Battery Charge Management System (BCMS)

[nickb2]

bmw almost limits, dont want info, up here we have one for disect. But now with this common cold natural selection deal. We have to go back to basics.

I wish beaver camp still existed.

Hello kids, bomb are commotion, come over here and hide under said desk. Trump is a joke, media is fire, and I am last resort when shyte hits the fan. It is my job. For now, shut up, and finance what u have, low time hole to make a $$

 

[NickD]

Think how cheap that could need these things if they had an AC induction motor and a trolley. No need for a transmission, just reverse one of the phases for reverse. Has both huge torque and high speed running, reason why train locomotives are electrically driven, but do carry their own electrical generation. Trolleys were popular well before the introduction of the internal combustion engine.

Vehicle will just need a small battery to get you off the road into your driveway.

Another popular idea in the early 20th Century was the overhead monorail. No need for tires and thousands of miles of road that need snow clearing and constant maintenance, simple shroud over the rail will keep it dry. The land underneath could be farmed. Speed limits? None, bodies very light on these car, speeds in excess of 400 mph.

What do we have instead? A rubber tire on ice, not a good idea.

 

[nickb2]

Well, sadly, I can only say today we got our diploma of presence for completing the first half of course, we got interupted by virus. Needed only one class to get it done, today, it got done.

But cant say when school will be back in session for good yet, teach was saying I dont know. Maybe sept, maybe oct. Anyway, half done, nothing new to say.

 

[nickb2]

Today was just finishing up what we forgot . So was monitoring proximty and pilot circuit, trouble shooting them and finding ways to interpret when with a scope was useless. We even saw how to modify a tesla charging connector for j protocal with just a few resistors to charge any bolt new gen volt, soul, bmw etc list goes on. .

Tesla sure is fun, but they suck in being compliant to industry standars, but hey, we will always find a way.

 

[NickD]

A Ford engineer finally came out and said hybrid vehicles up north are worthless. Trying to convert kinetic engine going down a hill to charge a battery going up the next hill is very inefficient at low temperatures. Could get rid of the hills.

Have energy saving nuts around here that do not drive hybrids like hybrids, but do brag they have a hybrid vehicle. Way before a stop sign, have to take your foot off the gas to get some battery charge. Doesn't work if you fly up to a stop sign and slam on the brakes, then slam on the gas pedal to take off again.

Next issue, any amount large storage of energy in any form is dangerous, latest is that huge lithium battery under your seats in a Tesla. Side impact, will short out the battery and will be just a tad short of a dynamite explosion, but you will be in a slower state being roasted alive.

Another factor for the government easy to put gas tax on a gallon of gas, but how about electricity. Add a huge electrical tax to everybody?

 

[nickb2]

 

[nickb2]

Professor nickd is in the house.

 

[nickb2]

btw, happy fathers day to all who fathered a child, or adopted etc.

 

[nickb2]

Well, dont have much to do today, my gf is on a 4 day loan to another care facility, so I am typing this again from her house, I had to come feed and take care of cat things.

In regards to battery management, I must correct Billr, some units do monitor each and every cell, but most do it in blocks. Again here, you will all have to bear with my poor translations. There are three different types of battery management units.

One which is not widely used is a unique master and in series monitoring using a voltage differential and is not very precise, hence not widely used.

Second one, more common, using slaves on cell blocks, reducing wiring in the entire HV battery.

Third one, which is my prefered one when diagnosing, is as billr wrote, a bms that actually monitors each and every cell.

The trend seems to be going for blocks sections rather than monitoring each and every cell, and I understand why they are doing that. It is probably for cost and also for easier block replacement.

Next year session (actually this year) who knows when, we will delve further into that. As of now, we have only taken out the battery with nasa suits on, and dissasembly but not have actually worked on the blocks themselves. That will come in second half of ev course when schooling resumes, if.

 

[nickb2]

Of note, again, I must say bmw is the worst I have encountered in the scanner array. It is all over the place, way to many hidden functions, almost looking like tesla.

The most user freindly units I see are the volt and bolts.

In courses we looked at the bmw I3 (not the REX one) and found very limited data, but I did surprise the teacher by finding and option in the autel 9 series they have, much like my own. I found we could see the past five days of SOC (state of charge) which I find usefull as a tool to see how the CLIENT is using the car in regards to complaint on work order. None of the others have that option. At least none that I have seen yet.

The teacher was very interested in that, and stated he may include this in the revised edition of the next rendition of the course text books. The one we are using is a oct 2019 and he said it may not be updated for lack of funds with this covid thing.

I must say, I feel rather enthralled in being part of this at my age. It was fun to go back and see some of the guys at school. We were down to 6 guys. Wish we would see more women in this trade, but sadly, they dont tend to go for this type of stuff.

I also liked seeing Raffick and Pablo, they are funny to be with. And they stuck with it. Kudos to them for learning not only a newish system, but also for learning english and french at same time. A very big feat in my opinion and I salute them for that. Those are fictisous names, but raffick is a very smart guy, sometimes to the point of being annoying. But damn does that guy have a winner attitude.

