Hello All,
I am no battery expert but have been messing around with sla and nicads for years. Built electric model airplanes in the mid 80's and learned the importance of cell matching. In fact just upgraded one of my scooters with 3 new 16 ah sla's. Charged each one up separately, then load tested them with an ordinary "toaster" type of automotive battery tester. Lucky I had a set of six to match with, all 6 did not put out identical current. I just use the tester's cca scale and write that number on each battery I test, then pair identical cells or batteries. Even then, once the matched cells are combined into a series pack some cells want to charge to a higher or lower voltage. While monitoring this I manually put a load tester on the cell with the high voltage until the voltage on all the cells is equalized. Usually after the first high current discharge, they will equalize (if they were matched properly). I am a firm believer in powercheqs and install them after a matched pack is built and tested. Why don't they make them any more?
All this sets the stage for my question to you all. How would you break in the batteries on your new Vectrix? We all know what kills cells quick, cell reversal during discharge or charge. My Gosh, the Vectrix has 102 cells and the internal BMS does not monitor them all! If it did not void the warranty I would do what Mr. Mik did, monitor all the cells and manually intervene on any imbalance. I really wish someone made powercheqs for nimh cells!
I am VERY concerned you have one chance to break the battery in right, the first time. We all know that cell reversal can happen during discharge or charge. I have had good luck equalizing sla batteries and think "overcharging" them in the beginning to get all of the cells to equalize extends the life as the cells will not reverse on discharge. Feel free to interject anytime a statement I make seems wrong, I am only speaking from personal experience with my batteries.
Now nimh is a different battery, and I have no experience with them (except for D size 10 ah). As we all know these cells draw more current when fully charged and equalizing them can hurt them. If they are not equalized properly, they will be harmed by cell reversal during discharge. Talk about a catch 22! How are we suppose to break in a 102 cell pack that we have no access to individual cells to check their health?
Of course the manual says to perform deep discharges, but suppose the cells were not equalized when charged the first time? Cell reversal will kill the pack early on. I do not agree with the Vectrix manual on this point. I do not want to destroy my batteries at the start of their life. With sla I always broke them in slowly, never discharging them right away. Gradually worked my way up to higher discharge currents and deeper discharges. Performing the deep discharges right off on a brand new 102 cell pack scares the hell out of me! But you folks know more then I about nimh cells. I know cell temperature comes into play here as well.
So, how would you folks break in YOUR 102 cell Vectrix nimh pack to have it enjoy a long and healthy life, without doing anything to void the warranty? I am SO concerned about this that I am considering taking the pack out of the bike spreading it out (so all cell voltages can be measured) and charging it and discharging it out of the bike. I can discharge the pack with a standard 120 volt electric heater (the kind that has the nichrome flat heater elements, it could care less it is on dc rather then ac). While monitoring the cells charge or discharge, I could shunt the high voltage cells with a large ceramic resistor, or just charge individual low cells by themselves.
But we know doing this would void the warranty, so I guess I am dreaming. However, if Vectrix goes belly up, I would never get a replacement battery pack for the one that could have been properly broken in, in the first place. What good is a 2 year warranty on the batteries if Vectrix does not exist in the future?
I need some guidance here, what would you experts do?
Take Care,
Louie
I also do RC flying.
I began breaking-in with very light loads, with speeds no more than 70km/h on the first 5 charges (like RC, when breaking in LiPo packs).
I had the misfortune, that one of the two battery cooling fans wasn't working and I wasn't aware of the fact, that there are two. So, one of my battery packs were overheating at full charge and cooking it good. It also created a capacity imbalance between the packs, of which full effect I'm currently experiencing by a complete battery failure.
My suggestion would be to try to fully discharge the battery as rarely as possible. Cut-off voltage has been raised (by the software update) from 108V to 125V (so they say), which further prevents overdischarge and cell reversal.
Keep that as close to 25'C as possible and run the pre-charging period for cooling down.
Hopefully, I'll be getting a new battery at the end of June, when I'll drive my Vectrix for repair. Until then, I'm very sad to see my Vectrix stand in the garage.
I wasn't going to respond, because you asked what the "experts" were doing, so that disqualifies my answer completely, but I'll repost here what I posted to Victrix under his "glitch" post earlier. Not so much as a "break in" for the battery, but as a "get to know the bike better" break in for you and the bike's controllers.
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If the bike has been sitting for a while (like when they sit at a dealer for weeks), it's battery gauge is going to drop rapidly for the first ride, and your range will be greatly reduced. It's nothing to freak out about. Electric vehicles can't just fire up and run flat out, full range the same everytime like gas engines can. EVs will lose efficiency with long periods of non-use. No big deal, just ease your range back up anytime the bike is left for a week or more without use.
