AGM Equalization - Some Benefit

[truk4u]

My house batteries are whimpy, when unplugged, they go to 12.4 almost immediately. With nothing to lose, I equalized them for 3 hrs at 15.5.

Batteries are now at 12.8 when unplugged and still had 12.4 after 7 hours of no shore power with just the fridge and a fan running.

If your batteries are marginal, this may help, but if they're bad, the equalization will have no effect. I equalized my Marathon and it didn't help at all. After removing the 6 batteries, 5 of the 6 were bad.

So, if you have some life left in your house batteries, give it a shot...

[JIM KELLER]

Good Information, Tom.

[Joe Cannarozzi]

We have a battery charger that can both "equalize" and "desulfate" but it is vague just what the difference is. According to the owners manual they both preform a similar function.

I desulfate our house batteries annually as a preventive measure, don't know if there is any benefit but I assume so.

[BrianE]

Tom, That's not bad considering you have only 3 house batteries. Would think that adding another one at this time might extend the life of the existing batteries significantly. Whad ya think?

[truk4u]

Brian - Thought I might make a trip to Battle Ground for a professional installation!:eek:

Joe - I think both terms are probably the same thing..

[Darrell and Linda]

Truk, by your title, do you have AGM house batteries?

It's my understanding that AGM (absorbed glass mat) batteries will receive no benefit by the "shaker". This equalization / disulfate charge will have no effect because the agm's have no liquid electrolyte (dry). The flooded or gel batteries are a different design and the disulfate mode "shakes off" the build up on the lead plates and the sulfate falls off the plates. The agm's are very tightly wrapped or matted plates with no electrolyte (liquid), so the equalization / disulfate has no effect. If fact, most three phase chargers mention that equalization may harm the agm battery (maximum charge 14.7v if my memory is correct).

If your voltage drops that rapidly, the batteries may be finished. But keep in mind, after a bulk charge, the batteries need to settle down for a few hours to give you an accurate voltage reading. The normal operating / constant drain parameters for an agm is no more than 1% drop in voltage over a period of one month, if no load or drain.

[Jon Wehrenberg]

Darrell,

Here is good information. AGM will benefit from an equalization charge.

http://www.windsun.com/Batteries/Battery_FAQ.htm#Using%20a%20deep%20cycle%20battery %20as%20a%20starting%20battery

You do not have to wait long for the "surface" charge to dissipate.

[truk4u]

Darrell,

Yes I have AGM's, that was the purpose of the post. I researched this at length and equalization does in fact help. I also was under the impression that equalization was for wet cell only and I was wrong. Gel should not be equalized.

My inverter/charger manual specifically has instructions for equalizing AGM's and the default setting was 4 hours, but I only did 3.

The proof is in the performance.;)

[BrianE]

Many thanks Jon. Great reference material.

[Darrell and Linda]

Good link Jon,

Truk, I guess I was misguided regarding the abuse of the agm's. I have house agm's and I have also put a red top optima for my starter battery for the genset.
I like the agm's for the winter storage and the lack of maintenance required.

My house batteries are lifeline and are four years old now. They seem to be performing well with no fast drain down time. Should I be budgeting for new ones after 5 - 6 service years. I've heard stories of agm's performing well for 8 -10 years.......

[truk4u]

Darrell,

I suppose the way a person uses the bus has a lot to do with the longevity of the house batteries. My experience has been the 5 year magic number seems pretty close. My Marathon was a 97 and it had new lifelines in 2002 and then I had to do them in 2007 and they were toast. My Liberty may be close to the 4 year mark (I'll have to check the log) and I know I'll never make 5 years. We will probably be dry camping for close to 2 weeks out of the next 30 days and I'll let you know if the equalizing had any lasting effect.

If your not into dry camping, maybe you could get 6, 7 or 8 years out of them because you wouldn't care if they drop off in between hook ups.

[Darrell and Linda]

Just to change the topic a little.

Today I started the genset and turned on the converters on the main interior electrical panel. The house batteries were sitting at 12.9v and converters usually start to charge the batteries but today nothing happened until I turned on the range and one of the a/c cruiseairs, and only then did the converters start charging the batteries. It seems the generator or converters need to be excited before they start to charge the batteries...... does this sound normal.

[Jon Wehrenberg]

Darrell,

On my 87 if I turned on the converters they reacted right away.

If I was using my inverter (not inverter charger as most coaches have now) it had to be excited by a current draw. It would not power a shaver for example, so to insure it would always come on we left the 120 Volt AC lamp on in the living room.

