Mex's Flash?
Does "Flash charging" mean we (some of us anyway) are wrong to hate it when the PowerMax or Iota converters drop their voltages so soon for the absorption stage? In another thread Mex says, "A flas...
Forum Discussion
Connect enough chargers to obtain 14.8 volts INSTANTLY
ABSOLUTE FACT different batteries different banks, will take a different amount of time to achieve light bubbling at 14.8 volts. This is specifically why I denoted "CHECK BATTERIES TO DETERMINE WHEN LIGHT BUBBLING IS EVIDENT"
My battery bank requires more or less 408 amperes to achieve 29.6 volts (my vmax voltage is less because of high ambient temps - but let's skip that for now).
It takes what it takes. Obviously doing this takes a suitable generator and charging system. The larger the generator the more relevant this becomes because of run-time cost. In my case it is a water cooled 6-cyl Kubota twisting a 12.5 Kw KATO. The generator is laughably de-rated and the Kubota is a 38 HP engine but operating at 1,200 RPM, with turbocharging added for low end power.
About 14,600 VA total. The gen has to go online slowly - about 12 minutes of ramping-up using the 4024 Trace as a lead-in to get oil temps stabilized. Remember I am starting with an average 88F ambient air temp. This is no cheapo setup. The generator has a lube oil cooler, with a 24-volt .5 HP pre-lube pump, a six row push radiator. A C750L Luber Finer element works in conjunction with an oil filter adapter and B88 oil filter for an 855 Cummins engine (the same as Quicksilver).
REGARDLESS! Diesel fuel down here is $3.33 gallon at the present exchange rate. When the Kubota gets cranked up it goes to work. The 400-amp charging rate can be supplemented by the Lombordini 385 amps engine if the batteries were discharged more than 60% SOC.
I've run the numbers on this and other Vmax charging installations so many times it isn't funny. Should diesel prices drop to $2.05 gallon or cheaper the tradeoff would become less clear, at $1.60 gallon, the crunching favors a 50% Vmax charge rate to increase battery life SLIGHTLY.
Now, someone running a teeny Honda 2000 and charger, and a single or dual RV batteries isn't going to go bananas, over savings. As a matter of fact, pseudo deep cycle car-jar batteries do not like to be Vmax charged nearly as much as thicker plate "genuine" RV batteries.
One of the components of safe and sane battery charging is cell temperature. It is safe to raise cell temps to 110F but not above this. Cell temperature is a must-check when configuring a Vmax charge regimen. But and consider this a BUT BUT BUT, high cell temps and "LIGHT BUBBLING" do not fit into the same space.
This formula was worked out during innumerable trial and error workups. It isn't derived from E=MC2 wishful thinking or conjecture. Nor is or was the number crunching for expense.
The main point is to CHARGE THE BATTERIES CORRECTLY meaning not under nor overcharged. The gen charging runtime (Vmax) is a derivative, to minimize fuel and wear and tear expenses. In my case it saves many hundreds, sometimes more than a thousand dollars in annual fuel cost. The nearest diesel is a 78 mile round trip drive. Times the fuel savings by the 22-year lifespan so-far of the system and you'll get the idea quickly.
ABSOLUTE FACT different batteries different banks, will take a different amount of time to achieve light bubbling at 14.8 volts. This is specifically why I denoted "CHECK BATTERIES TO DETERMINE WHEN LIGHT BUBBLING IS EVIDENT"
My battery bank requires more or less 408 amperes to achieve 29.6 volts (my vmax voltage is less because of high ambient temps - but let's skip that for now).
It takes what it takes. Obviously doing this takes a suitable generator and charging system. The larger the generator the more relevant this becomes because of run-time cost. In my case it is a water cooled 6-cyl Kubota twisting a 12.5 Kw KATO. The generator is laughably de-rated and the Kubota is a 38 HP engine but operating at 1,200 RPM, with turbocharging added for low end power.
About 14,600 VA total. The gen has to go online slowly - about 12 minutes of ramping-up using the 4024 Trace as a lead-in to get oil temps stabilized. Remember I am starting with an average 88F ambient air temp. This is no cheapo setup. The generator has a lube oil cooler, with a 24-volt .5 HP pre-lube pump, a six row push radiator. A C750L Luber Finer element works in conjunction with an oil filter adapter and B88 oil filter for an 855 Cummins engine (the same as Quicksilver).
REGARDLESS! Diesel fuel down here is $3.33 gallon at the present exchange rate. When the Kubota gets cranked up it goes to work. The 400-amp charging rate can be supplemented by the Lombordini 385 amps engine if the batteries were discharged more than 60% SOC.
I've run the numbers on this and other Vmax charging installations so many times it isn't funny. Should diesel prices drop to $2.05 gallon or cheaper the tradeoff would become less clear, at $1.60 gallon, the crunching favors a 50% Vmax charge rate to increase battery life SLIGHTLY.
Now, someone running a teeny Honda 2000 and charger, and a single or dual RV batteries isn't going to go bananas, over savings. As a matter of fact, pseudo deep cycle car-jar batteries do not like to be Vmax charged nearly as much as thicker plate "genuine" RV batteries.
One of the components of safe and sane battery charging is cell temperature. It is safe to raise cell temps to 110F but not above this. Cell temperature is a must-check when configuring a Vmax charge regimen. But and consider this a BUT BUT BUT, high cell temps and "LIGHT BUBBLING" do not fit into the same space.
This formula was worked out during innumerable trial and error workups. It isn't derived from E=MC2 wishful thinking or conjecture. Nor is or was the number crunching for expense.
The main point is to CHARGE THE BATTERIES CORRECTLY meaning not under nor overcharged. The gen charging runtime (Vmax) is a derivative, to minimize fuel and wear and tear expenses. In my case it saves many hundreds, sometimes more than a thousand dollars in annual fuel cost. The nearest diesel is a 78 mile round trip drive. Times the fuel savings by the 22-year lifespan so-far of the system and you'll get the idea quickly.
