Are My Batteries Toast?

[a64pilot]

For my AGM bank, all I have to determine full charge is acceptance rate, for my 660 AH bank, that is 3.3 amps at absorption voltage, don't forget about house loads, they add to that 3.3 of course.
I can't of course check specific gravity, but you can.
I'm suspicious of that one low battery, it may come back from an equalization charge, but I'm suspicious of its connections or maybe the way the bank is wired. I think it can account for the bank being a few percent from full.

On charging , think of filling a glass with your facet, however when it's close to full you have to resort to an eye dropper. Really the closer to full we get, the slower it will accept a charge.
I know you know this intellectually, but don't yet believe how slow that last 5% or so is, it takes time, hours not minutes. That is why I don't think you can overcharge with Solar, not If the bank is used during the night anyway, yes you can on a bank that isn't, like when the boat is in storage.

However leave the smart gauge alone, the darn thing is smart, I believe it's awfully close to accurate right out of the box and gets real darn good in just a couple of days, not a week, just a day or two, if you reset it, you start that over of course.
If your getting into the 90's daily, that may be as good as your going to get, 100% daily isn't really achievable without shorepower or at least maybe not realistically. You could start the generator a few hours early every morning before sun up and then likely get to 100%, maybe if your back to 90 by sun up or so.
But why? Amortize out the bank cost as compared to the cost of running the genny and likely it's cheaper to not get to 100% daily.
My plan is different than yours for a couple of reasons, first I plan on washing clothes aboard with an electric clothes washer, and making water with an AC watermaker. That means at least once a week, extended generator runs. May as well do that early in the AM and charge the batteries too. Plus we will take a a marina with shorepower at least once a month too for shopping etc. and to equalize the bank.
I do not plan on 100% every day, I don't think that is realistic, but if I can get there once a week with monthly equalization, I think my bank will live a good long life.
I think Sailorboy has a valid point on battery banks, you can either spend big bucks on programmable everything and continually obsess over the bank, constantly monitoring and fiddling with everything, or install a decent, not the best, but good charging system and forget about it. You'll save a lot of money up front, enjoy life without so much worry, and your bank lives one year less, but amortized out, it may still be cheaper than the guy with the perfect system, and you didn't worry about it all the time, waking up in the middle of the night to start the generator and you were a lot better neighbor in the anchorage too.

However some of us enjoy fiddling with things, trying to build the perfect system is enjoyable to us, it's a hobby or maybe a continuation of what we did for a living.
But if your not one who enjoys it, forget it. You have a good system, enjoy life, just replace your bank at seven years, while the guy who obsesses over it gets eight
Nice to remember the average joe maybe looks at his bank voltage and thinks, 24 volts, thats great, I have a 24 volt system and doesn't think anymore about it, and yet gets by.

[Dockhead]

Originally Posted by a64pilot

. . . If your getting into the 90's daily, that may be as good as your going to get, 100% daily isn't really achievable without shorepower or at least maybe not realistically. You could start the generator a few hours early every morning before sun up and then likely get to 100%, maybe if your back to 90 by sun up or so.

But why? Amortize out the bank cost as compared to the cost of running the genny and likely it's cheaper to not get to 100% daily.

My plan is different than yours for a couple of reasons, first I plan on washing clothes aboard with an electric clothes washer, and making water with an AC watermaker. That means at least once a week, extended generator runs. May as well do that early in the AM and charge the batteries too. Plus we will take a a marina with shorepower at least once a month too for shopping etc. and to equalize the bank.

I do not plan on 100% every day, I don't think that is realistic, but if I can get there once a week with monthly equalization, I think my bank will live a good long life.

I think Sailorboy has a valid point on battery banks, you can either spend big bucks on programmable everything and continually obsess over the bank, constantly monitoring and fiddling with everything, or install a decent, not the best, but good charging system and forget about it. You'll save a lot of money up front, enjoy life without so much worry, and your bank lives one year less, but amortized out, it may still be cheaper than the guy with the perfect system, and you didn't worry about it all the time, waking up in the middle of the night to start the generator and you were a lot better neighbor in the anchorage too.

However some of us enjoy fiddling with things, trying to build the perfect system is enjoyable to us, it's a hobby or maybe a continuation of what we did for a living.
But if your not one who enjoys it, forget it. You have a good system, enjoy life, just replace your bank at seven years, while the guy who obsesses over it gets eight
Nice to remember the average joe maybe looks at his bank voltage and thinks, 24 volts, thats great, I have a 24 volt system and doesn't think anymore about it, and yet gets by.

Really good advice

I don't know about Ken, but I've got more than enough things to manage and worry about on board, without micro-managing my battery bank.