I am not real clear on my memory of how the converters were connected to the house batteries so this is a guess. On my 87 the isolator between the chassis and house batteries was a relay that looked like the big solenoids that were mounted on the firewall of old cars. That had to close to allow charging of the house battiesis when the engine was running. I can't remember if it had to close when sensing converter output. In any event that solenoid was a high service item as it would hang up frequently.

But having said that, at 12.9 volts with no charging current going into the house batteries they are fully charged. The converters may need a small voltage drop before they resume charging. This is something you just need to monitor and may be normal.

[Darrell and Linda]

Jon, I was thinking the same thing. The batteries were fully charged, or close to it. The batteries need to drain to activate the charger of the converters.

But it seems it only does this when the generator feeds the converters. Switching to shore, the converters react immediately and begin to charge and no load is required to stimulate the charger. These are 3 brand new xantrex 80A converters installed last September.

My inverter is a 2000 watt Magnum that I have kept from my last motorhome. It works very well and it has a great controller to set the parameters. It only has a 30A transfer switch but has a 100 amp three phase charger. I would like to connect this to the the power sources because I feel the charger / controller is superior to the 3 converters I have and being used as chargers.
Your comments.....

[Jon Wehrenberg]

Our 87 had two 12 volt converters for the house, one 24 volt converter for the chassis batteries, and a 2000 watt inverter.

We had to turn a big black knob manually to select the source of AC power.

The bus was nowhere near as user friendly as our current coach with two inverter chargers that I never turn off. When the coach is not being used it is connected to power in the garage and the inverter maintain the batteries.

My point is that as functional as the original coach was (and trouble free) it can't come close to using inverter charger(s) with an automatic transfer switch. If you ever choose to update your systems that is definitely the way to go. The ease of operation is like night and day.

[Darrell and Linda]

Truk, sorry with the change of direction of this thread, but I just gotta know.

Jon, as mentioned before, I upgraded the converters last year. I also took out the old inverter and replaced it with the 2000w magnum inverter / charger with auto transfer switch and controller. This inverter is presently only utilized for the selected 120v appliances in the coach supplied by the D/C house batteries. I would like to connect this inverter up to A/C power to take advantage of the charger and controller.

Question; Here goes the madness. I would like to connect this to the AC power. The connection would be made to the same output A/C source (wiring harness) as fed to the converters. Will this cause issues. The converters and the inverter would be receiving the A/C power from the same source and would be both trying to charge the house batteries. Can they back feed each other and would this become a major issue... damage to either the inverter or the converters????

This electrical stuff gets a little complicated at times.

[Jon Wehrenberg]

On our coaches (all years, all converters I think) it is common to be charging batteries from multiple sources simultaneously.

For example, all of us have had our coaches powered by shore power or the generator and at the same time we have been running our engine. When doing that our inverter chargers or converters are maintaining the charge on the house batteries, while the alternator is doing the same. When that occurs the charging source with the highest set point is actually charging the batteries once they are at maximum voltage.

When modifying the coach electrical system the DC side can have multiple battery charging sources, but the AC side of the electrical system can only have one source supplying power to the AC panel at one time. When an inverter powers certain circuits in the AC panel those circuits are isolated from the other circuits, including the circuits powered by a second inverter if so equipped. The reason for isolating electrical circuits so no two AC sources can power the same circuits is related to phase issues.

[truk4u]

Darrell,

No problem on the thread... I have 2 Magnum's that Brian had installed and they are simple to operate and work great. Curious as to what the cost would be for you to dump the converters, add a 2nd Magnum and utilize the full capabilities of the inverter/charger functions?;)

[Darrell and Linda]

Jon, that's good news because I didn't know if I could or not connect the two charging systems (converter / inverter). A/C source can only come from one outside source at a time... generator or shore. The control is located in the A/C panel (black selector). On the A/C panel is the breakers for the converters also.

Truk, when I purchased the coach last year, one of the converters was toast. The old converters had no thermal protection and were late 80's technology. So I replaced all three converters with three brand new xantrex 80A RV converters. Simple install, no changes to the wiring and maintained the original liberty design. At the same time, I had the 2000 watt magnum /controller / auto gent start. So I removed the original 2000w pac inverter to upgrade to the magnum. The function of all 120V appliances are working great as designed through the inverter but I am not using the inverter charger to its full capacity because it isn't wired in to charge the house batteries.

The thought crossed by mind to fully intergrade the inverter, and even stack inverters, to upgrade to the newer technologies like the late 1990 designed coaches but this is where I am challenged. I believe there would be a nest of wiring / harness changes that would be very costly. I can do a lot myself but ..........

[Jon Wehrenberg]

Darrell, to integrate the inverter/charger will require you to get 120 volts AC from your 120 volt panel back to the inverter.

