Dual 6 volt GC2 batteries and charging characteristics

[busterbrown73]

We just returned home to Michigan from a 24 day trip around the southwest. This was the first big test of our new dual 6 volt battery bank (upgraded from a single group 24 12 volt).

As I have really no experience with charging behaviors of a serial 6 volt setup, I'm looking to see if I need to upgrade the OEM converter charger on my travel trailer. This is what I noticed during our trip.

1. Started with a fully charged 13.3 volt bank on the morning of our departure after plugged into shore power for 48 hours. The Duracell (215 amp hour) flooded batteries are brand new.

2. After using typical appliances through a dry camping night, (DC inverter for television/fan, furnace, led lights, LPG fridge, and water pump), the bank would drop to 12.4 to 12.6 volts. We would run our 3700 watt inverter generator for 5 to 6 hours during the next day to allow the converter to recharge the bank. I thought it was preforming as expected except that the converter would charge to about 12.8 to 12.9 volts. I never got back to 13.3 volts until we plugged into shore power at a full hookup campground.

3. On several legs of the journey, we would leave the dry camp location without running the generator in the morning and drive 4 or 5 hours to our next camp site. I checked the volts on arrival at the new site and my TV would barely provide a recharge (12.5 to maybe 12.6). The previous group 24 12 volt would be completely charged after just a couple of hours of running the truck. (Obviously, I have much more amp hours with the GC2s).

My concerns are:

1. Is my OEM converter the bottleneck in my coach's recharging capabilities?
2. For a dual 6-volt in-series battery bank (flooded), what should I expect as a full charge? I've read 13.3 volts as being 100% as a float charge but absorption voltage could be much higher.
3. Will a true 4 stage converter charger (bulk, absorption, float, equalize) help maximize battery usability and increase overall battery life?
4. If a new converter is needed, what size (amp) is preferred? Are converter/inverter types recommended as I see the price point goes much higher? Realistically, I would like to see a full charge after a couple hours of generator use.
5. Is a larger battery bank crippled by the inadequate charging abilities of the converter?

[MEXICOWANDERER]

Aiiiiii!
How dare you insult those hard working 11-year old Bangladeshi dawn till dusk Nike warriors! They stand on tire tread sandals all day making basketball shoes that grade school kids die for -- literally.

[2oldman]

wa8yxm wrote:
My 10 dollar Converse All Star High top tennis shoes from Big Lots way outlasted 150 dollar Nike's )

How did they fit?

[MEXICOWANDERER]

Hmmmmm I believe there is a difference between industrial products sold to engineers and style products sold for fashion. When a product is pitched to a manufacturer it has to pass a multi-level justification. Engineer to senior engineer. Then, on to production staff where an accord has to be reached. A presentation is made before executives of the company. Vital aspects are extracted and presented to bean counters who are perhaps the most reluctant element in the company. Net profit is their game and to challenge established profit margin upsets their apple cart. "Prove it to me Mr. Engineer, sit down and tell me how glass matting that will cost us 500% as much as our already proven existing mat is going to make us more money".

Versus....

"Oooooooo lookie! Anyone who is socially anyone has to have that stylized check mark blaring from their (-------). The $5,000,000 contract ball-bouncer even has his name on them. Yain't squat in da hood unless you got a pair"

[wa8yxm]

MEXICOWANDERER wrote:
When
Another tip: Correlate my suggestion above with Concorde's insistence that their hideously expensive glass mat ....."

Now that.. Is a comment I agree with.
All these folks sold on the Hideously Expensive Option cause if it costs more it must be better.. RIght? (NO IT just Costs more.. My 10 dollar Converse All Star High top tennis shoes from Big Lots way outlasted 150 dollar Nike's back before I wore 'em out, of course back then Converse was made in the USA today that's changed. the cost of manufacturer went down. as did the quality. and the price up.)

[jharrell]

MEXICOWANDERER wrote:
Despite the Lifeline's higher price I feel like the military provided a vast chasm of advancement for Concorde, right off the bat.

The fact that they say 5C charge rate is just fine so charge them at the max rate practical vs everyone else who pretty much says don't do more than C/5 tells me there is something a whole lot different going on. When Concord makes a lithium for recreational use that's when I'll be serious about changing chemistries.

[MEXICOWANDERER]

When I was young and yearned for answers to questions not yet asked was when the hook was set.

