The joys of outsourcing 12 volt batteries

The joys of outsourcing 12 volt batteries

Elon was just discussing at the end of the conference call the 12 volt battery issue. They had purchased from an American reputable firm the Tesla S 12 volt lead acid batteries. That company outsourced to China. The Chinese company then turned around and outsourced to Vietnam.

Quality was poor and explains the 12 volt issues owners report.

ian | May 8, 2013

Yup. That one kind of blew me away. Like I said in another thread, I hope that supplier feels like an idiot. I hope they lost the contract too!

JZ13 | May 8, 2013

So I have a Vietnamese battery??????? Yuck

ian | May 8, 2013

Until it dies and you get it replaced! Haha!

rdalcanto | May 8, 2013

Have they changed what they put in current builds?

ian | May 8, 2013

Yes, Elon said they have a reliable source now.

I don't know if it's from a new supplier or not though. I missed that detail.

jbunn | May 8, 2013

Nothing wrong with a Vietnamese battery, but the issue here is losing control of your supply chain. Tesla paid a price to a company that skimmed off a portion to deliver a battery. Then that company passed it to the Chinese who skimmed off another portion. Then passed it to a Vietnamese battery company that skimmed off another percentage to build the battery. Tesla did not get the expected quality and the cost of servicing these issues are passed on to Tesla and the customers. Meanwhile three companies got a cut of profits.

Having observed this for 20 years, I've seen PMs that have assumed you can outsource, offshore, onshore, or vendor out critical functions. I recall one saying "We can give this to the vendor and we don't have to worry about it." Wrong. You need to build in vendor management into the financial model.

Hopefully Tesla does a better job of writing contracts specifiying sub contracting in the future, or attempts to do a claw back on the 12 V battery manufacturer.

Kind of funny right now considering Elon was trying to give Boeing help with their battery issue a few weeks ago.

Regardless, seems like Tesla has been transparent on the battery issue, and resolving as they arise. Better if we had not had these though.

carlf9121 | May 8, 2013

My livelihood being with semiconductor design & manufacturing, in particular when fabrication, assembly, test & materials are outsourced, you can't just shake the supplier's hand with the understanding that they will meet all requirements set forth in your procurement spec. You have to work quite extensively with the supplier & be on site for initial design and the validation process. Travel onsite to where the product is being manufactured to perform source inspection, verify compliance to specifications and success to extensive quality & reliabilty testing.

Maybe the Roadster, which was suppose to validate its long term reliabiity & quality did not have the same supplier for the 12V battery or the design of the battery was changed & not fully field tested.

shop | May 8, 2013

I STILL think relying on a 12V lead acid battery (which die ALL THE TIME) to start the car and in the Tesla, is a pain in the ass to "jump start" since they don't give you terminals, is a BAD DESIGN DECISION. It is said it is needed as "backup" to power the car's computers in case the main battery gets drained. Well, it isn't a backup if it is REQUIRED to start the car. It is, in fact, a CRITICAL COMPONENT, with ZERO backups behind it.

The car could be designed to either not have a 12V battery, or the have a fail safe DC-DC converter that could be used for when the 12V battery dies, or as a last ditch, give us jump start terminals, so any ICE with cables could start our car.

Will Tesla make such a design fix???

rdalcanto | May 8, 2013

Since the 12V battery is not subject to high heat from an ICE, is should last a long time. Does anyone know where the battery is located? It would be easy to put a load tester on it once a year and make sure the battery is healthy if we can get to it.

nickjhowe | May 8, 2013

@Shop - so you can't use the terminals behind the nose cone to provide 12V to start the car?

Brian H | May 8, 2013

That's all wrong. The 12V directly powers various small devices, like the doors and screens. And there are terminals accessible behind the nose cone.

FLsportscarenth... | May 8, 2013

Hmm, could save some weight by making a LiIon pack that fits where the 12V Dinosaur battery goes... Years later you could use either/or...

Redundancy is super in important in spaceflight, Elon above all should know better!

GeekEV | May 8, 2013

@rdalcanto - Like during the annual inspection that's now optional? ;-)

shop | May 8, 2013

@brian, what's "all wrong"? If the 12v battery dies, can you start the car? Can you access the 12v terminals without tools? Where is it documented to access the 12v terminals?

jbunn | May 8, 2013

Thinking about this from the perspective of a thief, if the 12 V is dead, you can't open the car doors, therefore cannot open the frunk. Likewise with the mobile app. And the 12V, I thought was under the frunk liner (could be wrong on this). The trunk is as tight as a gnats ass, so that's a no go. The only place I can think of is the charging port, which you can open from the outside of the car (secret ninja karate chop maneuver). Or put 12 terminals somewhere near the 12v battery.

Me, personally? Would not have put them behind the nose cone, as it's first at the scene of the accident, but perhaps they are well shielded.

