Converter on Low AC Input Example

THere are multiple types of converters. The old Transformer based ones would simply stop charging. NO the regulation circuit would not overheat as the lower the incoming voltage the less power he has to shed (Waste as heat)

The more modern switching supplies I do not know enough about to speak with authority. I have never made one (Yes I've made transformer based units. still have one I made).

But if I am correct they may fail if the voltage drops too low due to the switching system going "off line" as it were. But I stress. I don't know enough about 'em. In theory they can take a fairly wide input voltage range. IN practice. I simply do not knwo.

BFL13,

How long is "long"?

I found a #10 50 foot cord at Peavy Mart. It was covered in dust and was selling for the same price as a #12. I glomed onto it immediately--and it is my first choice extension cord when dealing with 15 amp shore power.

Some of my own voltage drop issues are due to the design of my upgrades. The inverter sits near to the battery bank just behind the driver's seat. So my shore power cord goes from the mouse hole to the inverter, and then back to the mouse hole. It easily adds 20 feet. I can wire around it--but that would eliminate the load support feature. In hind sight I wish I had insisted on #8 wire.

I noticed an anomaly during the foot ball game last weekend. The voltage dropped down to 105 from the usual 115-17. I was on a friends dedicated 50 amp outlet. Fortunately I use the autoformer at that location--so it was not an issue. The subdivision was built starting in 1954 and I'm sure consumption and code have both changed since then. At another location when I plug in voltage is 120 to 121 and when running the roof air it only drops to 117. That's where I use the #10 extension cord.

"The load on the converter doesn't matter much. It's the regulating circuit that needs minimum voltage and current to be happy"

It's not an analog circuit. It's a PWM MOSFET circuit that works less hard at low voltages that it does at full potential. BTDT

IR scanning proves this. Even the WFCO regulation does not suffer.

BUT BUT BUT

Low voltage due to bad connections, arcing, and flashing will kill any regulator from the most to the least expensive. This is why I add tons of MOVS and TVS devices upgrade capacitors to the next higher DC voltage level and upgrade them from 85c to 105c. I can only hope it is enough.

I am ok with the RV on a long extension cord at home. I have learned what I can get away with running. I was only using the 55 amp converter (and getting less than that) at home, but now Mex has me doing high amps at home, so that means using the Honda gen when I need to do that.

The old story that you could do a recharge on shore power at low amps since you have lots of time (unlike generator time) is out the window for my AGMs. :(

I can better appreciate why some guys on here organize 30 or 50 amp pedestals at home now.

BFL13,

Trip-Lite makes some smallish voltage regulators that would take care of the low voltage to the converter. They range in size from 600 to 2400 watts. The large one *might* be enough for use with an air conditioner. They do both boost and buck. https://www.tripplite.com/products/power-conditioners~23

I once tried one with an MSW inverter--hoping it would "clean up" the wave form. It made rather nasty noises, even with no load.

ScottG wrote:

time2roll wrote:

ScottG wrote:
It may seem to work down there but its regulation circuit is likely to get very hot and fail. I would not run it that way.

Same effect if producing the more typical five amps or less?

Since low voltage is usually a poor utility power connection the converter could be kept off until nightfall when voltage typically recovers. By next day the draw should be fairly small.

The load on the converter doesn't matter much. It's the regulating circuit that needs minimum voltage and current to be happy.

What in a switch mode power supply regulation circuit is sensitive to moderately low voltage? I think most of the control chips just shut down without fanfare if the input or output are too wonky. The actual regulator itself, the switching transistor, doesn't really work extra hard for a low input voltage (and correspondingly reduced maximum load); it's acting as a switch and so not dissipating much power when switched on, and the frequency of operation isn't changing enough to matter.

Many modern switch mode power supplies are rated to work at any nominal input voltage between 100V and 240V or 250V, though I haven't seen that for converters specifically. Rather obviously such a power supply would be perfectly fine with an actual input voltage of 99.8V, which is about as close to a nominal 100V utility power as could be expected.

The PD 9200 manual states that "The INTELI-POWER 9200 series will supply "clean" nominal 13.6 VDC (Normal Mode) power from input voltages that range from 90-130 VAC (205-265 VAC for 92xx-230 models)....At normal input voltages the full load rated capacity is available.
At input voltages less than 105 VAC (205 VAC for 92xx-230 models) the converter may not supply full rated output capacity."

BFL13 wrote:
Don't have EMS. The 99.8v was loaded voltage of course. Does the EMS kick in from unloaded or wait till load comes on and kill that?

An EMS will disconnect whenever it sees source voltage drop below it's preset low voltage threshold (102 vac for TRC, 104 vac for Progressive). If there's no load on the circuit then obviously incoming source voltage will be higher than if the circuit is heavily loaded, especially when powering through excessively long cable or of insufficient gauge. Regardless, when incoming source voltage drops below threshold either because it's simply too low unloaded or because it's forced below threshold from a heavy load the EMS will disconnect power to the rig to protect any electrical devices downstream of it from being destroyed. That's it's purpose in life. It's either that or an autoformer that will detect excessively low voltage and boost it so it's not excessively low.

time2roll wrote:

ScottG wrote:
It may seem to work down there but its regulation circuit is likely to get very hot and fail. I would not run it that way.

Same effect if producing the more typical five amps or less?

Since low voltage is usually a poor utility power connection the converter could be kept off until nightfall when voltage typically recovers. By next day the draw should be fairly small.

The load on the converter doesn't matter much. It's the regulating circuit that needs minimum voltage and current to be happy.

ScottG wrote:
It may seem to work down there but its regulation circuit is likely to get very hot and fail. I would not run it that way.

Same effect if producing the more typical five amps or less?

Since low voltage is usually a poor utility power connection the converter could be kept off until nightfall when voltage typically recovers. By next day the draw should be fairly small.

Meanwell RSP has a graph that merely shows a percentage lessening down to 80% of output. Why would less wattage throughput overload a non transformer device?