Battery / Outboard Motor Alternator ?

I put a New AGM starting battery in my boat last week. The starting battery is not hooked to my onboard charger ( Just the 2 tolling batteries ) I put my manual / Automatic charger on the new AGM to make sure it was fully charged. I used the setting for AGM batteries. I set the charger to 2 amp ( I always slow charge if possible and didn’t think it would need much charge ) after 3 hr’s it still did not go to fully charged on the charger. Went out yesterday to check out that everything was working ok. It started the motor just fine and ran all the electronics fine. I did notice that when I would start the motor it would turn the graph at the console off. I’ve only had this problem when the cranking battery was low on charge or going bad. I put the battery back on the charger when I got home and again set it to 2 amp thinking it may just need to be charged a little more. After about 4 hr’s of charging it still did not read fully charged. This is my 1st AGM battery and I’m just not sure if they take longer to charge or if I may have got a bad battery.

As for my outboard motor alternator? My lowerance graph has a voltage readout. With the motor not running what should the voltage read? When running at top speed and the alternator working correct what should the voltage read? The voltage read about 11.3-11.5 without the motor running. It went up to 12 volts when started and went up to around 12.3 when running at full speed. not sure if this Info helps tell me anything or not.

I may have to just take the battery out and take it back to the place I bought it to have it tested. I’m going to leave it on the charger today to see if I can get it to read full charge.

fishthumper wrote:

The voltage read about 11.3-11.5 without the motor running. It went up to 12 volts when started and went up to around 12.3 when running at full speed. not sure if this Info helps tell me anything or not.

Mine are usually around 11.8. It’s going to depend on if you run it through a fuse panel and how much wire you have between your battery and your graph. There will be voltage loss.

With 12.3 volts at wide open tells me your voltage drop is very likely in the graph wiring. This probably accounts for it going black when you start. Mine used to do that until I upped the wire gauge and re-did all my connections.

As far as your battery not charging, 2 amps is going to take quite a few hours to get anywhere on a large battery.

It could very well be your battery so I would definitely check that first.

Get out your volt meter. At the battery you should read 12.5v on a fully charged battery without the motor running. With the motor running it might jump to 14.5v as it charges the battery.

Turn on everything that is normally running while you are fishing, radio, depth finder, graph, live well, lights, etc. Measure at the fuse block and the battery. If the fuse block measures lower than the measurements taken at the battery then you need more wire, either lower gauge or run a second line up to a second fuse block and split the load.

One thing to consider regarding smart chargers is that they may discharge and cycle a battery. This could take some time. In fact, you could actually have a less charged battery if you didn’t let it complete the cycle.

What type of charger? Does it indicate charging mode?

ClownColor wrote:

One thing to consider regarding smart chargers is that they may discharge and cycle a battery. This could take some time. In fact, you could actually have a less charged battery if you didn’t let it complete the cycle.

What type of charger? Does it indicate charging mode?

Its a BLACK+DECKER VEC1095ABD – Yes it indicates the charging mode

Charging at 2ah for 4 hours is only 8ah total charge that is the same capacity as a Vexlar Ice fishing battery. Let it charge over night. if you have a 600ah battery and new it has 70% charge it is going to take 180ah to fully charge it.

He probably has something closer to 200 ah total. At a 2 ah charge rate, it might act like a trickle charge and not show the green light on the charger. Try kicking it over to a higher rate charge for a couple hours and see what it reads.

Get an onboard charger for your starting battery. Why chance it?

MnPat1 wrote:

Get an onboard charger for your starting battery. Why chance it?

Space is a issue and I’m not sure how long I plan to keep this boat. My next boat will have a onboard charger hooked to all batteries for sure.

Update – After my last outing I hooked the battery back up and left it charge overnight at 2 Amp. When I got up the next morning the charger read full Charge ( Yah ) I did turn on the graph to see what the voltage read and it did read just under 12 Volts. I may have to dig out the handheld voltage meter and check the voltage directly at the battery and then again at the Fuse box as suggested. Thanks for all the help. I hate electrical and don’t understand it well at all. Last year I lost my brother in law. He was my go to for electrical ?’s

If you haven’t already, install a marine master cutoff switch on your battery.

All the electronic brain boxes are always active and draining your battery to some extent. I suspect your graph has background activity that is draining your battery even when the unit is off.

A master cutoff switch will stop all this current drain and it really saves your starting battery.

Grouse

A fully charged battery with proper size wires your depth finder should read between 12-12.4v.

With motor running somewhere between 12.4 & 15v.

If you have a fully charged battery at 12.4 but you depth finder reads anything less, your wire isn’t big enough.

FishBlood&RiverMud wrote:

…. your wire isn’t big enough.

Words that no man wants to hear.

A simple $20 switch between the battery and my accessory fuse block.

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TheFamousGrouse wrote:

If you haven’t already, install a marine master cutoff switch on your battery.

All the electronic brain boxes are always active and draining your battery to some extent. I suspect your graph has background activity that is draining your battery even when the unit is off.

A master cutoff switch will stop all this current drain and it really saves your starting battery.

Grouse

Yes a master cutoff switch would be great. Unlike newer models of the Crestliner fishhawk my older model does not have a power cutoff toggle switch. I do know there is something that is using power someplace when not being used. Where is the best place to purchase one of these?

SuperDave1959 wrote:

A simple $20 switch between the battery and my accessory fuse block.

I need one of those – Where do I get one ?

Got mine on Amazon. But Google Battery kill switch and you will see a variety of types and places to purchase.

Update #2. Decided to plug the battery back in to make sure still fully charged or at least close. It took awhile for it to read fully charged. I must have something drawing that I’m not aware of. Time to get a battery Kill switch installed. Once fully charged the battery read 13.5 on a volt meter. It also read almost the same at the fuse block so that’s good. I just want to make sure everything is good with this battery as I have a rather remote Canadian Trip coming up here in early June ( Not the place to have battery issues ) No power at the campground were staying at for a week. Anything to be aware of as far as charging batteries off of a Generator?

SuperDave1959 wrote:

A simple $20 switch between the battery and my accessory fuse block.

SuperDave – It looks like from your picture that you hooked your kill switch to the + side. I’ve read conflicting Info. rather it was best to hook to + or -. Did the install direction on the one you used say to connect to the + side?

No specific directions but I stand by a short in the positive lead to anything can ground to the hull and still drain the battery.

Regarding your battery level of charge, coming out of winter I was having a dead battery frequently which caused me to chase my tail looking for the problem. It was what caused me to install my kill switch. After trying several things, it ended up being a bad cell in the battery itself. I changed the battery and no more issues. What threw me was that the battery kept charging to a full charge. My past experience with bad batteries was that they wouldn’t accept a full charge so I kept looking elsewhere for the problem. Test your battery at the auto parts store.