Charging voltage for T-105s

RDMueller wrote:
Had some time today to test the Schumacher again. After seeing the charging voltage rise to 8.1 when individually charging a Trojan 6V, I wasn't about to subject them to that again. But I have a group 24 sitting around that I didn't mind trying it on and I wanted to see how it performed charging a 12V jug.

Started with the battery at about 50% and connected the Schu. Within a few minutes it was charging in the low 13V range and over the next few hours slowly rose to about 14.3V. Then when the battery was about 90% (according to the charger) the voltage jumped to 16V and stayed there until it reached 100% and it dropped to float.

It appears that this particular charger (SC-10030A) is designed to charge at 16V (8V for 6V battery) during absorption! Not sure any battery manufacturer would agree with that charge profile.

Also went to the Schumacher website and found a Q&A section for this charger. Someone posted a question asking about charging voltage and the Schumacher tech responded with the following:

"These units will put out variable voltage, based on the battery type and the stage of charge it is in. The lower voltage levels will be in the initial stages and the maximum voltage levels are reached in the last stage. For standard, wet cell battery types, the maximum it will reach is 16V; for AGM batteries, the maximum is 15.4V and for gel cell batteries, the maximum is 14.7V. Setting the charger for the battery type you are charging will get your battery charged completely and properly."

So, it seems to me if I want the 14.8V that Trojan recommends, I could just select gel cell and it would get me pretty close. Still amazing to me these chargers go that high! Frankly 14.7 is too high for a gel IIRC.

Remember 14.7 is towards the "end" of the charge cycle. At this time amps are low. At this point voltage can be raised. The higher voltage allows amps to be pushed in faster. Google "UIU" charging if you wish to understand it better. Its more then a top charge and easer on the battery then a full equalize.

I gave away a few of my $2.95 16-volt 5-amp power bricks. The price was really a killer. Dontcha love it when a three dollar item runs circles around a two hundred dollar gizmo?

"Why! It does everything (poorly) !

I connect the brick and return in two hours to check voltage. Niner's phone has a great timer!

Remember you can have a 500 amp 16 amp charger but if you run the battery lead series through a 50 watt lamp there's your 5 amps. Through 100 watts of bulbs there's your 10 amps which is correct for 6 cells golf car battery.

Had some time today to test the Schumacher again. After seeing the charging voltage rise to 8.1 when individually charging a Trojan 6V, I wasn't about to subject them to that again. But I have a group 24 sitting around that I didn't mind trying it on and I wanted to see how it performed charging a 12V jug.

Started with the battery at about 50% and connected the Schu. Within a few minutes it was charging in the low 13V range and over the next few hours slowly rose to about 14.3V. Then when the battery was about 90% (according to the charger) the voltage jumped to 16V and stayed there until it reached 100% and it dropped to float.

It appears that this particular charger (SC-10030A) is designed to charge at 16V (8V for 6V battery) during absorption! Not sure any battery manufacturer would agree with that charge profile.

Also went to the Schumacher website and found a Q&A section for this charger. Someone posted a question asking about charging voltage and the Schumacher tech responded with the following:

"These units will put out variable voltage, based on the battery type and the stage of charge it is in. The lower voltage levels will be in the initial stages and the maximum voltage levels are reached in the last stage. For standard, wet cell battery types, the maximum it will reach is 16V; for AGM batteries, the maximum is 15.4V and for gel cell batteries, the maximum is 14.7V. Setting the charger for the battery type you are charging will get your battery charged completely and properly."

So, it seems to me if I want the 14.8V that Trojan recommends, I could just select gel cell and it would get me pretty close. Still amazing to me these chargers go that high! Frankly 14.7 is too high for a gel IIRC.

You don't need to worry about the amps size much for equalizing as long as it has the power to do the amps at the voltage.

I did an equalize with my adjustable 100 amper that goes to 15.6 volts max on one pair of 6s while I put my VEC1093DBD 40 amper on the other pair of 6s.

The VEC has to be run at its 4 amp setting to do an equalize at 15.7v. Amps hold at around 4 then taper till the charger says Ful and shuts off. Done.

Meanwhile the 100 amper, set to 15.6v and having only its 100 amps as the amps limit, also kicked off at about 4 amps!!! and it did about the same taper profile as the VEC did. Only thing there is I have to shut off the 100 amper as it is not "automatic" for shut down--it is a converter that stays on.

So the battery is the amps limiter. You can't equalize till the batts are already "full" so they don't accept many more amps by just cranking the voltage up from 14.8 to 15.8

At a fixed voltage amps will taper. To do the Mex constant amps trick you have to keep raising the voltage. You can do that with one of those buck boost gizmos that have adjustable voltage and adjustable amps, so you have stay there to twiddle the settings to raise the voltage and keep the amps constant. (AFAIK :) )

MEXICOWANDERER wrote:

BOTH EQUALIZING AND TOP CHARGING REQUIRE A CONSTANT AMPERAGE OF FIVE PERCENT OF TOTAL BATTERY AMP HOUR CAPACITY.

So if I go the manual route, do I need two chargers, a low amp and a high amp? There seem to be a number of chargers that have an adjustable voltage output, but I haven't seen any where the amperage is adjustable.