The battery gauge will regain its accuracy after a couple of charge cycles, and an occasional deep discharge.
As for the estimated range indicator, put a piece of tape over that display so you can't see it. It's not a range indicator, it's a ride efficiency indicator, based on your use of power over the last half mile or so, and it cannot even guess at what lies ahead of you on your journey. It's a stupid gauge that would have been much better off being a voltage display or battery temp display. Forget your bike even has it on there.
Your bike is doing just fine. You just haven't bonded with it yet. As you gain understanding and "oneness" with the system, you'll be hooked just like the rest of us, but in the mean time, start off with short distances and work your way up. This will not only condition the batteries better, but you will gain confidence in the bike and it's abilities, and the two of you will understand each other much better.
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As for what's best for the longevity of a 102 cell NiMh battery pack (sorry if I got the letters wrong), nobody's had a Vectrix long enough to really know the answer to that.
I will say this though, based on my own personal experience in purchasing new vehicles for most of my adult life...if I get two to three years of decent use out of my Vectrix, it will have lost no more value than the average depreciation on a new ICE car or truck, so if the bike does cold turkey on me after that, it hasn't cost me any more than any other vehicle would have if it were still running. My wife's 2005 Limited edition Mazda "Shinka" RX-8 looks and drives like we just bought it, but it has lost $5000 in resale value for each of it's four years. That car has already totally blown twice the price of my Vectrix. If my Vectrix SHOULD happen to last, and function for ten years, it will have paid me BACK it's cost in fuel, tire and insurance savings. I've never owned a vehicle that even THOUGHT about paying me BACK!
I am hopelessly hooked on my Vectrix!!! If the company goes, and my bike goes, I'm hoping like heck that some of these other EV Entreprenuers have their acts together by then!
Hi and welcome!
The problem with giving advice regarding this is that I do not know what software version is running in your future Vectrix and how it behaves. It would be nice if someone could give a detailed description of the "Equalization charge" it now does, for example. A lot of the advice by Vectrix Tech is aimed at triggering the software to do certain things.
I am not monitoring all the cells individually, just 18 of them. The rest is monitored in lots of 8 or 9 cells.
That is the "negative delta-V" effect, it only causes trouble when Ni cells are connected in parallel.
Talking about NiMH (and NiCad) in general:
Equalizing a Ni series is done by slow overcharging. The charge current needs to stay below a threshold so that the excess gases created inside the battery can be recombined by catalysts present in the battery. There is a limit to how much can be recombined. The recombination process produces heat. The heat needs to be removed from the pack. If more gas is produced than can be recombined, then the pressure rises and the gases are vented through the safety valve, causing irrecoverable loss of capacity. The more is vented, the more capacity is lost.
The equalization charge gets done until all cells have reached a full state and produce heat. The usual advice is to charge at C/10 for 15 hrs if the Ni series is empty to start with. Some sources recommend C/15.
For Vectrix cells of 30Ah capacity this means charging with 3A (=C/10) or 2A (=C/15).
At that rate any full cells should be able to recombine all the gases and heat up only moderately, whilst the not-yet-full cells are catching up.
If you don't do this occasionally, then the cells with slightly higher self discharge rate will gradually fall behind, until they end up getting "charged in reverse" when they are empty before the rest of the pack. The pack will not live long that way.
If you do an equalization (over-)charge every time, your pack will not live long, either.
This is totally impractical. The risk of breaking something in the process outweighs any potential gain. You cannot get to the individual cells to measure them until you have taken it all apart, and then you cannot charge or discharge them in series because they are apart!
If you wanted to open the battery cover you could use a 70V power supply to charge the front battery with 2 or 3A until all cells are full, but they will get hot because the cooling impellers are in the cover which you need to remove to do this. The two parts of the rear battery can be charged with a 40V power supply.
You would need to remove the cover, connect you power supply, close the cover and connect a 12V DC (5A) power source to the cooling impellers to keep things cool during the equalization charge.
As I said before, I don't know how this new software behaves. The other unknown is how the pack was treated before you get it.
Ideally the dealer would program the bike to do a full equalization charge with cooling impellers running and do this just before delivery of the scooter to you.
Some general advice for the break-in:
- stay uphill of your charging point. You cannot push the thing uphill.
- avoid any hard acceleration or hill climbing; low cells can still provide a few amps, but get charged in reverse when you "open the throttle".
- don't get run over!
This information may be used entirely at your own risk.
There is always a way if there is no other way!