Boat Batteries

[ChrisOlson]

I just took my boat batteries off our big bank and getting ready to put them back in the boat:



These batteries will have their 8th birthday in April.  Every winter they have been taken out of the boat and hooked in parallel with our big battery bank as a way to keep them active and maintain them.  For years, that was a 12 volt system.  This winter they survived 5 months of being boiled at 30+ volts (wired in series) hooked up with our Surrettes and powering our place on our new 24 volt system that we installed a year ago.  Many days during the winter with heavy loads on our system they got pulled down as low as 11.5 volts.  I load tested them with my AVR (one hour test on each one @ 25 amps) and they both test with the same specs as new on the RC (Reserve Capacity) test.

I'm finding more and more, as I work with deep cycle batteries, that the cause of early death of these things is under-charging and inactivity, not over-charging and deep cycling.

The Mercury four-cylinder survived the winter too   

--
Chris

[DamonHD]

Would you imagine gels to suffer from the same, ie undercharging and under-use?

Rgds

Damon

[thirteen]

So many people end up getting new batteries or their batteries are weak from just sitting idle over the winter months when not in use. Decades ago we used to take all of the batteries out of all of our farm equipment and store them in the garage with a trickle charger for each one. Around every 2 months my dad would go out and put a load on each one while they played their card games in the office (now known as a man cave). Very seldom did we ever have a battery failure. I did not realize what he was doing until later in life. Unknown OJT works years later. Thanks DAD

[ChrisOlson]

I don't really know much about gel batteries and their care and treatment.  I've always had lead/acid ones.
--
Chris

[DamonHD]

Sorry not to be clear: I meant lead-acid gel batteries.

Rgds

Damon

[ChrisOlson]

Sorry not to be clear: I meant lead-acid gel batteries.

Well, again, I'm not familiar with those so I shouldn't comment.  I'm familiar with the run-of-the-mill flooded lead/acid variety.  And it appears to me that as long as you keep an eye on water usage, don't let the batteries get too hot (use temperature compensated charge controllers), and don't mismatch batteries connected series that using what would be otherwise excessively high charging voltages does not hurt them.

I can only surmise, based on my experiences, that it is sulfation (and possible electrolyte stratification) that kills most flooded lead/acid batteries before their time.  Not breakdown of the plates or separators.  To take two relatively "cheap" marine deep cycles that have been abused** (according to most standards) for 8 years and have them still test with new specs on a Reserve Capacity test seems to support that observation.

** by "abused" I mean these batteries have endured 8 seasons of pounding in the boat on rough water.  And other 8 seasons of being used on my off-grid battery bank.  They have regularly been deep cycled as low as 11.5 volts, and sometimes lower than that in the boat over a weekend of walleye fishing at night.  They have been recharged at excessively high voltage most of their life - in the boat with an onboard MinnKota marine dual channel battery charger, with temp compensation, that charges them at 15.7 volts during absorb in cooler weather and 15.0 in warmer weather.  At times last winter they went as high as 33.0 volts during equalization cycles on my battery bank.  And they have never been floated for very much of their life.  They're either being charged or being worked.  And yet, they're still good.

I have seen people kill Trojans on RE battery banks in half the time these have lived, and the RE batteries were not worked as hard as these have been worked over their lifetime.

So I just don't know.  The battery manufacturers will tell you that 14.4 volts (for 12 volt battery) is supposed to be the "ideal" absorb setting.  And float at 13.2, or whatever.  And don't cycle them below 50% or you'll shorten their life.  And the batteries die in 5 years anyway, being lightly cycled and "properly charged".  And then you got these cheap marine deep cycles, that aren't even premium batteries, and they live on beyond 8 years being treated like I have treated them.

Maybe the battery manufacturers like to sell batteries?  I don't know.  But I do know there's nothing special about these.  They were $58 apiece new and they're 95 amp-hour, made by Johnson Controls and sold thru Farm & Fleet.
--
Chris

[REdiculous]

1) Never above 14v, never below 12v.
2) Recharge ASAP.
3) No extreme temps, or extreme temp changes in a short period of time.

My SLAs have lasted a few years following those simple "rules". I'm sure I don't have more than 100 cycles on them yet, but I make sure to abuse them a little bit when I take my ebike out.

Lots of cheap ebikes kill their SLAs with an LVC around 10v (per SLA) -- that's why you'll almost never find a used ebike w/ good SLAs. They set the LVC low so you can go 10 miles instead of 8. Then someone forgets to charge after riding and the batteries kill themselves.

