Battery question

frick

Member III
I have not seen this mentioned. Lead acid batteries in a boat have a life expectancy of about 5 years. Also The battery output is not the amps hours listed on the battery. A 150 amp battery cans do the when it's new. By year two my best hours is you will only 50% of it's rating for the remainder of its life.
I forgot to mention that Untill this I have always lived up north in snow country.
 

N.A.

Member II
A battery analyzer can tell more about condition of batteries beyond voltage readings. This one from Harbor Freight gave me comparable result to units 2X the cost and have helped diagnosed my own and other boaters' battery issues. It measures resistance across the plates. From your description, it sounds like the battery/batteries is not holding charge.

All indications are that your batteries and charger are fine.
I am quoting Jerry and JTsai just so they both see this and understands my gratitude for their earlier feedback

First: thanks for the suggestion! Harbor Freight... took until now to deliver the analyzer to me.

Results:
Start batt: 12.66V; 6.79mOhms; 390 CCA (battery is nominal 800)
House batt 1: 12.75V; 4.04mOhms; 645 CCA (battery is nominal 800)
House batt 2: 12.78V; 5.04mOhms; 525 CCA (battery is nominal 800)

All batteries are same type AGM, Marine RV "Intimidator". No dates as to installation, but all look the same. Batteries disconnected from each other when measured (and let sit 30 min prior); house batts had positive cable removed; start battery did not, since that would have erased Xantrex memory, but main battery switch was "off".)

--> I am unsure how to interpret this; the CCA suggests the start battery needs to be replaced, but the internal resistances are all pretty low.

--> Does one need to replace ALL the batteries at the same time? I.e., if I just replaced the start battery, would that be a bad idea? I would replace with AGM. Concerned having batteries at different levels of age/capacity may somehow result in them damaging each other.

--> if I have to replace all batteries at same time, is it advisable to update the Xantrex to a newer charger (this would be a major time sink for me, which I would like to avoid. However, I do not want to wreck 3 new batteries with an old charger...)

Thanks again for all the help. Sorry for slow responses; takes me a while to get the equipment, and then go do the measurements.

Also, happy holidays!
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
No expert am I, but the advice I have received over the years was to replace all of the batteries in any one bank at the same time, if possible.
i.e. if you have two 6 volt GC batteries, replace them both at the same time. And ditto for a pair of 12 volt batteries always wired in parallel.
 

jtsai

Member II
I am quoting Jerry and JTsai just so they both see this and understands my gratitude for their earlier feedback

First: thanks for the suggestion! Harbor Freight... took until now to deliver the analyzer to me.

Results:
Start batt: 12.66V; 6.79mOhms; 390 CCA (battery is nominal 800)
House batt 1: 12.75V; 4.04mOhms; 645 CCA (battery is nominal 800)
House batt 2: 12.78V; 5.04mOhms; 525 CCA (battery is nominal 800)

I am not sure taking reading after unplugging the charger for 30 min. is long enough time for accurate state of charge reading. However the charger appears to be doing its work.

The start battery at 12.66v and low CCA after it has been charged does mean it needs be replaced. As far as the house bank, I suggest leaving the charger unplugged and everything off then repeat the reading in couple days and compare with this readings.
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Per most battery information from several sources, 12.6 volts is considered "fully charged."
 

Jerry VB

E32-3 / M-25XP
Results:
Start batt: 12.66V; 6.79mOhms; 390 CCA (battery is nominal 800)
House batt 1: 12.75V; 4.04mOhms; 645 CCA (battery is nominal 800)
House batt 2: 12.78V; 5.04mOhms; 525 CCA (battery is nominal 800)

The start battery at 12.66v and low CCA after it has been charged does mean it needs be replaced. As far as the house bank, I suggest leaving the charger unplugged and everything off then repeat the reading in couple days and compare with this readings.
I agree with jtsai; the starter battery is due to be replaced. The house batteries look like they are reaching (have reached) the end of their useful life.

If it were my boat and my batteries, per your measurements, I would replace all three.

