Sorry this was completely wisp unrelated, I only plan on connecting the batteries once and awhile and don't need them to be floated, etc.
So I'm guessing it's safe to parallel a power supply and a battery when the power supply is turned off? On Fri, Apr 24, 2015 at 6:20 AM, Mark Radabaugh <[email protected]> wrote: > On the subject Lewis brings up... > > There are a variety of battery charging schemes: > > Single Stage, Two Stage, and Three Stage. > > The very short version of this: > > Single Stage - usually a float charger, low amperage, fixed voltage. Not > intended to supply current to a load. Very slow to recharge batteries. > When used to power a load as well as charge batteries will usually leave > batteries undercharged. May also cause poor equipment operation when AC is > restored after an extended outage as the DC voltage will rise slowly - this > can cause unpredictable operation of attached network equipment. > > Two Stage - High(er) voltage and current to charge battery, float voltage > after fully charging battery. Usually dangerous to your batteries when > also powering a load - the charger can't tell the difference between the > current going into the batteries versus into the load. The charger always > thinks the batteries are still bulk charging and leaves the voltage too > high and will cook the batteries. > > Three Stage - Similar to two stage but also includes a boost voltage above > the bulk charge to equalize the voltage in all of the batteries. Can also > cook batteries when trying to supply load current. > > Best version - a 3 stage charger with separate current sensing for the > load and battery current, along with temperature monitoring of the > batteries. This allows the charger to know how much current the batteries > are consuming so that it can determine charge state accurately. > Temperature compensation is to adjust the float voltage for temperature. > > Mark > > > On 4/24/15 9:06 AM, Lewis Bergman wrote: > > And as a side note, you should be worried about the opposite issue. Every > supply is built to handle a load all the time. You need a supply that is > designed to both handle a load and float batteries. A standard PS has a > good chance of cooking your batteries if you constant load is much lower > than your PS rating. > > On Fri, Apr 24, 2015 at 7:46 AM, Mark Radabaugh <[email protected]> wrote: > >> DC power supplies rarely care if there is another source of voltage that >> the power supply sees on it's input. It is not unusual for a AC/DC >> supply to have to power up into an existing potential. Many DC loads, on >> a brief power interruption, still have significant voltage that the power >> supply is going to see when AC returns. >> >> * This comment is general and may not apply to every power supply * >> >> From experience the only supply I know that won't deal with power on the >> output is one of the larger MeanWell AC/DC 48V supplies. The internal >> voltage regulator is too slow to respond and ramps the voltage up over the >> high voltage limit and shuts the power supply down if it's powered up when >> there is already a battery voltage on the output. If you power up the >> supply and then add the battery it's fine - but not very practical. >> >> Every other AC/DC supply I have tried has worked fine doing what you are >> asking to do. >> >> Mark >> >> >> On 4/24/15 1:34 AM, TJ Trout wrote: >> >>> >>> I have a dc load that I need to power using a switching ac to dc power >>> supply but I also occasionally need to power the load from batteries, I was >>> planning to put the load, power supply and battery clamps in parallel, is >>> that a acceptable solution ? Can I power the load from battery and back >>> feed DC into the supply without damaging it? Would there be a significant >>> drain back into the supply? >>> >>> If this isn't ok, what's better solution? Diode ? SPDT switch ? >>> >>> The load is 50V 100A so that makes diodes and switches a challenge to >>> find. .. >>> >>> >> > >
