Got the Mega Watt today

I have 45 amp anderson Powerpoles on my Meanwell rsp-500-15.

When I need to feed the battery, I plug in the Meanwell and wait the half second it takes before it clicks and powers up my Wattmeter.

Then I twist my 10 turn potentiometer to dial in ~14.65 volts give or take depending on temperature. I've got 0.1 to 0.2 volts drop on my 8awg to battery I account for too.

Then I mate the 45amp powerpole connectors and watch those 40 amps fly. Battery voltage drags down the Meanwell voltage to the low to mid 13's, depending on the battery state of charge. The watt meter shows total Meanwell output, my battery monitor shows how much of that is going into the battery. The difference is what is required to power loads I have running.

When Amps into my AGM battery taper to 0.4 at 14.4v, I twist pot slowly back down to 13.6v, but if the load on the battery is not great at that time, I unplug the powerpoles, quickly lower voltage to 13.6v, and wait for battery to drop to 13.5v and then reconnect.

If I twist the dial down too fast the overvoltage protection kicks in with a click, then another click when it goes back On, and can do this several times, so I usually unplug the powerpoles when the fridge compressor or laptop are not running and sucking up 3 to 6 amps and helping remove surface voltage.

These power supplies get quite hot when maxed out by a depleted battery.
My Meanwell now has quiet Noctua 80 and 60 mm fans on the lid in addition to the extremely powerful and loud 40MM fan it came with internally.

I also added heatsinks to the casing adjacent to the heat producing transistors which use the casing as a heatsink. Now the loud 40MM fan only comes on after 15 minutes at maximum output at 85f, and it shuts off when amps taper to 34. A 10 amp improvement compared to no external heatsinks.

At 75f ambient temps, the loud internal 40mm never comes on at maximum output.

The Noctua fans are very quiet.
I've probably got thousands of hours on the Meanwell now, holding my battery at my desired float voltage while powering all DC loads.

red31 wrote:
'Keep the top of the battery clean of heavy dirt and oil to reduce the risk of electrical transients between the positive and negative posts, which will result in a quicker discharge.'

Ya well my factory battery boxes suck as they let in dust and water. I've cleaned them a dozen time this year. Need to get a better box but I'm not to worried about it or the little bit of crud on top of them right now.

NinerBikes wrote:
Go back and re read... you need to adjust the voltage from the MegaWatt terminals while disconnected from the battery, NOT while attached to the batteries, as the battery terminals will have dropped the voltage, due to battery internal charging resistance.

This is not something to mess with, set your voltage disconnected, always.

This isn't about fun, over volting a battery can cause it to explode. Don't twist knobs or increase voltage while connected to the battery, ever.

Easy there Niner, I adjusted the MegaWatt disconnected then stuck the probes in the clamps just to watch what was going on.

Do not disconnect any of the charger leads to the battery posts without shutting off the charger first. Spark! Gas ignition! POP! HOT BATTERY ACID IN THE EYES WILL CAUSE INSTANT TOTAL PERMANENT blindness. Wear glasses.

The power supply threads have been long. Lost in there are discussions about on-board pots. 10-turn external pots, special screwdrivers to fit Looney Tunes Chino-Fasteners, etc.

'Keep the top of the battery clean of heavy dirt and oil to reduce the risk of electrical transients between the positive and negative posts, which will result in a quicker discharge.'

Go back and re read... you need to adjust the voltage from the MegaWatt terminals while disconnected from the battery, NOT while attached to the batteries, as the battery terminals will have dropped the voltage, due to battery internal charging resistance.

This is not something to mess with, set your voltage disconnected, always.

This isn't about fun, over volting a battery can cause it to explode. Don't twist knobs or increase voltage while connected to the battery, ever.

Here is a pic of my temp deal, just had to try it out and there is no sense going crazy until I have all the parts to wire up.


What you fellers failed to disclose is how much fun it is to turn the little resistor deal to adjust voltage, after searching through a few screw drivers I finally found a flat blade that fit then the test of how stead of hand came in. One little itty bitty turn of the screw driver sends it into orbit or crashing to the ground.

MEXICOWANDERER wrote:
A chupacabra in traje de ova (sheep's costume) my 400 goes to 45.4 amperes @ 14.8 volts. I didn't waste my time buying a 350.

Give him a chance to hook things up and measure his output.

I've seen 38 amps output, peak, on my MegaWatt S-300-12, in 17F weather in Montana in Sept on my T-1275. But it quickly came down to about 30 amps in 20 to 30 seconds. yes, in that cold, at that temp, I did bump up the charge voltage to 15.0V.

A chupacabra in traje de ova (sheep's costume) my 400 goes to 45.4 amperes @ 14.8 volts. I didn't waste my time buying a 350.

The specs say the 400 has 36A at 90% and 30A at 100% duty cycle.