Portable battery charger. What do you carry?

[McKenziek]

I've had many over the years but most are cheap and don't last long. I'm looking for a good portable 12 volt Smart charger that can desulfate and get my batteries to full charge if needed.

What do you carry in your RV tool box?

[mena661]

BFL13 wrote:
I found some interesting Exide stuff I posted in another thread. They might not need or like the rough stuff same as US Battery (among others) recommends for theirs. They don't get into details much though.

Hmmmmm. Time for me to read some specs more carefully.

[BFL13]

I found some interesting Exide stuff I posted in another thread. They might not need or like the rough stuff same as US Battery (among others) recommends for theirs. They don't get into details much though.

[mena661]

BFL13 wrote:

So perhaps with shallow cycles like when on solar and low AH usage, they can get close enough to baseline without equalizing so you can't tell the diff. I wonder if it is the deeper cycling like in winter that makes it harder to get back up.

Unless it was a fluke, that seems to be the case with my batteries too. Shallow discharges (like ~85% SOC and above) don't require the high volt finish charge.

[BFL13]

mena661 wrote:
BFL, what voltage are you using for a finishing charge?

I use the 1093 15.7v temp corrected at whatever ambient is.

However, on solar this summer, where the controller high point is 14.6v, and after it drops back to float and does that several days in a row, I have seen SG very near baseline, if not there when temp corrected for the warm weather. (I keep not doing temp correction)

So perhaps with shallow cycles like when on solar and low AH usage, they can get close enough to baseline without equalizing so you can't tell the diff. I wonder if it is the deeper cycling like in winter that makes it harder to get back up.

[full_mosey]

BFL13 wrote:
It is easy to keep your charger at 10 amps for hours when on a battery? What kind of charger is that?

I don't know!

I do have a portable Schumacher SC1200A 12/8/2A automatic charger with an AGM setting. I guess I would take the battery out of service and run with 8A until it indicated charged. I might let it rest a day and repeat with the 2A setting. Just guessing!

I do routinely use this charger in the AM for bulk catchup until the solar takes over. This is on the bank that runs two 12V Dometic CF-35 portable fridges.

HTH;
John

[mena661]

Toss in the fact that most RV owners seemingly would rather get an enema than take care of their batteries and you end up with five thousand opinions and billions of dollars spent foolishly on gyro gearloose grade whizzo carnival chargers and devices that swear on a stack of bibles if you pay several hundred dollars you will be forever relieved of ever thinking about your batteries again.

LOL!

More questions for MEX!!! Is it gentler on batteries to equalize at higher volts/less amps than lower volts/more amps? My BD1093 EQ's at 2A but voltages can get as high as 16 (depends on the temperature). My HF charger uses more amps (~8A) but volts are typically in the low 15's. Also, the BD1093 takes longer than the HF. Not sure if that matters.

Another question. A number of battery manufacturers are recommending 15+ volts for finishing charges (basically going from somewhere in the high 90% SOC range to 100%). Based on what I have to do to get mine to 100% SOC, it seems they are correct. Are they correct?

[Rbertalotto]

Toss in the fact that most RV owners seemingly would rather get an enema than take care of their batteries and you end up with five thousand opinions and billions of dollars spent foolishly on gyro gearloose grade whizzo carnival chargers and devices that swear on a stack of bibles if you pay several hundred dollars you will be forever relieved of ever thinking about your batteries again.

LOL... 🙂

[MEXICOWANDERER]

The "issue" with modulating solely with a temperature limit, is that electrolyte acts as a heat sink transfer media but it isn't perfect. Hot spots can develop an they will cause burning - utter destruction of that plate area and worse yet the destructed area can grow as it remains hotter than unaffected plate area. Hard sulfated areas are sulfated on the surface. Ever wonder what is going on beneath the sulfate coating? Yes it is porous but the sulfation depth of penetration only extended so deep.