Another tip: Correlate my suggestion above with Concorde's insistence that their hideously expensive glass mat is yet another reason why the Lifeline is a unique product.

I am beginning to believe the 94 minute product introduction film I saw on youtube was a strictly proprietary in-house engineering piece that was "improperly copied"

It showed massive jigs in action where plate orientation and alignment was performed using laser guides, and pneumatic pistons. All computer controlled with builtin- go-no-go rejection and how through the cell connectors caused problems and loop over lead buss spread connectivity to the join plates.

This was aerospace grade assembly. What the mats looked like under 50x magnification.

Concorde must have had "consideration" assistance lent by the military. No one on their right mind would have a start up that demanded tens of millions of dollars invested in plate alignment machinery that was computer controlled. just-in-time batch plate pasting. Computer grid forming. Batch analysis of raw materials.

I wanted to see the video again. Concorde denied it's existence repeatedly. What was the giveaway is that they tried to bleed information from me and they pressed me for date and time of day I watched it and where in profile on youtube I saw it. When I mentioned that a flash of the plate alignment machinery had a prominent SIEMENS riveted production tag that's when things got serious. They asked me to get back to them quickly if I should see the video anywhere else.

Anyway it all adds up to the military contracts Concorde has paid the tab for the elaborate machinery. Doesn't take a genius to figure out the Magnehelic manifold pressure control the military batteries use is to compensate for sea level to rapidly changing stratospheric pressure differentials in warplanes. Recombinant pressure relief design will never be the same 🙂

Despite the Lifeline's higher price I feel like the military provided a vast chasm of advancement for Concorde, right off the bat.

[Atlee]

busterbrown73 wrote:

ktmrfs wrote:
let me guess.

your converter is a WFCO. If so that is likely the problem. they seldom will charge at more than 13.2V.

Get a good 3 stage charger PD or Iota.

I'm leaning towards that now. Any specific model recommendations?

I replaced the WFCO WF8900 55 amp Pwr Center with a Progressive Dynamics PD 4655L MBA Wildkat 55 amp main board assembly. It was a pretty easy swap. Continued to use the WFCO AC circuit breakers and DC fuses.

[pnichols]

MEXICOWANDERER wrote:
Circulation through the glass mat must reach 100% of the plates. Do you really want an E=MC2 answer?

Concorde does not publish gibberish, and frankly, to challenge their data findings in a less than professional setting raises my eyebrows. The process of complete and even ion plate saturation should remain beyond the scope of this message board IMHO

David - finally someone (you) may have finally written some non-E=MC2 eloquently simple words that I clipped from your post above: 1) "Circulation through the glass mat must reach 100% of the plates.", and 2) "The process of complete and even ion plate saturation ...".

Are those statements hinting at why one needs to start out using higher voltages initially, when charging AGM batteries, in order to bring them back to full design capacity? Hence is that why my AGM batteries may not be "really" charged to full design capacity - when I've charged them for hours at only ~13.8 volts until their charging current acceptance level has sunk down to around 0.5 amps or less?

Boy ... if so, that sure flys in the face of the decades old rule that trickle charging is the best way to recharge batteries so as to get the longest life out of them. :h

(IMHO and FWIW - if someone can't explain something complex in a simple way then maybe they don't truly understand what it is that they're trying to explain.)

[Vintage465]

wa8yxm wrote:

BFL13 wrote:
But still no answer to Phil's question why you have to push harder. Why is "low and slow" with AGMs not just as good given more time?

You have to push harder because the battery is PUSHING BACK BFL. it's that simple. If you are pushing me and I am pushing you with exactly the same force (Voltage) We go nowhere (Arm Wrestling???)

As for Why is "Low and slow' not as good as given more time??? I think those two terms mean teh same thing. Low and Slow takes more time. Fast and Furious takes less time.

LIFELINE says it "INitial charge" should be at lest 20 (used to be 30) % of the C/20 (That is if the battery is a 200 AH it shold be at least 40 amps) Now that's fast .. Most Wet Cells the REcommended MAXIMUM charge rate is 30%.. OR LESS of C/20.

I was told something one time. If you can't comprehend, then you need to apprehend. In this case, I don't completely understand all this. But I put the mans suggestions into practice and I I wake up with 12.5 volts after running two c-paps and the furnace all night in 24 degree weather. I apprehend and it works.

