AGM Battery Discussion-Discharge/Charge Cycles

I'd say continue this thread. You can edit the original post and thread title to reflect your desired route change to include chargers.

I'd likely follow BFL13's path and have the charger be a portable, especially since you have mentioned the possibility of scumbag thieves making off with your batteries in previous posts.

If you don't require something absolutely automatic, there is the adjustable voltage power supply route. You can set the desired AbsV, put this on a timer so that it does not hold batteries that no longer need Absorption voltages, at ABSV's.

I have a meanwell RSP-500-15 that will provide 40.94 amps into my Northstar AGM and about an amp less into my flooded battery.

They make a RSP-1500-15, which should do ~123 amps, but it is not cheap, but you could set it to 14.x, crank a timer to ~3 hours (depends on depletion level) and have the 3 31's in the 95%+ range.

Come back at your convenience, set it to float voltage and crank timer again, or just bypass timer to let float voltage safely top them off with no time limit.
Meanwell RSP-1500-15

rsp-1500-15 data sheet

It needs 17 amps at 115vac, so a 20 amp receptacle, which can pose problems, but can also handle 240v outlets so if you have one of those handy.

Anyway, it is one option.

Also if you leave the batteries in series for 24 or 36 volts, this presents more charger issues.

Mean well Makes -24 and -27 and -48 volt models with wide voltage adjustment ranges too they are in that PDF above. but no 36v options.

Likely the newer 100 amp powermax boondockers that have adjustable voltage can do the same task a smidge slower and for less money. but then there is the one 12v battery at a time factor

Those sealed marine charger units all seem to be low and $low, but I've not researched all their possibilities.

If you get the higher $$ AGMs which state no bulk current limits, then you will likely find that these batteries respond well to huge recharge currents, and a ~95% recharge in 3 hours could certainly come in handy too.

IMO since the charger is only used when alongside, there is no need to take it to sea and get salt water all over it. Alongside, it ought to be possible to keep it in the boat under cover out of the rain. (and under lock and key) Before sailing, put the charger in your RV.

Standard deck mount converters that have 120v plug- ins can be "portable." You just use output wires with battery clamps on them instead of ring terminals if you don't want to do any work connecting/disconnecting every time.

OP Back

For BFL13 - I need a charger to be waterproof. In an 'open' boat everything gets wet unless in a 'dry' box. Hopefully, I'll learn about saltwater fishing and saltwater is the 'king of corrosion'. Standard practice is to leave the batteries in the boat, charger either mounted on-board or loose in or near the boat, and use a proper guage extension cord for AC.

msimimoff-Mark- Thanks, I had 'sort of' dismissed the Sears offering because Sears seems to be on the 'way out' in store locations. (Just my 'gut' feeling, have no hard evidence).

And Marks comments about chargers is correct. I've 'over-loaded' my-self looking at the 'better' chargers. Web searching can be time consuming and additive.

My current thought was to get some ?'s on paper and start first calling East Penn Tech Folks, as I'm still wanting (thinking) a single Sam's Club Gr 31 AGM for a 12v powerpack/jump-start battery.

Reguardless, I now see that the charger selection is more critical that the battery choice for AGM's. I am NOT going to spend any money on AGM Batteries and Chargers until I have a solid plan for both components.

I felt that any 'Charging the AGM Battery' discussion should be a separate thread, keeping things simple, avoiding 'thread convolution', but now I believe that an AGM battery(s) and charger need to thought of together, as a single 'unit' much more so the FLA's.

In other words, a 'best' charger for AGM Brand A may or may not be the 'best' charger for AGM Brand B.

Not sure which is best. Close this thread down and start an AGM charging thread OR keep this one going?

Let me know.

Fred

Hi Shootandfish,
You have gotten a lot of good advice here so far! I am in agreement with your (and other's) assessment that AGM's are the best type of battery for your intended use.

Full disclosure; I don't own a trolling motor… or a boat for that matter. I also acknowledge that my opinions are biased due to the fact that I exclusively use Odyssey batteries in my truck (two Group 65's) and truck camper (three Group 31's)… However, I frequently operate high current appliances (microwave & air conditioner) for extended periods of time from my battery bank/inverter. I can say that I have abused the heck out of my Odysseys and after five years of use they continue to provide outstanding performance. They tolerate extremely high discharge current and have no limit on bulk charge current (@ 14.7V). They are rated to 400 cycles at 80% DOD (same as NorthStar). Here is a link to their Technical Manual.

So, all that said; I strongly suggest that you include Sears DieHard Platinum (Group 31) batteries as part of your evaluation. The Platinums are re-badged Odysseys... made on the same production line at EnerSys and have the identical performance spec's. As an added benefit these batteries have a 36month free-replacement warranty and are stocked at Sears stores across the country in the event you ever needed a replacement.