[thirteen]

best battery I'v ever had was a Willard used from 1960 to 1974 in a 1959 Buick Invita. Never had one problem with it. Just an odd thought of worthless information good for nothing. Car killed a nice deer at around 85 mph and then died. 

[ghurd]

1) Never above 14v, never below 12v.
2) Recharge ASAP.
3) No extreme temps, or extreme temp changes in a short period of time.

My SLAs have lasted a few years following those simple "rules". I'm sure I don't have more than 100 cycles on them yet, but I make sure to abuse them a little bit when I take my ebike out.

Lots of cheap ebikes kill their SLAs with an LVC around 10v (per SLA) -- that's why you'll almost never find a used ebike w/ good SLAs. They set the LVC low so you can go 10 miles instead of 8. Then someone forgets to charge after riding and the batteries kill themselves.

Agreed, 99%.

I would change 1) to: "never above 13.8V, never below 12.2V, if humanly possible".

They only last so long, even if they are never used, so may as well use them while they work.
G-

[REdiculous]

Agreed, 99%.

Back at ya! Here's my change...

12-14v for EVs.
12.2-13.8v for off-grid [and most other] applications.

I'm used to thinking "EV" by default.

[ChrisOlson]

12.2-13.8v for off-grid [and most other] applications.

I must be not understanding something.  How do you charge an off-grid battery bank at 2.3 VPC?  The electrolyte will stratify, excessive sulfation will occur on the bottom of the plates and the batteries will be dead inside two years.

That's kind of like batteries that live their whole life on float, like in these computer UPS outfits.  Those batteries rarely last more than two years living on constant float charge.
--
Chris

[REdiculous]

We're still talking about SLAs, right?...

The "off grid" part is just about the type of installation; stationary, rather than in an EV.

I dunno what 2.3 VPC is.


It's just my general rule of thumb that's worked ok for me. I've been running a small SLA pack, now a whopping 12v 50ah, on my ebike for a few years now.

[ChrisOlson]

VPC= Volts Per Cell.  Those sealed batteries are probably different.  They might bulge up and explode if you put too much volts to 'em.
--
Chris

[REdiculous]

Duh@VPC...lol..I should've known that one.

14.4v is as high as I'd ever try to take a general-purpose SLA...

Mine say up to 14.8v for cyclic-use and 13.8v for stand-by but I've never gone above 14v since there's only a few WHs up there and it takes forever for it to absorb the last little bit.

[ChrisOlson]

Is that the same kind of batteries that they use in those computer UPS units?

I've always figured that those things were made to die so you have to replace them all the time.
--
Chris

[REdiculous]

SLAs are extremely common in UPS units and emergency jump starters. The most common size is 12ah. On the high end they're starting to use LiFePo4 batteries though.


Even a "dead" SLA can be useful in the right hands. I've got an SLA sitting next to me and half the gel is gone - has been since I got it - it works just fine as a 6v battery.

[JW]

There's also another class to consider Valve Regulated Lead Acid or VRLA. These type of batterys (usually 12volt) can be boiled out. Ive gotten good results adding ACS sulfuric acid when combined with a discharge (load) cycle. Distilled water was used to top off the cells, then the concentrate electrolite(10ml usually).

[dbcollen]

Interesting the different tangents that this identical post went on both forums. 

[tecker]

These are prone to freeze at 11.5 or lower . When scrounging for used batteries that's the first thing I look at . Most in the recycle have some swelling .
 Those with low fluid freeze and swell
  Taking the batteries out of the boat and keeping them from the elements probably is the main reason they have lasted
 

[ChrisOlson]

I know a lot of people who leave their batteries in the boat because they got a battery maintainer built right into the boat.  So they put it in storage and plug the maintainer in.  Those people are replacing batteries every three years, from what I've seen.
--
Chris

[tanner0441]

Hi

We used to replace batteries on boats every year, conditioner chargers help, but the customers who took their batteries off and ran them over the winter on company vehicles had the least trouble.

The type I preferred were the VRSLA or the AGM. basically because they didn't weep like the standard flooded ones did and you could tip them up to lift the from the ridiculously placed battery boxed.  The boat designers never lifted a battery in their sheltered little lives.  The AGM batteries seemed to be the most robust but they were also the most expensive. I have a 95 Ah on my motor home and it does everything I ask of it.

I don't know what engines you have on your boat Chris but we used to fit 113Ah at 12V on anything up to 800 BHP above that the engine manufacturers didn't give the option it was 24V only.



