RV Voltages too high while charging

[Chandalen]

I have a problem and have been wrapping my head around this for a few days.

I have four 100w Solar panels, and a Morningstar RJ-45 programmable charge controller wired to batteries. I have Four Interstate golf cart batteries in serial/parallel to make a 12v bank.

I have a Pure sine 2k inverter wired to batteries with two 1/0 wires per pole, and fused @150 amps per positive line.

My (major) problem is the Absorption phase of charging is at 15.3 volts.

This changes the RV wide battery powered voltage to 15.3 +- volts. This is really high for the LED lights I have, and I am afraid they are going to start burning out.

Because the absorption voltage is 15.3, the inverter turns off. Its voltage threshold is 10-15v.

For now, I dialed down the absorption voltage to 14.9 and everything is working. I am aware that my batteries will not fully charge with that voltage as its 0.50 less than needed. I was planning on equalizing once a month, when I'm not using the camper, as that voltage is 15.6

I can’t imagine I am the only one who has run across this issue, so is there an inexpensive fix, that won’t waste valuable battery power?

I have a small (1 amp) voltage stabilizer for a battery venting fan that can tolerate no more than 14v (which I found out the hard way) that works well for the fan.

I know that the DC items in campers can tolerate 11-15ish volts, I’m just wondering how well and for how long that fridge can run on 14.9v while the batteries are topping off, and the inverter is useless if I cant run it when the batteries are topping off either!!

I appreciate any feedback and insight!!

-James

[grizzzman]

grizzzman wrote:

jrnymn7 wrote:
RE; IUI charging:

http://www.mpoweruk.com/chargers.htm

Scroll down about a third of the page. Article is dated 2005.

Is that to be considered "recent"? Not sure. All I know is "multi-stage charging" has been around a lot longer than I've been RV'ing. I admit I am not at all familiar with linear type chargers, or single voltage chargers, but I can't imagine flooded lead acid battery technology has changed a whole lot.

Anyway, I doubt any of this has to do with establishing proper charging voltages. All I know is what I've seen first hand. I do not cycle my bank deeply, nor do I let it sit in a discharged state or any real length of time. But I am seeing the effects of regular over-charging. Self discharge has increased by leaps and bounds, and resting ocv's have dropped noticeably. I doubt anyone recommending I charge at 15.3v on a regular basis is going to reach deep into their pockets and cough up the near $700 to replace my bank.

Sorry that was a copy and paste. I agree IUI charging has been around for a while. The reason i even brought up IUI charging is because of the OP interstate battery charging profile. I was able to get a hold of a upper level tech and he admitted that they screwed up there IUI recommended charging profile. But i talked to a lower level tech and he was convenced that the profile was correct. I find it intrusting that Rolls , Fullriver , US battery , GMB and others provide charging profiles for IUI charging. I use this charging at work and my RV and has worked well for me. Sorry to here about your batteries. O and MEX the batteries in question ARE hybred antimony pos calcium neg cunstructed batteries.

[grizzzman]

jrnymn7 wrote:
RE; IUI charging:

http://www.mpoweruk.com/chargers.htm

Scroll down about a third of the page. Article is dated 2005.

Is that to be considered "recent"? Not sure. All I know is "multi-stage charging" has been around a lot longer than I've been RV'ing. I admit I am not at all familiar with linear type chargers, or single voltage chargers, but I can't imagine flooded lead acid battery technology has changed a whole lot.

Anyway, I doubt any of this has to do with establishing proper charging voltages. All I know is what I've seen first hand. I do not cycle my bank deeply, nor do I let it sit in a discharged state or any real length of time. But I am seeing the effects of regular over-charging. Self discharge has increased by leaps and bounds, and resting ocv's have dropped noticeably. I doubt anyone recommending I charge at 15.3v on a regular basis is going to reach deep into their pockets and cough up the near $700 to replace my bank.

Sorry that was a copy and paste. I agree IUI charging has been around for a while. The reason i even brought up IUI charging is because of the OP interstate battery charging profile. I was able to get a hold of a upper level tech and he admitted that they screwed up there IUI recommended charging profile. But i talked to a lower level tech and he was convenced that the profile was correct. I find it intrusting that Rolls , Fullriver , US battery , GMB and provide charging profiles for IUI charging. I use this charging at work and my RV and has worked well for me. Sorry to here about your batteries. O and MEX the batteries in question ARE hybred antimony pos calcium neg cunstructed batteries.

[jrnymn7]

.

[jrnymn7]

RE; IUI charging:

http://www.mpoweruk.com/chargers.htm

Scroll down about a third of the page. Article is dated 2005.