Example: say I get a 55A charger like the PowerMax. Set it to 14.8V and connect it to the 2 105s in series. During bulk, the output should remain constant at 55A while the voltage slowly rises to the set 14.8V. During absorption the voltage should stay constant at 14.8 while the amperage tapers off (but I have no control of that - it's up to the battery). Once a hydrometer dip shows 100%, you are done.

But to equalize, sounds like I need 16V at about 11A (5% of 220AH). Can't do that with a 55A PowerMax. So I need basically a 10A charger that I can set to 16V?

Not really worried about generator charging yet. This is all taking place on my work bench connected to household power, so time to charge is not an issue.

Trojan is like every other OEM. They are afraid of customers who have an uncanny ability to screw up a steel ball with a feather duster.

Sorry, but Battery Council International trumps Trojan Battery Company.

16.0 volts is appropriate for EQUALIZATION charging ONLY. PERIOD. But equalization charging the CORRECT WAY is getting impossible to do because of idiotic fear by charger manufacturers. A message for some forum participants: Sometimes equalization and recovery is hard to do. Even at 16.0 volts. I've seen too many high antimony batteries to keep track of DEMAND 16.0 volts for 24 - 36 hours. Drop voltage to 15.5 and you are talking five full days at 24 hours a day. A generator will love you for this. 120-hours of operation. How much fuel is that? Obviously this apples to off-grid.

Top charging likes charging to 15.0 volts

BOTH EQUALIZING AND TOP CHARGING REQUIRE A CONSTANT AMPERAGE OF FIVE PERCENT OF TOTAL BATTERY AMP HOUR CAPACITY.

The fastest safe charge level is 14.8

What takes an idiot smart charger 9 hours to do, when they rise to 14.4 for minutes then droop to an intermediate voltage, will take 2-hours at a constant 14.8

This is intelligent for boondocking?

What happens when a smart charger meets a sulfated battery? You'd better be hooked to public power cause you ain't gonna like my answer for how long it'll take if ever to drive sulfation back into solution.

Connection to public power is magic. Batteries have hundreds and thousand of hour to correct.

Connection to a generator is different. A world apart.

Like the difference between baking with a gas stove oven versus a campfire.

Yes, managing batteries when connected to public power is ideal with a smart charger, er, that is a few smart chargers.

Change this to generator connected charger then you tell me which smart charger has a prayer of managing batteries correctly.

Achieving 83% state of charge that takes forever running a generator ain't smart living.

Maybe 83% works for you. Just don't tout it that it works for everyone.

landyacht318 wrote:
The Schumachers are well known to go to too high a voltage, whenever it dang well pleases them to do so. Other times it drops to float voltage well before the battery would like.

My SC2500a shoots to 16.4v at a constant 15 or 25 amps, skipping the constant voltage stage at the high 14's and just beats the F out of the battery.

Yup, appears mine did both. Went really high charging a single T105. Charging the grp24 Interstate, did just the opposite - dropped to float at about 90% SOC. Still intend to try charging the the Trojans in series and see what happens. But based on what I see so far, I don't trust it. I see a PowerMax or a MeanWell in my future...

The Schumachers are well known to go to too high a voltage, whenever it dang well pleases them to do so. Other times it drops to float voltage well before the battery would like.

My SC2500a shoots to 16.4v at a constant 15 or 25 amps, skipping the constant voltage stage at the high 14's and just beats the F out of the battery.

While sometimes 16v is required on a heavily cycled bank that was not brought up to 100% often enough, 16v is NOT required each and every recharge.

I know you are charging 6v's but just halve these numbers.

Unless your batteries are in need of an Equalization, I would not let that Schumacher loose on them.

My Sc2500a is disassembled, in a paper bag. I do not trust it to leave it unattended on any battery I care about. I am hoping some thicker DC output cabling might tame down its neurotic proclivities. I would like to have a 'lender' charger. They are not getting my Meanwell.

The voltage potentiometer would make their head explode as it would seem to do to some people here who have complete faith in 'automatic' blinking and soothing green lights

MEXICOWANDERER wrote:
Set an Intermatic 12-hour timer with that Shumacher and you create a charger worthy of a brick of gold bullion. But it's not yours unless of course a deal could be struck. Heh heh heh.

So are you saying that 8.1V is ok as long as I limit the time? The question I can't yet answer is what will it go to when charging both in series with the same charger. Will it go to 16.2V??? Considering that Trojan recommends 7.75/15.5 for an equalization charge, I'm concerned that ANY amount of time at such a high voltage may be damaging.

I've taken the batteries out of the trailer and managed them in the garage since we bought it. The 2/12/70 has kept the grp 27 happy all this time but I wouldn't trust it on my big bank. That bank chewed up and spit out a Megawatt and would do so again without a lot of mods to it. I'll go with the 120a version of what BFL is using since it is made to take it and won't need a 10 hour run of the generator if I ever did get the bank down to 12.0v.

Right now the big bank lives in the Expy until the solar is mounted to take care of it. There is a 230w panel up top of the truck that keeps the bank up and the charge controller can be set to match the manufactures specs for the most part.

I had two Schumackers but the 2/10/50 started charging everything at 15 volts one day.