This is why maintaining a gentle constant amperage equalization is so important. You are trying to revert a mineral coating back into chemical solution. The action is simple on the face of it, but orchestrating a maintenance regimen should be done with minimizing the overall cost of battery ownership, operation and maintenance. Toss in the fact that most RV owners seemingly would rather get an enema than take care of their batteries and you end up with five thousand opinions and billions of dollars spent foolishly on gyro gearloose grade whizzo carnival chargers and devices that swear on a stack of bibles if you pay several hundred dollars you will be forever relieved of ever thinking about your batteries again.

[mena661]

BFL, what voltage are you using for a finishing charge?

[Rbertalotto]

I have an old "Sportsmans 10" battery charger that ONLY outputs 10A and has a mechanical timer on the front so you can set the number of hours you want to charge. Beforte "Smart" chargers like the Optima, Deltran and Black & Decker, this was the recommended way to charge trolling motor batteries.

[BFL13]

It is easy to keep your charger at 10 amps for hours when on a battery? What kind of charger is that?

[full_mosey]

MEXICOWANDERER wrote:
A separate answer about equalization using the HF. Worst case, using a generator where time is money for fuel and noise is anguish for the ears.

Charge however until you have to modulate (adjust) the voltage so it does not exceed 14.8. When the GC's charge rate reduces to around 18 amperes at 14.8 volts (not the easiest thing to orchestrate)change over to the HF. Try 10 amps. If the voltage surges a lot higher than 14.8 reduce the setting to 2 amps which will probably start out around six to eight. This is where the HF 6 amp charger rather than the 10 amp may be a better choice if this exercise is done on a regular basis.

Let the voltage rise slowly and when it gets to 15.5 re-check the specific gravity with a hydrometer.

Equalization is not like giving the batteries a vitamin pill. It is ONLY done when the specific gravity varies greatly from cell to cell. Equalization SHEDS PERFECTLY GOOD ACTIVE POSITIVE PLATE MATERIAL as well as forces sulfate from coated plates back into solution. What equalization is, is choosing the LEAST OF ALL EVILS to maintain a battery in the best condition you can.

Lastly, any "expert" that tells you a VRB valve regulated battery cannot sulfate is either bending the truth or ignorant of it. They are harder to sulfate and even harder to de-sulfate correctly (without damage). You can tell a VRB is sulfated when it loses capacity at an early age and a strict recharging regimen has not been maintained.

Great explanation!

I have two Optimas in their 4th year and have not detected a loss of capacity yet.

I wrote them about what I should do if I suspected sulphation. Their reply was to charge for 12hrs at 10A. That seems too easy!

HTH;
John

[Gjac]

KJINTF wrote:
This is one of the best explanations I have seen regarding equalization of wet cell batteries - thanks Mex

"Equalization is not like giving the batteries a vitamin pill. It is ONLY done when the specific gravity varies greatly from cell to cell. Equalization SHEDS PERFECTLY GOOD ACTIVE POSITIVE PLATE MATERIAL as well as forces sulfate from coated plates back into solution. What equalization is, is choosing the LEAST OF ALL EVILS to maintain a battery in the best condition you can."

My batteries (Costco CG's) typically last 8 to 10 years, get Equalized no more than once every two years (individually per 6Vdc battery), have their SG checked about twice a year and water added once or at most twice a year. They have never been below 60% SOC and typically stay above 75% while camping. The rig is not used in the winter time.

Not sure if my use/service is "normal" aka typical or not - wondering what others do

I do the same as you except travel south in the winter and equalize 2 times a year. My Sams Club batteries are 7 years old and will last 7 days before reaching 50% soc. I always run out of water and gray tank space before I run out of battery power.

[BFL13]

I think that is what happened to my Exide 6s. When I got them, I charged them up and took the "baseline SG." Then on recharging every time, I equalized to get them back to that SG.

I was treating them the same way as my GC2 XHDs which do want that in their specs. I ASSumed the Exides would have the same spec, but never read their recommended charging spec-couldn't find it. In fact their proper SG is a bit lower than I was using for baseline, so I was shedding them.

Later, I drew some black stuff up with the hydrometer and thought they were toast. Turned out they were fine (but shedded more than for their age no doubt) and now I don't do that anymore. Mex has made it all understandable, even to me.