Parallel chargers

Here is another old thread with way more detail than most would want to know I suppose. You can see in the OP how changing the voltage of the Paramode from 14.1 to 14.8 changed its place in the pecking order.

http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/25115984.cfm

wa8yxm wrote:


The reason is very tiny differences in manufacturing will cause one of them to read the bulk mode output of the other as "Fully charged"

What, tell BFL and the rest of the word they are WRONG.

'bulk, they read batt voltage which should be less that ABS set pt.

more pissing up kit strings

IF the chargers are properly designed and you put two in parallel then one of them will charge and one will not more than likely. At least in Bluk mode.

The reason is very tiny differences in manufacturing will cause one of them to read the bulk mode output of the other as "Fully charged"

Damage, however, should not happen.. Now I will admit with a few bargain basement models. i'm not so sure of that, but with anything I'd care to install there is enough protection to make sure damage does not happen.

I remember my cheapowatt holding a pretty steady voltage when loads were added or removed, but it as a while ago, and I probably remember it more fondly than I should, as it led to me purchasing the Meanwell rsp-500-15 which I love.

Quiescent wattage paralleled chargers...

Transformer based chargers have quite the energy consumption even when leaning on a shovel. My ferroresonant charger draws 144 watts just sitting there grinning at me. But the Meaniewells, Cheapos, Megas and wall warts do not draw anything according to my super-duper 120 volt metering.

Of course none of the solid-state units are smartass chargers. But if a charger does not draw any wattage, then what is the need to take them totally off line?

SMART CHARGER / CONTROL
My entry for OXYMORON of the decade.

Sloppy regulation honorable mention: The Cheapowatt. Set to 13.22 on the bench. Connect to battery. 13.16 to 13.22 float voltage variation. Five amp load, droops to 13.05
If it does a Chernobyl act I am out twenty-two bucks. The cost of dinner, dessert, drink, and tip at a Denny's. Or, seven gallons of gasolina.

2oldman wrote:

BFL13 wrote:
So just because two chargers are "adding their amps" it doesn't mean each one is putting its full rated amps into the battery.

For now, my ammeter is how loud my generators get when the charging starts.

It is easier if each charger has its own amps readout. Using a Vector and the normal converter with no amps readout on it, you use your Trimetric for the total amps, subtract what the Vector says, and the remainder is what your converter is doing.

If you can't tell what each one is doing you don't know when to yank one, so just leave them all on till you reach your "marker" for knowing when you can shut off the generator. (It is easier to use an ammeter for your marker, but if none, you can use smk's rule of thumb--get the batteries up to 14.x (whatever the charger's program is for the highest voltage it gets the batts to) and leave it run for another hour.)

Obviously if you were combining a PD converter with your solar where the solar is likely to be set to maybe 14.6 or more, you want to force the PD into its 14.4 with the Charge Wizard.

That will keep the PD in the mix until the battery voltage gets near 14.4. (Instead of it dropping out at 13.6) After that the solar will keep raising the battery voltage to 14.6 and all the amps will be from the solar.

Be interesting if the solar has a two-hour time limit at 14.6 like an EP Solar one, and the PD is still within its four-hour 14.4 time then. Now the solar will drop to its 13.6 as programmed, and all of a sudden the PD is now doing the amps :)

I have not worked out proper tactics for if the lower voltage one does higher amps than the high voltage charger. You wouldn't want the high voltage one to squeeze out the low voltage one and get fewer total amps. You would need to experiment with your collection of chargers and see what works best (gets most amps)

BFL13 wrote:
So just because two chargers are "adding their amps" it doesn't mean each one is putting its full rated amps into the battery.

For now, my ammeter is how loud my generators get when the charging starts.

landyacht318 wrote:
the schumacher is about as predictable as a meth addict who also smoked some PCP during a full moon.

Yeow!..that's pretty flaky! :)

Should that fact give me pause about putting another identical Schu in parallel with the 48vdc /17amp one I have now?

I found it interesting to see how the Schumacher and meanwell worked together before absorption voltage was reached. The Meanwell's behavior is predictable, but the schumacher is about as predictable as a meth addict who also smoked some PCP during a full moon.

Having an Ammeter and voltmeter on each charger gave me a good insight to how they behave together. They were not hooked directly to battery terminals which would likely have changed how they interacted.