Battery Chargers - Tech Talk 101

[mobiledynamics]

I just received our new 25amp Smartcharger for our AGM batteries.

For the garage queens + snowblower/OPE batteries, I've been using the Cteks for years . 7amp units.

I picked this charger up as our AGM's like HIGH AMP charges. All these chargers have a AGM setting which puts out 14.7 (note, some of my garage queens have been swapped from wet cells to AGM's as they aged)

Humor me, as I'm not no EE guru

It's my understanding that voltage causes heat and NOT amps.
Does that mean ANY battery can take a HIGH AMP charge as long as volt threshold is at 14.1, etc and when it see's the battery at 14.1, it trims/lowers the amp down to absorb/float stage.

Or for wet cells, do I stick with low and slow as a general rule.

The same ? applies for Lifepo4 batteries in automotive usage. Low and slow, or will it take a 25 amp charge well, as long as it maintains the 14.2 volt charge during bulk, and then trims it down to 13.6

 

[SLYDIT]

agm's like slow charging not fast charging.

you cant "push" current into battery, you can only provide a voltage difference that allows a certain current to flow from the charger to the battery. you dont want to be pushing more than 2.4volts per cell into an AGM

 

[mobiledynamics]

So I thought since it's just a wet cell ...just encapsulated.

But if you call Odyssey up, depending on battery size, they are recommending 25 - 50 MINIMUM AMP charging on their batteries

 

[SLYDIT]

i dont see how you can get that kind of current without exceeding the voltage per cell limit unless the battery is FULLY discharged

 

[SLYDIT]

So I thought since it's just a wet cell ...just encapsulated.

But if you call Odyssey up, depending on battery size, they are recommending 25 - 50 MINIMUM AMP charging on their batteries

im pretty sure thats some sort of rating, not a recomendation on how much to push into them. if you charge an agm or gell cell too fast you will get bubbles between the plates that are very hard to get out. i mean how fast do you need to charge them? do you NEED the battery to be fully charged again ASAP?

 

[mobiledynamics]

I don't know what the cutoff is for traditional 3 step chargers when it gets into absortion mode--let's assume somewhere around 14.1-14.2, but the Odyssey rep was adament that ~their~ batteries do like to be charged at higher amps

 

[dogdog]

this might be a good article...
http://batteryuniversity.com/learn/article/what_is_the_c_rate
http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery


Maybe odyssey have thicker plates. dunno. 50 AMP seems a lot. Maybe the initial high current is needed to break free those lead sulfides formed on the thick plates, higher self discharging.....

but either case I would rarely charge any batteries at rate more than 10AMPs @ about 2.3 volts per cell. Just to make sure the plates don't warp or puncture / shorted cells with too much current flowing even if it is taking longer time to completely charge the battery...... speaking of this, I just destroyed an UPS sealed lead acid battery of thinner plates but not an odyssey though....

 

[mobiledynamics]

Just spoke to the horses mouth per say.
I asked them if the recommended amp rating was for only Deeply Discharged Application and the rep said no. I asked at what voltage did they want to see a high amp charge for the initial bulk charge during a typical 3 step charge and they recommended anything reading 12.6 or below, give it the high amp charge as per their recommendation

 

[jkwilson]

Odyssey batteries want that fast charge rate because their recommended charging process includes a 3-4 hour cleaning cycle of 13.5V after full charge is reached. You need to charge it at the higher rate to allow a large battery to finish the charge cycle in a reasonable time.

Slow charging kills batteries. 10-15A is a minimum for best battery life. High performance systems use integrated thermocouples inside the battery to allow for charging at 40A or more.

Power causes heat. Raising the charger voltage above the current battery voltage is what causes current to flow into the battery.

Most AGMs are fairly picky about voltage. A standard flooded cell can be charged in the 16V range with no issues, but few AGMs will tolerate more than about 14.7V even though their operating voltage may be nearly 0.5V higher.

Chargers rely on current to determine when the battery is charged. At a fixed voltage, current into the battery falls as the battery charges. Most chargers consider a battery fully charged when the battery draws less than 0.1 times the Amp-Hour rating of the battery. At this point, many chargers reduce their output voltage to 13.1-13.4V to float the battery. Some chargers completely stop charging at this point and cycle on every 24 hours to check the battery and charge as needed.

 

[Sal Bandini]

It's my understanding that voltage causes heat and NOT amps.

Current causes heat, not voltage.

 

[mobiledynamics]

I called Braille as well - running one of theirs in my trak rat. They recommend low and slow at 2 amps.

