Do I need to "top off" the battery if it is fully charged?

[profdant139]

I keep my batteries on a BatteryMinder Plus. I recently got a portable solar panel that puts out about 14 volts in full sun. If I hook the panel to a fully charged battery just before a camping trip, does that really accomplish anything? Or is the battery already as "full" as it can get?

And if hooking up the solar panel is helpful, how do I know how long I should leave it hooked up? (Obviously, when we are camping, I leave it hooked up all day, since there is always a parasitic draw on the batteries from the fridge, etc.)

Sorry if this is a naive question, but a search of the archives did not turn up a clear answer. Thanks in advance for your advice!

[MEXICOWANDERER]

IMPOSSIBLE!

According to forum pundits the know-all-see-all Phart Chargers are INFALLIBLE. So what you are seeing is obviosly an optical delusion of Gran Mal proportion. Ypu must have hit button A six times extending charge time in 10-minute increments. Or maybe your power receptacle is inside-out. Or maybe you are overcharging the battery which makes it run longer.

All of the above, of course is sarcasm directed at some forum partcipants who actually BELIEVE a 79 cent IC chip can out think the human brain.

When the cells start bubbling a good battery is near to being full charge. A hrdometer check will will tell you when enough is enough.

[Gjac]

I think in general the answer is yes depending on your charger. I notice on my "smart charger" it will say full when charged and shuts off. I don't think it ever gets to 100%. If I charge for a couple of more days with my old Magnatec single stage charger I can get a few more days of dry camping before my batteries get to 50% SOC. 5 days vs 7 days. I do use the equalize function on my 40 amp B&D charger several times a year which is a much higher voltage.

[NinerBikes]

profdant139 wrote:
Mexicowanderer, I did put in "top charging" in the search bar, and I got an amazing load of contradictory and very strong opinions, mostly about the proper voltage, and the types of batteries, etc., mixed in with some extremely advanced electronic analysis. Literally 155 different "hits" during the past 12 months alone.

So here is my very simple question -- what device can one use to create a charge greater than 14 volts? My three stage automotive charger does not, the charger in my trailer does not, the solar panels do not.

Thanks in advance!

Find an IBM/Lennovo 17V 4.5 amp hour charging brick for a laptop computer, and charge until you have 15.0V at the battery terminals for a "top Charge" for one on your Group 27 batteries. About $10 to $12, cut off the computer plug in, and replace with alligator clips in red and black for positive and negative.

[pnichols]

Getting back on topic .... I have a real jewel of a DW as she let's me do as I please re topping off, or not topping off, our RV's batteries. 😉

By the way Dan,

I keep our motorhome's engine starting battery on a BatteryMINDer Plus continuously while the MH is in storage at home. I got around 7 years out of the last FoMoCo engine starting battery doing this, and it probably wasn't bad when I just in case replaced it this summer.

I got around 8 years out of the last set of coach batteries keeping them on the stock 13.6 volt RV converter almost continuously while the MH was in storage at home ... and will do the same with their replacements that I just in case installed this summer. However, I intentionally use AGM coach batteries that have an actual specified float voltage of 13.6 volts to help insure that this continual float voltage doesn't harm them.

So ... to address your "Do I need to "top off" the battery if it is fully charged?" subject question: I don't know what is meant by "top off", but so far my RV batteries have had some kind of voltage on them for most of their lives and some of their lives have been long. FWIW, I've always called my coach's batteries "fully charged" when they won't accept any more current no matter what voltage I hook them up to ... at that point I continue to leave them hooked up to the stock 13.6 volt RV converter for floating.

[NinerBikes]

MEXICOWANDERER wrote:
At least you don't wake up and automatically say "Honey I don't know what I did wrong yesterday, but I'm sure sorry about it". Fifteen pure magic words to avoid Daily Armageddon.

Contract Law taught me to read every single little word in the fine print and agree to it before I sign the contract. Don't sign the contract or the license if you can't or won't be bound to the terms set forth. Our courts in the USA have proven to be biased in redistributing the fruits of our rewards. I saw the devastation of many a good friend that got married and paid the ultimate price. I learned from their mistakes.

[MEXICOWANDERER]

At least you don't wake up and automatically say "Honey I don't know what I did wrong yesterday, but I'm sure sorry about it". Fifteen pure magic words to avoid Daily Armageddon.

[NinerBikes]

MEXICOWANDERER wrote:
Compared to a human of the feminine persuasion taking care of a battery is a piece of cake.

/\ Why did you need to remind me? DEKA is at home, went on the baby, stripped down version of The Borg at 14.4V at 11:15 AM this morning, in the garage, on the grid, for it's 12 or 24 hour full plate massage and stimulation in the deepest darkest extended tiny nooks and crannies, seeking out sulfur to put back in solution, until the lead plates realize The Emperor has No Yellow Clothes, made of sulfur.