[MEXICOWANDERER]

There is overwhelming evidence to support Concorde's claim. They flat tell people "Do not use our AGM nor any other AGM battery for risky recharge profiles" And I am a firm believer in saturated acceptance charging for AGM batteries. Too manmy AGM batteries have onionskin plates, and I do not like the idea of pushing saturated charging rate through them for too long of time. An IR thermometer IMO is a must during warm weather if you want that last 10% of lifespan in 90F weather. But 99% of AGM battery failures due to battery charging weigh on the insufficient charging side not on excessive temperature buildup.

Re: You'll never see a challenge when a battery fails 3 months after the warranty expires. But let a battery that pops the recombinant vents six months before the battery warranty lapse will end up in court.

Motto. "Our charger's reputation will not be damaged but the company if found of overcharge, guilty, it is legal and publicity suicide" At risk may be 6-9 years of usable lifespan when things are done right. You may be satisfied to achieve warranty lifespan. I am not. The underchargers are nailing a board over their ass versus achieving rational lifespan.

[BFL13]

Marine/RV 27s (flooded) like low and slow best of all to get them properly full. But you must keep the charge going as the battery voltage rises to 16v before stopping. At that point, the SG will be well up where it belongs. Now you can go to your float voltage.

I do that with my VEC1093 at the 4 amp setting and with the Equalize button pushed, so it keeps going all the way up to 15.7v at low amps. I used to try fast charging with them, but the SG never came up properly.

BUT--AGMs are the opposite. They want fast charging or no go. Mex says that is to get the chemistry to happen right.

You can't do the low and slow to 16v with the usual converter or charger. No amps level setting, so can't keep them low and voltage limit is in the 14s, so can't get to 16v.

You can't do AGMs right either unless you can run a big enough amps charger (to do the 20% rate) with your 120v supply. With many, you can't keep it from dropping to 13.6 volts before the amps have tapered down to 0.5a per 100AH. I do that with my adjustable voltage PowerMax so it stays at 14.x until I say so.

So you are basically up a tree as an RVer unless you do after-market equipment buying and are willing and have the time to do it right. I figure most folks don't have the time or situation to baby their batteries. (trailer kept in storage lot with no 120v available because not allowed to keep it in your sub-division in your yard, eg)

Or you just live with it and buy batteries as part of the price to be an RVer. Luckily batteries are not very expensive on a three-year basis.

[wa8yxm]

BFL13 wrote:
But still no answer to Phil's question why you have to push harder. Why is "low and slow" with AGMs not just as good given more time?

You have to push harder because the battery is PUSHING BACK BFL. it's that simple. If you are pushing me and I am pushing you with exactly the same force (Voltage) We go nowhere (Arm Wrestling???)

As for Why is "Low and slow' not as good as given more time??? I think those two terms mean teh same thing. Low and Slow takes more time. Fast and Furious takes less time.

LIFELINE says it "INitial charge" should be at lest 20 (used to be 30) % of the C/20 (That is if the battery is a 200 AH it shold be at least 40 amps) Now that's fast .. Most Wet Cells the REcommended MAXIMUM charge rate is 30%.. OR LESS of C/20.

[BFL13]

MEXICOWANDERER wrote:
Circulation through the glass mat must reach 100% of the plates. Do you really want an E=MC2 answer?

Concorde does not publish gibberish, and frankly, to challenge their data findings in a less than professional setting raises my eyebrows. The process of complete and even ion plate saturation should remain beyond the scope of this message board IMHO

Don't need the science, just to know it is true that you need to follow the specs or else. The question is how bad do things get if you don't follow the specs, and whether you can "live with that" by just buying new batteries as needed if you don't follow the specs.

You only learn that afterwards, ie "the hard way", but how hard is that? I would like to know the real penalty if I always use the correct Vabs and get the AGMs down to 0.5a per 100AH , but ignore the 20% rule.

There is no way to know. So just do what is reasonable in your circumstances, and get new batteries when the time comes, whenever that will be. It only matters if you go off-grid when your batteries are on their last legs. So don't do that.

[MEXICOWANDERER]

Circulation through the glass mat must reach 100% of the plates. Do you really want an E=MC2 answer?

Concorde does not publish gibberish, and frankly, to challenge their data findings in a less than professional setting raises my eyebrows. The process of complete and even ion plate saturation should remain beyond the scope of this message board IMHO