Personally, I would not replace the charger.

Going waaaay back in this thread:
The Xantrex current monitor (shunt) is on the ground for both banks -- they are all interconnected as far as I can tell. I think the Xantrex is only aware of total Ah used from any connected bank, not which it is coming from. Its voltage sensor is only on the start battery (though this is nominally the same for all when switch is on 'Both', I think).
It is important to verify the current monitor connection. If it is truly on the ground of both banks, the PO wired your batteries to be One Big Bank and you should always (normally) have the battery switch set to "All" or "Off", not "1" or "2" so they are connected as One Big Bank. If this is the case, you need to replace all three batteries at the same time.

If the current measurement shunt is only on the house bank ("2"), you can replace the starter bank ("1") independently of the house bank because they are used as separate sources. This is the traditional way of connecting batteries and your use of the 1/2/All switch would be in accordance with tradition (e.g. "1" for starting and running the engine, "2" for house supply when anchored).

Diagram of difference between "One Big Bank" and "Traditional" with the current monitoring shunt:
onebigbank.png
 
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Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
No sure how relevant this is, but we 'never' have our 1-2-all switch set to 'all'. I have read Maine Sail's advice for years, and it makes sense to me to do this.
We leave it on '1' which is our large house bank, for everything. Position '2' is our emergency battery. The last time I replaced the emergency battery was when I put a starting load on it and the voltage dropped too low to be useful. Of course when the charger was turned of it read the usual 13 volts for a little while -- then started dropping. It was an old Optima AGM, and had served us well for way over a decade. Interesting that the failure came rather quickly.

We normally "test" that spare 12 volt battery a couple of starts a year.

And, as is always true, "YMMV".... :)
 

Jerry VB

E32-3 / M-25XP
No sure how relevant this is, but we 'never' have our 1-2-all switch set to 'all'. I have read Maine Sail's advice for years, and it makes sense to me to do this.
We leave it on '1' which is our large house bank, for everything. Position '2' is our emergency battery.
Yes, that is another good option. I actually practice a variant of this; because both of my batteries are identical, I alternate between the two. I use "1" and hold "2" for reserve for odd days and use "2" and leave "1" for reserve on even days. When we are at the dock on shore power, I use "All" to use the batteries equally.

Bottom line is that you need to use the 1/2/All technique that works with how your batteries are sized and wired. My batteries are two identical ones, Loren's batteries are big/little (backup), N.A.'s batteries are identical in size but one bank is two batteries and the other bank only has one (effectively big/little).

That is why I'm so focused on the battery shunt - it shows the intent of the previous owner in how the batteries should be used... either One Big Bank or a traditional starter/house (or Maine Sail house/emergency) technique.
 

Pete the Cat

Member II
Just an alternative way to think about "emergency back up" power and battery health. I have run both of my golf cart banks through a common ground/shunt and carry no starter battery for 30 years through a bit of serious cruising taking down my 440ah in two banks by 150 ah in 24 hr with some regularity. I run "All" all the time. It spreads the usage and makes sure I know the status of my banks all the time through the BMS. While I generally respect my fellow Mainer's (Mainsail) suggestions, this is one where I deviate from his advice. My theory is that monitored batteries fail suddenly only through a shorted cell or external short and, if you have two banks that you maintain and monitor regularly (instead of having an emergency starter battery system that requires some special inspection to assure it is working) I am more likely to note a problem and tend to see it early. If I were to awaken to a completely discharged bank, I would suspect a shorted. cell or some short outside the whole system. This would be easily located. If it is in the bank, I simply isolate it and let the good bank recover. A lead acid battery that has been suddenly discharged will recover enough to start a small diesel (they do not require much CCA) in a couple hours. I have started other folks' boats from "dead" batteries (that are simply discharged and not internally shorted) a couple times by simply disconnecting all the connections and letting the battery sit for a few hours and they came back enough to start the engine. To me the simplicity of this system makes sense. I also wonder why folks carry the weight and complexity of "starting battery systems" when they could buy an automotive jump start system for. $60 that will start most auxiliary diesels. I have never really had a problem of any kind with my own boats and I generally just change out my two sets of golf cart batteries every 7 or 8 years (and they seem to be functioning just fine, though I have not tested their capacity at change out. I do keep the banks on a trickle charger in the offseason and watch fluid levels closely. I got this idea many years ago from an experienced world cruiser and have never found a reason to change. FWIW.
 

