No I don't think the inverter-induced AC ripple on the batteries is anything we need to worry about with the cells we're using because the peak load isn't sufficient to locally deplete (move lithium faster than the cell can transport it between layers) the cell's charge.
Cinergi's 28 kWh / 4 kW Solar / 10 kW inverter RV build
- Thread starter cinergi
- Start date
Bottom line, I think in the interest of all of us you need to invest in that o-scope and report what you see.
Well now I need some recommendations for something fast enough to capture this but not burn a hole in my wallet or be huge (remember, I live in an RV)
There are some handheld Atmel based scopes which probably have enough resolution.
I have the bare hardware version of this in my home shop.
I have the bare hardware version of this in my home shop.
That's it? Wow I was expecting to spend at least $200. Aww man, you guys are a horrible influence ?FYI since I'm in a heavy charge cycle right now, I used my DMM clamp meter which can measure both AC and DC current via the clamp and DC current reads 120 amps and AC current reads 99.
I also tried to measure voltage drop at the terminals but I can't reach the terminals - the bus bars are in the way. That said, I have an extraordinarily consistent 1.9mv drop across the long (4 cell) bus bars. Even if I measure the studs, it's consistently 2.2-2.5mv. Cells are showing 30mv of variation according to the Orion BMS. DMM just sees a nice steady voltage.
Also interesting -- while the Orion in-utility graph shows 30mv of variance, I only see 1-4mv of variance when I tell Orion to log to a CSV (10 data points per second). Makes me wonder what the built-in graphing tool is really showing! I might contact Orion and ask what's up.
Your DMM uses internal averaging to make a human readable value. It won't pick up high frequency stuff. My Fluke meter has a frequency measurement option, and I can see medium frequency ripple. If you set your meter to AC volts, some of them can measure the DC ripple that way. Not all of them are fast enough for high frequency stuff, as they are designed for 60hz typically.
The orion BMS has both an average and unfiltered value for current and voltage, so if you pick the average it will show much less variation.
The orion BMS has both an average and unfiltered value for current and voltage, so if you pick the average it will show much less variation.
The siglints look really good and have a good reputation. Thats what I'm saving for.Well now I need some recommendations for something fast enough to capture this but not burn a hole in my wallet or be huge (remember, I live in an RV)
I was graphing and logging instantaneous cell values. The CSV version doesn't line up at all with the displayed version.
My DMM used to pick up .2 or .3 AC volts on the battery when I was using the provided bus bars... but I think the resistance is so low now that the DMM can't see it anymore.
Hedges
I See Electromagnetic Fields!
- Joined
- Mar 28, 2020
- Messages
- 20,505
This is what I think you need ?
Tektronix TDS784D 1GHz 4 GS/s 4-Ch DPO Color Oscilloscope Tek LCD display GUAR! | eBay
Tektronix TDS784D 1 GHz, 4 GS/s, 4-Ch DPO-Color-Oscilloscope. DPO - Digital Phosphor Oscilloscope with a GREAT BANDWITH OF 1 GHz ! with LCD display. PASSES ALL SELF TESTS!
www.ebay.com
Is that for one single-ended signal referenced to ground?
I suppose battery powered or isolated AC adapter, you can get away with having the negative terminal to to one busbar and positive to next busbar, so scope chassis is raised to an elevated voltage? (just not for use with hazardous voltages)
Does it offer AC coupling so, while DC referenced to ground, he can see voltage ripple on a busbar?
Maybe have to add a blocking cap for that.
Actually, it's current ripple we're also interested in, right? So need a clamp probe of sufficient bandwidth.
When used with an isolated power supply (or battery) either probe can be referenced to ground.
Yep, no high voltage stuff.
Yes, you can switch from isolated, DC, and AC coupling
If there is a busbar of known resistance (or shunt etc), that should yield a good result. With an isolated power supply, it shouldn't be necessary to use 10x probes, assuming the voltage being measured is just the AC on a single bus bar or shunt.
On a completely different note, I acquired the CBA IV Pro tester and am re-testing 1 of my 4 worst cells. I'm doing it at 5 amps so I can capture a graph of nearly open-circuit voltages so I can more accurately program my Orion BMS's SOC drift feature. Will be interesting to see how this number compares to the cheapie tester. At 5 amps that'll take more than 2 days.
Here's a link to my VRM data: https://vrm.victronenergy.com/installation/76892/share/d5bbdd04
Yesterday I made 2.6kWh here in CT from my 2x210w panels.
