Stranded on the lake

[Red Rider Wannabe]

I have an older boat with a 1988, 90 HP Evinrude pusher. Attached to my starter battery are my accessories: 2 Humminbird units, bilge, live wells, lights, etc. After a day on the water, my battery is discharged and will not start the engine. I run my Evinrude a few times during the day for short hops to other fishing spots.

How can I determine the amps my Evinrude is delivering to the battery. I can tell the voltage increases when the engine runs but I'm guessing the charging system on this era engine cannot deliver the power that today's electronics demand.

Can I install a second battery to serve the Evinrude and the electronics? Can I simply connect two batteries in parallel to give me more battery capacity? I have an on-board battery charger connected to my starter battery. Will it charge both batteries simultaneously if connected in parallel?

[CatFan]

Check your battery voltage while the outboard is running. You are in the era where a charging system may have been unregulated. If the voltage at the battery terminals rises above about 15V while at speed, it would point to an unregulated charging system which limits you to a standard flooded lead acid battery. These stator systems were low power and generally supplied less than 10A, which would help recharge the outboard battery and be enough to run the lights and bilge pump while the outboard was running.

As you said, these things were not designed with electronics or even bilge pumps in mind.

My recommendation would be to get the electronics and live well onto a battery separated from the outboard. Just have the bilge pump and lights on the engine battery. I would not parallel the batteries, because our outboard likely doesn't have much more than what is needed to take care of the necessary boat systems.

Ideally, a nice deep-cycle battery for the electronics and live well pumps. Best would be a lithium. You can figure your units draw about 2A each, plus 4A per livewell pump. At 8A, 80AH would be needed for 10 hours on the water, so a 50AH lithium would probably do the job. 100AH would be even better.

[styler]

You need to have the battery tested also . it may be bad. I don't see those electronics running it down that much in a day unless you're running those bilge pumps a lot.

[bassfisher444]

What battery do you have now? Always important information to know when you are having a battery problem, nearly impossible to make an accurate recommendation without knowing what you have now.

[MichAngler]

Yes having two batteries in parallel is fine and will help
But they should be the same size and preferably bought at the same time

BUTT

You can do yourself a big favor by getting a 100ah or 125ah lithium battery
Sure it costs a little more upfront compared to the two batteries but you will never have a battery issue again and your graphs will thank you and you can even consider upgrading a graph or two

[CatFan]

Yes having two batteries in parallel is fine and will help
But they should be the same size and preferably bought at the same time

BUTT

You can do yourself a big favor by getting a 100ah or 125ah lithium battery
Sure it costs a little more upfront compared to the two batteries but you will never have a battery issue again and your graphs will thank you and you can even consider upgrading a graph or two

It's very possible his outboard produces 6A at 16V. Not a good fit for a lithium battery

[MichAngler]

It's very possible his outboard produces 6A at 16V. Not a good fit for a lithium battery

Good point never even considered that

[twitch]

my friend runs an older boat that cannot take a lithium on the motor and has added a standoff lithium just for accessories and has a lead acid for starting everything is good at the end of the day but will have to have a charger for the lithium also

[2dwoods]

Shoot I would think today's electronics would be more efficient than back in the day but like always I'm probably wrong ,check volts while it's running and how old is battery .I run pumps,aereator, 3 graphs,on a reg 29 diehard with no problem all day without the price of a lithium. Older engine and all be sure all connections are clean and tight might be pulling alot of amps to turn starter

[WillFishforBeer]

Hey neighbor, I'm in a similar situation. 2002 Merc 90 w/ a 950cca lead acid starting battery running a first gen HDS 5, HDS 7, bilge, and 4 speaker stereo. Generally, the HDS 7 is run continuously, the bilge for a few seconds, and the stereo occasionally. It can easily kill the battery in a day. Currently trying to decide my plan of attack.
Only saving grace is that my boat's home-lake is 230 acres, so worst case scenario is I can troll my way home.

[bassfisher444]

Hey neighbor, I'm in a similar situation. 2002 Merc 90 w/ a 950cca lead acid starting battery running a first gen HDS 5, HDS 7, bilge, and 4 speaker stereo. Generally, the HDS 7 is run continuously, the bilge for a few seconds, and the stereo occasionally. It can easily kill the battery in a day. Currently trying to decide my plan of attack.
Only saving grace is that my boat's home-lake is 230 acres, so worst case scenario is I can troll my way home.

What size battery? I run more than that off of a Group 31 commercial lead acid battery and I can fish for 8-10 hours without any problems.

[CatFan]

Shoot I would think today's electronics would be more efficient than back in the day but like always I'm probably wrong ,check volts while it's running and how old is battery .I run pumps,aereator, 3 graphs,on a reg 29 diehard with no problem all day without the price of a lithium. Older engine and all be sure all connections are clean and tight might be pulling alot of amps to turn starter

Better displays and faster processors use more power.

[CatFan]

Hey neighbor, I'm in a similar situation. 2002 Merc 90 w/ a 950cca lead acid starting battery running a first gen HDS 5, HDS 7, bilge, and 4 speaker stereo. Generally, the HDS 7 is run continuously, the bilge for a few seconds, and the stereo occasionally. It can easily kill the battery in a day. Currently trying to decide my plan of attack.
Only saving grace is that my boat's home-lake is 230 acres, so worst case scenario is I can troll my way home.

Look for high RC in a battery to handle constant loads.

[KandKKustomz]

Most likely your battery is bad or simply not enough. Instead of paralleling a new good battery with a bad one I would have your battery load tested, before I would put 2 in parallel I would go out and either get a large 31 agm or spend the money and get a lithium cranker or put all your electronics an a dedicated electronics battery be it a agm or lithium.