Chargerverter Current Ramp (Slew Rate / Rise Time)

[??????]

There's been a bit of discussion about the chargeverter current ramp rate being too fast, so I wanted to post my experience with my gen 1 CV (yellow enclosure), purchased circa Mar 2024 from Signature Solar. I believe this was the very last of the gen 1 CVs. X-axis gridlines are in 15s increments, Y axis is in kW AC as measured from the AC input of the CV (240v single phase). Data is sampled at 1Hz. Output voltage of the CV is 56v DC and current setpoint is 25A. Input AC is from the grid so can be considered 'bottomless' / not current limiting on the source side. No configurations / firmware updates were made to the CV - totally stock from supplier. Hope this helps somebody

 

[ksmithaz1]

I'm not sure what I'm looking at. This shows ~15s to 1.4kw? 1.4kw ~= 25A@50v?

I can tell you if you have the CV only connected to a 30KWH pack of batteries (NO AC), and you flip the breaker on, it will trip a low voltage alarm on the inverters, as in shut things down, no matter what you have it set to as it drags the bus down briefly. Not pretty, plug in the AC first.

If you turn on an AC feed and it's at it's rated 5KW it will put the hurt on it as well.

This chart does not seem to reflect my experience, but you have the settings fairly low.

 

[??????]

@ksmithaz1 - CV board breaker is always 'ON' (connected) and CV is always connected on the DC side to the pack (this one is a 30kWh pack; 6x100aH) so the CV caps always stay charged/ready. The AC side of the CV is switched with a 2 pole contactor. The power (current x voltage) through that AC side of the CV is then measured and graphed (see above). It seems like it jumps to about 0.65kW immediately, then ramps from 0.65kw --> 1.4kW (2.7A --> 5.8A) over the course of about 15s. That's 3.09A/15s = +0.206A/s rate of increase.

I'm still figuring out efficiency of the CV but from the preliminary numbers it looks like it's less than stellar; about 50% from AC --> DC (landed in the battery bank). If anybody's got thoughts on optimizing this (i.e. starting/stopping charging at a certain SoC of the battery bank, or charging at higher/lower current or voltages), I'd be interested.

 

[ricardocello]

I'm still figuring out efficiency of the CV but from the preliminary numbers it looks like it's less than stellar; about 50% from AC --> DC

The power supplies inside the chargeverter claim 92% efficiency (but ymmv).

Chargeverter efficiency is around 75%

I was having an issue with a breaker popping while using the chargeverter. In the investigation process I discovered that to put 5.1kW into the batter bank using the chargeverter I was pulling 6.8kW from the generator. I was a little surprised that the efficiency was that low. That is like a...

diysolarforum.com

Chargeverter alternative

sorry should have been more clear. I quoted "rectifier" because that is the term the telecom industry uses for its AC to DC power supplies. I agree they are much more than just a rectifier only. That is the industry term, however, and knowing that can help somebody searching for product...

diysolarforum.com

 

[ksmithaz1]

@ksmithaz1 - CV board breaker is always 'ON' (connected) and CV is always connected on the DC side to the pack (this one is a 30kWh pack; 6x100aH) so the CV caps always stay charged/ready. The AC side of the CV is switched with a 2 pole contactor. The power (current x voltage) through that AC side of the CV is then measured and graphed (see above). It seems like it jumps to about 0.65kW immediately, then ramps from 0.65kw --> 1.4kW (2.7A --> 5.8A) over the course of about 15s. That's 3.09A/15s = +0.206A/s rate of increase.

I'm still figuring out efficiency of the CV but from the preliminary numbers it looks like it's less than stellar; about 50% from AC --> DC (landed in the battery bank). If anybody's got thoughts on optimizing this (i.e. starting/stopping charging at a certain SoC of the battery bank, or charging at higher/lower current or voltages), I'd be interested.

The CV has a couple of apparently huge caps. As long as you leave it hot to your batteries your ramp should be minimal.

 

[??????]

The CV has a couple of apparently huge caps. As long as you leave it hot to your batteries your ramp should be minimal.

It was hot against the battery bank (DC side connected / caps fully charged) when that chart was generated