The circuits that are now powered by the inverter must be isolated from the AC panel bus bar. You will need a minimum 30 amp 120 volt AC cursuit (and likely a 50 amp) to come from the panel to the inverter. When 120 volt AC power is sensed by the inverter the inverter becomes a battery charger and maintains the charge on the house batteries. When the AC power is available for the inverter, the inverter transfer switch sends that power to the circuits powered by the inverter.

As soon as AC input power is removed from the inverter the batteries become the source of power and the inverter provides 120 volt AC power to the inverter supplied circuits.

The key to remember here is that you MUST isolate the circuits powered from the inverter from the rest of the 120 volt panel bus bars. Any power to those circuits, even if on shore or generator power must come through the inverter transfer switch.

If you do not understand the how and why there are some good sources on line to understand how to hook up inverters. This will be a fairly significant amount of work, only lessened to a degree if the 120 volt panel in your bus is over the electrical bay to make fishing wires easier.

[Darrell and Linda]

Jon, your 87 liberty was the same as my Liberty, or a least very close, so you are very familiar to the floor plan. The main electrical panel is approx. 3-4 feet aft of the electrical bay. I mounted the magnum controller in the salon panel and tried fishing wire to the electrical bay..... tough, if not impossible. I clipped the old inverter controller wires and soldered in the new magnum controller.

I think I'm lucky here..... I have the small electric BBQ in the opposite bay. It doesn't fit the size of steak I like anyways... so I won't miss it. It is a single designated appliance 30A with a breaker on the panel. I could wire this to the transfer switch on the inverter so that the inverter will charge the house batteries. Label it - house battery charger.

This should work.......right? I think it is worth the effort.

[Jon Wehrenberg]

The installation requirements of your inverter will determine the circuit breaker required.

Remember, you could be transfering or inverting up to 30 amps, plus you need additional input power to handle the battery charging and that could draw as much as 20 amps.

On my current coach each inverter is on a 50 amp circuit. The output is 2500 watts. Wires are sized appropriately. The actual wiring is not complex, but getting new wires where they need to go could be involved because you are not replacing a component, you are actually adding one.

I added a 12 CD pllayer to my coach last year and I wanted it to look like it was installed from new. To run the wires with the other wire bundles was a pain and that took more time than anything because I had to disassemble so much.

What you want to do can be done, and the ease with which you do it depends on how easy it is to run the wiring you need.

[Darrell and Linda]

Thanks Jon, You have been great help.

The specs on the inverter is a 30 Amp AC input - transfer switch. The max. output is 16 amp for the charger.
I think the electric kenmore BBQ breaker on the AC panel is a 30 amp but will have to confirm that. The weakness here is the wiring size but will check that out also.

I will only connect if all requirements match... We don't fool with this electrical stuff. I fight fires for a living and I don't want to be discussing my actions with my fire investigators.

[Jon Wehrenberg]

Obviously the people building the inverter know the requirements and if they call for a 30 amp circuit for input that is all you need to provide.

Since you already have the breaker, it seems you only have to run the input wire. I am assuming the output from the inverter transfer switch is already in place. Since your original inverter did not function as a charger, and you probably have a manual selector switch to select the electrical (120 volt AC) input source I am guessing you will have to isolate the inverter circuits from the rest of the circuits in the 120 volt panel. The inverter supply can remain, but those powered through the inverter transfer switch (probably some outlets, a microwave and TV) will need to be on a separate bus bar isolated from the other 120 volt circuits.

Typically those circuits will be located near the end of the bus bar and the bus bar will be cut, separating those circuits. The supply coming through the inverter transfer switch will then connect to that short section of bus bar.

It may involve moving a few breakers and relocating the labels but I don't think that will be difficult.

I like your comment about discussing your actions with fire investigators.

[jelmore]

My house batteries are whimpy, when unplugged, they go to 12.4 almost immediately. With nothing to lose, I equalized them for 3 hrs at 15.5.

Batteries are now at 12.8 when unplugged and still had 12.4 after 7 hours of no shore power with just the fridge and a fan running.




Tom, after reading this I'm interested in equalizing my batteries. Checked the manuals, talked to Lifeline and talked to Xantrex. I have 3 8D AGM batteries and 2 Freedom 2500s inverter/chargers. Lifeline said yes, the AGMs will benefit greatly from equalization. Xantrex said they don't support equalizing AGMs, but if I do, to equalize from only one inverter/charger and to disconnect the other inverter/charger from the batteries. Their manual says to disconnect all 12V loads when equalizing.

Did you follow all of that? For me, disconnecting the one inverter/charger leaves me without a water pump. Also, I wonder about the high voltage during equalization affecting any 12V house items, like lights.

Can you detail how you did the equalization?

