SHENZHEN FACTORY TECHNOLOGY battery packs- is it real?

[jayyzz]

Call me suspicious, but you've joined the forum today to comment on this specific thread and to agree with the supplier in China that its not a problem with a battery... Tell me why I'm a cynical old git

Dude, you are too cynical. I had been following these Chinese guys for a long time. I dig into this and hope can get my 30kWh sawpped one day. You know this post is always on top, right???

 

[Ianlighting]

Dude, you are too cynical. I had been following these Chinese guys for a long time. I dig into this and hope can get my 30kWh sawpped one day. You know this post is always on top, right???

Dude, you know the date you joined is literally underneath your name, right???

 

[noelho]

Dude, you are too cynical. I had been following these Chinese guys for a long time. I dig into this and hope can get my 30kWh sawpped one day. You know this post is always on top, right???

We have to be skeptical and cynical because this isn't some cheap replacement.

I don't mind taking a risk on overseas purchases if it is a few hundred, but this would be over NZD10K for me!!! You better believe I'm going to do my best to verify regardless if the manufacturer is in China, Europe or the US!!!

 

[cornbinder89]

Dude, you know the date you joined is literally underneath your name, right???

True, but you can read the forum and not be a posting member. Not that I am not skeptical either.
Long and short: you need to trust who you are buying from when purchasing long distance. I am not comfortable sending that much of my limited funds to something that isn't well proven or doesn't have a local representative that can be held accountable.
It takes those that are less risk adverse to get us some answers. I am not that person.

 

[kmcmahan]

Hello, this is a link to the video that I did on my Chinese Battery.

 

[MikeinPA]

Hello, this is a link to the video that I did on my Chinese Battery.

Thanks! For discharge, I use ohmite 300 watt resistors off Ebay arranged in banks. They sell a mounting clip for these. There are also plenty of DIN rail 600 VDC breakers made by CBI available--surplus out of telecom hardware.

Are you planning on charging the entire pack, or just one of the modules? I never managed to find a proper power supply I could afford, and had vision of making up longer cables in order to connect the loose pack up to a nearby Leaf.

Also, I get that your are experienced around these voltages, but , ah gloves? I bought the correct gloves for the cell replacement I had to do, and used those to break the pack down somewhat, then switched over to two layers of good nitrile gloves with a thin cotton work glove over that. The latter arrangement was quite comfortable and I felt safe with those.

Again thanks! Keep us posted. The intro was dead on--many Leaf owners are stuck with a need to repair, while defacto we do not have the right to repair.

 

[kmcmahan]

Thanks! For discharge, I use ohmite 300 watt resistors off Ebay arranged in banks. They sell a mounting clip for these. There are also plenty of DIN rail 600 VDC breakers made by CBI available--surplus out of telecom hardware.

Are you planning on charging the entire pack, or just one of the modules? I never managed to find a proper power supply I could afford, and had vision of making up longer cables in order to connect the loose pack up to a nearby Leaf.

Also, I get that your are experienced around these voltages, but , ah gloves? I bought the correct gloves for the cell replacement I had to do, and used those to break the pack down somewhat, then switched over to two layers of good nitrile gloves with a thin cotton work glove over that. The latter arrangement was quite comfortable and I felt safe with those.

Again thanks! Keep us posted. The intro was dead on--many Leaf owners are stuck with a need to repair, while defacto we do not have the right to repair.

Thanks Mike. I will just be working on one module and one cell at a time. I will need .4 ohms art greater than 40 watts for resistance to discharge a cell at 10 amps. I will need an adjustable power supply that will do 10 amps at around 4 volts. I will start looking for that stuff now. I will just be looking at the one module and will make sure that it is in balance with the rest of the pack when I am finished.

I am pretty comfortable around the battery and I understand the hazards. I wish I would have thought of that before I made the video. If you get into the wrong place, you can find 400+ volts. The other hazard is the amount of power available if you short something out. Even dropping a metal tool on top of one module could create a disaster. I do wear gloves when I think they are needed. I broke down a leaf battery and wore insulated gloves until I got all the cables and bus work off. That gets the voltage level to a low and safe level. For anyone reading this that is not comfortable inside the battery, do not do what I do, wear protective gloves!!!

I will get back at it and get this thing working

 

[Ianlighting]

Hello, this is a link to the video that I did on my Chinese Battery.

Thank you for taking the time to do this. If you get it back in the car and you have time to show or explain the problem that would be good.

