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.

[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

[Lost Horizons]

I have 2x100 A*h Odyssey batteries and a 50 A charger (and a Honda 2000). The batteries do take full 50 A up until almost fully chrged. I don't remember exactly when the current starts to get reduced, but it is very close to 100% charge. If you use a genetator or a diesel to charge the batteries, Odyssey batteries will reduce your charging time, but for the full benefit the charger needs to be properly matched to the size of the bank. Getting these batteries just to accelerate the last 5% of chrging time is probably not good enough a reason.

[barnakiel]

The last 15, 10, 5, 4, 3, 2, 1 % of the charge does not depend on how big and powerful your generators / chargers are. The batteries' acceptance rate drops and it is just a question of time (I mean - you cannot 'push in' the last amps into the battery.

Off course, with different technologies the acceptance rate differs and so differs or capability to get as close to 100% as possible, with perhaps the best solution being to have two banks and using one while charging the other (?).

b.

[Rick]

Having tested and cycled (harshly in many cases) all types of deep-discharge lead-acid batteries designed to perform well with heavy loads (such as inverters driving microwave ovens etc) I can attest to the fact that ALL types of non-flooded batteries can outperform any flooded ones.

The reality is that if a proper acceptance voltage is applied (equal to or exceeding 14.4V at 20 deg C) gel-cel and AGM batteries WILL tolerate better an average level of discharge than will flooded batteries. The problem is that most users are afraid of overcharging and kill their sealed batteries with undercharging.

It is the lead purity and quality of manufacture that creates a lead-acid sealed battery that tolerates spending a significant time in a state of discharge. Applying high acceptance voltage reverses the sulphation so that equalizing does not become necessary, if done properly.

You might be surprised to learn that US built and German built gel-cel batteries charge accept quite closely with the good AGM brands with a good charging regimen. Odyssey batteries are no better or worse than the other good brands in this regard. No flooded-cell battery will match these in charge acceptance OR resistance to damage from excessive sulphation (called sulphatation).

[bobfnbw]

I have 6 of the sears platinum batteries, at 100 ah each.
I have not done any cruising yet with them, but can tell a few things so far.
After purchase, they sat for some months without charging.
When connected to the vitron phenoix 120 amp charger they quickly went from bulk to float, showing to me that they had not discharged much at all.
And finally while costing much more than say trojan T105's, I expect better perfomance, better overall satisfaction due to no off gassing, better quality of my life as there will not be any battery acid spills, or burned clothing. I paid roughly 250 bucks each so 1500 total for the bank. I expect to not need as large of a bank due to the higher charge acceptance these guys have. I charge it wiht both the victron while at dockside, and a balmar 120 amp alt with a balmar max charge. I also have 2 100 watt solar panels but is currenetly not connect as I have not gotten a solar controller yet for them. Last one destintregated in the salt water enviroment.
Since I currently reside in a marina, with occasional cruises, I do not worry about topping the to 100%, but would get them full with the engine /alt when out.
Bob

[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.

[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.

[Livia]

Originally Posted by barnakiel

The last 15, 10, 5, 4, 3, 2, 1 % of the charge does not depend on how big and powerful your generators / chargers are. The batteries' acceptance rate drops and it is just a question of time (I mean - you cannot 'push in' the last amps into the battery

Excellent point to remember, however, if I understand correctly the extra amps will shorten the bulk charge time (because the bank can take more amps then) and thus shorten the overall time by reducing the front end, not the back end.

[Livia]

Originally Posted by Lost Horizons

I have 2x100 A*h Odyssey batteries and a 50 A charger (and a Honda 2000). The batteries do take full 50 A up until almost fully chrged. I don't remember exactly when the current starts to get reduced, but it is very close to 100% charge.

Thanks. Like I said earlier it is difficult to find real world info on these. I really appreciate it.