Is that to be considered "recent"? Not sure. All I know is "multi-stage charging" has been around a lot longer than I've been RV'ing. I admit I am not at all familiar with linear type chargers, or single voltage chargers, but I can't imagine flooded lead acid battery technology has changed a whole lot.

Anyway, I doubt any of this has to do with establishing proper charging voltages. All I know is what I've seen first hand. I do not cycle my bank deeply, nor do I let it sit in a discharged state or any real length of time. But I am seeing the effects of regular over-charging. Self discharge has increased by leaps and bounds, and resting ocv's have dropped noticeably. I doubt anyone recommending I charge at 15.3v on a regular basis is going to reach deep into their pockets and cough up the near $700 to replace my bank.

[MEXICOWANDERER]

If a new battery DEMANDS a different charge formula than what I offer above, take it back and tell the vendor to stuff it. You have junk for a battery. I am remiss in not mentioning this early on. I received pallets of batteries sometimes for testing. One cycle had me on the floor pounding the concrete with my fists. When finished I telephoned the manufacturer and told them to come pick up the batteries.

I see where PERSPECTIVE is lacking in some of your observations. Assumptions are based on a single or multiple of samples that themselves start life inferior. They will finish a short unhappy life inferior(erer)

Compare junk to a genuine Rolls or Trojan INDUSTRIAL battery. Experience the ease in which 100% recharge is accomplished, the resistance to sulfation and the ease of sulfation recovery. PERSPECTIVE. Jeez I wish there was a way to give it to all...

[MEXICOWANDERER]

"One can sit around and argue ideal voltages all day long, but the best value for each battery will be different"

Convince a 5% or 2.75% antimony battery of that...any difference will be insignificant to the point of being ludicrous.

Different alloys, hyridization or extremely different plate construction (automotive versus extremely dense industrial) are valid reasons to adjust absorbsion voltage SLIGHTLY. Perhaps a .4 volt total range.

TIME SPENT AT ABSORBSION VOLTAGE LIMIT is only 500-times as important as determining where in the .4 of a volt absorbion voltage band the battery must spend for most efficient rapid charging.

Like the Chambers Brothers screamed T I M E
Alters the formula

And I'll clue you that T I M E has more of a real effect on voltage than voltage does on time.

So WHY did I pick 14.8 volts as an optimum voltage potential at 20c?

Around 500 to a thousand trial and errors, using exact time, kWh and .1 of a gram weight scales to measure water loss. And a hydrometer, and autopsying sediment chambers of car jar, Golf car, and L-16 batteries. Damned tough to try arguing past reality.

For badly poisoned batteries, reduce maximum voltage to 14.4 and time spent there accordingly. Usually when that much antimony transfers the battery is obviously objectionably depleted capacity wise.

I did not invent electro-chemical physics. I am a slave to it just like everyone else.

But when I tore down batteries with X-amount of kWh activity spent with say a 15.1 volt absorbsion value limit and found 3-times the plate shed in the sediment chamber which agreed with 80% lifespan compared to same lot batteries with a 14.8 volt absorbsion limit, it tends to make an impression.

This fact is EXACTLY where the boys in the battery OEM labs did NOT spend time and find out facts versus hyperbole. Conjecture and assumption are poor substitutes for evidence and facts gathering.

Chemistry is weird science. TIME enters the picture. Absolutely nothing substitutes for time when chemistry and electricity reach optimum levels. Reach the optimum electro level FIRST then determine the time element. Too small a voltage potential molests the time level beyond usefulness. Too great a voltage potential molests the plates/electrolyte (needlessly) themselves.

[jrnymn7]

"The problem with that for fast charging is that the charger causes an initial "spike" in battery voltage, but there has been no time for the battery SOC to rise. The voltage regulator sees this spike and cuts the current right back."

I'm wondering if the problem has to do with the fact that many alternators can put out more current than a small car battery can handle? If the alt's current was limited, would it not eliminate that voltage spike?

IOW, wouldn't charging a much larger (and depleted) battery with that same high output alt result in a cc/cv profile?

I read this morning, the proper way to utilize current limiting is to have a higher limit than the actual load. (thus not needing to utilize its built in protection). In this case, it would be like using a 100a smart charger on a bank that's only capable of accepting less than 100a. The result? Instant cv mode/tapering amps.

And which is faster... tapering from 100a from the get go, or a lower (say 60a) constant current 'til near 80%soc?

[jrnymn7]

As one blogger put it, cc just happens automatically as a result of cl. But they are not the same.