CC | May 8, 2013

@shop @jbunn

The 12 v terminal is behind the nose cone, which can be removed with a panel removal tool.

nickjhowe | May 8, 2013

Brian H misses an important point - One of the big reasons for the 12V is to operate the contactors that isolate the battery pack. The contactors fail safe in the open position. 12V power is required to close the contactors and connect the battery to the motor.

@Shop - you are right; you would need some kind of tool to remove the nose - but any blade should do (though plastic would be required to reduce the risk of marking the nose)

shop | May 8, 2013

Yes, I know about the nose cone. Removing the nose cone panel is not easy, not documented, and not recommended by Tesla. When I said Tesla could provide access to the 12V terminals, I meant in an easy way like you can on an ICE vehicle. When the 12V battery dies (and it will, given enough time, right???), Tesla's way of dealing with it is to send a tech or a flatbed truck, so even they don't want you to start taking apart your car.

My point is that the 12V battery system is not well designed. It is a single point of failure with no backup.

Brian H | May 8, 2013

Driving accessories with dedicated stepdown transformer voltages requires a far more complex setup. Keeping a 12V topped up is (in theory) much easier. But it requires a non-crap 12V.

Flaninacupboard | May 9, 2013

A 12V lithium battery is a nice idea, but it can't really thermally manage -itself-, so starting in cold temperatures could be a problem. A 40ah lithium battery would also be reasonably expensive to replace when it fails...

shop | May 9, 2013

@Brian - you don't use step down transformers in a DC powered car. You use a DC-DC converter which is a somewhat complex assembly of discrete electronics. But DC-DC converters are reliable. 12V lead acid batteries are not. I don't know, maybe Tesla has figured out how to reliably get 8 years from a lead acid battery (well, obviously not yet since a bad batch doesn't even last 6 months!), but I really, really doubt it.

TheAustin | May 9, 2013

therealmach3, that story is exactly what I thought of when I ready about this 12-volt battery outsourcing shenanigans.

EcLectric | May 9, 2013


Thanks for the excellent explanation of the 12v battery. That makes perfect sense. The contactors have to have power to connect the main pack, and some things have to still work when the main pack is not connected.

Litennn | May 9, 2013

Anybody else consider that since China is building an electric car sponsored by the Chinese government that they gave an undercutting bid to the supplier and then deliberately contract with the Vietnam company for less than specified quality to undermine Tesla's position in the market ?

Just a thought !

Oscar | May 9, 2013

@shop - Not sure ICE are any better. Almost every luxury car (and not so luxury cars) uses a FOB to get into the car. If the battery is dead, you don't get in. Usually this means you can't release the hood. And if you do get the hood open, surprise - the battery is either hidden under big plastic engine covers that requires tools to get to, or it's under the back seat.

My experience with ICE lead-acid batteries is when they get to the end of life they give you a bit of warning (1-2 days) with cranking slowness. No dashboard warning usually appears with battery death.

The Tesla 12v battery is also monitored and has a warning when it's about to die. Not sure how much warning you get, and it seem some batteries have died too quickly to get a proper warning.

Pungoteague_Dave | May 9, 2013

@shop - it is super-easy to remove the nose cone and access the 12v terminals. No tool required. although some recommend a panel remover tool, that's a waste of money. I have had mine off four times so far (testing locations for our EZ-Pass transponder). All you need is a credit card or similar thin piece of plastic under the lower edge to get enough purchase to pull it off with your fingers. Pops right off and snaps back on in seconds.

shop | May 10, 2013

@Pungoteague_Dave - from a similar thread over at TMC: "Spent an hour on the phone with Tesla trying to remove it [nose cone]. Actually, they were not giving me the right procedure as my nose cone was a different design that they've expected."

@TeslaTap - ICEs ARE better in this respect. Many people have had their Tesla 12V battery die with NO warning. The jump terminals are NOT easily accessible.

It would have been relatively easy for Tesla to incorporate a self-jump mechanism with a dedicated DC-DC converter. A protected, but accessible switch that is effectively a manually operated main pack contactor switch. That is only one way to solve this. Actually providing easy access to the jump terminals is another.

This is a design flaw - obviously Tesla never thought through what happens when the 12V battery dies. I hope they are paying attention and don't think that simply getting more reliable 12V batteries 'solves' the problem. That's a band-aid, not a solution.

Pungoteague_Dave | May 10, 2013

@shop: The person on TMC does not know what they are talking about and your comment is a misdirection based on old news. Please take it from someone who has done it. The first time it took me five minutes start to finish. Now it is seconds. I agree that getting the nose off to access the terminals isn't obvious, but once done, it is as easy as opening your toothpaste, with even less complex wrist motions. It isn't necessary to complain about nonissues?

shop | May 10, 2013

How do you know they didn't know what they were talking about? Have you talked to him? The post I quoted was posted today. How is that old news?

