AGM Battery maintenance/charging for dummies?

[dwh]

Hadn't seen the genius before. Looks decent. Only gotcha is Step 12 on this page:

http://www.geniuschargers.com/G26000/specs


Battery equalization (equalizing the cells) is defined as "a controlled overcharge". You take it up to a full charge, then overcharge it a certain amount in a certain way to get all the cells equal.

13.6v ain't gonna cut it. Here's a short and sweet write up on it:

http://shop.pkys.com/battery-equalization.aspx


But, I suppose NoCo's "16v Boost" at Step 14 might be doing something like a proper equalize.

WHY do half the battery charger manufacturers in the world pull their own unique nomenclature out of their a**es?

[taugust]

Though to be fair, a trickle charger/maintainer is not designed for this purpose - better as you say to use a higher-amperage charger to get them up to some reasonable state of charge first.

The one I have is not the 2A version (trickle). I have the 8A charger. If the battery is too low, it won't bring it back. It will attempt for a short time, then kick out of the cycle. If this is done enough times, you might bring it back enough to get it to top up and desulphate. I prefer to get it back up quickly, then run the multi stage and desulphate with the BatteryMINDer.

[FellowTraveler]

I'm running dual Delco CS130D 105 amp ea. which GM calls generators regulated by engine management controller (EMC) and wired with larger gauge cables as per the GM upfitting manual instructions then into 2 AGM Oddessy batteries.

I had tried to go w/voltage sensing lead on each and the CS130D's appeared to be chasing each other w/output so I kept the upfitter wiring layout and all is well. These CS130D's have some features (some kind of chip on reg/rect) referred to as pulse width modulation (PWD) in the alt/gen world which I really don't fully understand but they have worked for me even after being submerged in the Suwanee and other rivers.

Anyway, I plan to install yet another (3rd) AGM battery inside the passenger compartment its a big 100 lb unit w/120 ah rating. I was going to wire it with an 80 amp solenoid and fuse then wire it to an ignition on circuit to switch on for recharging it w/o need for stand alone charger. after reading this thread I suspect I need some good advice.

Are the CS130D's capable of this recharging of 3rd battery w/o over charging the other batteries, or do I need to wire in some solenoids to take the other batteries out of the mix unit 3rd battery is charged, or should I draw power to inverter through all the batteries to avoid charging issues and include some kind of voltage sensing alarm to warn against too much drain?

[dwh]

These CS130D's have some features (some kind of chip on reg/rect) referred to as pulse width modulation (PWD) in the alt/gen world which I really don't fully understand...

Factory PWM? Or an aftermarket add-on? Would this be the mod you are referring to?:

http://www.perfectswitch.com/downloa...130D5020-B.pdf

PWM stands for Pulse Width Modulation. Basically, what it does, instead of just "turn it on and leave it on", it "turns it on and off very fast". That's the pulsing. Modulating the width of the pulse, means controlling how long it stays on, and how fast it switches on and off.

Typical automotive voltage regulators, will switch on the alternator when the voltage of the "12v bus" (the entire electrical system is the "bus") drops to around 13.5v. It will leave the alternator switched on, until the bus voltage gets to around 14.5v and then switch the alternator off. The loads will then start pulling down the bus voltage. When it gets to 13.5v, the regulator switches the alternator on again.

On and off, up and down - the end result is the bus voltage averages out more or less around 13.8v.

PWM doesn't do that. What it does is, as soon as it detects ANY drop in the bus voltage (anything sucking power out of the bus, will cause the voltage to drop), it gives the bus a quick shot of juice. A pulse.
If the bus voltage has dropped a lot, it will let the pulse last a little longer, or maybe start doing the pulses a lot faster - modulating the pulse width.
It will pulse as as long or as often as it needs to, to hold the bus at exactly the set voltage.

So a normal regulator is somewhat sloppy. It allows a lot - generally around a full volt - of variance, whereas a PWM regulator keeps the bus voltage within a very tight range.

Anyway, I plan to install yet another (3rd) AGM battery inside the passenger compartment its a big 100 lb unit w/120 ah rating. I was going to wire it with an 80 amp solenoid and fuse then wire it to an ignition on circuit to switch on for recharging it w/o need for stand alone charger. after reading this thread I suspect I need some good advice.

