[Battery Buyer]

Thanks to covid, I'm never in a hurry when ordering anything anymore...

I know that's right! They were slow loooooong before covid, though.

Stupid Amazon has people wanting things yesterday!

 

[Balto]

Thanks to covid, I'm never in a hurry when ordering anything anymore...

...

I've been meaning to analyze the data from these first cells... been super busy these past few days, so haven't had a chance to even switch over to non-damaged ones.

Rough overview:
-EHW5 cell has QTY938 cycles on it and is still going strong.
-47 Ah FoMoCo cell has QTY260 cycles on it and is still going strong.

Now 928 cycles. Isn't that like 3 years? It's basically one cycle per day right?

I'm kinda confused with the 'cycles' thing. I understand on say, a Chevy Volt, where the battery is driven on until it's low, then the gas engine kicks on, then when you get home and charge, that's essentially a cycle.

However, in the insight, I rarely go below 56% SoC and rarely above 65%. Does that increase the 'cycle' count because I'm not using the whole 10-85% SoC range?

 

[*sean*]

However, in the insight, I rarely go below 56% SoC and rarely above 65%. Does that increase the 'cycle' count because I'm not using the whole 10-85% SoC range?

One would expect that if one charge/discharge cycle consumes 25% of the capacity, you would get four times the number cycles than if you used 100% of capacity instead.

In fact, the interwebs claim, and I think this applies to most rechargeable technologies, that you would get somewhat more than four times the number of cycles.

Such a claim deserves data, though. If you are inclined to find a paper on the interwebs that shows this, please post the link. (I'm not in a place to do this.)

 

[mudder]

Now 928 cycles. Isn't that like 3 years? It's basically one cycle per day right?

To your point, yes, I suspect that each actual day of driving is maybe one or two complete cycles. So yes, QTY1000 cycles is around 700 actual total days of driving the car really hard.

I'm kinda confused with the 'cycles' thing.

An ideal cycle is completely discharging the battery to 10% SoC, then charging back up to 85%.
On these first cells, I didn't always hit that goal... more like 10% discharge, then 90% charge... but that's harder on the cells, which is good because the goal is to gather the most realistic abusive data as fast as we can (at least initially, but given how good the results are so far, we probably don't need to perform any additional tests... cell aging is going to be what kills EHW5 modules).

I'm doing these discharge/charge cycles VERY rapidly. On average, I am:
-discharging the EHW5 cell in 162 seconds, then;
-recharging the EHW5 cell in 267 seconds, which is;
-completing each cycle in 429 seconds (7.2 minutes), or;
-completing 201 cycles per day.

As you might imagine, this test is incredibly abusive. And yet, the EHW5 cell is taking it like a champ.

In the insight, I rarely go below 56% SoC and rarely above 65%. Does that increase the 'cycle' count because I'm not using the whole 10-85% SoC range?

Not for lithium. On a NiCd cell, each local maximum counted as a cycle, but lithium doesn't have this 'memory' effect. For lithium, a cycle occurs each time you accumulate 160% total abs(SoC change) (i.e. 80% total assist SoC and 80% total regen SoC). For example, if you consume 20% total abs(SoC change) per day (65% to 55% to 65%), that's essentially 1/8 of a cycle.

Aside: This isn't actually the case, though, as shallower discharge sessions will increase battery cycle life. So maybe the above example is 1/10 of a cycle. Regardless, the point is that any result I gather with this abusive testing is worst case by a country mile.

Edit: @*sean* proposed this more simply above... I didn't see his post until after writing this one. Don't want the ic.net police to harp on me again for not giving credit where it's due.

 

[mudder]

I just stopped testing the first EHW5 and 47 Ah FoMoCo cells. They're both still doing just fine, but I decided to stop testing them given how much my test code and setup evolved while they were under test. Now that the test setup is solidly working, I want to switch over to fresh cells before I let the test run for a month.

First let's look at the EHW5 cell:

The area to the left (shaded in red):
-should NOT be compared to the data on the right (shaded in green).
-shows wildly varying results due to several changes made to the test hardware and software.