Kenneth K

Contributing Partner
Blogs Author
No sure how relevant this is, but we 'never' have our 1-2-all switch set to 'all'. I have read Maine Sail's advice for years, and it makes sense to me to do this.

I've never been able to buy into the uproar over setting the battery switch to ALL. I do it regularly. The usual explanation for NOT doing it is what can go wrong if you later forget to take it out off ALL.

But sailing is full of such decisions. Forget to open your raw water seacock and you overheat the engine. Forget to slip the gearbox to neutral while sailing and you glaze the gears, forget to untie a line at the dock and you tear off a cleat.

Perhaps if people viewed the battery switch as more of a recurring-use-item, it would be less likely that it is forgotten as an afterthought.
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
But sailing is full of such decisions. Forget to open your raw water seacock and you overheat the engine. Forget to slip the gearbox to neutral while sailing and you glaze the gears
With the Hurth trans, I have always heard that it should stay in reverse when under sail, to lock the prop. Ours would make noticeable noise from wind-milling the prop if left in neutral.
 

Kenneth K

Contributing Partner
Blogs Author
With the Hurth trans, I have always heard that it should stay in reverse when under sail, to lock the prop.
Thank you Loren, reverse is what I meant to say. Wish mine would make that noise when windmilling. It doesn't. And I have, on occasion, (ahem) forgotten to put in reverse while sailing.
 

bgary

Advanced Beginner
Blogs Author
Yes, that is another good option. I actually practice a variant of this; because both of my batteries are identical, I alternate between the two. I use "1" and hold "2" for reserve for odd days and use "2" and leave "1" for reserve on even days.
I do a variant of your variant.... I use "1" in odd-numbered months, and "2" in even-numbered months.

B
 

N.A.

Member II
Thanks again, folks. I looked into Firefly batteries (Maine Sail seemed to like them), but at $550 each locally, and out of stock, I think I'm going AGM. Multiple folks have suggested Lifeline batteries ($1200+ shipping for 3 group 27's); due to significant heeling in the strong winds here and desire to go offshore, I am not going to do flooded lead acids, despite their huge $ savings. Just before I pull the trigger:

--> Anyone have opinions on gel vs AGM?
Prices seem similar. My main use is day sailing off the dock (so full SOC after each sail), but for offshore I have no solar, so it would be a lot of PSOC (e.g. on a trip to Hawaii from the bay area).

--> Battery jump starters (e.g. Matco, etc, like used by AAA for cars): does anyone carry one of these?
I have 3 batteries, but only two fit in a well; the other is well wired but not strapped down. I could strap it, or... cut back to only two group 27's, both of which fit in the battery well, use both as house/all batteries, and keep one of those $100 car chargers around for emergencies. Curious if anyone does this. [For offshore, I'd go to an even/odd day thing, which I had learned to do to keep battery wear even on both banks, and maybe add a 3rd battery back in.]

Thanks again for all the help!
 

David Grimm

E38-200
I keep a Noco Genius jump pack with me. Not so much to start the boat but to extend the life of my cellphone. You can find it at Autozone. I believe there are 3 available sizes. It's small, light weight. Has a built in flashlight and come with a charge cord. However you will need your cellphone wall charger to charge it.
 

N.A.

Member II
Well, I have gotten new batteries (Lifelines), and installed them. Or installed 2 of the three; it became clear that the boat had previously been badly wired -- previous owner added a 3rd battery, but it was not wired properly in parallel, so load was not evenly shared between the batteries. So a later task is to get the crimper and make myself new cables to get that right, and add fuses within 2" of the positive terminals. [Does anyone add to EACH positive terminal, when setting up a parallel set of two batteries, or just a single fuse off the combined positive output cable?]