Their doesn't seem to be any general consensus on any battery just short of traditional wet cells..

 

[mobiledynamics]

Slow charging kills batteries. 10-15A is a minimum for best battery life. High performance systems use integrated thermocouples inside the battery to allow for charging at 40A or more.

JKWILSON,

Mind expanding more into the 10-15 statement.
I was always the impression low and slow is best.


Might as well ask, have you done HIGH AMP charges on any particular AGM brands . Just short of hearing from tech support, I'd be curious to hear what real world experience is, charging at such a high amp.

 

[theoldwizard1]

you cant "push" current into battery, you can only provide a voltage difference that allows a certain current to flow from the charger to the battery.

Correct ! More voltage differential = more current.

Most modern chargers have "feedback" that will occasional measure the voltage and then decide if it should switch to a lower current.

P.S. Not a fan of AGM or SLA. IMHO they are not worth the extra cost except in applications where they are required. "Flooded cell" lead acid batteries are almost always a "better bang for the buck".

 

[mobiledynamics]

OldWizard. I do agree that standard wet cells are best bang for the buck.
Longevity wise, I have not noticed a bigger difference in lifespan in a daily driver application vs. AGM.

I use AGMs in garage queens due to discharge rate. Yeah, it's pricey...
On my dailys, they have come stock with AGM and the brains of the vehicle .....it's a different beast electrically these days, so I have replaced it with AGM to keep them ~simpatico~ with the vehicle system.

New garage queen actually came with a Lithium Battery which was a bit surprising to find out !

 

[mobiledynamics]

OT, as I just shot this specific inquiry to one of my charger makes. I have 3 brands......in my stash. Their rep was uesless and told me they need to forward the inquiry over to overseas...I would have expected more from such a big brand company....

For AGM's, do you guys make sure your batteries are reading a certain voltage before you put it on your smart charger...

I asked them 2 questions. What was the voltage cutoff if which the unit determines a battery is sulphated and what is the CHARGE PROFILE in AGM mode with RECONDITION being added in the mix.

This is relatively important cause if these units are in AGM mode but is still sending/Pulsing a volt higher than 15 to the battery, whether it has any detrimental long term effects or not is questionable.

In my tech talk with Odyssey, even their current dedicated high amp chargers do send pulse voltages higher than 15, hence they are discontinuing their current chargers and coming out with new ones --- aka, their current chargers are made by Schumacher to ~their~ specs.

 

[DonPowers]

Looking for new all around wheeled charger. Have AMG starting, deep cycle and regular starting.

Which do you guys recommend, automatic, manual, high frequency and why.

Brand preferences.

 

[DonPowers]

Is this a decent charger from Home Depot?


http://www.homedepot.com/p/CAT-40-A...42&gclid=CNGLy8yAi8gCFYG0NwodI-sCBg&gclsrc=ds

 

[DenisG]

Heat generated in a battery is the result of I^2 x R (current squared times the resistance of the battery). For the same internal resistance, using higher current gives you more heat. Internal resistance goes up as a battery ages and it cuts down the amp-hrs and the maximum current you get. As batteries age, the internal resistance goes up. Internal resistance also varies with the state of charge (SOC) of a battery.
http://batteryuniversity.com/learn/article/how_does_internal_resistance_affect_performance

 

[jkwilson]

Looking for new all around wheeled charger. Have AMG starting, deep cycle and regular starting.

Which do you guys recommend, automatic, manual, high frequency and why.

Brand preferences.

It really depends on how you are using the charger and the batteries. If you just need to boost a battery up so the vehicle charging system can take care of it, the charger operation isn't as critical. If the battery is in a situation where the charger is the only thing charging it when it runs down, it may be more important to charge with the exact parameters needed for the battery.

The high-frequency is BS. The idea of a three-stage charger is pretty well BS too, though the ones that claim it tend to be the better choice.

The stages the chargers claim they have are actually just the limitations of the charger. When you first hook a charger up, the charger tries to raise the battery to whatever charge voltage the charger is designed for. Typically that is about 14.7 or 14.8V now. On a battery that is way down, the charger may not have enough current to raise the voltage, so the current is constant at the max current of the charger while the voltage rises as the battery charges. They call that one of their stages. Once the voltage gets to around 14.8V, the voltage stays constant, but the current starts dropping. The charger isn't doing anything special, it's just a natural effect of the battery charging. They call this a stage too.

