Battery pack with AC output with modified sine wave - SA330X

[agedhorse]

Generally it's safer with an SMPS, but many older, less expensive designs had high inrush current that could shut down MSW (and even some PSW) inverters. Noise is generally less of an issue in SMPS based amps because of the rectification and added inductive filtering these designs have.

[Puerto Player]

MSW inverters are fine for running guitar amps and tools. You need PSW inverters for laser printers and some of the newer LED lighting. Personally, I wouldn't use any inverter smaller than 1000 Watts for any guitar amp. Not that's it's needed, but remember, it's about a 10:1 ratio 12Volts to 110Vots. 10amps at 12 volts is needed for 1 amp at 110volts.

[agedhorse]

Originally Posted by Puerto Player

MSW inverters are fine for running guitar amps and tools. You need PSW inverters for laser printers and some of the newer LED lighting. Personally, I wouldn't use any inverter smaller than 1000 Watts for any guitar amp. Not that's it's needed, but remember, it's about a 10:1 ratio 12Volts to 110Vots. 10amps at 12 volts is needed for 1 amp at 110volts.

The ratio isn't what dictates the size of the inverter, it's the dynamic load and start-up current.

Battery capacity is a simpler calculation, 12 volts to 120 volts is a 10:1 ratio, so the battery current is the AC load current divided by the efficiency, times 10. The battery capacity required is this current times the number of hours required. Different battery types have different maximum discharge rates and discharge depths.

[jonfields45]

My experiment with cheap eBay Lithium rechargeable batteries to an inverter was a failure. The batteries had energy capacity (mAH) but could not deliver enough power (watts) capacity to start up my inverter.

Looking more carefully at my inverter's low voltage trigger it becomes clearer that it was not designed with the typical lithium discharge curve in mind either. Its low voltage trigger will kick in at roughly 50% battery capacity remaining. This is not exactly a bullet list spec on most inverters that are targeted at cars.

I don't want to drag around and maintain (periodically charge or keep on a trickle charge) an AGM SLA battery.

This leads to an integrated battery and inverter, which will be essentially disposable when the battery fails. Too many brands I've never heard of and prices all over the map, but pure sine wave lithium models do appear on eBay for a little more than $100. On Amazon the threshold is around $200. Drop down to MSW (which I've tested with the CP8 as I've got one of those cheap 75 watt cigarette lighter ones in my car) and/or SLA, and the selection of brands and products is staggering.

I went over to the pavillion we will be playing in a few weeks and paced off about 100 feet to my likely parking spot. I've got a 100 foot extension cord for my chainsaw and that's going to be my solution for this gig.

Now even I am tempted by a Bose S1 but it won't handle our bass guitar repertoire and my CP8 will.

[Puerto Player]

Originally Posted by agedhorse

The ratio isn't what dictates the size of the inverter, it's the dynamic load and start-up current.

Battery capacity is a simpler calculation, 12 volts to 120 volts is a 10:1 ratio, so the battery current is the AC load current divided by the efficiency, times 10. The battery capacity required is this current times the number of hours required. Different battery types have different maximum discharge rates and discharge depths.

See the post below yours. That's what happens when you go small with inverters or batteries.

I have built full solar systems for cabins, built wind generators and solar systems for RV's and remote fishing camps, and full solar systems for charging electric golf carts. Despite the math, if you go the bare minimum, the system will fail quickly.

Also, with regards to inverters and batteries, always unhook the positive wire from battery when you're not using the system. Almost every inverter will drain the battery even if it's off.

[jonfields45]

Since I apparently have more money than brains, I just ordered this and it will be here tomorrow:

BEAUDENS 166Wh Portable Power Station, Lithium Iron Phosphate Battery, 2000 Cycles, 10 Years Battery Life, with Multiple Ports, Perfect for Tablet, Laptop, Appliances Use

https://www.amazon.com/gp/product/B0...5PXF9ZXG&psc=1

Since I know my gear is fine with MSW, LiFePO4 is a more robust battery than all the options, it has good reviews on Amazon, Beaudens has a high volume of good reviews on their iRobot like vacuums, and $15 off today, I pulled the trigger.

