RV Voltages too high while charging

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.

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... !

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.

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.

Grizzzman,

Thank you, but I'm quite familiar with the terminology regarding c.c. and c.v.. In fact, I much prefer to think in those terms, rather than bulk and abs. But what is missing in those recommendations is the fact that true c.c. chargers are hard to come by. What these folks are calling "constant current" is actually the result of "current limiting". If it wasn't for a factory preset c.l., during "bulk" stage, the current would not remain constant. It would go as high as the bank would accept, and then taper; (provided the charger didn't go up in smoke, first). Same goes for constant voltage. It is actually the result of the charger's voltage limit (i.e; Vabs set-point). And yes, I'm guilty of calling bulk stage 'cc', and abs stage 'cv', but technically I'm wrong, doing so. I do it if I think it will help someone understand what's going on during the various charge stages.

I have a gophert cps 1620 that is an adjustable variable (i.e; cv cc) power supply, and can be manually operated in either cv or cc. I use it for individually EQ'ing my 6v batteries. But even then, it cannot hold both voltage and current steady... likely due to thermal issues, nor can it operate in both modes simultaneously. So all this talk about cc and cv is nice, but not really technically correct, nor practical, when dealing with so-called "smart" chargers. You simply cannot hold both current and voltage steady on an ever changing load like a battery. The best you can do is limit them.

Moreover, not all chargers follow the same profile. My pm4b, like the vector portables, actually has tapering current and rising voltage during the abs stage... which results in the highest voltage occurring at the very end of the charge cycle... just like so called "3 stage" charging. In other words, my Vabs set-point is not reached until the very end. And in my experience, raising voltage above my Vabs set-point, at the end of the cycle, actually results in lower, uneven ocv's among my four 6's.

I do not float my bank, and therefore I essentially do "2 stage" charging. A third "finishing" stage is simply a higher voltage charge at very near full. If a charger was so equipped, it would hold the bank at a preset current limit (there's that term again), just like when in float mode.

But as I have said many times, one must familiarize oneself with their own batteries. Recommendations and suggestions are just that. If I believed folks when they told me 12.6v IS a full battery, I'd be chronically undercharging by bank to only 85%, and if I believed folks when they told me 15.3v is required to fully charge my bank, I'd be chronically over-charging... something I'm quite familiar with, seeing as my Peak 40a portable "smart" charger loves overcharging my bank.

Establish a baseline for SG's and resting OCV's, while the bank is out of service. Then, while in service, try to maintain those baselines as best you can. That's it! If your bank responds well to 15.3Vabs, then go for it. If it does not, then find out what does work well. And if you do not cycle your bank hard (i.e; deep) on a daily basis, there should be no need for daily "finish" charging nor frequent EQ'ing.

Following the spirited advice offered, I found out that US Batteries makes the batteries I have.

WOW.. their specs and charging profile is way off of Interstate.

I would have to agree with another post that was made that the sellers have a vested interest in destroying your batteries.

The correct voltages are:

Bulk 7.35 (14.7)
Ab 7.35 (14.7)
float 6.51 (13.02)
equal 7.65 (15.3)

Interstate recomendations are 0.30 to 0.60 -higher-

I'm adjusting my charging profile accordingly!

grizzzman wrote:

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.

Look for IUI charging for fullriver batteries Here

Rolls battery also shows IUI charging Here

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.

Look for IUI charging for fullriver batteries Here

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.

Temperature compensated charging is a "must do" where I live.