Vawlkus | May 10, 2013

@shop: you're overlooking something obvious. Tesla WANTS a secondary battery I there that is not connected to the main pack. It's a failsafe to help keep something bad happening to the main pack, as its an expensive piece.

shop | May 10, 2013

Having easily accessible 12v jumper terminals or a manually activated contactor wouldn't change the safety aspects. Honestly, why are people so defensive on this issue? The model s remains a great car, but every car can have improvements.

jjaeger | May 10, 2013

And I just saw a Ford forum post where it took the driver 25 minutes to get the hood open so he could get a jump. Ford really has a problem on their hands is the conclusion that I draw...

Mark K | May 10, 2013

TM has done some very aggressive safety engineering, which is very smart and highly appropriate.

The external battery acting as a disable mechanism is a classic deadman trigger arrangement so that if something isn't right, the clusters of batteries disconnect to prevent the possibility of discharge under compromised circumstances. That trigger must be outside the pack itself so the pack cannot self-supply its own destruct current if it's compromised. This is very smart.

That said, I think it would be wise to have a backup 12V pack that takes over automatically when the primary is degraded. That way, if one fails you'd get a warning but could go on your way until you have time to replace it. I predict that this will be added at some point.

Not a common thing though. But the supplier snafu made it show up with uncharacteristic frequency, which is actually helpful to brightline the advantage of a backup.

FYI my MB SL has two 12V batteries.

rihhanarachel | June 13, 2013

12V battery suits well. Some suggestions here:

wcalvin | June 13, 2013

Could also manufacture battery with a tap at 4x3.7V for use in 12V failure. Contactor is held open by 12V; closes to apply tap when 12V battery fails.

amluto | June 14, 2013

@wcalvin: If they did that, then they'd lose the property that all the cells wired up in series stay at the same state of charge. Then you'd need a special recharger and you'd have uneven wear.

The Roadster has no 12V battery, and Tesla decided that was a mistake. Supposedly the Model S has a giant (200A at 12-14V) DC-DC converter, but lead acid batteries are excellent at handling very quick changes in load. Those quick changes happen when you open windows, steer, and presumably even when you use the brakes and deplete the "engine" vacuum (which is certainly not supplied by an intake manifold).

Whenever they get sleep mode working, then presumably the 12V issues will mostly go away. FWIW, it still boggles my mind that the electronics draw more than a few tens of watts even at full load -- a Tegra 2 and Tegra 3 have very low maximum power draw on the scale of things like a Tesla battery. | June 14, 2013

It's hard to tell, but with over 50 processors in the car, I expect quite a few are powered up most of the time. I suspect that's where quite a bit of the work is being done to see which can reliably be powered off or powered up and down on some interval timer.

A few areas that come to mind that may be powered on all the time - door handle processors (4), security system, 3G, and FOB detection. In addition the battery systems may also be powered most/all of the time, which may have another 16 CPUs.

Here's my list of all the CPUs in the MS:

If the system decides the main battery needs to be cooled or heated, even briefly, that would be a significant load as the HVAC system would have to run, maybe taking 500-3000 watts while running (a total wag).

mdtaylor69 | June 15, 2013

I had my 12V battery replaced in April and it already started going into deep sleep again late this week. I also walked out to the car after work to find the driver window rolled down. Good thing it was in a garage. Ran a few errands today and the car would not start at all even holding down the steering wheel buttons. Called Service and they said the 12V battery was below minimum level and needed to be replaced again. Will have it towed in on Monday. The driver door handle is intermittently not presenting, so I will get to have that replaced at the same time.

The WAF is at an all time low.

justineet | June 15, 2013

@mdtaylor69....this sounds something more of an electrical issue which is draining your battery more that it should.

justineet | June 15, 2013

By the way does any one know if the Tesla has an alternator to recharge the 12V batter like ICE cars?? u know if there is an recharging alternator in your Tesla?? If there is, the battery is probably dying because the alternator is not working properly.

justineet | June 15, 2013

correction above I meant @mdtaylor69

Bubba2000 | June 15, 2013

Power management in the Model S is work in progress. Look at job listings. Tesla is hiring engineers with skills to deal with these issues.

Brian H | June 15, 2013

An alternator in an electric car makes no sense. Use electricity to drive the car, turning the wheels, which drives an alternator to generate 12V?? Pointless.

Power is just fed directly from the main battery, stepped down in voltage.

shop | June 15, 2013

Yes, no alternator, but instead a DC-DC converter that chargers the 12V battery from the main pack.

justineet | June 15, 2013

@Brian H

The battery has to be recharched some how regularly. Otherwise it will drain and die pretty fast. Recharging the 12V battery is not pointless; it's a must!! An alternator is not as strange as you may think for electric car. It's basically mini version of the main motor on MS. But another way for recharging the 12 battery is through a DC to DC step down convertor as you mentioned a not only from the main battery but also from a charging station to the 12 V battery.

Brian H | June 16, 2013

OK, a little slower so you can follow.

The alternator would be getting (after several lossy conversions) power from the main battery indirectly. There is no other possible way the alternator could spin. It is far more efficient and direct to charge the 12V from the main battery directly with a DC-DC voltage converter. It happens continuously, controlled by the car's electronics.