Charging to 100%

[Livia]

It is difficult to ask a battery question without starting a war, but I'll try!

1) Let's assume I want to buy AGM batteries not Flooded for my own reasons.
2) AGM batteries like to be brought to 100% charge for their longevity.
3) I have a Honda2000 with 100amp charger, a 100amp alternator with smart regulator and am adding 215W of solar in the next few months.

Therefore, if we buy AGM batteries we need to get them to 100% periodically with the 'how often' to be further researched. We can do this using a combination of the following: pulling into a marina with shore power (not our favorite option), charging to 90 or 95% in the morning when the sun is shining and hope the solar tops them off over the day, motoring until they are 100% full, and running the generator until they are 100% full. We are likely to do some of each of these, but we will need to rely sometimes on the generator to do the trick.

I heard in a seminar the news about the shiny new Odyssey batteries. The charge acceptance rate is not particularly interesting to me as we will have a large enough battery bank (between 400 and 600 amps) that our piddly 100Amp input (max) won't take advantage of it.

*However* my understanding from Odyssey's literature (figure 7, page 14) is that they take a higher rate of charge closer to 100% full than other AGM batteries.

Using their graph, I estimated that it would take an 80Amp charging device 3 hours and 40min to restore a 50% discharged 400AH to 100%. We actually can put in 100Amps so a periodic 100% charge would in theory take less time than this. In reality, we would be draining the banks somewhat when charging (the fridge kicks on, etc) unless we turn everything off so, back to 3.6 hours.

I called Odyssey and asked this question (without giving him my answer to the math) and the tech they forwarded me to also estimated "between 3.5 and 3.75 hours". By the way, they also verified that the Sears Diehard Platinum batteries are made by them and are the exact same battery inside in a different color box.

What I can't find is the same literature for a different type of AGM to compare my math so I can verify that this is a shorter time to 100% with the same input than other AGMs and if so, how much faster. In short, for our particular situation, would the additional cost of buying Sears Diehard be worth the piece of mind (and gas and time) so that we could run the generator a shorter period of time.

When I went to Lifeline, all I could find was this.

Thoughts from the battery pros?

[jkleins]

I just put in a bank of Odyssey batteries before winter and while I haven't put them all through their paces I can see already they seem to allow more amps in near full charge then my old Lifelines. The Lifelines were old though so I want to see what happens this spring when I can discharge them below 50% and see how quickly they get back up.

Jim

[Livia]

Thanks Jim - there just isn't a lot of real world data on the odysseys so any info is appreciated.

[Zednotzee]

Not really an answer to your question, but I have referred to this site a bit, mainly regarding long term storage of Li-Ion batteries (works great by the way).

Welcome to Battery University

[Livia]

Thanks Zed. Informative although I agree I don't think it hits this question on the head.

[chala]

Originally Posted by Livia

*However* my understanding from Odyssey's literature (figure 7, page 14) is that they take a higher rate of charge closer to 100% full than other AGM batteries.

How close?

Originally Posted by Livia

Using their graph, I estimated that it would take an 80Amp charging device 3 hours and 40min to restore a 50% discharged 400AH to 100%.

close to 100% or 100%?

Originally Posted by Livia

In reality, we would be draining the banks somewhat when charging (the fridge kicks on, etc) unless we turn everything off so, back to 3.6 hours.

May be not draining the banks, but geting more power from the charger if charger power full enought.

[Livia]

Originally Posted by chala

How close?



close to 100% or 100%?



May be not draining the banks, but geting more power from the charger if charger power full enought.

Hi Chala, Thanks for your response.

I should have said "takes a higher rate of charge all of the way to 100% than other AGMs" meaning that at 94% the odyssey/diehard would be taking a lesser amount than at 90% but at 94% it would be accepting more charge than another AGM would be at 90%. So, the curve still flattens but less so than other AGMs.

100% - said the graph and tech.

Excellent point - the Honda can provide more than the charger can take so the charger would run what was pulling during the charge.

[ka4wja]

Originally Posted by Livia

It is difficult to ask a battery question without starting a war, but I'll try!