My formula is really simple:

1. Have enough capacity to keep my electric-guzzling boat happy for a good while. 420 amp/hours * 24v.

2. Don't hesitate to crank up the genenerator when there are heavy loads or the batts start to get a little low. Don't try to eke out the last 10% or 20% of capacity down to 50% -- if you charge at 60% or even 70% you are extending the life of lead acid batteries. It really helps this point to have a heavy duty, low speed generator. For two reasons: (a) they are quiet (inaudible from outside the boat) and the frequency of the sound is pleasant, not the hysterical screaming of the 3000 RPM ones; (b) they are rated for continuous duty, usually 20,000 hours, which you'll never get to in a whole lifetime of cruising, so you're really only just spending fuel.

3. Always charge at least until the bulk phase is over.

4. Charge until the absorption phase is over at least every couple of days.

5. Charge to really full at least once or twice a week. And equalize fairly often if they are being left partially charged a lot.

6. Have a heavy duty externally regulated alternator, so the batts get a good charge whenever you do any motoring.

7. Use them and don't worry about it. They're just batteries -- consumables.


I am in general a data and control freak, but with batteries -- I don't really care to know whether I've achieved 85% or 90% on this charging run, or 75% or 80% or whatever. It just doesn't matter. What I really want to know is when do I need to charge -- and simple voltage reading does this just fine; and the SmartGauge does it better than anything.

Another way to look at it -- if you have a heavy duty generator -- you only need the batteries for coasting between generator runs to conserve fuel and machinery hours. They are not actually so much mission critical. If they get low a little faster than you expected, it's no big deal -- just crank up the generator.

[td0tz]

'Scuse me, off topic, but what?

Originally Posted by Kenomac

another being that all the bearings on our main sail furling swivel from 73ft up came raining down on me the other day, they'll need replacement otherwise no mainsail for a while... which isn't the end of the world.

They just randomly came loose, and fell out of the mast?

[Kenomac]

Originally Posted by td0tz

'Scuse me, off topic, but what?
They just randomly came loose, and fell out of the mast?

No, the bearings wore out and need replacement. Didn't notice until they fell out of the swivel. That's sometimes how it goes with exposed bearings.

Nothing "random" about it.

[john61ct]

Originally Posted by Dockhead

My formula is really simple

Great approach for those with a solid genny, you're right, that frees you up from needing to monitor things too closely if you prefer not to, long as you have solar for the long tail most cycles.


A nitpick:

Originally Posted by Dockhead

3. Always charge at least until the bulk phase is over.

4. Charge until the absorption phase is over at least every couple of days.

5. Charge to really full at least once or twice a week. And equalize fairly often if they are being left partially charged a lot.

That last just should never happen if you've invested in the proper gear, even in overcast conditions.

And all charge sources should be set so Absorb continues until the bank is 100% full. IOW points 4 & 5 are in fact the same.

Premature infloatulation is the most common mistake murdering banks.

For me #3 is "always charge well into Absorb", sunny days shorter than overcast ones.

[john61ct]

Originally Posted by a64pilot

If your getting into the 90's daily, that may be as good as your going to get, 100% daily isn't really achievable without shorepower or at least maybe not realistically. You could start the generator a few hours early every morning before sun up and then likely get to 100%, maybe if your back to 90 by sun up or so.
...
My plan is different than yours for a couple of reasons, first I plan on washing clothes aboard with an electric clothes washer, and making water with an AC watermaker. That means at least once a week, extended generator runs. May as well do that early in the AM and charge the batteries too. Plus we will take a a marina with shorepower at least once a month too for shopping etc. and to equalize the bank.

I do not plan on 100% every day, I don't think that is realistic, but if I can get there once a week with monthly equalization, I think my bank will live a good long life.

Yes, but why not shoot for as many days as possible and maybe double the bank's life?

By running high amp charge like you say while the genny's doing other things, maybe just an hour or two in the morning, even a small solar setup can get to 100% every day.

Just missing that 1-2 days a week will make a big difference. Once or twice a week will really shorten lifespan a lot.

If you really have no choice, the bank will be getting PSOC half the cycles or more, then next bank go with the least cost option, Sam's FLA GCs, replacing every 3-5 years.

Or check out Firefly Oasis, or maybe even LFP.

[john61ct]

Originally Posted by Kenomac

It's looking increasingly likely that my goal to run the generator for only 1-1.5 hours every other day in the morning is within reach.

With a bit of solar, maybe 45 minutes will get you to 100% every day.

Get into that routine, the next bank might go 15 years.

[Kenomac]

Originally Posted by john61ct

With a bit of solar, maybe 45 minutes will get you to 100% every day.

Get into that routine, the next bank might go 15 years.

Trojan batteries are expensive over here. Around €1800-€2200 for eight 6v batteries. I'm trying to get the most out of them.

