Battery charger for AGM batteries

[Shrew]

Originally Posted by john61ct

Try 200A, .4C is their reco **minimum**

Do you have any references you can point to on this?

I'm digging through Lifeline documentation now.

This looks like the formula Lifeline is saying the following:

ChargeTime=(((<DoD>/100) * <Capacity>) / <Output>) + AT

DoD: Depth of Discharge
Capacity: Battery Capacity (Ah)
Output: Charger Output
AT: Absorb Time

Example:

100Ah battery @ 40% Discharge (DoD) with a 25A charger:

(((40/100) * 100) / 25) + 3 = 4.6 hours

10A Charger:

(((40/100) * 100) / 10) + 3 = 7 hours

So with a 500Ah bank and a 100A charger and a 25% Discharge we would see:

(((25/100) * 500) / 100) + 3 = 4.25 hours

I'm having a bit of a hard time calculating Float. Can anyone clarify?

###### REFERENCES ######

http://2cw8eb1vmmgg3g5i7jzt6upo.wpen...cal-Manual.pdf

[john61ct]

Sorry my mistake, that's Odyssey (Enersys)

Northstar and Lifeline publish .2C as their minimum.

But all same TPPL design / tech, Enersys was the inventor, the others "spun off".

All have good support centers

[Saltyhog]

Originally Posted by john61ct

Sorry my mistake, that's Odyssey (Enersys)

Northstar and Lifeline publish .2C as their minimum.

But all same TPPL design / tech, Enersys was the inventor, the others "spun off".

All have good support centers

Just FYI, Lifeline are not TTPL.

[DLECF]

Originally Posted by Shrew

Do you have any references you can point to on this?

I'm digging through Lifeline documentation now.

This looks like the formula Lifeline is saying the following:

ChargeTime=(((<DoD>/100) * <Capacity>) / <Output>) + AT

DoD: Depth of Discharge
Capacity: Battery Capacity (Ah)
Output: Charger Output
AT: Absorb Time

Example:

100Ah battery @ 40% Discharge (DoD) with a 25A charger:

(((40/100) * 100) / 25) + 3 = 4.6 hours

10A Charger:

(((40/100) * 100) / 10) + 3 = 7 hours

So with a 500Ah bank and a 100A charger and a 25% Discharge we would see:

(((25/100) * 500) / 100) + 3 = 4.25 hours

I'm having a bit of a hard time calculating Float. Can anyone clarify?

###### REFERENCES ######

http://2cw8eb1vmmgg3g5i7jzt6upo.wpen...cal-Manual.pdf

Shrew:
I have exchanged emails and had phone conservations with 3 different Lifeline Battery support techs this week about the recommended size of a new battery charger. Two of them recommended a 50 amp charger and one a 30 amp charger after I told him that my vessel is a trawler. I was told that the Lifeline engineers recommendation for sizing the battery charger output at 0.2 to 0.4 of battery capacity is based on starting with a 100% discharged battery. I have never even tried to charge a 100% depleted battery. I can count on one hand the number of times that a battery on one of my vessels was below 50% before recharging. The way we currently cruise Puget Sound on our trawler does not include several days on the hook drawing down the house battery bank. The start and house batteries are typically 13.2 VDC after we are back in the slip.
I decided to order a Pronautic 1230 30 amp charger. Only time will tell if I have made the correct decision. I appreciate all of comments and advice from the CF community.

[ranger58sb]

Originally Posted by DLECF

Two of them recommended a 50 amp charger and one a 30 amp charger after I told him that my vessel is a trawler.

I wonder why "trawler" made him suggest only a 30A charger.

Maybe assuming your engine(s) would be supplying DC power while underway... unlike with a sailboat?

Hmmm...

-Chris

[john61ct]

Yes stinkpots can produce a lot of power every time they get underway.

Only those sitting for days on the hook need any alternative power.

[a64pilot]

Page 20 of the Lifeline manual, second paragraph, see where it says that current for the bulk phase should be as high as practicable, then goes on to say the battery can tolerate as high as 5C.
This tells me that Lifeline is saying the bigger, the better up to 5c anyway, which would be an over 3000 amp charger in my case. And that isn’t practicable.
Remember your house load comes off of that 30 amps, so it’s not a 30 amp charger.

