The Once And For All On Batteries...

Awesomeness

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Nice Charger but big bucks to at $400.00 each on sale.
They have sales and stuff. I think I got mine <$300, like 4-5 years ago. I assume it pays for itself over time, by maintaining the batteries better and prolonging replacement. I don't know how old the batteries in the truck were when I got it (or how many times soldiers had mistreated them and run them dead), but one finally failed last year, and two this year. So I'm satisfied with it.
 

Ronmar

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The 6TL’s I have are 120AH(says it right on the lable).. AH capacity is only additive in parallel, just like voltage is only additive in series, so the 4 battery bank on the LMTV is 240AH... a pair in series would be 120AH...

The limiting factor for charging a battery, is the same as for discharging one, which is the ammount of time it takes to draw or push the sulfur ions out of or into the electrolyte solution, and this requires that the electrolyte move into close contact with the plates. Thats why batteries are usually rated at 20 hour AH rates, as that is the most efficient time frame with the least loss to circulate the electrolyte and draw out the batteries full capacity. As mentioned the faster you try to push or pull, the more heat is made and heat = loss...

The mat in the AGM’s are way more efficient at distributing electrolyte(like the wick in a oil lamp)so they can deliver more current and also draw more current during a charge. Since the plates or grids are supported and surrounded by mat, they are more resistant to vibration, but In my experience they are no more tollerant of mistreatment and undercharge than any other lead acid(maybe less so) and I have experience with a couple different platforms to base that opinion on.

I wouldn’t use AGM’s for a house battery or deep cycle application for a couple reasons. They do have a slight edge on charge efficiency, and they can charge faster(if you have the energy source), but in deep cyclic use, they typically have a significantly shorter lifespan, and cost significantly more. IE: a good wet cell will typically last 1.5 times as many cycles before dropping to the 50% capacity point as an AGM...

Off-road race car, motorcycle, ATV, go-fast boat or airplane, or even a slow moving wheeler that operates at extreme angles, and where weight and vibration resistance are important, AGM is the ticket. The added cost and shorter life just don’t make sense to me for an RV house battery... And unless you are fitting out one of these trucks to race in Dakar, they don’t make a lot of sense as a service battery either...
 

Awesomeness

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The 6TL’s I have are 120AH(says it right on the lable).. AH capacity is only additive in parallel, just like voltage is only additive in series, so the 4 battery bank on the LMTV is 240AH... a pair in series would be 120AH...
The CCA/charge current only adds in parallel, but the AH capacity adds both in series and in parallel. So adding 4 batteries @120AH/each equals 480AH.

(The AH capacity is basically "how big of an energy bucket" they are. So adding more "buckets" literally adds more energy volume to drain from. Or think of it like gas tanks. Putting two gas tanks in series, one after the other, doesn't let you drain it any faster, because it's still just going through one hose. But you do get twice as much volume to drain. And putting two gas tanks in parallel, side by side, lets you both drain the extra capacity of two, plus drain from two hoses at once.)
 
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doghead

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Don’t forget to factor in the size of the hoses.

And the hose connections as well.
 

Ronmar

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The CCA/charge current only adds in parallel, but the AH capacity adds both in series and in parallel. So adding 4 batteries @120AH/each equals 480AH.

(The AH capacity is basically "how big of an energy bucket" they are. So adding more "buckets" literally adds more energy volume to drain from. Or think of it like gas tanks. Putting two gas tanks in series, one after the other, doesn't let you drain it any faster, because it's still just going through one hose. But you do get twice as much volume to drain. And putting two gas tanks in parallel, side by side, lets you both drain the extra capacity of two, plus drain from two hoses at once.)
No, Amp hours is the wrong term to express the amount of energy storage gained in series... IE: A 12V 100AH battery would support a 12V@10A load for 10 hours. Two 12V 100AH batteries in series to make a 24V battery, would support a 24V@10A load for the SAME 10 HOURS... It is twice the amount of work being performed, but it is still the same application to the amp hour rating... the 24V unit takes the same amount of time to charge as the 12V unit given the same charge current at the two different voltages. The difference from 12V to 24V doubles or halvs the energy in play, but has no bearing on an amp hours rating. Now if you parallel another set of batteries, you have now added to the amp hour capacity while maintaining the same voltage.