 

[cornbinder89]

It is human nature, the more familiar we are with something the less we pay attention to the safety edicts. If we have done something 500 times without incident it is human nature to think we will be fine and not pay attention to the danger.
It kills pilots, it is the fear of all aircraft mechanics, and surgeons.
In theory it is possible to disassemble a 400 volt battery pack with no insulated tools and no PPE. Those are not used because they are required to do the job, they are used to minimize risk from a mistake.
Once you pull the service disconnect, the battery is cut roughly in 1/2 and the metal case is always neutral to the battery voltage inside... unless there is a leak!
400 VDC is a whole different animal to 240 VAC that is the high limit of what most are familiar with.
I know enough to know that if I ever decide I am going in a pack, I am going to kit up, not because I don't think I could disassemble into low enough voltage sections to be safe without the PPE, but because I recognize the danger both from the potential in the battery and the potential for "un-planned" events.

 

[MikeinPA]

Even 50 VDC is dangerous.

Heavy duty heat shrink tubing with adhesive liner is great for insulating hand tools. I kind of like the way they look too.

 

[cornbinder89]

Even 50 VDC is dangerous.

Heavy duty heat shrink tubing with adhesive liner is great for insulating hand tools. I kind of like the way they look too.

Back in the 80's there was talk in the automotive industry that we would switch to 48 or higher voltage (No, Elon didn't come up with it, it pre dates him). Operating voltage of a "48 volt system is 56 volts, more then enough to enter the body.

Once a hard look into what it would take, we still have 12 volt as the standard in North America. Heavy vehicles in the rest of the world, and motor coaches in North America, use 24 volt system. Some older Marine systems were 32 (four eight volt) or 36 (3 twelve volts). Turns out higher voltage comes with a lot of problems, along with some benefits, so far the benefits haven't out weighed the problems.

 

[OntarioSV2018]

Back in the 80's there was talk in the automotive industry that we would switch to 48 or higher voltage (No, Elon didn't come up with it, it pre dates him). Operating voltage of a "48 volt system is 56 volts, more then enough to enter the body.

Once a hard look into what it would take, we still have 12 volt as the standard in North America. Heavy vehicles in the rest of the world, and motor coaches in North America, use 24 volt system. Some older Marine systems were 32 (four eight volt) or 36 (3 twelve volts). Turns out higher voltage comes with a lot of problems, along with some benefits, so far the benefits haven't out weighed the problems.

48V DC (40-60VDC) is not significantly more dangerous to people than 12V or 24V. I regularly work with all three voltages and use the same precautions. Above 60V, DC starts to become potentially dangerous, but over ~100VDC becomes actually dangerous.

The biggest drawback of 48V is the higher wear on relays and switches, which causes reliability problems and increased component costs.

The reason 48V vehicle systems are feasible now is because of all solid-state vehicle architecture.

Solid-state semiconductor switches dont wear out the same way relays do. They can tolerate switching much higher voltages with minimal differences in cost.

Smaller wires provide the cost savings from higher voltage and lower current. Higher voltages don't make sense if you have to upgrade all your relays to survive 48V, but they do make sense if you are already going to use solid-state switching; you can save money on wiring.

There is something to be said about reliability vs repairability on these solid-state vehicle systems. I am all for the change if reliability increases to the point where the electronics almost always outlast the car but if the system is designed poorly. If the solid-state stuff fails, it will be expensive and time-consuming to repair.

 

[cornbinder89]

We were taught, and until I see otherwise in writing, that over 50 VDC can overcome skin resistance. Is 50 volts dangerous? not really but as the voltage increases so does the danger.
Almost impossible to strike and maintain an arc with a 12 volt battery, 24 volts is easy and 48 anyone can. That right there is the primary reason for why when possible, to keep the voltage down.
I worked on 48 volt DC equipment, I wouldn't call it dangerous, but at the same time, takes a little more precaution to work around.
Mechanical air gap in contactors and switches have to be greater, yes solid state switching eliminate some of it but not all.
12 volt is used, because 1) it has been since the 50's so why change. and 2) you can grab ahold of two bare conductors and not suffer any ill effects.
Most electrical loads in vehicles are low current, so low voltage is fine. Only the traction and A/C compressor motors draw significant power, so are operated from their own battery pack at higher voltage.

 

[OntarioSV2018]

In UL 3010, 60V is the safe limit for dry conditions and 30V for wet.

48V battery systems can potentially charge up to 60V, which is common in consumer-grade backup and off-grid power systems.

In the off-road heavy equipment industry, where I work, 48V is a thing but is generally not used because it requires special, expensive switching components.