Are the CS130D's capable of this recharging of 3rd battery w/o over charging the other batteries, or do I need to wire in some solenoids to take the other batteries out of the mix unit 3rd battery is charged, or should I draw power to inverter through all the batteries to avoid charging issues and include some kind of voltage sensing alarm to warn against too much drain?

Overcharging won't be an issue. Even with a Mobi-Arc regulator with PWM, it's still just a single-stage charger. I.e., it will hold the bus voltage at whatever it's set at - lemme just pull a number out of thin air...say 13.8v.

So, the voltage regulator will hold the bus at 13.8v, and all the batteries connected to the bus will absorb power at their own rate until they have all reached 13.8v and then everything just stays at 13.8v and that's that - no worries about overcharging anything.

So a solenoid isolator would work fine for that.


The worry about overcharging happens when you use a multi-stage charger. Specifically a 3-stage charger.

With that sort of charger, the absorb stage will hold a higher voltage until the amps flowing through it drops below a certain amount. Well, if one battery is already full, but another is still absorbing power, then the charger will continue holding the higher voltage, and the full battery will end up being held at that higher voltage for too long, and by the time the one battery finally gets full, the other battery ends up overcharged.

Not an issue with a 2-stage charger because a 2-stage charger omits the absorb stage.
Also not an issue with a single-stage charger such as an automotive voltage regulated alternator.



So, your main problem is not overcharging.

Your main problem, is that using a single-stage charging system to recharge a BigAss(TM) deep cycle battery, can take a VERY long time. If the voltage regulator just holds the bus at 13.8v, then it can take 8 or 16 (or more) hours for the big battery to finally absorb all it can.

Also, taking a big deep cycle only only up to 13.8v is only going to get it 90 or 95 percent full. It will never really reach "fully absorbed". That can measurably shorten it's life.

So, depending on how much you use that big battery, and how far you drain it when you use it, you'll probably get a lot longer life out of it if you use a multi-stage charger rather than just using a solenoid to tie it to the 12v bus.

(For that battery alone that is - the cranking batteries will be just fine being charged off the bus, and you don't want to use a charger with an absorb stage on multiple batteries anyway.)


I've got a 115ah deep cycle battery in my camper. I use a solenoid and let it charge off the vehicle bus while driving, and use a small generator and battery charger for charging it when I'm not driving (or I can use shore power).

If I had an expensive battery, then I'd probably invest in a DC-DC multi-stage charger. That's basically the same as a shore powered 3-stage charger, except it gets it's power from the vehicle's 12v bus.

That will take the 13.8v from the bus, kick it up to 14.4v and then do a proper multi-stage (with absorb) charge on the big battery.



Or, yes you could also power an inverter from the vehicle bus, and use the inverter to power a multi-stage charger. One advantage of that scheme, is that you can also use that same charger from shore power when you want.

EDIT: One big disadvantage, is that you better make damned sure it's turned off when the engine is off - or you'll suck down your cranking batteries.

[FellowTraveler]

DWH, Thank you for your response.

My factory regulator (s) include the pwm function, my bus is set @ 14.37 volts so I'm thinking it will no problem to fully charge the AGM battery.

I'll be updating my old 45 amp power converter to include newer tech 3 stage charger like you suggested to use w/shore or gen-set.

[teotwaki]

Great technical thread. Am bookmarking so as to use for a reference or referrals.

[dwh]

DWH, Thank you for your response.

No problemo.

My factory regulator (s) include the pwm function, my bus is set @ 14.37 volts so I'm thinking it will no problem to fully charge the AGM battery.

Hrmm. Well, that could "possibly" be too high for long term health of the batteries.

Most flooded and AGM batteries specify their "optimal" charge routine as:

Push it to 14.4v (bulk stage).
Drop to 14.2v and hold until fully absorbed (absorb stage).
Drop to 13.6v to maintain (float stage).

Holding the absorb stage too long is not recommended. Most multi-stage chargers will drop from absorb to float when the amps flowing to the battery drops below 2a or so. Some, like the Iota with IQ/4 control module put a timer on the absorb stage. The Iota IQ/4 will drop out out of absorb after 8 hours regardless if the amp flow hasn't lowered.