[Jon Wehrenberg]

Jim, I think I remember equalization taking about 8 hours, but I see Tom did three. Regardless of how long I would try to do the equalization when you can do without whatever circuits will be affected.

I would definitely avoid using the DC circuits when equalizing but I don't think we can turn off all 12V stuff (or 24V) because there is so much that is "key off" always working in the background such as the alarm system, clocks, dash radio and sound systems, etc..

[truk4u]

Jim,

I didn't do any of that stuff. I just followed the inverter instructions for equalizing and it did help for a short period of time, but the real cure is new batteries. If I remember, I cut off the house 12 volt, but there were still many 12 volt sources that had no adverse effect from the high voltage during equalization.

[BenC]

Also remember when discussing/thinking about battery voltage, that without a charge and ANY load, 12.9v is considered fully charged, and 12.1v is considered at 50%, or needing recharged. Also, the voltage drop-off is not linear and a good indication of their start of charge. Due to internal resistances, depending on the load on the battery/bank, voltage may be down to 11v, or at 12.1v before needing recharged. Just some food for thought.
The reason Xantrex does not "support equalization" for AGM batteries is that they, or many charger manufacturers, do not want to be responsible for the cost of a set of batteries because they were destroyed. AGM batteries only have overpressure relief valves, they do not have vents. When the electrolyte is burned off, it cannot be recovered like a liquid battery (by adding more electrolyte). The same is the case with gel batteries. With overvoltage, gassing WILL occur, releasing the electrolyte, and causing hydrogen gas pockets in the gel/wicking material. This results in lower surface area for the chemical reaction that allows electron flow from plate to electrolyte to plate, and thus current flow through the battery. Overall, decreased battery high-current capability. The short-term equalization voltage does, however, reduce sulfation on the plates, which in small durations helps increase surface area for the reaction. It's a gamble to equalize gel and AGM batteries. It can, however, get you a little more life out of them if done for very short durations, and I don't mean hours. Hope this helps someone.
Ben

[Alek&Lucia]

Ben,

Very good post,

Alek

[JIM CHALOUPKA]

Good tid bits of knowledge today Ben.

Thanks, JIM

[merle&louise]

I have a bad AGM in my house batteries. My 6 Lifeline 8Ds are 4 years and 7 months old.

Has anyone gotten much more than about 5 years out of a set of AGMs?

[Jon Wehrenberg]

I had about 5 years 6 months on mine when I pulled them.

They all tested OK but the ability to hold a charge compared to the new ones was poor. After 8 hours on the old ones I would be down to 24V and with the new ones, same time period and loads the end voltage is 25V.

I do not use auto start. If I did I am sure the life span would have been less but I have no proof of that.

[merle&louise]

Do batteries have a certain number of charge cycles in them?

If a fully charged battery is at 13.2 let's say and then it is run down to 12.4 volts then the charger kicks on and charges it back up to 13.2. Is is better for the charger to be set to kick on at 12.2 than 12.4? It would seem that the lower setting would give you more charges in the life of the battery.

How about if the cut-off voltage is raised from 13.2 to 13.6 - would that reduce the life of the battery?

Am I understanding this right?

[ajducote]

Tuga,

Check out this link. The downloadable manal has a lot of information. Check out the chart on page 35.

http://www.lifelinebatteries.com/

All the way on the right side click on "Technical Manual" , then "LifeLine Technical Manual"

example: 50% discharge rate will give 1000 charge/discharge cycles.

[merle&louise]

Thanks Andre, I appreciate the effort. I will read the Lifeline info tonight.

Karen said to tell Ann Hi !

[Jon Wehrenberg]

Tuga,

The charge voltages for a battery are specific to the type of battery and are important. The manufacturer specifies the bulk, absorbtion and float voltages and the inverters need to be programmed to provide that set of charge rates.

Undercharging a battery is as bad as overcharging.

The number of charge cycles a battery can expect is based on how low a voltage they are before re-charging. The lower the voltage the lower the number of cycles a battery can take. That is why Jack modified his autostart set point. By going to a higher set point he will get more cycles. There is a thread in which that was discussed.

Batteries are also affected by their environment. A gel cell battery cannot handle a high heat environment, but a conventional lead acid battery is much more tolerant of heat.

Here's more good reading....

http://www.vonwentzel.net/Battery/01.Type/index.html
http://www.windsun.com/Batteries/Battery_FAQ.htm#Using%20a%20deep%20cycle%20battery %20as%20a%20starting%20battery

There will be a test in the morning.

[merle&louise]

Thanks Jon, I have read the some of the attached articles and if I have to replace any batteries I will surely go with AGM. Those are both good information sources about batteries. I've got some reading to do.