Brian

[Simen]

The problem are that most, if not all alternators aboard those boats are standard car alternators; or so called 'marine' versions of them; they do not treat the batteries nice at all...

[vtpeaknik]

Regarding SLAs, I use some small ones (from 4 to 12 AH, 12V) and always wondered how to recharge them.  They're used in sailplanes to run radios etc for several hours, so they're something like half-empty by the end.  For years I used a constant-voltage charger, and to make sure they get reasonably full in a finite time (several hours, or overnight) I set it to about 14.2V.  Is that too high?  I do not leave them connected on "float" after that.

More recently I got a cheap little switch-mode SLA charger, made in China, that is supposed to be a 3-stage smart charger, but I am not sure what it really does.  It changes its LED from red to green after not that long a time, and after that I am not sure whether it's "full" or should stay connected for a while longer.

There's also the question of how to maintain the SLAs in the winter (no flying).  They seem to maintain their open-circuit voltage OK for months, but I try and put them on the charger a couple of times during the winter anyway.

If/when the grid power goes out the SLAs become LED-lamp power supplies.  A 1 or 2 watt LED lamp can run for days off such a battery.  If I ever had to recharge them while the grid is still down, need to somehow connect them to my much bigger (450AH) 12V system with PV and inverter.  In that case, should I simply connect them in parallel with the big battery bank, or run a smart charger off the inverter?  The latter is much less efficient unless the inverter is turned on and running a larger load at the same time.  I do have a couple of little 5W PV panels with integrated charge controllers (old VW dealer battery maintainers), that's another option if the sun is shining.

[ChrisOlson]

We used to replace batteries on boats every year, conditioner chargers help, but the customers who took their batteries off and ran them over the winter on company vehicles had the least trouble.

I could believe that.  I just got done putting in a new power bus and dual feed switch panel, and rewired the boat for 24 volt.  The engine starting is still 12 volt, though.  I spent $280 for two 100 foot spools of Ancor marine grade wire for that project   
--
Chris

[tanner0441]

Hi

I am still not happy with the capacity of my RE batteries, they charge OK, get the resister on my drop tester to the point of melting but don't seem to run the inverter as long as they used to, in fact I could leave it on all night and the batteries would still be over 12 now just the quiescent current pulls them down.  So decided to read up on batteries. As for AGM and gel batteries they seem to be more robust re: vibration and banging about but the sites I looked on all advised against over charging, though there was no mention of the low voltage point of damage.

So I think for me as unlike a boat switching back to grid is not life threatening if the batteries go flat, so my wallet will decide for me.  On my own boat I had two 85Ah batteries fitted and charged both but radar, plotter, radio's, nav lights, and depth sounders were isolated from the engine battery, but could be switched in if needed.

Brian

[ghurd]

Is that the same kind of batteries that they use in those computer UPS units?

I've always figured that those things were made to die so you have to replace them all the time.
--
Chris

They are the same batteries used in UPS units.
I think 7AH is more common than 12AH.

The things were NOT designed to die.
The chargers in the UPS units were designed to intentionally kill them.
ie: 
Wally Wonker's cash registers need UPS's.  The guy in charge of that calls a $150/H guy who knows enough to put an UPS on a cash register.  Neither of them know what they are dealing with.  In a year when the UPS says the battery is substandard, it is cheaper to BUY A NEW UPS than change the battery, when labor is figured in.
Many UPS makers intentionally make it impossible to know what the DC input voltage is from the data sheets or manuals, because they intend to sell new batteries at 3 to 5X the going rate, or a new UPS.
It is usually cheaper to have new UPSs installed.
And that is why used UPS's with no batteries are cheap or free or thrown in a dumpster.

I have used removed from UPS as 'used and faulty' 7AH 12V SLA for 10 years after the date code, and they still work fine for what I want to do with them.
The trick is to use a decent controller actually suited to them (properly adjusted ghurd controller, VW PV with the built in controller, PB137ACV <137 is 13.7V>, etc?) that will not go past 13.8V.

Don't believe everything you read on a battery charger box.  HF crap with coupon box says "13.2V regulated, suitable for 5 to 125AH", but the last maybe 10 I bought go way past 14V.

Below 12.2V is when hard sulfation happens.

If possible, keep SLAs between 13.8V and 12.2V.
I try to keep the 7AH ones in my house between 12.5 and 13.7V.  Works for me.

Brian, "robust", yes.  As pilots know, that is why they are commonly used in aircraft.

