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Sorry I'm not getting involved FOC with the detail this time around.
All the info about the vpin and pre-resistors has been posted and explained in detail before.

Be aware faking the voltage down might mean you overcharge your pack or it could lead to other unexpected behaviour.
Personally I might use more assist or so the pack is not at such a high voltage, then it will regen naturally.
 

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retepsnikrep: I just don't see how changing the voltage with the vpin and pre-resistors would help him. Those things should only be adjusted so that the LTO battery works within the insights voltage constraints.

Lets assume minors 72 cell pack is reaching 180 volts maximum with the current vpin and pre-resistors. At 180 volts pack voltage it should turn off regen.


His issue is 100% too much charge and too little discharge. Messing with the VPIN & pre-resistors to try and increase his pack voltage above 180 volts would only make him overcharge the pack.

Minor has no way around it except to increase assist with the IMA Boost. Or what I do is turn off the coast regen. There is simply no way around his issue, he will always be overcharging the pack unless he changes his driving habits drastically to use more assist and less regen.
 

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I did basically say that.. But not as directly as you.

I'm not advocating he adds vpin resistors etc I suggested he adds the IMA boost.

I did say adding them might mean he overcharges his pack.
 

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One thing I wonder about is, why isn't everyone who did a lithium ion conversion complaining about this issue? I had the issue, it seems Minor has the same issue.

What about all the other people who did LTO conversions, they don't seem to be complaining about the regen issue.

It is possible that many of them are using a joystick to control the assist, but I doubt that.
 

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If you drive with a heavy right foot in high gear at low rpm you can use a lot of assist and not much petrol.
Change up early WOT at 1000/2000 rpm maxes out assist and brings the pack down.

Perhaps it's just down to driving style, terrain, local conditions, mods etc etc.
A morase of unquantifiable variables.

Some will have IMAC&C P&P/MIMA but not all.
Some may use clutch switches to disable assist/regen etc.
Some may not be bothered regen goes away at the top of the SOC so never mention it.

Don't forget there is a wide range of different firmware versions available for the main modules in the car. ECM, MCM & BCM.
Most of us will not have the same combinations of modules or firmware.
Differences in firmware programming could significantly change how they behave when confronted with Lithium.
 

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One thing I wonder about is, why isn't everyone who did a lithium ion conversion complaining about this issue? I had the issue, it seems Minor has the same issue.
I don't have that issue. I think it may be a combination of BCM/MCM type Originally I had an issue with the battery gradually discharging over time so that I had to charge ocassionally. After I added my 10K preresistors, the battery now stabilizes at 154-156V by the OCBII C&C gauge.
 
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I would think the issue is more how you drive then BCM/MCM related. I may have bad driving habits in that I constantly accelerate and then take my foot off the gas to slow down, than accelerate again to get back up to speed. I do not hold my gas pedal down at a constant speed. This caused my car to constantly coast regen charge.

On the highway, I had much less of an issue with an overcharged pack.


The simple solution is the IMA Boost, this will cause the car to use more assist through the RPM range. Optimally one would want to modify the IMA Boost to turn off coast regen and that will 100% solve this issue.
 

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I would think the issue is more how you drive then BCM/MCM related.
Just for grins, put your BCM/MCM data into this spreadsheet so we can start doing some comparisons:


Be sure to enter "LTO Conversion" in the comments section so we can keep on subject:)
 

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Discussion Starter #369
As I was driving from Detroit to Chicago last night I noticed my OBD2C&C BAM (IMA Battery Amps) value was +0011, i.e. charging at 11A while LTO voltage was 178 and SOC was 65. The dash regen gauge indicated zero. Can someone please explain this?
 

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No one is going to figure that out remotely with the information available. retepsnikrep reflected on the differences in perfarmance back in #365. That is probably as close to an explanation as you get. One solution would be a clutch switch which could disable all regen on long trips.

As I recall, you have have an IMA P&P. You could set that for a low constant level of assist, which would burn off some charge, You might only need 10A or so.

Please put your BCM/MCM information in the spread sheet as noted in #368 above. If we get enough data, we might make sense of folks differing performance:)

Later: Maybe you have a fixed level of regen programmed in your IMA P&P???????
 

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Discussion Starter #371
@jime, I've already added the info to the spreadsheet. I don't have an IMA P&P. I'll have to look that one up. I do have the Current hack. I don't think that's the same??

Is it normal to have 10A background charge with no dash gauge indication?
 

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How long was that 10 amp background charge going on for?

I wonder if your pre-resistors are not set up correctly and your car thinks the pack voltage is too low.

The other thing it could be is are you using the upgraded Interceptor software that has qbatt? Peter has been messing with the software to try and charge your pack at certain levels. Who knows what it could be doing if you are using that modified software as its not been perfected and it also requires your pre-resistors to be setup correctly.

You would have to give us this information.
 

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Discussion Starter #373
it charged at 11A for a several minutes then went down slowly, then I think went up. I only monitored it for a short period of time. It may have been to that level before or after but I would have to look at the OBD2C&C since there was no dash indication.:(
I am not using any pre-resistors or the Vpin resistor and I'm not using any Qbat, that I know of. Actually I was thinking of the Qbat thingy in Mode 2 so I wouldn't get any background charging. I think that would go a long way to improving my situation.
 

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This could be almost anything.

Yes errors in code are possible but the devices are pretty well field and age tested.

If you have a BCM Interceptor you can use switches on the ALF/RLF flag lines to turn assist/regen off at will.

Yes you probably could use a QBATT device to turn off regen.