Wow, isn't that the truth.....but, I'm not going to fire off any missles...
And, I won't say that anything you decide on is wrong.....if it's right for you, that good enough for me...

Originally Posted by Livia

2) AGM batteries like to be brought to 100% charge for their longevity.
Thoughts from the battery pros?

A) Just for clarity's sake, may I add one minor correction.....
ALL lead-acid batteries, "flooded-type", "gel-type", and "AGM-type", like to be brought to 100% charge for their longevity......

This is sometimes misunderstood, since equalizing is verbotten on many/most agm-types (and all gel-types), therefore you cannot remove sulfation on the plates caused by consistant undercharging (failure to get the batteries up to 100% charge regularly), like you could with a flooded-type battery......
So, with agm's or gel's, not getting them back to 100%, doesn't allow for a "whoops" / fudge-factor, that you'd have when using flooded-types....
(the ability to "abuse" flooded-type batteries is a big plus for some who choose them....)

Hey, this may sound like a distinction without a difference, but in my opinion it is important to understand this.....if for no other reason, than to remember that AGM's are lead-acid batteries and are subject to many of the same foilbles of all lead-acid batteries.....


B) Are you sure that you can get your Honda 2000 to run your 100amp charger????
I may be mistaken here, but I've read (I've no first hand experience on this) that the max charger that the Honda 2000 can relaibly run is 75 - 85 amps...
I'd check into this before you spend any money on new batteries....


C) And, as for the genset run times vs. charge levels vs. charge acceptance rates vs. getting batteries as close to 100% as possible vs. Odyssey's batteries, etc. etc. etc....

I practice what I preach, in that I use a large solar array to provide my electrical needs, including ice cream in my ~5 cu ft freezer and ~5 cu ft frig, etc. etc....
So, I have no need for high charge acceptace rates, etc.....
And, since you asked for our thoughts, here's mine:

1) Concentrate on alternative / renewalable energy (solar, wind, water, etc.) and not on how many hours you'd need to run a genset to recharge your batteries....and
2) Remember that reducing your energy consumption, does NOT mean sacraficing your comforts, nor being a "watt-miser".....(\adding frig/freezer insulation, use of Sensi-Bulbs / other LED's inside, hi-quality LED Nav Lights, low-power-consumption instruments, etc. etc. will all improve your comfort / lifestyle AND save energy at the same time....


Okay, no battery war here ...
Just trying to give you some practical, real-world, experienced advice....

Fair winds...

John

[Livia]

Originally Posted by ka4wja

ALL lead-acid batteries, "flooded-type", "gel-type", and "AGM-type", like to be brought to 100% charge for their longevity......

Excellent point.

Originally Posted by ka4wja

B) Are you sure that you can get your Honda 2000 to run your 100amp charger????
I may be mistaken here, but I've read (I've no first hand experience on this) that the max charger that the Honda 2000 can relaibly run is 75 - 85 amps...

Yes, the 75-85 limit is the Honda 1000W which is the more common model. The Honda 2000 is 2000 (max, not sustained)/12V = 167Amps DC.

Originally Posted by ka4wja

1) Concentrate on alternative
2) Remember that reducing your energy consumption,

We agree with you completely and are already doing as much of #1 as we feel we can on a 35' boat without creating an unsafe heavy weather sailing environment and are still working on #2 (need to reinsulate the darn fridge - yucky project). We are using about 100Amps per day right now, but will be installing an SSB and probably a watermaker later. Our solar panels won't give us as much in the PNW but will increase when we head south.

[ka4wja]

Originally Posted by Livia

Yes, the 75-85 limit is the Honda 1000W which is the more common model. The Honda 2000 is 2000 (max, not sustained)/12V = 167Amps DC.

Livia,
While I'm quite aware that the Honda 2000 should power your 100amp charger just fine, it's just that it isn't likely to produce 100amps of charging....
And, the numbers that you used are an over-simplification (and are not accurate)....

I'm assuming that you have an efficient charger, and were basing your numbers on that, but even with that NOBODY is going to get ANYWHERE near 167amps of charging from a Honda 2000...

