12 volt to 24 volt conversion Notes

[HRTKD]

I think that's probably how I would do the test too. I don't have any tools that can measure cumulative amp draw other than the BMS, shunt and the inverter.

How did you measure each BMS at the same time?

 

[chrisski]

I used my iPad on one and the phone on the other, so as quick as I could print screen on the phone.

I do wish I remembered the clamp meter this trip.

I wonder what others have seen doing this test. I got these packs from Amy and top balanced, but did not capacity check. Just built them based off the data she sent.

I do think my results are good, but like to see others.

 

[HRTKD]

I used my iPad on one and the phone on the other, so as quick as I could print screen on the phone.

I do wish I remembered the clamp meter this trip.

I wonder what others have seen doing this test. I got these packs from Amy and top balanced, but did not capacity check. Just built them based off the data she sent.

I do think my results are good, but like to see others.

My "test" involved me switching from one BMS to the other on the same phone. The amp readings were awfully close, like less than .5 amps. I chalked up any difference to my inability to quickly switch between each BMS.

My Fluke clamp meter doesn't accumulate amps. At least not that I recall. Min/max and current value is all I get.

 

[chrisski]

My "test" involved me switching from one BMS to the other on the same phone. The amp readings were awfully close, like less than .5 amps. I chalked up any difference to my inability to quickly switch between each BMS.

My Fluke clamp meter doesn't accumulate amps. At least not that I recall. Min/max and current value is all I get.

Nice to hear I had similar results. The 1580 watt test was .75 amps off. The 250 watt test was .5 amps off.

 

[chrisski]

With watching my battery State of Charge on the Battery. Monitor and the app for both BMS, I start to see how people say monitoring from multiple devices does not match up.

The Xiaoxiang app for the BMS is not yet stabilized. The BMS I used for the pre-charge reads 74% when close to its battery being fully charged, but the newer one has not had enough cycles to stabilize and has reread SOC at 100%. Last night was both their first time being used, so I hope to see it stabilize.

The Victron BMS is not reading everything going back into the battery. The readings were spot on for my 4 Golf cart lead acid batteries, but lithiums will take some tweaking. The lithium readings seem to be losing about 5 ah per day, so today it read -15 ah when my batteries went from absorption to float. Showed last night’s discharge at -170 ah. I doubt I’m losing 5 ah a day, so the monitor has a charge efficiency factor that I changed from 92% to 100%, so I’ll see that gets me a reading closer to 0 at the end of the charge cycle tomorrow.

 

[chrisski]

This 560 ah 24 v battery pack is a little different than the 50 ah 24 v pack I use. Turns out the absorption and float settings are different. For the 50 ah pack, I use 27.6 absorb and 26.7 float; for the 560 ah Eve pack, I use 27.8 absorb and float.

After a bit of experimentation for the 50 ah pack, I use 27.6 absorb and 26.7 float. This worked perfect where the batteries would charge to 100%, and once charged would float, and any load I had would be replaced in float. Watts used = Watts in.

For this 560 ah Eve pack, I tried those same settings, 27.6 absorb and 26.7 float, but charging seemed to stop before the energy was put back in the battery with my battery monitor showing every day the pack going down by about 5 ah total. Also, when I turned on a load, I would only get about 75% of the power back. If I had a 400 watt load, 300 watts was solar and 100 watts was battery. I adjusted the float to equal absorption, but the same thing. Both the little less charge every day, and after charge float not making up for it left me a less energy than I wanted at sundown.

I Just adjusted my absorption and voltage to 27.8, and seems like its working good. Battery is back to 100%, and if I have a 400 watt load, all 400 watts comes from the battery.

 

[chrisski]

Pulled the old AC to DC converter out. Turns out it was a 12 volt 65 amp converter, but never delivered more than 10 amps. No adjustments externally with rheostats or dip switches and the case is riveted, not screwed on, so it’s a mystery to me how it limited production to 10 amps.

Must be some internal adjustment set at the factory.

 

[12VoltInstalls]

Pulled the old AC to DC converter out. Turns out it was a 12 volt 65 amp converter, but never delivered more than 10 amps. No adjustments externally with rheostats or dip switches and the case is riveted, not screwed on, so it’s a mystery to me how it limited production to 10 amps.

Must be some internal adjustment set at the factory.

There’s often one or two tiny adjustment devices inside these- sometimes a switch that selects battery charging profile on newer stuff; and a flathead eye-glass-screwdriver-sized ‘pot’ for fine-tuning voltage. The unit I bought recently and didn’t like had the pot and slider switch accessible though some customer rigs from past employments had nothing visible or you could find the potentiometer through an air slot with a flashlight.

Not that can’t or didn’t do the math but 1260W at 120V that’s 10.5A input. It professes 13.6 output that’s and if we guess the typical 45-55% efficiency that’s only ~45A +
It bothers me 75% of the output was MIA
How does one trust stuff like that?!

That’s why I’m sending the unit I bought back. It was supposed to be 15A but it actually was doing 34A+/- and I just couldn’t trust it.