How to Identify a Dying Battery?

[Jonah]

Hi all,

Just wondering how to identify a dying starter battery. Will it begin to behave like a dying car battery—slower to start the engine, quicker to go dead, etc? Or will I find that it won't take a charge at all one day, out of the blue? Just wondering as I troubleshoot a charging issue I'm having.

 

[DennisG01]

Either scenario can play out. Remove battery... charge with a known, good "normal" (preferably "smart") charger... load test it.

How many volts at the battery when the engine is running (use a volt meter), upon shut down, and the next day? Fluid level?

 

[seasick]

To do a proper load test, you have to fully charge the battery first.

Batteries can go bad slowly as it 'wears' out or sometimes quite fast when one cell goes bad.
Some batteries with a bad cell will still measure the proper voltage (not loaded).

Heat kills batteries but weak batteries often show up in colder temps since the voltage of lead acid batteries varies with temperature.

One thing that will shorten the life span of a starter type battery is running it down . It is designed for heavy loads for short periods. House type batteries are designed for long time discharge at low to medium currents.

A charged battery should measure about 12.2 to 12.5 volts without load. If your motor is running and charging correctly, the voltage at high idle should be 13+ volts to just about 14 volts depending on the charge state of the battery. These numbers are not absolute but general guidelines.
Overcharging can damage cells either by distorting the plates or boiling off the acid.

 

[Doc Stressor]

Most of the time, batteries fail either because of sulfation deposits on the lead plates or because of a cell shorting out.

With sulfation, which is sort of the normal aging process of a battery, you first notice that the battery gradually gets weaker. It's ability to accept a charge gets reduced so cranking will get slow after an initial burst. You can sometimes rescue a sulfated battery by giving it a high rate of charge for a short period or by using a chemical additive. But it's not worth it for critical applications like boats.

When a cell shorts out, the battery generates a lot of heat as the other cells rapidly become drained. A battery with a shorted cell will not accept a charge at all and will usually give an error code if you use a smart charger. A battery with a shorted cell is toast.

The best way to test a battery is to get it fully charged and then use a load tester. Most auto parts stores will do a load test for you for free. What the tester does is to put a high resistance load on the battery and measure the time it takes for the voltage to fall. If the battery passes the test, just recharge it and you will be good to go. If it fails, replace the battery.

 

[Jonah]

Thanks everyone. This is very helpful. As usual, I'm getting my education on this thread.

Here in Nassau, I'd rather not try to find someone to help me do a proper load test, and would like to see if I can diagnose this on my own. Tonight, I will take Dennis's advice of charing the battery overnight with a known, trusted charger. But first, let me share this:

I just used my multimeter to measure the faulty battery at its terminals. I got 3.5V. Is that even salvageable? (I thought I once read that a discharged 12V battery shouldn't actually ever go below a certain point.) I then flipped the selector switch to "both", so that it was connected to the other starter, and of course the voltage jumped up to just over 12V. When I flipped the selector switch again, and held the multimeter to the faulty battery, I could see the 'surface charge' (if that's the right word) slowly dropping, as the voltage quickly ran down to the 4.5V range.

I can still try to trickle-charge it this weekend, to see if it takes a charge, but thought I'd ask whether the very low voltage was an indicator of anything.

If this battery is indeed dead, then my theory is that I killed it by treating it as a house battery. I mentioned in another thread that I recently discovered the PO had wired all electronics to this starter, rather than to the house battery. So, I have unknowingly drained this starter on several occassions, and I understand that this can be the kiss of death for starter batteries, since (as Seasick said) they aren't designed to trickle down so low.

 

[DennisG01]

Yeah, that battery is toast. Don't even bother putting any more time into it.

FYI... look into Battery Minder charger/maintainers. I have about 10 of these, scattered across a few states and various vehicles. Some of them, I've had for close to 15 years. What I like about these is that de-sulphate a battery to make it last longer. Best thing you can do for a battery is have it on a maintainer (NOT a cheap trickle charger) all the time.

 

[Jonah]

Thanks Dennis,

That's what I thought. Funny thing is, I do have both batteries on a decent, new battery charger that also maintains. (ProMariner ProTournament 240 Elite Series.) I suppose I left something on that drew more current than the charger was supplying, or perhaps didn't have the charger on at the time.

Either way, it seems clear that I killed the battery by unknowingly using it as a house. I'll get a new battery and double-check that my charger is maintaining properly.

Two final questions:

1. I checked the other starter battery (port engine), and even while on the charger/maintainer mentioned above, I'm getting 12.12V. Seems low. Is this a sign that I should replace it too? It was bought at the same time as the other, in 2016.
2. Since the PO wired all the electronics to the starboard starter battery, how do others feel about whether the replacement battery should be a house or starter? I realize I should ideally have two starters (one for each engine), and one house, but for reasons I won't bore you with, that's not an option right now. I hear you can get some "deep cycle" house batteries that can still start an outboard if needed?

 

[DennisG01]

A healthy, fully charged battery should actually read about 12.6 - even a tad higher, depending on age. 12.12 is way low... Way low. And, if the charger is on/operational, you should either read resting battery voltage or higher (charging voltage).

I think the next step, before you do anything else, is to check the health of your charger (and the boat's charging system, for good measure). It's quite possible that a bad charger could kill a battery. There are tests that can be done to check. I've done them, but don't recall the exact procedure. I believe they are listed in the charger's manual, but you can also call PM and talk to them directly - their customer service is very good.