The third "stage" is the only real thing the charger does that distinguishes it from a "dumb" manual charger. When the charger senses that the battery is drawing less than about one amp, the charger switches to float mode where the voltage drops to a little over 13V to keep the battery charged.

 

[DonPowers]

It really depends on how you are using the charger and the batteries. If you just need to boost a battery up so the vehicle charging system can take care of it, the charger operation isn't as critical. If the battery is in a situation where the charger is the only thing charging it when it runs down, it may be more important to charge with the exact parameters needed for the battery.

The high-frequency is BS. The idea of a three-stage charger is pretty well BS too, though the ones that claim it tend to be the better choice.

The stages the chargers claim they have are actually just the limitations of the charger. When you first hook a charger up, the charger tries to raise the battery to whatever charge voltage the charger is designed for. Typically that is about 14.7 or 14.8V now. On a battery that is way down, the charger may not have enough current to raise the voltage, so the current is constant at the max current of the charger while the voltage rises as the battery charges. They call that one of their stages. Once the voltage gets to around 14.8V, the voltage stays constant, but the current starts dropping. The charger isn't doing anything special, it's just a natural effect of the battery charging. They call this a stage too.

The third "stage" is the only real thing the charger does that distinguishes it from a "dumb" manual charger. When the charger senses that the battery is drawing less than about one amp, the charger switches to float mode where the voltage drops to a little over 13V to keep the battery charged.

Thanks JK

The batteries all have different services.

The AGM Starting battery is on an excavator which may only get 50 hours a year use in my sandbox.

Have two deep cycles which are use on tilt trailers and need to be charged using a charger. The little charger that I use now keeps tripping on thermal overload when the batteries are low.

One deep cycle battery used to run a diesel fuel pump and needs to be charged.

One vehicle sits for the winter so it requires charging every now and again.

One marine starting battery which sees very little use these days and requires occasional charging.

Three vehicle batteries which get regular use so I don't work about them.

One generator starting battery which sees little use and needs occasional charging.

Tractor starting battery which gets regular use so I don't worry about it.

Four small batteries for ATVs, motorcycle and snowmobile.

Anyways, thats a lot of batteries.

Have one small automatic charger, which trips and two 1 - 2 amp tenders.

 

[jkwilson]

For the batteries that need maintenance charging, which I'd consider the excavator, the vehicle that sits over the winter, the marine battery, and the generator starting battery, I'd look at something like a NOCO Gen 3500. I have one and use it regularly during the winter. Every Sunday I move it from one piece of equipment to the next.

For the rest, a 10A charger should be sufficient, though the 40A with 110A boost might be nice to have.

 

[ttpete]

Correct ! More voltage differential = more current.

Most modern chargers have "feedback" that will occasional measure the voltage and then decide if it should switch to a lower current.

P.S. Not a fan of AGM or SLA. IMHO they are not worth the extra cost except in applications where they are required. "Flooded cell" lead acid batteries are almost always a "better bang for the buck".

I've totally switched to AGM for my bikes. They are kept on battery tenders 24/7 when not in use. I sold the bike with the oldest battery this year, and it was installed in 2003, a period of 12 years, and still OK. The others are 5 and 7 years old and are just fine. Flooded batteries wouldn't have lasted anywhere near that long.

And I no longer have to add water and deal with vent hoses, corrosion and acid destroyed clothing. No hydrogen build up, either. Now that lithium-ion is available, I'll replace them when the time comes with that technology.

 

[All]

I wish there was some sort of consensus regarding the correct charger for automotive AGM batteries.

I've got four Odyssey AGMs, two 850cca/68Ah, and two 950cca/74Ah. I would LOVE to find a good proper so called "automatic" "multi-stage" charger for them. I've called Odyssey (Enersys). I've received the same difficult to comprehend advice about how I'm going to RUIN these batteries FOREVER (that cost almost $300 each) UNLESS I charge them (once they've been run down to "dead") at 40% of their amp hour rating (expressed as C, for Capacity), starting at 14.4 to 14.7 volts, for a certain number of hours.

That calls for a charger that can deliver 27 amps for the 68Ah batteries, and 30 amps for the 74Ah batteries. The Odyssey techs are really adamant about this... yet Odyssey discontinued their former 30 amp, 40 amp, and 50 amp line of chargers, because their own chargers weren't working right. Just recently, Odyessy introduced a new line of chargers, but the highest rating of those is only 20 amp.