[MEXICOWANDERER]

Compared to a human of the feminine persuasion taking care of a battery is a piece of cake.

[JiminDenver]

The Megawatt charged for 9 hours the other day and that was just bringing the bank up from 12.5v. That would be a 4 gallon tank of gas on the Champ. However it would have the power to run both the mega and the trailers converter up to 13.6v for 91a. That should help some.

Bringing the grp 27 home...no problem. Even one 8-D was doable. Once the three big boys are mounted, I hope to never touch them again.

[NinerBikes]

MEXICOWANDERER wrote:
5% AH charge amperage to 15 volts for top charging. Let amperage continue to raise voltage to 16.0 for equalization. A 31 makes for a poor excuse of a cyclable battery. Poor quality batteries eat power like peanuts. If you buy a good quality battery you will be pleased when you experience the Charge Efficiency Ratio. High voltage regular charging poisons the negative plates. Save fifty dollars on a golf car battery and spend two hundred more dollars fighting it generator charging over it's off grid lifetime. Good battery management is cheapskate battery management.

It wasn't quite that bad... the battery was free, the 150W solar panel was $120 new. So what ever was given up by the sun was pretty much free. Still have the 150w panel, and rumor has it AGM's don't like too much solar charging, unless supplemented with some serious high amperage deep cycle amps sucking recharging genny time, from time to time, to shake things up. I think I am going to just store this AGM in the garage at home, and take with to the TT when going on a trip.

[MEXICOWANDERER]

5% AH charge amperage to 15 volts for top charging. Let amperage continue to raise voltage to 16.0 for equalization. A 31 makes for a poor excuse of a cyclable battery. Poor quality batteries eat power like peanuts. If you buy a good quality battery you will be pleased when you experience the Charge Efficiency Ratio. High voltage regular charging poisons the negative plates. Save fifty dollars on a golf car battery and spend two hundred more dollars fighting it generator charging over it's off grid lifetime. Good battery management is cheapskate battery management.

[NinerBikes]

MEXICOWANDERER wrote:
Maybe it's because I have twenty-three grand worth of batteries at risk that I am so sensitive about this. What some folks consider "chump-change" means eating tortillas and salt for a month or having a normal diet.

The formula DEMANDS 5% of ampere hour amperage and it demands starting with a full as possible battery and it demands that charging cease when voltage rises to 15.0 volts. For benefit of some I can repeat TWICE PER YEAR on an otherwise floated battery, and as often as once every two weeks on an off grid battery that is cycled daily and manages to have a cell that slumps specific gravity despite trying your best to arrive at full charge daily.

I would be happy as heck if a battery came along and had fewer demands than a Hungarian Movie Actress. I would MUCH prefer to spend my time elsewhere. But the way things stand now if I ignore the few minutes a week needed to keep the monsters happy I end up having to scramble for money to cover the cost of premature battery death. It's a free-world. Do as you wish. I do not criticize people who destroy their batteries by neglect and remain silent about it.

Is 15.0V for top charge? What do you suggest for an equalize charge? 16.0V? landyacht318 and I were using 16.0V for the screwy 31 and the T-1275. Landyacht had to go 15.4V to top charge on his US battery group 31.

[MEXICOWANDERER]

It's sensitive. It's cries a lot if not hugged properly (injector lines not alternately tightened. It stamps it feet (noise and vibration). And it can play the greatest cold-shoulder game (no start) on the face of the earth. But for it's size the motor is a hot tamale. It adopted me. Yotta see the Magnetti Marelli starter motor. It insists it is a Stradivarius and if you hit a sour note taking care of it, it'll screech like a Mexican fiddle.

[NinerBikes]

MEXICOWANDERER wrote:
Alternative charging sources. The Gould is a 24 volt charger. The 50DN Delco is also a 24 volt charger. Also I picked up a 200 foot spool of 300 MCM space shuttle surplus wire at Lockheed. Teflon. Silver plated. The lugs were pricey though about eight dollars each. Twelve cells is 24 volts. The twin cells have a pair of 15" X 1" X 4" paralleling buss bars that I can hacksaw to isolate a bad cell. Then I will have a single 24 volt string, and a cherry picked 12 volt string left.

56 volt regulators for alternators are pretty scarce. Push comes to shove, I can rob the Niehoff off the bus and substitute it for the Delco on the Lombordini. Air cooled and N-O-I-S-Y But she gotta the nice lines...

If she's Italian, she's got the Fix It Again Tony syndrome.

My father owned a Fiat, the day he sold it was one of the happiest days of my life. Broke 3 clutch cables in it's lifetime, the distributor had the ability to throw itself out of timing, drive gear would somehow disengage from the gear on the crank driving it, permanent camber alignment problem that no amount of custom work could fix, and a never ending nightmare getting spare parts for it.

I doubt I will ever again own something Italian for transportation needs.