I'm still impressed with the cheapowatt, especially for $22.59 and 2 day free delivery. I am glad I got it. I've enjoyed experimenting with it. I believe that for the task for which it was made, a 30 amp adjustable voltage power supply, it could do 36 amps all day long without modification.
My main desire for acquiring this was as a overnight float charger for when I plug into the grid, and let it power my 12v devices, and for this task it will laugh quietly in my cabinet, remain cool and hold a rock steady voltage as relatively minor loads cycle on and off.
I do not own a generator, have no plans on owning a generator, and super fast charging is not a goal of mine. Yet, I do not have much battery capacity and 30 amps is a fast rate anyway, and on my screwy 31, exceeds the 'recommended' 10% bulk rate by a good amount.
Since I basically have no time limit when I do have 120vAC available I don't really need a 30 amp charger, or in this case, a 38.2 amp charger.
I was not looking for instant ABSV on a well depleted battery, I know that is unreasonable and likely detrimental if done every single cycle, and certainly not needed in my usage. I was hoping to dial in 14.9v and let the cheapowatt take however long it takes to get the battery upto 14.9v. BUt this causes it to absolutely max out at 38.2 amps and make that undesirable sound.
I left it to make that sound for about 4 minutes while I took voltage measurements, and temperature measurements and typed in the results, and the temps really rose fast. When I backed off on the trim pot enough to stop the noise I was surprised to still see 36 amps and case temps dropped even holding 36 amps for the next 10 minutes or so when amps then began to taper and I'd turn up the voltage pot a bit more and it cranked out 38.2 amps again and started buzzing until I backed off on the trim pot until it dropped to 36 amps
When I left the voltage pot alone, and battery voltage rose closer to the cheapowatt setpoint, amps tapered. Temperatures also tapered. When I increased the voltage pot again, 38.2 amps, noise, temp rise, back off till noise stopped then 36 amps and temps lowered slightly. Time and again.
I repeated this 5 times until the screwy31 could not accept over 36 amps, and at that point I could just max out the trim pot with no noise, and no excessive heating.
So, I always knew I'd need to monitor the cheapowatt, but the noise made it so I was uncomfortable leaving it alone where it would max out and buzz. Also 38.2 amps on a 130 A/h battery seems abusive since I am not running a genny or trying to save gas or watching the clock until generator hours expire.
I do not expect many situations to arise where I need to cram in as much as possible in the shortest amount of time. I know many of you do however, and I think that long term operation of this device at 8.2 amps over its rating will cause some magic blue smoke to escape, but 6 amps over its rating and it could laugh.
I am tempted to run the same test again with the lid off, and a separate fan blowing on the unit, and use a hose to my ear to find out what electronic thing inside is making the noise which makes me so uncomfortable.
I wonder if there is a way to limit the maximum output to no more than 36 amps, other than fine adjustment of the voltage pot keeping it just ahead of battery voltage.
And on another note, while I determined through much experimentation with settings and a hydrometer that 14.9 ABsv for around 2 hours followed by 15.3v finishing is what this battery likes from 198 watts of Solar, I do not think 14.9v is needed when charged at the significantly higher rate by the cheapowatt.
Once 14.9v was reached at the battery terminals the battery was still taking ~ 16 amps and I feel this is excessive. I never let it drop below 26 amps before turning the trim pot higher and bringing it to 38.2 then lowering it to 36.
So for me, this will make an excellent top charger, and an excellent converter when the battery is charged enough that setting it to 13.2 volts does not cause it to produce 38.2 amps, but as a bulk charger on a depleted battery, and then it needs close supervision to prevent the noise and possible damage, blue smoke ejection.
I would be interested if the Meanwell/Megawatt makes the same noise when maxed out on depleted batteries. I know the fan noise of the original fan makes it much harder to hear. My quieter fan certainly made the noise much more apparent than in my original test. I noticed the noise in that original test but it was of shorter duration when maxed out. The battery was my Northstar AGM in the 75 to 80% charged range and I was using 2 sets of halogen fog lights (220 watts) to max out the device.
When I do cycle the AGM deeply, I want to feed it those 36 amps. Every time I have charged it at a higher rate, and then used it to start the engine, it had noticeable more cranking amps to deliver, compared to if the low and slow solar did the same task over a longer period of time. So this cheapowatt bulk charging the AGM likely would require even closer supervision, because the AGM is a thirsty devil.
I am so tempted to see at what point the magic blue smoke does escape, and for 22.59$ I could afford to, but I dislike being wasteful and viewing everything as disposable like so much of current society.