So I'm tired of their double talk. And if I could understand EE, then I wouldn't be fooling around trying to charge batteries. I'd be raking it in all my stock options from an engineering career at some computer company, ordering a new Tesla everytime my previous one needed a charge. But alas, I struggle to even calculate percentages.

I'd just like to buy a known good, known AGM appropriate, known capacity appropriate battery charger that I can plug in, hook up, and not worry about whether or not it is "right".

I'm sold on AGMs, and never going back to wet cells, no matter what economical advantage wet cells have. I have so very much enjoyed not having to remove, neutrualize, wirebrush, sand, and repaint battery trays... a chore that has haunted my weekends every 5 years since the 1970s, that I will NEVER go back. I've never had a single drop of acid, nor a single spec of white or green powdery residue, since switching to AGM batteries 10 years ago. I don't care how much they cost, I'll never retreat.

However, I would like to get the right charger for them, and I've learned that the NOCO Genius models (I have one) are not the right charger for them, despite having a setting for AGM. So FRUSTRATING... all the BS claims of every damn company out there.

Sorry for yelling, but it just torques my stove how difficult it is to just get a good, professional duty, reliable, and appropriately applied charger for AGM batteries... crazy.

 

[ttpete]

I wish there was some sort of consensus regarding the correct charger for automotive AGM batteries.

I've got four Odyssey AGMs, two 850cca/68Ah, and two 950cca/74Ah. I would LOVE to find a good proper so called "automatic" "multi-stage" charger for them. I've called Odyssey (Enersys). I've received the same difficult to comprehend advice about how I'm going to RUIN these batteries FOREVER (that cost almost $300 each) UNLESS I charge them (once they've been run down to "dead") at 40% of their amp hour rating (expressed as C, for Capacity), starting at 14.4 to 14.7 volts, for a certain number of hours.

That calls for a charger that can deliver 27 amps for the 68Ah batteries, and 30 amps for the 74Ah batteries. The Odyssey techs are really adamant about this... yet Odyssey discontinued their former 30 amp, 40 amp, and 50 amp line of chargers, because their own chargers weren't working right. Just recently, Odyessy introduced a new line of chargers, but the highest rating of those is only 20 amp.

So I'm tired of their double talk. And if I could understand EE, then I wouldn't be fooling around trying to charge batteries. I'd be raking it in all my stock options from an engineering career at some computer company, ordering a new Tesla everytime my previous one needed a charge. But alas, I struggle to even calculate percentages.

I'd just like to buy a known good, known AGM appropriate, known capacity appropriate battery charger that I can plug in, hook up, and not worry about whether or not it is "right".

I'm sold on AGMs, and never going back to wet cells, no matter what economical advantage wet cells have. I have so very much enjoyed not having to remove, neutrualize, wirebrush, sand, and repaint battery trays... a chore that has haunted my weekends every 5 years since the 1970s, that I will NEVER go back. I've never had a single drop of acid, nor a single spec of white or green powdery residue, since switching to AGM batteries 10 years ago. I don't care how much they cost, I'll never retreat.

However, I would like to get the right charger for them, and I've learned that the NOCO Genius models (I have one) are not the right charger for them, despite having a setting for AGM. So FRUSTRATING... all the BS claims of every damn company out there.

Sorry for yelling, but it just torques my stove how difficult it is to just get a good, professional duty, reliable, and appropriately applied charger for AGM batteries... crazy.

My AGM's last because I DON'T cycle them. They are always on tenders and always topped up. AGM'S are still lead-acid, the acid is contained by fiberglass separators so there's no spillage. They are sealed and the gas is reabsorbed. Like any lead-acid battery, they can sulfate if left discharged. If they're kept fully charged, there's no way they can become sulfated, so they last much longer.

Any application where batteries must be cycled requires specialized deep-cycle batteries. This would include golf carts, trolling motors, and off-grid solar systems.

 

[Showkey]

Get a GOOD smart charger.............they are likely smarter than the user.

Like ............http://smartercharger.com

 

[t100]

http://www.hotrod.com/how-to/interior-electrical/hrdp-1009-how-to-charge-a-agm-battery/

 

[All]

My AGM's last because I DON'T cycle them. They are always on tenders and always topped up.

My trucks can't fit in my garage. They are parked on a public street. I can't run an extension cord to the public street, for a variety of legal, liability, and logical reasons.