Assuming that the Honda 2000 could supply 1800 watts continuous, if you had a 100% efficient charger (not possible), that would be 124 amps at 14.5vdc.....
But assuming that your charger is about 85% efficient (at best), that would get you 105 amps.....
BUT, that 85% eff charger is NOT the norm, most are more likely to be 60% - 75%.....
Again all assuming that the Honda 2000 can supply 1800 watts continuous, and that its voltage and frequency output is at the proper values for most efficient operation of your charger, then the "math" makes it look like a very efficient 100 amp charger would work....
However, I do not know what charger you have, so I cannot be exact.....although, I suspect that you'll get about 85 - 90 amps max out of your 100amp charger, and quite possibly less....
I've read that many have found 75 - 90 amp is about all their chargers are capable of producing, when driven with a Honda 2000.....
If I'm remembering incorrectly, please forgive me.....

But, you also need to understand that there's NO way that a Honda 2000 could produce 167amps of charging thru any charger.....

I'll look for the info, and pass it on if I find it...


{EDIT: Wow, lots of posting going on, while I've been typing (and distracted by other things) in just the last few minutes.....
Looks like most of what I typed has been posted already....
Oh well....more to come...}

Fair winds.
John

[Livia]

Originally Posted by ka4wja

But assuming that your charger is about 85% efficient (at best), that would get you 105 amps.....

I'm learning - fantastic and thanks.

Our Magnum lists 85% efficiency. Based on the fact that other things will be running we'll have to trial and error what amps to set the Magnum as "max".

[ka4wja]

Originally Posted by Livia

We agree with you completely and are already doing as much of #1 as we feel we can on a 35' boat without creating an unsafe heavy weather sailing environment and are still working on #2 (need to reinsulate the darn fridge - yucky project). We are using about 100Amps per day right now, but will be installing an SSB and probably a watermaker later. Our solar panels won't give us as much in the PNW but will increase when we head south.

Livia,
Okay, this has drifted way past the "100% Charging", but that's cool with me, since it's your thread!!!

1) Not sure how your boat is equipped, nor what your application is.....and without knowing those (as well as a few other things), there is NOBODY that can recommend batteries, chargers, solar arrays, wind gens, water gens, watermakers, frig/freezers, etc. etc. etc....NOT even Nigel !!!!

Is it possible that you've gotten a little bit ahead of yourself????
Sort of gotten the cart before the horse????
Heard some great news at a boat show seminar, or read a nice article, etc. and figured "Hey, here's the answer to our energy needs"????
But, no matter what your energy storage method is, you will need to replace that energy (actually about 110% - 115% of what you use)!!!!
And, this is why reducing your energy use can have a BIG impact on your choices....

{Please take note that I use the phrases "your choices", "your application", etc.....this is specifically meant to impress on you that it is YOUR boat, and YOUR application, and therefore YOUR choices.....not mine, not others.....}

a) You need to make decisions on how you want to sail/cruise/live on-board, and....
b) How much energy that will use, and.....
c) Calculate an energy budget, and....
d) Decide how you'll generate that much energy (110% of what you use).....solar, solar/wind, water-gen, diesel (main eng or genset), gasoline (genset), etc....or some combination of any/all of the above.....
e) Decide where you will mount whatever energy devices, and their fuel supplies (if applicable), and how much of them will impact other parts of your life on-board, sailing ability, etc....

Once you've made these above calculations and decisions, THEN you can look at what batteries might make life easier....
Yes, AGM's (and it appears Odyssey's more so) do have a higher charge acceptance rate, and yes in some applications (mostly NOT small/mid-sized sailboats) this can be a significant advantage, but without all of the above info, anyone counseling you to buy Odyssey's shouldn't be taken too seriously.....

I realize that some assume that if it's Nigel Calder saying how great they are, it must be true....
And, it might turn out that he's correct.....
BUT, that doesn't mean they are a correct choice for everyone....just like flooded-types aren't the correct choice for everyone, but are for some!!!!
And, it may also turn out that for your application and your lifestyle, they're a great choice....but, you cannot know that until you've figured out the above....