It is definitely about proper voltage regulation. My Peak 40a has poor v.r., and as a result, voltage slowly creeps up, instead of being held steady, and therefore current is not forced to taper down. The result is it never gets to the point where it would go into float. Instead, it just hums along for hours, slowly rising in voltage, and barely tapering in amps.

[BFL13]

There is a difference in the way the "smart charger" does Bulk with constant , current-limited amps, and the "other" chargers.

Barre, in his 2002 book, "Managing 12 Volts" goes into this quite a bit. His terminology for the different types of chargers may not be universal, but you can translate.

He compares them by how they do "voltage regulating" He explains how the voltage regulator works with the alternator in a car. The initial high current is cut right back to maintain the voltage and this "constant voltage" charger has a tapering current profile from the beginning.

The problem with that for fast charging is that the charger causes an initial "spike" in battery voltage, but there has been no time for the battery SOC to rise. The voltage regulator sees this spike and cuts the current right back.

A "multi-stage charger" uses a different regulation, that Barre says has an initial "constant current" regulated stage that produces a fixed amount of current. The battery will accept this high constant current while in the mid-SOC range but at some point this has to be changed and it goes into a voltage regulation stage with tapering current.

(He does not get into "regulated constant current" vs "current limited" which confused me greatly back when we had threads on this. Eventually I think I got it straight that there is no current regulator, just a current limiter)

So the whole thing for fast charging is to keep the current high despite that initial "spike" in battery voltage when you turn on the charger. Only let the current taper later on when it has to once the battery has reached a "gassing voltage" or what we call Vabs for this.

Barre also mentions how they add a "smart" regulator to a cruising boat's alternator so it can do the fast charging with constant current in the Bulk stage instead of suffer the big taper you get with an ordinary voltage regulator. Mex has posted about those too.

[jrnymn7]

grizzzman wrote:
IUI Charging

This is a recently developed charging profile used for fast charging standard flooded lead acid batteries from particular manufacturers. It is not suitable for all lead acid batteries. Initially the battery is charged at a constant (I) rate until the cell voltage reaches a preset value - normally a voltage near to that at which gassing occurs. This first part of the charging cycle is known as the bulk charge phase. When the preset voltage has been reached, the charger switches into the constant voltage (U) phase and the current drawn by the battery will gradually drop until it reaches another preset level. This second part of the cycle completes the normal charging of the battery at a slowly diminishing rate. Finally the charger switches again into the constant current mode (I) and the voltage continues to rise up to a new higher preset limit when the charger is switched off. This last phase is used to equalize the charge on the individual cells in the battery to maximize battery life.

AFAIK, The older "single voltage" chargers (not "single stage"... how am I doing BFL :)) did the exact same thing. Current was limited by the chargers current limit, while voltage rose to the voltage set-point, then amps would taper. I don't believe this is a recent development, as you say. So called "smart" chargers simply have an extra stage, called float, or maintenance. The addition of a float stage simply allows one to leave the charger hooked up, indefinitely.

EQ is yet another added stage, but works on the very same principals, namely, if voltage is limited, current will taper, and if current is limited, voltage will rise. But you can't be in both modes at the same time.

[landyacht318]

One can sit around and argue ideal voltages all day long, but the best value for each battery will be different and change as the battery ages, and depend on the depth of its discharges.

My screwy31 required rather excessive voltages to get the SG into the green via low and slow solar, 14.9absorption and 15.3 finish, and 16 volts for 45 minutes to 2 hours every 2 weeks to max out SG.

Yet when pumped upto and held a 14.7 for 2 hours via my 40 amp meanwell would do the same thing as the low and slow solar.

The hydrometer will tell you what your flooded batteries want and how they respond to your charging sources. Or you can go stick your head in the sand and drink the Kool aid and believe the marketing department of your charging source and thump your chest with the 'works just fine' mantra while trying to get others to agree with you.

[jrnymn7]

Let's look at those recommendations from U.S. Battery. On page 5, 2 stage charging, it says to bring the bank to less than or equal to 3% of C, at 14.7v. If I brought my 430 ah bank to 13a @14.7v, it would not be full. I usually bring it to about 2.5a at 14.8v... a huge difference... lower acceptance at a higher voltage means way deeper into the charge. So, yes, those charts are a great visual tool, but the numbers must not be taken literally.

And look at page 6, 3 stage charging. While current is limited at 3% during stage 3, voltage rises. And during stage 4 (EQ), voltage is limited so current tapers. As the song goes..., "That's just the way it is. Somethings'll never change".

As for that 15.3v the dealer says for my bank, I really don't know where he came up with that? For all I know, he may have just pulled it out of his... !