The area to the right (shaded in green):
-is valid long term data, using the final test configuration.
-Certainly shows a slightly downward trendline... capacity decreases ~5% after ~QTY600 cycles (several years of driving).
-Remember: this is an extremely abusive test.
-There is less temperature variability than was seen on the 47 Ah FoMoCo cells. I suspect this is due to how much warmer the EHW5 cell gets compared to the 47 Ah FoMoCo cell (because the EHW5 is only 5 Ah, whereas the FoMoCo is 47 Ah, and yet both are sourcing/sinking roughly the same current)

Overall EHW5 summary:
-The EHW5 cycle life is incredible!
-Age will certainly kill EHW5 cells before cycle life does.
-I don't think the G1 Honda Insight's PDU or IMA motor can abuse these cells.

...

Now let's look at the 47 Ah FoMoCo cell:

The area to the left (shaded in red):
-is much longer than the EHW5 module, because the EHW5 test started several days later than the FoMoCo test. Specifically, the EHW5 cycle#1 started around FoMoCo cycle#110.
-Cycles 1 to ~110 should probably be shaded in green, but I err towards certainty, and I can't guarantee the data is the same.
-The major deviation from cycle ~110 to ~175 is due to integration hell when I added the second test head hardware (to test the EHW5 cell in parallel). I ended up rewriting a considerable portion of the Lambda Gen driver to deal with many poorly-coded issues that didn't rear their heads when hiking the happy path... but as soon as I started testing in parallel things got messy... also, the OEM driver doesn't use error checking, and boy are there signal integrity issues when you're casually switching 100+ amps on and off.

The area to the right (shaded in green):
-You can still see the daily temperature fluctuations, but note they aren't present in the latest two days because it's been raining a bunch (so it's not getting nearly as hot during the day). I suspect that these daily oscillations will come right back as soon as it heats up again.
-As I mentioned above, the FoMoCo cell is likely more influenced by temperature, due to the relatively lower charge/discharge rate (as a function of battery capacity).
-Assuming the initial test results are valid (cycles 1:110, see above), there is a small downward trendline, but it's too soon to tell.

Overall 47 Ah FoMoCo summary:
-Age will almost certainly kill these 47 Ah FoMoCo cells before cycle life does.
-I don't think the G1 Honda Insight's PDU or IMA motor can abuse these cells.

...

Overall, the above data should be taken with a grain of salt, given how much the test setup changed... but the areas in green certainly show a strong trendline towards "awesomeness". Battery advancements over the past 20 years are an unsung hero.

 

[Battery Buyer]

This image is supposed to be a side by side with the CMAX cells and EHW5 View attachment 98106

Both of those cells are Panasonic. CMAX and Insight cells.. The picture is from about 3 years ago when the seller didn't know what he was selling. A couple of us set him straight, though. He thought they were EH5. You don't know till ya know.

Also, EHW5 looks nothing like that.

 

[Battery Buyer]

Thanks for posting that graphic. From it, I've determined that the bolt-top cells we purchased last year are definitely EHW5 modules:

No idea yet whether the tab-welded Blue Sky packs are EH5 or EHW5.

I've handled so many of those silver cells, that I don't even have to watch the video and can identify it while laying on it's side lol... 100% not an EHW5. It's late, so hopefully tomorrow I will shed some light on a few misconceptions you guys have on these cells.

 

[cb88]

Since I have an Insight now... would say rebuilding it into a plug in hybrid sometime next year, and potentially converting it to a 2nd gen Prius all electric AC system be feasible with the FoMoCo pack, I assume you are going to reopen orders for the LiBCM board sometime next year? I would assume the electric AC would just tap directly off the battery pack and add a relatively mild additional load.

From what I am reading the Prius AC should work even better with a 60S pack also since it should be able to get to 6000rpm, whereas a 144v pack can only get to 4000rpm (still usable at this performance level).

Anyway going that route would eliminate the AC as an engine load (and it burns about 1-1.7kwh) so would work fine for my commute as a plug in hybrid with a largeish pack.

For the time being my NiMh pack seems to be working ok... got 70mpg on the way to work, it was background charging yesterday and I only got 56 pretty sure I wasn't lean burning properly either which I am pretty sure I am now though I don't have any instrumentation to indicate that at the moment.

 

[mudder]

I've handled so many of those silver cells, that I don't even have to watch the video and can identify it while laying on it's side lol... 100% not an EHW5. It's late, so hopefully tomorrow I will shed some light on a few misconceptions you guys have on these cells.

Looking forward to reading any clarification you can provide.