My batteries run down because I'm sometimes sent out of town for weeks at a time. Sometimes, I don't know how long I'll be gone. I have battery quick disconnects, but I have 15amp fused bypasses to leave the alarm active, and sometimes need to leave the engine computer active if a smog inspection is due. The batteries drain below the ability to start, but the alarm is still blinking. For a variety of reasons, I do not have the ideal situation for maintaining batteries perfectly. And I'm not perfect either.

Because of that, I sometimes need to charge the batteries from a depleted state. I just want to find the right charger to get that done.

 

[All]

The CTEK Multi US 25000 25Amp charger for $325 doesn't appear at first glance to be much different than the NOCO Genius G26000 26Amp charger for $189.

The folks at Odyssey STRONGLY advised AGAINST the Noco Genius. But of course, Odyssey sells their own line of chargers. Still, they rambled off some gobbledy gook about what makes the Noco type charger bad. I didn't understand what Odyessy folks said, but I did understand what some reviewers said on the reviews at Amazon.

A few of them metered the output rate of the Genius charger, throughout all of it's incremental stages. They found that it only reached about 14.5 volts for a few minutes, very late in the charge cycle (hours later).

Again, I don't know about batteries, but several sources seem to corroborate that if I want to restore the original capacity (or as near to the original capacity as recoverable), that the AGMs need a high voltage (but no higher than 14.7v) bulk initial charge... something like that.

I honestly don't care what they need. I just need a charger that knows what they need, that the battery manufacturer can agree has the correct charging profile for the type of battery that it is.

 

[All]

When I look at the top of the line CTEK 25Amp charger, that fits in the palm of my hand, for $325, and compare it to the new state of the art CAT (Caterpillar) 70Amp multibank charger, for just $299, I have to wonder which is the real charger, and which is the real value?

Hard to tell. There certainly is a more informative LCD screen on the CAT charger, the ability to charge three batteries at three different voltages at once, and a control dial. There is also the cost of wheels, a cart, and the heavier cabling.

Yet the CAT piece is made in China, and the CAT yellow paint, the oversized housing (as if it were a transformer based charger when in fact it is a high frequency inverter like charger just like the CTEK and NOCO above), all screams marketing to me. Make it big, make it yella, and brand it with a traditional American tough tractor brand, and it'll sell.

Yup. To suckers like me. But at the end of the day, other than the space it occupies, it still does seem like a better value than the CTEK and NOCO... from what the specs and photos indicate.

 

[All]

http://www.hotrod.com/how-to/interior-electrical/hrdp-1009-how-to-charge-a-agm-battery/

T100, thanks for the tip.

My issue isn't getting my charger to start charging my dead AGMs. My issue is restoring my AGM batteries to their full capacity. My issue is trying to find a "smart" charger that correctly applies ENOUGH current and ENOUGH voltage to make this restoration, without damaging the battery by doing too much.

 

[MadTinkerer]

Maybe someone here can help me out. I am looking for a compact batter charger that can put out 30-40amps. I currently have this motomaster charger. It puts out 25a. You can select auto, 4,10,15 and 25amp setting

I have checked out Schumacher and a few other brands but have come up short. Canadian tire use to sell a 40 amp version but it has been discontinued.

 

[ttpete]

My trucks can't fit in my garage. They are parked on a public street. I can't run an extension cord to the public street, for a variety of legal, liability, and logical reasons.

My batteries run down because I'm sometimes sent out of town for weeks at a time. Sometimes, I don't know how long I'll be gone. I have battery quick disconnects, but I have 15amp fused bypasses to leave the alarm active, and sometimes need to leave the engine computer active if a smog inspection is due. The batteries drain below the ability to start, but the alarm is still blinking. For a variety of reasons, I do not have the ideal situation for maintaining batteries perfectly. And I'm not perfect either.

Because of that, I sometimes need to charge the batteries from a depleted state. I just want to find the right charger to get that done.

You can get a maintainer that uses solar power and installs in a vehicle. The US military uses these.

http://www.pulsetech.net/Assets/ProductSpecifications/735X305.PDF

 

[bmwpowere36m3]

No reason a good battery will be dead in a month or two... likely the batteries have lost capacity over the multiple discharges and won't stay charged long. I'd buy a new battery (biggest) you can fit and leave it be.

Add a solar charger if you're real worried. I use a "dumb" old Snap-On boost/charger (transformer) for larger battery to bring them up quick and a CTek for smaller stuff, or to charger slower and/or maintain.

 

[TigerDude]

There is a huge amount of snake oil, smoke & mirrors in batteries and general and chargers specifically. I personally wouldn't spend much on any technology.

 

[All]

TigerDude.... snake oil is exactly what concerns me about chargers.