[john61ct]

Yes, even more so, get your support infrastructure and habits in place, and you can get many many more years than most people do.

In the end all batteries are consumables.

If you get a chance, get a proper 20-hour load test done.

Once their capacity declines by 25-30% not much point in continuing to use them, they go downhill from there very quickly.

[Paul L]

Originally Posted by Kenomac

I did what the pilot said to do, I kicked the battery bank in the amp this afternoon for an hour after the solar went 100% into float status. The charger ran for 1.5 hours worth of 6amps which returned the Smartgauge back up to 100% on it's own which is where it will stay (hopefully) until the sun sets. I checked the specific gravity a little while later (1/2hr) and half the cells were at 1.275-1.277 or 100% and the other half were between 1.265-1.270, and one battery at 1.255-1.260. So I'm going with these figures for 100%. On a Trojan 24v 450ah battery bank five years old, things look surprising good.

I've set my Magnetronic capacity to 420ah just to see how things match up and will make adjustments tomorrow if necessary.

It's looking increasingly likely that my goal to run the generator for only 1-1.5 hours every other day in the morning is within reach.

You are taking data that clearly shows at least one battery is not at 100%. You'd be better off determining why the battery is not charging properly or if it is starting to fail. The specific gravity reading is more accurate than your battery monitors, no matter what state you initially set them at.

[td0tz]

Originally Posted by Kenomac

No, the bearings wore out and need replacement. Didn't notice until they fell out of the swivel. That's sometimes how it goes with exposed bearings.

Nothing "random" about it.

Sorry, what I meant was did they go without any warning. It would be hard to visually check on bearings 73 feet up and inside the mast. For instance, was there increased friction, new noise, or any such indication?

[Kenomac]

Now I really don't understand this Smartgauge.

At 8am this morning, the Smartgauge read 75%. Bright sunny day, so my Magnetronic counted 40ah being added to the bank along with taking care of the daily refrigeration finishing at 5:30pm which is about right. Amp hour counter at 8am 318, counter at 5:30pm 358. Sunny day, 450w of solar.

The Smartgauge never moved from it's 75% reading all day long. Not even one percent in either direction. Looks like this gauge might be a dud. Will see what it reads in the morning.

Is this possibly related to the inherent inaccuracy of the gauge during the charging phase?

[Dockhead]

Originally Posted by Kenomac

Now I really don't understand this Smartgauge.

At 8am this morning, the Smartgauge read 75%. Bright sunny day, so my Magnetronic counted 40ah being added to the bank along with taking care of the daily refrigeration finishing at 5:30pm which is about right. Amp hour counter at 8am 318, counter at 5:30pm 358. Sunny day, 450w of solar.

The Smartgauge never moved from it's 75% reading all day long. Not even one percent in either direction. Looks like this gauge might be a dud. Will see what it reads in the morning.

Is this possibly related to the inherent inaccuracy of the gauge during the charging phase?

Just remember - it works superbly well when discharging with no charging sources attached. If something is putting juice in - all bets are off.

[Kenomac]

Originally Posted by td0tz

Sorry, what I meant was did they go without any warning. It would be hard to visually check on bearings 73 feet up and inside the mast. For instance, was there increased friction, new noise, or any such indication?

Yes, there was increasing noise and squealing when under tension, but we thought it was the pulley at the end of the boom, which we lubricated several times. Somehow the noise must have transfered down the mast and out to the tip of the boom (hollow aluminum), which fooled us. So yes, in hindsight if this turns out to be where the bearings came from, we had plenty of warning. But I won't know for sure until next Monday when help arrives and we drop the mainsail to examine the swivel.

Actually, it's not difficult to check on them, I just failed to clean and lube them anually when I did the others (staysail and yankee), an oversight on my part. When the halyard comes down with the sail, the swivel can then be easily reached and serviced at the gooseneck. I thought it had sealed bearings.

[Kenomac]

Originally Posted by Dockhead

Just remember - it works superbly well when discharging with no charging sources attached. If something is putting juice in - all bets are off.

OK I'm getting smarter and the Smartgauge seems to be schitting the bed.

I just took specific gravity readings which seem to correlate well with my Magnetronic counter which currently reads 91%. I obtained readings between 1.248-1.265 which indicates a charge somewhere between 85-92% with the one troubled cell giving me the 1.248 reading.

The Not-So-Smartgauge continues to hold steady at 75%... which corresponds with none of the specific gravity readings.

The one calculation which seems to have come from all this (mostly specific gravity stuff), is that my bank capacity seems to be at 380-390ah when full based on the new settings entered into the Magnetronic.

The Smartgauge is getting one more day to perform before it's officially declared a POS.