There are lots of possible solutions/ways to control the systems
 

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The other thing it could be is are you using the upgraded Interceptor software that has qbatt? Peter has been messing with the software to try and charge your pack at certain levels. Who knows what it could be doing if you are using that modified software as its not been perfected and it also requires your pre-resistors to be setup correctly.
This might be a real possibility. I do not have this problem of overcharging and I am running a very old version on the BCMI - year and half old approx. I do run the two 10K pre-resistors. My BCMI seems different from both minor and insightbuyer.
 
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As I was driving from Detroit to Chicago last night I noticed my OBD2C&C BAM value was +0011, i.e. charging at 11A while LTO voltage was 178 and SOC was 65. The dash regen gauge indicated zero. Can someone please explain this?... Is it normal to have 10A background charge with no dash gauge indication?
Haven't been following this thread, not privy to the LTO mod specifics, etc. But, in general it's perfectly normal to have a 'background charge' at a nominal 65%, driving at night with headlights ON, no indication of charge on dash CHRG gauge. The only thing abnormal here is that your pack voltage is at 178V, but I presume you have some sort of fooler, so the BCM doesn't see that true voltage. If it did it would have 'pos recal-ed' already...

[edit] One more thing that's maybe slightly abnormal: 11 amps is quite higher than I'd normally see. If I were just cruising it'd be around 6-7 amps at that nominal charge state. I'd guess your fooler or whatever other mods are spoofing values that result in a higher-than-normal current rate... I'd see higher currents if the charge state were lower, and I think that's 'actual' charge state rather than just the nominal, such as a reading based on Qbatt, or maybe voltage, etc.
 

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If he has the current hack that may increase it to 11. I know my background charge is around 10 amps using an amp meter, but that is when I have a few green bars and using Qbatt to force a background charge. I didn't know that you could get a 10 amp background charge and it not show up as green bars.

This is why I keep my setup simple, BCM Interceptor with the software that sets everything for maximum power. Then I use a simple single cell volt gauge to know exactly my battery pack voltage.

Using an 84 cell setup, I set the fooler pre-resistors and Vpin, so that my battery cuts off around 2.00 volts per cell. Luckily, since I can't set both my low voltage and high voltage cutoffs, my regen gets cutoff around 2.5 volts per cell, and that alerts me before my battery gets overcharged.

If I needed to charge up my battery, I will just use Qbatt and get a background charge going when I need it.

This setup gives me everything I need, and is quite simple and is also less likely to suffer any software glitches as its based mostly on the cars battery management system. Using a single LTO cell as battery voltage will also give you the easiest and most precise way to monitor your pack voltage.
 

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^ Single cell voltage display seems like a good idea... Or maybe two cells, one from each half...

...I didn't know that you could get a 10 amp background charge and it not show up as green bars.
Not sure what the trigger is for whether you see the bars or not, I think it's probably commanded power, like the 'Ikw' parameter. If you have 'hacks' or what-not, a fixed power level will be commanded, but then your hacks manipulate current or voltage - current hack boosting current by 40%, for instance, or fooler spoofing lower voltages. So the current ends up more, but the commanded power is still the same - hence, no bars.

If I downshift and take engine speed higher, I'll see the bars - because commanded power ends up being higher. Current is higher, too, but I think it's the commanded power that triggers the bars...
 

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eq1, I think the single cell voltage is honestly the best way to monitor your pack voltage. Not too many people seem to think so, especially in the ebike community, I've argued with some of the guys who design the ebike controllers to offer an option to display a single cell voltage, but they never go for it.

What I like about it is all your cells should be in balance, so you really want the easiest way to know whats going on at the cell level.

It is much easier to think of your battery pack in terms of a single cell, and you should be really familiar with exactly how capacity is related to voltage. With LTO you know that 2.00 volts your pack is pretty much empty and you need to be cautions, at 2.5 volts your pack is very full and you have to be very cautious. You normally want to keep your pack around 2.3 volts for optimal longevity.

Thinking in terms of a single cell voltage allows your brain to more easily determine the cell voltage and the capacity, instead of converting from a pack voltage to a cell voltage.

It also allows you to switch between packs of the same chemistry and more safely know your pack capacity, switch from a 72 to 84 pack, you know exactly your pack voltage with the single cell voltage,.

You want to discuss your battery pack with other people, using cell voltage makes it much more easily understood instead of saying 170 volts.

Another big benefit is that you can easily run a very cheap and precise volt gauge to the front of the car safely, something you don't want to do with a 170 volt line run to the front of the car. This x.xxxx volt gauge really gives you precise feedback what is happening with your pack, is it charging , discharging etc.

single cell voltage is honestly so much better, but I'm yet to really meet anyone else who sees the advantages of it. Most people like to see the full pack voltage, which to me is not advantageous. I guess this is because they are used to the full pack voltage, which will work well, but takes more brain processing power to really know what is going on at the cell level.

I have two volt gauges run to the front now, one is actually for my 12 volt LTO battery and the other is for my pack voltage. I didn't do the single cell for my 12 volt pack because this voltage is always constant at 14.2 volts, and I didn't want to confuse myself having two single cell gauges next to each other.


 

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^ Preaching to the choir here - I totally understand. Look at cell voltage and it's instant, actionable feedback, look at other voltages and it's like, 'um, let me make that conversion, OK, that should be x.xx voltage at cell level, which would be xx.x voltage at tap', etc etc. I'm doing this all the time with the stock pack total voltage and OBDIIC&C... It was really tough when I first had to make a conversion from a total voltage value that was off by like 3 volts -- like 3 to 4 conversions, in my head, while driving. Not good, not too fun.
 
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