So, since it seems like there's a couple variables going on here, step back and check each individual component. That 12.12V battery may be kaput, as well - but see if it takes a charge (check fluid, if relevant)... for now, use something else besides your PM

When you get around to actually getting new batteries, you may want to consider a "dual purpose" battery. Generally, I'd like to have (2) dedicated starting batteries and a dedicated house system. But I've recently learned that Deka (who has always made a great battery) has a new(ish) dual purpose battery that would fit your needs perfectly. FYI, I learned of that battery through this site and am including the info posted by Doc Stressor:

FROM MEMBER "DOC STRESSOR":

The Deka 27m6 is indeed a dual purpose battery that was developed to meet the Yamaha requirement for a starting battery with a reserve capacity of 182 minutes yet also provide >800 cold cranking amps.

http://www.eastpennmanufacturing.co...ine-master-27m6-startingdual-purpose-battery/

It actually has more reserve capacity than their DP27 that only provides 650 CCA and a 150 min reserve capacity (minutes @ 25 amp).

http://www.eastpennmanufacturing.com/wp-content/uploads/Marine-Master-Spec-Sheet-0194.pdf

The point is that the 27m6 is the one you want in most cases.

I don't know if Gradys come from the factory with batteries, but all the new ones I've seen had 27m6s in them.

 

[Jonah]

Dennis,

Thanks again. Very helpful.

I just went out and bought replacement for my 24M5 That was reading 3.5V. Bought the same Deka Marine Master starter. It read 12.5V when I got home from the store, and it read 14.5V as soon as I turned on the charger. Meanwhile, the other battery (which was reading 12.18) is reading 13.5 while on the charger.

I will probably replace the other one too, just so that the batteries are on the same schedule. However, I’m going to wait for a friend who is boating over from the US in a few weeks, since that will save me $100 in price.

Thanks for the advice about checking my charger. I feel fairly confident that it’s all right, since it is so new, but I will do some research into what I should look for. Thanks also for the advice about this dual purpose battery. I will look into it as I decide how I would like to replace the other battery (and whether I could potentially set up a separate house battery as well).

 

[Doc Stressor]

If you have fuel injected 4 stroke engines, you really want the group 27 dual purpose battery with the extra reserve capacity. Running an engine at low rpm or while running a lot of electronics can deplete the battery even with the engine running. The fuel pumps and computers draw a lot of amps when the engine is running.

I had an experience just 2 weeks ago after running 30 miles offshore in my friend's boat. He has a single 225 Honda and was running the engine with his battery switch in the "both" position. Everything was fine while running out at 4400 rpm. But as soon as he slowed down to set up to anchor, the engine sputtered and died. I would not crank up. Luckily, he had a third battery on board and a set of jumper cables. We had to Gerry rig the cables directly to the existing battery cables in order to get the engine to start and run. Both batteries were dead and wouldn't accept a charge from the third battery. The problem turned out to be a shorted cell on one battery that ran down the second battery as well.

Lesson learned: never run batteries in parallel unless you need to. Use a battery isolator or an ACR to keep one from depleting the other.

 

[Lt.Mike]

https://www.tractorsupply.com/tsc/p...MI1c7tl8ad3QIViR-GCh0kuQOWEAQYCSABEgIIzPD_BwE


Pick yourself up one of these. It takes the guesswork out of whether the battery is good or bad. You fully charge the battery and let it sit overnight then check the cold cranking amps. If it’s rated at 650 and comes up short it’s bad.
Also I’ve said it 100 times but here’s 101, get and use a Deltran battery tender jr., one for each battery. You’ll get a lot more use out of your batteries. When parked between trips mine always have them hooked up. My batteries are 8 & 9 years old and still perform perfectly.

I also carry a “Blue fuel” lithium jump starter sold by NAPA Auto just in case.
I’ve used it to start my motorcycle (6cyl Valkyrie) and a pickup. They are small but work amazingly well.
It’ll jump start a V8 engine several times before needing for itself to be recharged and it has a port to recharge cell phones.
If you don’t have one get it, you’ll thank me!

 

[Jonah]

Thanks Lt. Mike. I'll look into the load tester and the blue fuel. Good ideas for sure.

But about a year ago, I received one of your other 100 recommendations for the Battery Tender, and have enjoyed using it ever since. I haven't been using it lately, since my new boat has a good charger that auto-charges, auto-maintains, and also auto-conditions on a monthly basis. I figure that's got to be as advanced (or more) as the Battery Tender Jr. If I get myself set up with another house battery, though, I'll use the Battery Tender to charge it whenever I'm at dock.

 

[Jonah]

Ok, here’s a happy ending for this thread.

After some more wire tracing, I found that the previous owner’s wiring to the house battery (which was moved to under the aft cabin) was still in place. Only trick was locating and inline breaker that had tripped. So, I can now go back to having a dedicated house battery, and I have just ordered a Deka Marine Master DP27. Thanks to Dennis and Doc Stressor for the recommendation.

I’m ordering it through a friend in the US, who will boat over soon. Much, much cheaper. I also ordered a replacement for my other starter. But instead of another 24M5, I went with the DP24. Same size, same cranking amps, but some extra reserve/deep cycle power if I ever need to use it as a house, the way the previous owner had things wired most recently.

So, one new 24M5 starter, one new DP24 starter, and one new DP27. Plus some jumper cables. I’ll think about picking up a lithium jumper if I start doing more overnight trips.

Anyway, thanks again for all the help. I learned a lot this time.

 

[Fishtales]

Keep an eye on Amazon. I got a two bank Minn Kota on sale with a $25 rebate. All in was less than $40.
https://www.amazon.com/dp/B0042T4GIW/ref=twister_B07CP55NGX

Great little charger for the money.