 

[nickb2]

Here is an interesting read for my lack of poor translation. In this article, we see daisy chain. Which seems to be the trend. https://www.st.com/en/applications/electro-mobility/automotive-battery-management-system-bms.html

 

[nickb2]

The goal here I think is to reduce the amount of wiring and at same time giving the tech the ability to monitor the depletion on a particular cell block and giving us the ability to balance the units.

I am so very sorry I have not updated this thread more, and yes this is a disclaimer of sorts, we just got sideswiped by this pandemic thing, As alot of ppl here also.

So maybe after summer, I may have more interesting stuff to write. But most of what I write here is all on google is your friend. And yes, I like the yellow tank top.

 

[Jeffrey132]

In that other thread, nickb2 noted that there are a couple of "common" problems that relate to the BCMS:

1) Most (all?) EVs, both BEV and hybrid, have two "batteries"; a high-voltage (HV) one for main driving power and a low-voltage (LV) one for controls/accessories. Leaving the car connected to the day-to-day HV charger does not keep the LV battery charged. If the car is left for a long time, the LV battery will run down enough that the car will be inop, even if on the HV charger all that time.
I wonder how long it really takes for the LV battery to go too low, even in the frigid zones? In my area a LV battery will last a few months with the "keep alive" loads of a modern car. That is way longer than would be problem for most folks that can't afford to have a car as just an idle toy, I feel. I also wonder why they even bother with two batteries??? Yes, it is a good idea to keep most of the car wiring at the safer LV, but that could be done easily with a DC-to-DC inverter to get the LV off the HV battery.

2) There is an increasing mix of battery types for the LV. There are "flooded", "AGM", "VRSLAB" and gel in the lead-acid family; and maybe some lithium or nickle variants as well. Sticking with just the LA, charging can be different, so just advising to keep the LV battery on a charger can also cause problems.
I disagree that using a standard charger on AGM is a "huge no-no"; some AGMs are designed to handle higher (flooded) charging voltages OK. However, I do agree that it all depends on the battery design and the charger design; you gotta be sure they are compatible. This problem begs me to ask, why the not-so-recent trend for charging voltages up in the 14.5-15V range? That isn't even real good for a flooded battery. In the "olden days" a 12.6V battery charging system was usually in the 13.4-14V range. That is plenty enough to fully charge the 12.6V battery, and not enough for detrimental overcharge. Of course, if there were no separate LV battery, then this is all moot...

I purchased a 2017 Nissan Leaf last month and measured the voltage of the small lead acid 12 volt battery with the car on and it was 14.4 volts.

 

[Jeffrey132]

Do know with a lithium-ion cell phone battery, if the voltage drops below 3.7 volts that's the end of that battery. Requires a current cut off circuit so the voltage does not get any lower. If you leave a discharged lithium-ion battery lying around, like any other battery, its dead.

Wonder what will happen to your Tesla battery if the car is left in your garage for a couple of years without a maintenance charger, you could be out a couple of bucks.

Nickel cadmium batteries are entirely different, should be full discharged first before recharging. But they also have a high self discharge rate. If left in a power tool for a month or two, have to recharge them first.

Sulfuric acid batteries will freeze below freezing if not fully charged. If you take a lab type power supply set to exactly 13.5 V should fully charge the battery and show 0 amperes charging current. Had some that would only go down to 3 amperes, this means the battery has a high self discharge rate. But don't try to explain this to the party you purchased this piece of crap from, they are idiots.

Ask that question first before buying a battery, if they agree, they have a sale, self discharge is a very common problem, 60 AH battery will be stone dead in about 20 hours. See signs were frozen batteries are not covered under warranty, but darn things can leak internally just as well as externally, so stay far away from those places.

Anybody remember 15 bucks for a new battery, more like 200 bucks today.

Generally charging a battery looses about 30% of total energy, heat loss in the battery and the efficiency of the charger itself. Discharge runs about 10%, current is flowing inside of the battery that has internal resistance.

Not that really bad for a cell phone, but what about a car? Not sure about the Tesla, on the GM EV switching on the heat or AC will reduce your driving range in half.

For electric vehicles, coal in Nevada is still used for California EV's, power and heat losses in turbines to generator electricity, more in those super long high voltage towers, plus maintenance cost, more in the inefficiency of the chargers and the charging process itself, more in hauling the huge weight of these batteries, and more in converting chemical, to electrical to mechanical energy. And a lot more if you want to ride in comfort.

But the big deal is that the major pollution fall outside of the state of California.

One gallon of gas contains approximately 120,000 BTU's of heat. A kilowatt hour of electricity is 3412 BTU.
My EV has 30 KWH capacity = to 102,360 BTU and cost to charge is @$3.50 giving it a range of 100 miles+. 75% of the gallon of gas is wasted in the form of heat. Unless you have a car that gets 100 miles per gallon.
Also the heater cuts mileage from 100 to 90.