So, if the vehicle charging system is holding the bus at 14.4v all the time, that could end up overcharging the batteries.

Whether or not it's an issue, depends on how many hours a day you are doing it. If you push the batteries up to 14.4v and hold them there for...oh...with good batteries probably less than 8 hours a day...then it's probably not an issue. If you were running a commercial vehicle all day every day though, I'd want the bus voltage down somewhere under 14v.

I'll be updating my old 45 amp power converter to include newer tech 3 stage charger like you suggested to use w/shore or gen-set.

New converter box or Parallax upgrade?

I'm not a big fan of the Parallax. Good quality, but most of their units are 2-stage and they only bulk to 13.8v or 14v. Probably okay for an RV that spends 99% of its time sitting in the driveway or at a full hookup campsite - i.e., plugged into shore power - but otherwise, not so great for really getting batteries fully absorbed.

[FellowTraveler]

DWH, Again thanks.

I'll have to keep tabs on the voltage over a period of say 5 hours on an upcoming trip combined day/night.

I was thinking Parallax but you have me rethinking that now this Burb is used everyday, any suggestions? IOTA IQ/4 or?

[dwh]

DWH, Again thanks.

I'll have to keep tabs on the voltage over a period of say 5 hours on an upcoming trip combined day/night.

I was thinking Parallax but you have me rethinking that now this Burb is used everyday, any suggestions? IOTA IQ/4 or?

Um...

Who is it sells the Magnetek/Parallax upgrade kit? Lemme check.

Best Converter:

http://www.bestconverter.com/Magnete...a_ep_13-1.html

They've got a few different options for upgrading older load centers using Parallax, Progressive Dynamics or Iota.

Personally, I'd go with Iota DLS (built-in IQ/4 control module) and stick to no more than 45a so it would run even at full load from a 1600wC/2000wS rated generator like the Honda eu2000i. Any so-called "2000w" generator would run a 55a unit at sea level, but sometimes, 55a is too much load for the generator at higher altitudes. But they'll run a 45a anywhere.

The only drawback, is the Iota doesn't have temperature compensation, which is a really nice thing to have to get the battery as perfectly charged as any goofy pile of lead and sulfuric acid ever can be.

Not a deal breaker though if you ask me.



I'm not a fan of Progressive Dynamics either. They are one of those who like to jimmy up the nomenclature. If you look at the specs for their Charge Wizard control module:

http://www.progressivedyn.com/prod_d...zard_9105.html

You see what they call "Boost Mode" is what everyone else calls "Bulk Stage" (14.4v).
Then, it drops to what they call "Normal Mode" which is actually what everyone else would call "Float Stage" (13.6v).

So...really, it's what anyone else would call a 2-stage charger (bulk then straight to float - no absorb stage).

Then, after 30 hours of no activity, it drops to what they call, "Storage Mode", which is really just a lower voltage (13.2v) float stage. (Personally, I think that's actually a nifty feature for a rig that spends most of its time sitting in the driveway plugged into shore power.)

And then, as if they haven't screwed with people's minds enough already, they have what they call "Equalizing Mode" - which is just popping back up into 14.4v bulk again for 15 minutes every 21 hours.

That's HORRIBLE. Geez, no wonder people get confused.

In the real world, "equalizing" means "a controlled overcharge". You charge the battery up fully, and then overcharge it a precise amount for a precise time to get all the 2v cells' specific gravity "equal". And, it's something that you are, for the most part, NEVER supposed to do to a sealed battery. (It *can* be done, but you better know what you are doing and better have a damned precise power supply to do it with.)

What their charger does is sure as hell NOT "equalizing" - at least, not according to how the rest of the battery world understands the term.

And then, there is a button on the control module so you can manually initiate the 14.4v bulk stage - I mean, "Boost Mode" - if you choose to.


Don't get me wrong, the PD is actually a well built unit and does a pretty damned good job of battery charging. But having to translate their marketing techno-gibberish leaves a bad taste in my mouth.

[FellowTraveler]

DWH
You convinced me on going w/the Iota 45 amp w/IQ/4 my gen-set is a 2.7k unit so the 45 amp will be easy, thanks.