Full report by Friday.

[Puerto Player]

Originally Posted by jonfields45

Since I apparently have more money than brains, I just ordered this and it will be here tomorrow:

BEAUDENS 166Wh Portable Power Station, Lithium Iron Phosphate Battery, 2000 Cycles, 10 Years Battery Life, with Multiple Ports, Perfect for Tablet, Laptop, Appliances Use

https://www.amazon.com/gp/product/B0...5PXF9ZXG&psc=1

Since I know my gear is fine with MSW, LiFePO4 is a more robust battery than all the options, it has good reviews on Amazon, Beaudens has a high volume of good reviews on their iRobot like vacuums, and $15 off today, I pulled the trigger.

Full report by Friday.

That's only going to give you less than 1.5 amps at 120V. Crank your system when get it to make sure it will deliver the current you need.

[jonfields45]

Originally Posted by Puerto Player

That's only going to give you less than 1.5 amps at 120V. Crank your system when get it to make sure it will deliver the current you need.

I've got a cheap power meter and my CP8 consumes about 15 watts of wall power when blasting louder than we will ever play. I will test it with a two hour continuous run as soon as it is charged.

[Mandobart]

Originally Posted by jonfields45

Since I apparently have more money than brains, I just ordered this and it will be here tomorrow:

BEAUDENS 166Wh Portable Power Station, Lithium Iron Phosphate Battery, 2000 Cycles, 10 Years Battery Life, with Multiple Ports, Perfect for Tablet, Laptop, Appliances Use

https://www.amazon.com/gp/product/B0...5PXF9ZXG&psc=1

Since I know my gear is fine with MSW, LiFePO4 is a more robust battery than all the options, it has good reviews on Amazon, Beaudens has a high volume of good reviews on their iRobot like vacuums, and $15 off today, I pulled the trigger.

Full report by Friday.

Wow, sounds very advanced "LITHIUN IRON PHOSHATE BATTERY: Powered by advanced lithium iron phosphate battery." I didn't even know about "LITHIUN IRON PHOSHATE" technology.....now I am familiar with lithium ion batteries; guess that's too old school. Its important for either the seller or consumer to have a little understanding of the technology.

166Wh will supply a 100 W load for a little over an hour. That wouldn't do much for me. Hope it works; I've never had good luck with Amazon returns.

[Mandobart]

Originally Posted by Big Band Guitar

A 1 to 1 isolation transformer would smooth out the modified sine wave.

The more iron in the power supply the better.

I would say if there is no power transformer in whatever your using don't use modified sine wave. I wouldn't run a switching power supply off one either.

Absolutely false. You cannot change a square wave (the output of a MSW inverter) to a sine wave with any transformer. A square wave contains only the odd harmonics. To get back to a sine wave you need to add the even order harmonics back in - a transformer can't do that. All the transformer does is shift the phase of the incoming waveform and isolate the ground, which sometimes causes noise.

[jonfields45]

I think we are getting carried away with PSW vs. MSW.

A typical power supply in modern audio will optionally be transformer coupled, then rectify, then filter, and then go to the boost/buck switching regulator. Poorly design any of these stages and you might have trouble. The wall socket itself can deliver some pretty nasty harmonics if you've got dimmers or motors nearby.

After rectification the pure sine wave and the modified sine wave both contain a DC component followed by harmonics of 50/60 Hz. Decent design should handle either and bad design would most easily have been rooted out for the pure version in product test. A slight win for pure.

Certain loads, in particular induction motors (and some electronics can have a large startup current as the power supply filter is charged), need a lot more inverter power (really current) headroom. Both pure and modified are equally hit by this problem.

Pure designs are generally newer and more expensive which might also mean higher basic quality. Win for pure.

My inverter is pure because $25/MSW or $60/PSW for a basic 300 watt inverter did not matter to me, and the fan on the pure was temperature controlled.