[MEXICOWANDERER]

The ONLY way 15.3 volts would be correct absorbsion limit for a flooded lead acid battery is if that battery was calcium/calcium OR as a maximum 1.0% antimony in the positive plate and calcium in the negative plate making it a HYBRID battery making it a cruel joke for cycling.

Try and find an affordable constant current charger. You won't. Constant current is for the big-boys whose battery banks are worth more than your rig plus your house.

The formula I gave here years ago, 14.8 vdc for 5% antimonial flooded batteries @ 20c is still absolutely valid. It will NEVER become obsolete. Apply 14.8 vdc until the electrolyte in all cells starts bubbling lightly then reduce voltage to 14.0 vdc for 20 min. If the electrolyte in the cells continues to bubble instigate float maintenance voltage value.

This will bring unsulfated batteries so close to 100.00% state of charge it isn't funny. Not 98.6 percent or 104% but dead-on.

CONSTANT CURRENT is a protocol with precise and exacting requirements results and uses. Regular battery charging on a recreational vehicle is NOT ONE OF THEM.

Looks like the pocket protector crowd is feeling paranoid once again. Come up with something new or get the pink slip. This is entirely unneeded and confusing to the public. Battery merchandising is dog-eat-dog competitive. Ten minutes in an engineering space would cause the company to call in a SWAT team on me. There would be blood spatters on the walls.

Wayward engineers did not like it when I proved in public they were FOS in front of management.

But the cycle continues. If you swallow the B.S. bait and smile - fine that's YOUR issue. But for crying out loud don't represent it as holy gospel in front of other consumers. It belittles you.

[NinerBikes]

MEXICOWANDERER wrote:
These so called "battery experts" are crazier than a s---house rat. From one extreme to the other they veer and wander. Lost little children trying to find their way. Man this is even worse when I had the company. I guess no one wants to represent electro-chemical reality anymore. "Oh! Charge at no higher than 14.4 volts! No wait a minute! 15.3! No! Nothing is correct! Where did I put the cyanide supplement pills?"

Ever heard the term "Fart In A Whirlwind"

It's when you allow ignorant people to do your thinking for you.

There is enough VALID informatiin on this site to educate a novice more thoroughly than what 80% battery peddlers will EVER know. If you choose to ignore valid information please weep in silence. The whirring funnel cloud noise of utter confusion is distracting.

Hey my car is not starting up fast every morning. Quick! Call the salesman - he'll know what to fix. Only MANUFACTURERS can properly represent proper battery care. Not Interstate, sears, Kragens, Wal-Mart or Dairy Queen. Interstate is a battery merchandiser. They are experts in warehousing, distribution and stocking batteries from whatever manufacturer they can strike a deal with. Imdividual distributors are FRANCHISES just like McDonalds and the corner Chevron station. I've met a few distributors who knew their product enough to offer decent service. Then I've met others who were dumber than a freshly dried mud pie. They managed their business well and rotated stock and kept good books but their knowledge of batteries was pathetic. Same issue for Sears Roebuck. A guy comes swaggering out with an impedence meter and proceeds to heap enough B.S. onto a question to properly fertilize the eastern half of the county park.

Some of you need to get whacked over the head with a baseball bat to get your attention?

If you do not trust the -correct- information on this forum TELEPHONE THE BATTERY MANUFACTURER. They have people called application engineers whom are a lot more savvy than a battery peddler.

Yes 15.3 volts absorbsion is too high except for Fargo North Dakota in January. 14.8 volts to 15.3 volts is half a volt too high. Even .2 volts greater than Top Charging limit.

Sometimes I think my time spent here is reaching too few people. Grumble Snivel

You can lead a horse to water, but you can't make it drink. Been doing 14.8V on mine for a year now, and 15.0 to 15.1 every couple of days or so, and to 16.0V for an hour or two when I get home right before it goes into the storage yard disconnected.

Not worried when my T-1275 dies, pretty sure I am treating it right, and storing it right. It's a tough old bird. Best improvement I ever did was matching the solar panels watts output to the amperage capacity of the battery, so that the solar charging system is balanced to the battery. Next best thing I did was get that MegaWatt 30 amp Power supply unit, and learned how to use both of them manually.

So forgive me for being a slow learner. These settings work for my current battery, and my current battery only. YMMV, talk to the manufacturer of your battery. Heavy lead plates with high% antimony from a sweeper may be different from what you are running. My battery likes low amps, slow slow charging most of the day, with an added voltage bump tweak near the end of the day to top things off. All I know is that the specific gravity readings don't lie. It works, for me.