Do you spend time at anchor, if so how do you recharge? If by generator, then you certainly want bigger than a 30 amp to keep from running the generator all day, although some do I guess anyway.

[john61ct]

Their minimum is .2C

Anything over .6C would be complete waste, soon as SoC climbs even a bit, CAR drops very quickly.

Tolerating 5C is just bragging about how robust they are, especially with all the vendors that spec silly-low max charge rates.

Practical or not, best longevity is from higher amps, .2C really is a **minimum**, .4C is better.

But not cycling too low and avoiding PSOC are certainly much more important in that regard.

[Shrew]

Originally Posted by john61ct

Yes stinkpots can produce a lot of power every time they get underway.

No need to attack people choices of boat. Incidentally, you still have not cited your sources.

[ranger58sb]

Originally Posted by Shrew

Do you have any references you can point to on this?

I'm digging through Lifeline documentation now.

Originally Posted by Shrew

No need to attack people choices of boat. Incidentally, you still have not cited your sources.

I can't tell what info you're looking to source. The .2C recommendation? If so, see Lifeline' Technical manual, document No. 6-0101, Revision E, February 2, 2017, maybe that's it.

For repetitive deep cycling applications (deeper than 50% DOD), chargers should have an output current of at least 0.2C (20 Amps for a 100 Ah battery).

Slightly further up on that page is the part about tolerating "in-rush current levels as high as 5C (500A for a 100A battery)."

Or maybe you're looking at Odyssey batteries? They suggest "0.4C or more" in their Application Manual, Sixth Edition, Publication No: US-ODY-AM-001, April 2006.

Table 5 shows the minimum charge currents for the
full range of ODYSSEY batteries. When using a charger
with the IUU profile, we suggest the following ratings
for your ODYSSEY battery. Note the charger current in
the bulk charge mode must be 0.4C [endnote 10] or more. A list of
chargers approved by EnerSys for use with
ODYSSEY batteries is available at
http://www.odysseyfactory.com/odycharg_c.htm.

Those docs, or their updates, should be on the respective websites...

-Chris

[a64pilot]

I was wondering why a Trawler would make more electrical current than a sailboat?
Unless a small sailboat, they can and often do have rather large alternators.

The OP will do fine with a 30 amp charger, if their main focus is leaving a marina fully charged and motoring to the next Marina and plugging in, then likely a 30 amp charger will service most if not all of their house loads.

However if they anchor out and often run a generator to recharge the bank, then a 30 amp charger is way undersized and they will be running the generator many more hours than if they had a larger charger, especially if they have some Solar to do a “topping charge”.

What I am saying is for example, that overnight I will use 150 AH, if today is a little overcast, I can crank the generator and in one hour put 100 AH back into the bank, then Solar can top off the bank even on a cloudy day.
If I had only a 30 amp charger, it would take about 5 hours to put 100 AH back in, reason is our house load is about 10 amps, leaving of course only 20 amps out of the 30 amp charger to charge with.

I’m also of the opinion that any charger If run at less than 100% max output will due to a lack of heat build up, last longer than a charger that spends hour after hour at max output.

Likely one of the biggest advantages of an AGM bank is that you can really put a large initial charge back into the bank rather quickly, however to realize that advantage, you need a charge source large enough to make that happen.

It doesn’t really shorten the time to fully, 100% charged though because it takes hours at lower acceptance rates to get there, and those hours are ideally accomplished with Solar.

[maine50]

I've been very happy with the performance and capabilities of the Sterling charger I bought from Rod at(Compass Marine) who sells them discounted.
He is a frequent contributor here and his web site is a great source of "how to" articles.

[john61ct]

I mean stinkpot in the most affectionate way.

[john61ct]

Call Concorde, ask for Dave.

Godber more likely, Dave V is harder to get through to.

Or https://marinehowto.com/how-fast-can...ry-be-charged/

[ranger58sb]

Originally Posted by a64pilot

I was wondering why a Trawler would make more electrical current than a sailboat?

Maybe engine running more often, always, when underway?

??

-Chris