However: When I put them in, and reset and set up my Xantrex Link 1000, it allows me to set the final (float) voltage, and the Peukert coefficient, and set for AGMs, but... when charging, it goes from bulk (which does not seem to happen at the maximum current the charger can do) to Acceptance (which should be at 14.4-14.5V for my temperature and batteries, per the lifeline manual) which is NOT at 14.4V (runs lower), and then ends at 13.3 despite my having set it for 13.4 [actually ends higher, about 13.85, then drops to 13.3 after a while]

I am unclear whether I need a new charger -- I though I should have it giving max current during 'bulk', then fixed at 14.4 during 'acceptance', then staying at 13.4V during 'float'. I seem to only be able to set one of these. Unsure how problematic that is, or whether I'm understanding properly. I think the charger is working properly, just unsure if "properly" for the charger is what is right for the batteries.

Thanks again for all the help so far.

PS: MarineHowTo apparently does not think much of those batter resistance testers, like the Harbor Freight one -- c.f.: https://marinehowto.com/are-battery-conductance-testers-worth-it/ , and the Lifeline manual talks only of doing the same type of load test that MarineHowTo discusses. So I am unsure the meter I got is actually worth anyone else's time (if you are reading this thread years later) -- a load test seems to be what I should have done. [To be clear, this is not a complaint/I am not unhappy; live and learn, and now that the new batteries are in and working right it appears certain my old ones (or at least some of them) were bad -- so the battery replacement was worthwhile.]
 

Jerry VB

E32-3 / M-25XP
@N.A., you refer to the Xantrex Link 1000 as your charger. It is a battery monitor and charger controller, not the actual charger. Looking at what the Link 1000 is compatible with, my guess is that your charger is a Xantrex Freedom Marine (pdf manual). You should verify what charger you have and how it is connected, especially since you discovered the third battery was connected improperly.

In the Freedom Marine manual, p.20, it has voltages vs. temperatures. The charger has an optional external temperature sensor (p.10). Per the manual, "If no sensor is connected the charge voltage levels are set to defaults based on battery type." Per p.20, the default is 70 degrees => 14.3v / 13.3v.

My understanding of battery charge voltages are that they are "about what you can expect" values. Note that all the voltages are of the form XX.X which is the scientific notation that indicates significance to 0.1v and accuracy to +/-0.05v. You are measuring a voltage (and/or current) which is an indirect measurement of a chemical reaction so the measured voltages and currents are an estimate of what you really want to know - the state of the chemical reaction (charging or discharging).

Bulk charge currents are entirely dependent on the current state of charge of the battery (the "acceptance rate" of the battery, which drops as it charges). A charger will put out full rated current only when the battery is relatively deeply discharged (deeper than, say, 80% charge level). The batteries you installed were probably above 80% charge level so the bulk charge stage will not be putting out full charge for long, if at all.

Bottom line: I have not seen anything that you measured that indicates that your charger is bad but it is hard to make a definitive diagnosis over the internet (and, hey, you don't know that I'm not a dog). There are New Improved chargers (inverter/chargers) with New Improved battery monitors that likely are Now Smarter And Better than the one you have. They also run two boat Bucks.
 

Kenneth K

Contributing Partner
Blogs Author
So a later task is to get the crimper and make myself new cables to get that right, and add fuses within 2" of the positive terminals. [Does anyone add to EACH positive terminal, when setting up a parallel set of two batteries, or just a single fuse off the combined positive output cable?]
I think the ABYC standard is fusing within 7" of the battery. If the paralleled batteries are in the same location, you ignore the inter-battery/paralleling cables and just fuse the output post of the last battery in the bank.

20200622_204220.jpg

If the batteries are located in separate compartments, and there is a chance of chafing/shorting on the paralleling cables, it would make sense to fuse each cable that may be subject to chafing/shorting.
 
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