 

[mudder]

Since I have an Insight now... would say rebuilding it into a plug in hybrid sometime next year, and potentially converting it to a 2nd gen Prius all electric AC system be feasible with the FoMoCo pack,

Yes, but it's a custom project. Based on your previous posts, you're probably well equipped to figure it out.

I assume you are going to reopen orders for the LiBCM board sometime next year?

I still have a few LiBCMs available right now. If you order today, it'll ship this week.
So far, one customer has purchased an LiBCM for use with FoMoCo modules... instead of sending finished current and BMS cables, I just send a 10' piece of wire and all the crimp-on connectors... you have to connect them yourself for now (since I haven't designed anything for FoMoCo yet). You also need to figure out how to secure the modules in place (again, because I haven't designed anything for FoMoCo yet).

I would assume the electric AC would just tap directly off the battery pack and add a relatively mild additional load.

Safe assumptions. You'd need a fuse, but otherwise that's the theory.

From what I am reading the Prius AC should work even better with a 60S pack also since it should be able to get to 6000rpm, whereas a 144v pack can only get to 4000rpm (still usable at this performance level).

I haven't looked into it.
If you're going the custom route and want to use 60S, it's only "a few lines of code" in the LiBCM firmware to handle 60S. I can't promise you anything short term, but if you want to start with 48S, maybe in a couple months we can figure out 60S together.

Anyway going that route would eliminate the AC as an engine load (and it burns about 1-1.7kwh) so would work fine for my commute as a plug in hybrid with a largeish pack.

If you place a 1.7 kW load on the IMA system, the MCM is going to counteract that load by constantly applying 1.7 kW of regen from the engine. If you don't want it to do that, then we'll need to figure out how to lie to the MCM (so it doesn't see this power draw). It won't be hard, but just an FYI.

For the time being my NiMh pack seems to be working ok... got 70mpg on the way to work, it was background charging yesterday and I only got 56 pretty sure I wasn't lean burning properly either which I am pretty sure I am now though I don't have any instrumentation to indicate that at the moment.

With a cheap scan gauge, you can tell when you're in lean burn when the A/F ratio suddenly jumps up above something like 18.

 

[Recovering_Gasaholic]

Shoot. I think he is right, it seems that Honda found a very similar sized cell from Panasonic that they used for the G3.

Are we going to have issues mixing EH5W 18S with Panasonic G3 12S modules?

Is it possible to convert a EHW5 18S to 12S? Maybe we could cut a bus bar? The battery management leads are crimped on to the welded bus bar connector. It looks like we can bend the tabs to take the module apart without cutting the BMS tabs.

 

[cb88]

If you place a 1.7 kW load on the IMA system, the MCM is going to counteract that load by constantly applying 1.7 kW of regen from the engine. If you don't want it to do that, then we'll need to figure out how to lie to the MCM (so it doesn't see this power draw). It won't be hard, but just an FYI.


With a cheap scan gauge, you can tell when you're in lean burn when the A/F ratio suddenly jumps up above something like 18.

I'm supprised the IMA system can detect that? Is that due to the load causing a voltage drop or what? I don't see how else if I was directly tapping off the battery. Anyway we can pick that up in a separate thread once I get to that point... I'll probably wait for the next batch since my IMA battery is doing OK at the moment and I'm going to focus on the mechanicals first.

Toyota prius's battery pack is about 201V apparently... in any case since driving it with a MOSFET you can modulate that at some value below the pack voltage since you have to generate 3 phase AC to drive the compressor anyway I'd just have to plan for whatever maximum pack voltage looks like the MOSFET he used is AWOL of course.

I have a cheapo wifi version of the ELM327 hooked up at the moment but haven't programmed torque with all the things I wanna look at and such yet.

 

[Recovering_Gasaholic]

I believe some of the Prius batteries used EH4 blue energy cells.

 

[cb88]

I believe some of the Prius batteries used EH4 blue energy cells.

Yeah its a NiMH prismatic pack apparently. The peak pack voltage is around 230-240V for the prius since its 28*6 cells * 1.41 etc... so a 60S lithium pack should be very similar to that.

 

[mudder]

Shoot. I think he is right, it seems that Honda found a very similar sized cell from Panasonic that they used for the G3.

Whatever we found, it's working just fine. I'd like to know what to call it, but I'm not certain @Battery Buyer is going to stick around to dispense his industry knowledge.