2) As for you being on a 35' monohull, and using 100 a/h per day, in the Pacific NorthWest????
Wow, that's a big energy budget....almost as much as mine, anchored in the Bahamas in the spring/summer, with ice cream in the freezer, watermaker making lots of fresh water, talking on the HF radio for hours, listensing to the stereo (and VHF) all day, etc....(although when underway offshore, my power consumption does go up significantly, due to 24/7 use of autopilot, etc. but as long as the sun shines every 2 - 3 days, I'm still energy independent.....and keep my diesel for propulsion when the wind is completely calm....)

If you're using that much power now.....do you know how much of that is your frig????
And, assuming you make no changes in the refrigeration insulation, etc. you can figure on doubling that consumption as you get into the tropics....

There's a LOT more to go over, and I'll answer (honestly) anything you ask......but a good deal of this info is available in many threads on the SSCA disc boards...have a look....

Also, here's some of my articles/photos on my solar array / energy thoughts, watermaker, electronics, etc....
Solar Panels
Towed-Water-Generator
Watermaker
Frig/Freezer
Nav Station



I hope this helps some...

John

[Highlander40]

Have not used Odyssey batterys but have used two sets of Lifeline AGM's

Some things that made a difference. (longer life)

Install a temperature sensor on the battery bank. For Both charger and alternator.

When the charger gets to the float stage, you are close but not there.
The best compromise is to NEVER stop charging in the middle of acceptance rate.

That 50% limit is good advise, start charging at 12.2V

We have no room for more batterys so instead changed all bulbs to sensibulbs and put in a new fridge. Much better.
As we speak the TV is being replaced with an all in one TV-DVD so the main stereo is shut down while watching.

You make your choices and have fun.

[Livia]

Originally Posted by Highlander40

Some things that made a difference. (longer life)

Install a temperature sensor on the battery bank. For Both charger and alternator.

When the charger gets to the float stage, you are close but not there.
The best compromise is to NEVER stop charging in the middle of acceptance rate.

That 50% limit is good advise, start charging at 12.2V

Thanks - very useful - these tips are going in my maintenance notes. We have the temp sensors for both.

[Livia]

Originally Posted by ka4wja

Once you've made these above calculations and decisions, THEN you can look at what batteries might make life easier....
....
2) As for you being on a 35' monohull, and using 100 a/h per day, in the Pacific NorthWest????
Wow, that's a big energy budget....almost as much as mine, anchored in the Bahamas

Thanks John - we really have thought through all of those issues already and the batteries are our last decision. We are putting on 215W of solar. We aren't going to get a wind generator yet unless it is also a tow generator because we aren't convinced that they are as useful in the S Pacific as they are in the Bahamas after reading others reports. Wind is a "wait and see" item which we'll decide on after a year or two of cruising. We upped the alternator so we could use the stock as a spare and also because we might as well maximize energy while motoring. We *know* that 215W of solar is not enough for our first year of cruising up here in the PNW so we bought the Honda. We know where we will store our gas (strapped into our vented bulkhead isolated anchor locker on the bow).

Still, we've only been out on the boat for a month at one time so far. We ARE new to cruising and still learning a lot (and will continue to learn when we are no longer new to it).

Our fridge insulation sucks - stock, 26 years old. It is a major issue for Pretoriens heading S and it is an amp hungry beast now so we know we have to deal with this before heading South. We will. We hope that the reinsulation will keep the amps similar down south to what they are costing without new insulation up here.

We also have forced air diesel heat running 24 hours a day 1/2 the year up here and almost every night the other 1/2. It is relatively efficient but those amps add up a lot. That usage will go down as we head south and at some point go away.

Also, everyone puts a different price on reducing boat maintenance. Buying higher end gear for more money sometimes (yes, I realize certainly not always) reduces the amount of work you will do later. I might pay a lot more for batteries I didn't have to dig up the aft cabin to water than someone else in order to keep my fun-to-suck ratio high. Before I derail my own thread, this is NOT our primary reason for AGMs.

We were feeling pretty smug about our 100AH considering 150AH is the average AmpHour daily usage on SSCA's survey. You've put us to shame!