The correct term for capacity added by adding in the series dimension would be watt hours, which is not as often used... It is twice as much energy(watt hour capacity), when you add two batteries in series, but you are also drawing from it at twice the energy rate(24V vis 12) so it is still the same draw on the amp hour capacity...
 

Mullaney

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Hoses / Cables (similar enough?)

Strangely enough, the M1088 with 4 batteries that were replaced (after the thief stole mine) had a charging problem. I went to the local parts store months ago. Bought 4 twelve inch "lugged ended cables". I attached them to the batteries with lots of help on here. Struggled but finally connected the wires to the right place - again with help here.

Everything was fine for about a month. And then one day I went to to crank the truck. The normal sounds where relays clicked, after-cooler fans came on, and dash lights came one - except they didn't happen (turn on). All the 12v stuff was down around 9v. Measured with a volt meter to confirm.

ANYWAY,

I charged all four batteries one by one. Charged to about 13v +/- and while everything was disconnected I figured out that the small "jumper" wires were just too small. When I replaced them from McMaster Carr 2/0 wire, my problems disappeared.

So, size definitely does matter. In battery cables anyhow...

.
 
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Awesomeness

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No, Amp hours is the wrong term to express the amount of energy storage gained in series... IE: A 12V 100AH battery would support a 12V@10A load for 10 hours. Two 12V 100AH batteries in series to make a 24V battery, would support a 24V@10A load for the SAME 10 HOURS... It is twice the amount of work being performed, but it is still the same application to the amp hour rating... the 24V unit takes the same amount of time to charge as the 12V unit given the same charge current at the two different voltages. The difference from 12V to 24V doubles or halvs the energy in play, but has no bearing on an amp hours rating. Now if you parallel another set of batteries, you have now added to the amp hour capacity while maintaining the same voltage.

The correct term for capacity added by adding in the series dimension would be watt hours, which is not as often used... It is twice as much energy(watt hour capacity), when you add two batteries in series, but you are also drawing from it at twice the energy rate(24V vis 12) so it is still the same draw on the amp hour capacity...
You're right. The AH rating stays the same, but the "two gas tanks" analogy is still meaningful. In series you now have 2x the voltage, you'll be drawing 1/2 the amps for a given work (Watts), and thus run 2x as long with two batteries. So it is a capacity improvement, and still takes 2x as long to recharge too.
 

Third From Texas

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I was watching the 4 New Batteries I just put in. Found that one 12 volt was dropping and not the other? It was not tied into the other 12 v. Charged all 4 at 24 volts they did not charge equal for me. To get them all floated even I had to do one at a time at 12v. The 12 v part is going down slowly over a few days? It did the same thing with the 4 Red Tops that were in it. Pulled them out and found only one was bad out of the group. I still have them. Going to put a amp meter on the cable to see where it is bleeding off to. The Cold Temps I was talking about was me freezing my butt off. I did not have gloves. It is blowing 23+MPH and 39 MPH Gusts at 19 degrees. Did not take long unhooking my batteries to get my fingers froze! Will be dropping down to 1 degree real soon here.
12v vampiric drain?

Add a balancer and all will charge evenly.
 

Ronmar

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You're right. The AH rating stays the same, but the "two gas tanks" analogy is still meaningful. In series you now have 2x the voltage, you'll be drawing 1/2 the amps for a given work (Watts), and thus run 2x as long with two batteries. So it is a capacity improvement, and still takes 2x as long to recharge too.
Correct, except the 2x as long to charge part. That would only be true if you are charging at the same wattage input for both voltages. IE: A 12V@100Amp alt is 1200W. A 24V@ 100A alt is 2400W. Now if your 24V alt is only 50A/1200W, then yes, the 24V will take twice as long to charge the 100AH battery, because your alt has half the amp output at the higher voltage...

If your two different systems, 12V @ 100AH and 24V@ 100AH Both use 100A alternators in their respective voltages, they will both recharge in the same amount of time...

AC systems typically deal in watts, but I think DC systems, particularly those with batteries usually stay in amps so it is a little easier to design and eval just looking at labels, because for a given voltage everything is already in like terms...
 
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