The 50V threshold from OSHA is an older arbitrary limit, which is just a nice round cut-off, but it limits the use of 48V that could peak upwards of 60V.

It's all arbitrary. The actual safety threshold depends on many factors. Arcing, as you mentioned, is a big reason why 48V is harder to work with and why it's so damaging to relays.

However, if you take proper precautions, 48V does not pose a significantly greater safety risk than 24V, which is very common for trucks and industrial equipment.

The don't change what works philosophy in the automotive industry has definitely contributed to the longevity of 12V. Still, the increased cost of mechanical relays required to use 48V has been a huge roadblock to anyone even experimenting with it in production.

24V came about because things like hydraulic power packs, winch motors, etc., need more power, and bigger wires can end up costing more than beefier relays needed for 24V.

But as more car components, such as power steering, brake booster pumps, and even AC compressors, become electrified, 48V becomes more tempting.
48V allows those components (motor mainly) to function more efficiently with smaller wires.

I have actually been working on a project that requires a dual 24V/48V system and navigating some of the safety issues around it.

 

[MozzoAU]

Thanks guys for the interesting aside on the safety stuff. Useful for the uninitiated. I do wonder how safely these packs are wired vs the Nissan original packs.

 

[MikeinPA]

It occurred to me to search on line for any electrocution deaths from electric golf carts, since many of them run 48 volt systems, and all I saw was one incident where someone was outside unplugging a charge cable during a storm, and it was uncertain whether it was lightning, AC, or DC. So that's a data point. A lot of ebikes are running 48 volts, and they are out in the rain often enough--so this does matter.

 

[cornbinder89]

It occurred to me to search on line for any electrocution deaths from electric golf carts, since many of them run 48 volt systems, and all I saw was one incident where someone was outside unplugging a charge cable during a storm, and it was uncertain whether it was lightning, AC, or DC. So that's a data point. A lot of ebikes are running 48 volts, and they are out in the rain often enough--so this does matter.

It is not so much straight up electrocution that is the danger. When there is a crash, fire, stopping the heart and incapacitating movement of muscles, can be the danger. Unlike A/C where the current passes through the 0 point twice based on frequency, DC does not, which can cause muscles to contract and lock. This can do as little as prevent you from moving and arm or finger to as much has preventing your heart from beating.
You might be able to pull away from an A/C voltage that the same DC voltage you can not.

 

[ginetto]

please please please, can we remain in the thread of the chinese packs? or open a new thread where to talk about common safety stuff that IMHO the web is already full of info.
@Riore any news about your pack?

 

[Zero Emissions]

Back in the 80's there was talk in the automotive industry that we would switch to 48 or higher voltage (No, Elon didn't come up with it, it pre dates him). Operating voltage of a "48 volt system is 56 volts, more then enough to enter the body.

Once a hard look into what it would take, we still have 12 volt as the standard in North America. Heavy vehicles in the rest of the world, and motor coaches in North America, use 24 volt system. Some older Marine systems were 32 (four eight volt) or 36 (3 twelve volts). Turns out higher voltage comes with a lot of problems, along with some benefits, so far the benefits haven't out weighed the problems.

I'm in the RV bizz and some of our 45ft. Diesel pushers have 24 volt starting systems. Most of our sales people are so scared of the battery banks so I have to educate them and remind them if you touch DC Positive to any metal surface with a wrench or any kind of metal then yes you will burn down the Coach! (I've seen 3 units burn to the ground in 40 years) So then I open the compartments and show them that how safe DC voltage is when you use common sense and clear knowledge when Jump starting! Then I show them that grabbing the negative post in one hand and the positive post in the other hand makes nothing happen! But then I tell them if that was AC voltage even as low as a 1/2 Amp it can bite and even kill a full grown man and I tell them even as low as 300MA (three one thousands of an amp...same as GFCI rating) can kill some older people with heart issues etc. use common sense! So today's lesson folks with common sense and proper knowledge you should never get shocked it's when you put your ice cold beer down and grab the live circuit without protection and/or the right tools you can and will get bit and trust me I've been knocked on my butt how could I have been so stupid! (beers influence?) When it comes to electricity a little bit of knowledge can get you into a lot of trouble so always use common sense, be careful (and sober) and always think 5 steps ahead with invisible electricity... it could save your life!

 

[jayyzz]

please please please, can we remain in the thread of the chinese packs? or open a new thread where to talk about common safety stuff that IMHO the web is already full of info.
@Riore any news about your pack?

My daughter's 2018 40kWh also got one bad cell. Still trying to figure out which will be the best way, change one or the entire pack