My current RV is plugged into the 50-amp receptacle provided by the Quattro's (and the Quattro's are plugged into the 50-amp receptacle on the side of the house).
My consumption is very high because of the electric floor heat and heated water hose. This RV is pretty inefficient anyway. But it's giving me the ability to cycle the battery daily using the power I'd be using anyway (so I'm not just wasting it).
Yesterday I made 2.6kWh here in CT from my 2x210w panels.
My current RV is plugged into the 50-amp receptacle provided by the Quattro's (and the Quattro's are plugged into the 50-amp receptacle on the side of the house).
My consumption is very high because of the electric floor heat and heated water hose. This RV is pretty inefficient anyway. But it's giving me the ability to cycle the battery daily using the power I'd be using anyway (so I'm not just wasting it).
My 4 Lishen 272's just arrived ... 95 days later -- must have been part of the barge snafu.
The terminals are higher than the EVE's so that will make inserting them into my current configuration more difficult (using rigid bus bars). Right now I'm series charging them and then I'll top them off and start testing them with my new CBA IV tester -- should provide us some nice solid test data for these Lishen's especially since I'm using the same test gear for both EVE and Lishen.
Oh, and it looks like my RV is still (somehow?!) on schedule for end of this month! OMG OMG OMG! 2 weeks from today I may take delivery and start installation!!!
The terminals are higher than the EVE's so that will make inserting them into my current configuration more difficult (using rigid bus bars). Right now I'm series charging them and then I'll top them off and start testing them with my new CBA IV tester -- should provide us some nice solid test data for these Lishen's especially since I'm using the same test gear for both EVE and Lishen.
Oh, and it looks like my RV is still (somehow?!) on schedule for end of this month! OMG OMG OMG! 2 weeks from today I may take delivery and start installation!!!
I know I said this before but DAMN I love the Victron power assist (especially with the "generator" option turned on; I forget what it's called). I've broken in my generator (which can sustain 2800 watts on propane) so I set the max shore power to 25 amps, I set the generator to economy mode (it's an inverter generator so it will vary its speed depending on load in this mode), and then did all kinds of crazy things ..
* Charged to full at full load with 600 watts of power going to AC loads and rest to battery charging, and generator ramped down
* Turned on 3,000 watts of additional stuff and observed no power issues in the RV and the generator ramped up perfectly to full load
* Turned off the 3,000 watts and observed no power issues and the generator topped off the battery and ramped down
I'm just drooling over this. I mean, it's even doing this with single-phase generator input while providing split-phase output during all of that. Amazing. Frickin' amazing.
* Charged to full at full load with 600 watts of power going to AC loads and rest to battery charging, and generator ramped down
* Turned on 3,000 watts of additional stuff and observed no power issues in the RV and the generator ramped up perfectly to full load
* Turned off the 3,000 watts and observed no power issues and the generator topped off the battery and ramped down
I'm just drooling over this. I mean, it's even doing this with single-phase generator input while providing split-phase output during all of that. Amazing. Frickin' amazing.
Now that I have the CBA IV tester, I graphed an EVE 280 that tests to 273 with a 5 amp charge and discharge so I could get a close-to-open-circuit voltage graph vs. SoC, which allowed me to properly program SoC drift within the Orion BMS. Once again, it's truly amazing to witness the flat charge curve and the crazy hockey-stick curves at the knees in person, despite seeing the graph 100 times ... there's just something about seeing it yourself and hovering your mouse over all the data points ...
I'll share the Orion BMS settings at some point, including the voltage <-> SoC mappings at the knees.
I'll share the Orion BMS settings at some point, including the voltage <-> SoC mappings at the knees.
First Lishen 272 tested to .............. 287.7Ah! Wow.
I've got a small set of modifications I'm going to make which I'll document after I'm done. I purchased another set of BMS cables (balance leads and main power/temp sensor/CANBUS) so I can make changes and have a backup/spare in case I really screw up or change the design in such a way that the leads I modify won't work.
8 days until I pack up the truck and head west! Eep!
I've got a small set of modifications I'm going to make which I'll document after I'm done. I purchased another set of BMS cables (balance leads and main power/temp sensor/CANBUS) so I can make changes and have a backup/spare in case I really screw up or change the design in such a way that the leads I modify won't work.
8 days until I pack up the truck and head west! Eep!