I've finally found a solid 5 star charger that no reviewer had complained about. The ProMariner ProNautica P Series 1260. 5 stars. $500.00. And you must provide your own cabling. Designed for permanent installation on boats, to charge both house and engine batteries, the ProNautica has 12 different charging profiles for all different kinds of battery chemistries. It is remarkable to read how it just works (in rejuvenating and restoring weakened batteries), when it was used to replace other marine grade battery chargers that apparently didn't work.

 

[ttpete]

I have a commercial shop type charger/booster on wheels and a booster pack for on the road.

 

[Showkey]

There is a huge amount of snake oil, smoke & mirrors in batteries and general and chargers specifically. I personally wouldn't spend much on any technology.

Before gel, AGM and dry cell..........any old charger might have gotten the job done........but.........even then it was easy to overcharge, boil off water and or over heat a battery if you did not pay attention.

Any battery used used in seasonal application will benefit from a smart charger or maintainer. Motorcycle and boat guys are always having battery issues if not serviced and charged correctly.

 

[All]

I'm still looking for choices in chargers that will output 40 amps at 14.7 volts during the bulk stage, and will still maintain the voltage at 14.7 while automatically reducing current during the absorption phase, while keeping tabs on the temperature of the battery and while not exceeding 15 volts... and that will automatically kick down to 13.6 volts for maintenance / float charging... and that has rapid pulsing capability to desulfate plates.

Just like an impact wrench or a hammer drill is better at knocking loose tight fasteners, a battery reconditioning setting that pulses is better at finding the weak spots in the sulfated coating on the plates.

That yellow CAT branded charger has pulsing, but otherwise, it is not intended to be used for marine or dry cell batteries. The company who actually markets it is has nothing to do with Caterpillar other than paying a license fee to use the name to add credibility to the Chinese import product. The technical service rep knew less about chargers than I did, and that is downright scary. It is scratched off my list.

Contrary to what I thought earlier, the CTEK chargers are NOT like the Noco Genius line of chargers at all, even though they look sort of similar, as if they had the same guts inside, and just different plastic housings. NOT the case. The charging profiles are very different between the CTEK and the Noco Genius, and after doing some voltage measurements on my own Noco Genius during the charging cycle, I can now see why my AGM batteries are getting ruined by this Noco Genius charger. The charging voltage is less than 13v for much of the time. This is not good for the Odyessey batteries I use.

The CTEK, specficially the M25000, is on the Enersys (Odyssey) Approved Charger List. I now see why the Noco's are NOT on that list, despite the so called "AGM" setting on the Genius chargers.

There is much to learn here... and not a lot of products out there deliver the correct charging and reconditioning voltage and current profiles needed to keep the pure lead AGMs in their optimal condition.

I make the distinction of "pure lead" AGMs, because there are a lot of recently introduced AGM batteries on the market today, built by companies who are hoping no doubt to cash in on consumer awareness of the advantages of AGM batteries. However, some of these AGM batteries are using Lead Calcium, instead of pure Lead. The Lead Calcium batteries require a different charging profile, because the dissimilar materials (lead and calcium) are subject to galvanic corrosion in the immersion of the sulfuric acid electrolyte. Higher amperages in charging can permanently damage the plates.

 

[All]

Adding more content to this dead thread.

Dual Pro Marine PS-4 and PS-3 professional multi-bank chargers come highly recommended by boaters. When I learn more about them, I'll hopefully have time to report back how they compare with the competing Pro Mariner brand.

Also, the dry land Industrial INC-800A 80 amp commercial bench charger caught my eye.

 

[All]

Get a GOOD smart charger.............they are likely smarter than the user.

Like ............http://smartercharger.com

And that is what I finally ended up getting. Specifically, their MUS 25000 model:

http://smartercharger.com/products/batterychargers/ctek-multi-us-25000/

What convinced me, or shall we say "conned" me for short, in a nod to TigerDude's healthy dose of skepticism regarding the "smoke and mirrors" in the battery charging business... is the ripple voltage of traditional linear chargers exceeding, by several hundred percent, the maximum ripple recommended for valve regulated sealed batteries.

I've had the MUS25000 for a few months now. It seems to do a very good job... one can really tell how it is doing different things during the charging cycle, and those things are very much dependent on the specific battery connected. Even when charging the same type, size, and age batteries that were deployed in the same application, the MUS25000 might whir a little longer with one battery, or remain at one level a lot longer than the other battery, etc.