Are we going to have issues mixing EH5W 18S with Panasonic G3 12S modules?

From a safety standpoint, there's no issue... if the tabbed modules end up having less capacity or a different discharge curve, then worst case LiBCM is going to be angry at you, but it'll still be safe.

Is it possible to convert a EHW5 18S to 12S?

Only if it's bolted together.

Maybe we could cut a bus bar? The battery management leads are crimped on to the welded bus bar connector. It looks like we can bend the tabs to take the module apart without cutting the BMS tabs.

I've tried messing with bus bars before... it's way beyond the scope of anything I'm willing to support. I'm not interested, but if the community wants to figure it out and make a new thread for it, then have at it.

 

[mudder]

I'm supprised the IMA system can detect that? Is that due to the load causing a voltage drop or what? I don't see how else if I was directly tapping off the battery. Anyway we can pick that up in a separate thread once I get to that point... I'll probably wait for the next batch since my IMA battery is doing OK at the moment and I'm going to focus on the mechanicals first.

The MCM has indirect access to the battery current sensor (the 'BCS', which is measured by the BCM). The problem with bypassing the BCS is that then LiBCM won't be able to tell you the actual state of charge (because it won't see the bypassed current). Yeah, start a new thread and we can continue discussions there. There is a solution, I just don't want to think about it right now.

Toyota prius's battery pack is about 201V apparently... in any case since driving it with a MOSFET you can modulate that at some value below the pack voltage since you have to generate 3 phase AC to drive the compressor anyway I'd just have to plan for whatever maximum pack voltage looks like the MOSFET he used is AWOL of course.

To drive the compressor, I recommend just using an off-the-shelf, open-source VESC controller.

 

[cb88]

To drive the compressor, I recommend just using an off-the-shelf, open-source VESC controller.

Yeah I could probably take 150KW VESC | VESC Project and use smaller IGBTs since I don't need to push 100kw etc... lol

I guess this will all be a moot point anyway once you redesign the MCM.

VESC seems like overkill but I am also all for reducing the work I need to get to something usable.

 

[Recovering_Gasaholic]

From a safety standpoint, there's no issue... if the tabbed modules end up having less capacity or a different discharge curve, then worst case LiBCM is going to be angry at you, but it'll still be safe.

Ok I'll fire it up tomorrow and report back if there are any issues.

 

[mudder]

Yeah I could probably take 150KW VESC | VESC Project and use smaller IGBTs since I don't need to push 100kw etc... lol

Ha, that would work. There are cheaper off-the-shelf 300 volt VEST controllers that are pushing 50 amps or more.

I guess this will all be a moot point anyway once you redesign the MCM.

Sure, but VESC will be cheaper than LiMCM, plus VESC is shipping now.

VESC seems like overkill but I am also all for reducing the work I need to get to something usable.

VESC is amazing... it'll eventually penetrate the open source brushless motor market just like grbl already has for CNC motion control.

 

[Battery Buyer]

Shoot. I think he is right, it seems that Honda found a very similar sized cell from Panasonic that they used for the G3.

Oh, I'm right as rain! The Panasonic G3 Insight modules are, like your picture denotes, Lithium Manganese Oxide. Think of it as a newer Ford CMAX cell. Same company, same size, same exterior (with different color wrap), same capacity, same same... blah blah blah

EHW5 cells are Lithium Nickel Cobalt Manganese Oxide, or Li(NiCoMn)O2. The older EH5 was, as well, but they adjusted the mixture to get better Energy Density and Power Density and reduce the IR some. Thus allowing the cell to be 17% lighter and 7% smaller than its predecessor.

Different company, different manufacturer, different chemistry, different lifespan, different energy, different power, different charge/discharge profiles. They're just different.

I know the words of some random, internet stranger challenging what you know to be right, comes off as apprehensive, but I have no reason to waste my time lying to anyone on the internet. I'm also low on free time right now, so this brief comparison is the best I can do. For now.

Also, the EHW5/EHW5B series cells are the only ones with the crazy lifespan. Those are the cells you want, for longevity sake. Not the Panasonic Insight cells, as @mudder is quickly noticing in his testing when he says "capacity decreases ~5% after ~QTY600 cycles". That's HORRIBLE compared to the EHW5 cells.

EHW5 come in 18s welded packs
EHW5B in 36S welded packs

This is all just off the top of my head.