignition switch, it looked fine, but it was 32 years old.

I cleaned all of the connectors with a dremel, and a wire brush attachment, (I think this made a big difference). The connections looked fine to me, but I was amazed how much crud I got off with the wire.

I also figured out that, my no voltage issue was incorrect grounding, I have several cables that must connect to the starting battery, and through the course of the ignition issues (the faulty ignition switch) they had been erroneously connected to the deep cycle battery. Not sure if it is normal, but it seems my trolling motor, fish finder etc.. is completely separate from the motor ignition nav lights etc..

Boat is now starting strong every time, I can hear a difference in the strength of the electric choke even. Fingers crossed for this week or next when I bring her out again. Thanks for all the advice, feels good knowing y'all are here.

 

[dingbat]

I also figured out that, my no voltage issue was incorrect grounding, I have several cables that must connect to the starting battery, and through the course of the ignition issues (the faulty ignition switch) they had been erroneously connected to the deep cycle battery. Not sure if it is normal, but it seems my trolling motor, fish finder etc.. is completely separate from the motor ignition nav lights etc..

The supply should be different, but you want to keep a common ground between both batteries to prevent ground loops.

Normally the (two) ground cable are tied together at a common point. Either via a dedicated bus bar or daisy chained between the battery ground posts then on to engine ground.

 

[jheydubya]

The supply should be different, but you want to keep a common ground between both batteries to prevent ground loops.

Normally the (two) ground cable are tied together at a common point. Either via a dedicated bus bar or daisy chained between the battery ground posts then on to engine ground.

Do I need to do the common ground if the systems are seperate? I believe the systems attached to the deep cycle have dedicated wiring.

 

[dingbat]

Do I need to do the common ground if the systems are seperate? I believe the systems attached to the deep cycle have dedicated wiring.

Yes, just like the ground for every circuit in your house is tied together at the fuse box to maintain a common ground potential.

 

[KD4UPL]

Dual purpose batteries are very common and have been around for decades. They are quite popular on boats and work fairly well. They won't quite deliver the CCA (or MCA) of a same size starter battery and they aren't quite as heavy duty as a "real" deep cycle. However, as long as they deliver enough CCA they work just fine. That's what I run on my boat. No problems in over 17 years.

 

[jheydubya]

Yes, just like the ground for every circuit in your house is tied together at the fuse box to maintain a common ground potential.

Which connects to the ground, never thought about a boat, so could I just run some sort of wire from the negative of both batteries to connect them?

 

[dingbat]

Which connects to the ground, never thought about a boat, so could I just run some sort of wire from the negative of both batteries to connect them?

I have a 4 awg ground cable running between the two batteries.

 

[Tjy7510]

Ayuh,.... Welcome Aboard,..... Start off by cleaning to shiny metal Clean, All of the battery connections,.....
Both ends of all the cables,.....

I agree, makes a big difference. I also found grounds in the loom covered with green corrosion under electrical tape. Redid it with heat shrink after cleaning