[bob golding]

i have  8 450 amp hour surrettes. i use a morningstar ts45 charge controller set to deep cycle. which is 15 volts. surrette do say you should cycle them to increase the area of plates being charged. i use all of them in the winter and they sit at around 23.5 volts (24 volt system) in the winter they do get fully charged and the dump load kicks in  occasionally. in the summer i charge them fully and just use half of the bank as i dont get enough wind to fully charge  all of them. hopefully i will have 750 watts of solar to add later in the year so will see what that does. had them 3 years so far. and they seem to still be fine. i charge them from a generator and  can safely put around 50 amps in without cooking the charger.

[ChrisOlson]

Bob, if I had it to do over again I might look at something different than Surrettes.  They take such gawd awful high charging voltages that I think it "wastes" a lot of power just in charging losses.  But, on the other hand, they seem to have more capacity than they're rated at too.  Our bank (2,400 ah @ 24 volt) will deliver 3 kW continuous for 12 hours with no incoming power and it's still above 24 volts - under load.

We would have bought Trojans except the guy at the RE place where we got them told us that these Surrettes are what we need with our setup.  He had the Trojan 6 volts in stock and he had to order the Surrettes.  But I still would've like to try some Trojan batteries.
--
Chris

[bob golding]

hi chris, agree on the charging voltages. i have tried various charging regimes and have ended up with a home made one. i couldn't get enough voltage with anything standard when using a genny. had to crank the genny output right up to get any charge into them. what i have now is a 160 volt transformer running though a variac. the genny puts out 240 volts so i have some leeway. enough to cook the transformer if i wanted to charge them fast. the open circuit voltage on the dc side is around 50 volts.

 i was told the surrettes are better than the trojans but i have no way to tell if that is true at £2000 for a set of batteries i wasn't going to gamble. i just went on what the .dealer said. as i got them at trade price though a friend the dealer wasn't making much anyway so didn't need to hype up the surrettes over the trojans. he mainly sold to boat owners rather than static systems.
 i don't know if the constant movement in a boat makes a lot of difference to the stratification issue on different makes of battery or not, or how we could test that theory. i am in an old bus so get  a bit of movement in gales, nothing like what you would get in a boat though, but more than if they were sitting on the ground.

[ChrisOlson]

What the dealer told me is that they have to have the snot boiled out of them on a daily basis to keep them from stratification because they're low specific gravity batteries.  Otherwise they end up using only part of the plates and lose capacity real fast, then require what Surrette calls "corrective equalization".  But, man, does it ever take volts to get them boil decent.  Even in float they take a lot of power.  It takes 25-30 amps just to float my bank.

My bank is a year old now and they're still like new - not even a sign of any reduction in capacity after a year of hard use.  And when it comes to capacity, they do have that.
--
Chris

[dbcollen]

My bank of Surrettes (24 S-530) will float at less than 4 amps @ 54.4v. Float is set to 52.4v and the temp compensation brings it up to 54.4@56f. If you need 25-30a just to float them the batteries are still hungry and you probably need a longer absorb cycle. My bank is 1600AH@100hr rate 48v.

[ChrisOlson]

Mine usually kicks out of absorb because of the max 3 hour timer.  If we got really good power coming in then it will sometimes kick out on the low amp setting for absorb, and will take a little less power to float.  I try to get 95% SOC at the end of absorb and do the last 5% on float @ 27.0 volts.

If I cut the float voltage back to 26.0 then it takes only half the power to float them.  But they never reach full charge at that float setting (24 T12-250's).

If I set the absorb timer longer, they tend to use a little too much water.

I also use the capacity at the 20 hr rate, which is 200 ah.  At the 100 hr rate they're 266 so then my bank would be 3,200 ah.  I use the 20 hr rate because we work them down to 65% SOC or so every 24 hours, on average, and they should be charged during bulk at 240 amps.  Most days we can manage the 240 amps pretty easy for bulk charging and get them into absorb by noon (depends on how much wind power we get during the night).
--
Chris

[bob golding]

without digging out the  morningstar docs to check mine run mainly with the red and yellow lights on. if it goes down to just the red light i try and recharge them from the genny. plenty of wind today so sitting with the yellow  and the green lights on at the moment. doent usually sit there for long except in the winter. my loads are fairly low and constant. 1kw inverter, on all the time. laptop around 100watts on intermittently satellite about the same as the laptop 100 watts hard disc recorder on all the time 25 watts few  led lights 20 watts. total around 300 watts. the turbine will supply this most of the time except when we get weeks of high pressure, hence the solar. have just disconnected one bank today for the summer. summer?? lashing  gale out there at the moment, must be because its easter monday.