As you already know, to get the best performance and long service life from AGM batteries you will need to have an appropriate charger… one that can provide high charge current and have the appropriate voltages for each stage of charging, as well as temperature compensation. Selecting a charger may prove to be an even bigger challenge (and more expensive!) than choosing which battery to buy. As a starting point I suggest that you take a look at the offerings from KISAE and Mastervolt.
FWIW I use a ProSine 2.0 (no longer in production) which can charge at up to 100A and is highly configurable in terms of voltage, charge termination, and temp-comp. However, it doesn't sound like you're in the market for an inverter/charger.

I also own one West Marine SeaVolt Group 31 AGM (re-badged East-Penn/Deka) which I use in my travel trailer. Its performance has been just fine, no complaints at all. But to be honest I really haven't abused it at all since it is only used for lighting & running the water pump.

Good luck and please let us know what you finally decide to go with.
Cheers,
-Mark

Not clear why the charger has to be marine spec. Will the charger be fitted in the boat where it can get wet? Can't you just keep it in a plastic bag? Will charging be done at sea or just when alongside?

What is the 120v source to run the charger with?

If alongside then you can use ordinary portable chargers (kept in your RV) Marine spec chargers are insanely expensive compared with the same amps size "ordinary" charger with the same charging profile.

S&F1, thread clarification is always good as they will drift with personal agendas and egos that seek to be stroked.

I wish I could give you cyclic data about the Northstar. I have cycled it 2 to 3 dozen times deeply, and it does hold higher voltages for longer than a flooded battery rated at 40 more amp hours. It does have impressive ability to crank my starter. I do have great confidence in it, but I paid 285$ for it too so I want to have confidence in it to justify the large purchase price.

What gives me less confidence about the Northstar, is Not Mex's opinions on a start up company he is not familiar with, but the lack of documentation provided by the company itself. However, I am confident in the quality Odyssey batteries. I've read that NorthStar was started up by some disgruntled Enersys employees, but have no Idea if that is indeed true. There are many similar claims between Odyssey and Northstar, and looking at their spec sheets for the same size batteries, CCA nad AH capacity is pretty much identical.

Odyssey's recommended charger list is much smaller than Northstar's though.

Marketing claims are just that, claims, and in this day and age, marketing mumbo jumbo rules the day, there is no consequence for deception or outright lying, and often the only thing we have to base purchasing decisions on are the marketing mumbo jumbo, written by people completely unfamiliar with the product, or reviews by others who might have no concept of the same product's care and proper implementation.

Whichever battery you choose, it is the recharge regimen and the equipment that you implement which will determine cycle life, Not words on paper or worthless opinions with their own agendas.

If you get lifeline 14.3 or 14.4 absorption voltage and as many amps as you can muster, if you go Odyssey, bump that up to 14/7 and no less than 40 amps per 100 aH of battery, and if Deka intimidator, perhaps no more than 30 amps per 100 AH of battery.

A fully sealed marine charger that can meet the specs of these different demands will prove to be the biggest challenge to achieving maximum cycle life.

I did speak with an Odyssey engineer at length and he did say there was one condition where the Deeply cycled ODyssey battery could be returned to maximum energy density without the 40% rate to 14.7v then 14.7 for 4 hours was acceptable, and that was a charger which could slowly , very slowly bring the battery to 16.5V after a regular slower and lower recharge.

The engineer I spoke with mentioned this Brand specifically as capable of this, though I am not sure if it is this exact model.

http://www.powerprosinc.com/Pro-Charging-Systems-Professional-PS3-Battery-Charger.html

OP Back-Just to clarify.

What started this discussion was that I was researching the Sam's Club AGM Gr 31 the simple reason(s), price, availability (I can drive 45min and be at SC, and SC is located in about every town of size where I want to travel to), The SC aka Deka (East Penn) AGM has a good reputation, and 'icing on the cake', East Penn has published info that one can study.

East Penn, on p10 in the 16 Tech Manual shows that @ 50% DOD, one can expect 370 cycles. When I saw that Cabelas/NorthStar was claiming 900 cycles @ 50% DOD, The Engineer in me had to question 'such a large difference in cycle life'.

Plain and simple.

BFL, I think you have come closest to answering the O/P's question.

Seems the batteries he is looking at advertise 900 cycles, HE thought that was a bit low,, You say LIFELINE, considered by many to be the best, only estimate 1000 cycles. I have not done the research recently but... I do recall a surprisingly low number listed as well (And said so)

Still, as Mexico and I both agree, his job screams AGM.

And for the other guy.. Used Flooded myself in that condition but.. Well, there is danger in that (Mostly when you haul the battery back to shore for charging, if it's not properly "Seated" in the transport vehicle and it turns over.. Mel of a Hess when the acid leaks all over your carpet or paint job.

NinerBikes wrote:
Before you do cost comparisons, what happens if your whole battery get up set up gets stolen down in FL? Figure that into the equation for loss and replacement cost also.

Then replace it with a larger battery setup. Ya know, non-lithium batteries can get real heavy if they get big ... heavier than even drug-infested young bodies want to mess with! ;)

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