Modules dying when 24V vehicles are jump started
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From: Joerg on 6 Jul 2010 09:32 Tom Gootee wrote: > On Jul 4, 7:56 pm, Joerg <inva...(a)invalid.invalid> wrote: >> Tom Gootee wrote: >>> On Jul 3, 5:05 pm, Muzaffer Kal <k...(a)dspia.com> wrote: >> [...] >> >>>> One solution would be to use a protection circuit at the input of the >>>> system using an IC like LT4356 or a discrete implementation of the >>>> same:http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1003,C1142,C1... >> Way to go. Although this one (as most others) is limited to 80V and for >> a truck with a 24V system that's borderline. Might have to roll your own >> here. >> >> >> >> >> >>>> -- >>>> Muzaffer Kal >>>> DSPIA INC. >>>> ASIC/FPGA Design Services >>>> http://www.dspia.com-Hide quoted text - >>>> - Show quoted text - >>> Yeah, that type of circuit would be nice. Jim Thompson also has one >>> that's similar in effect I think, but all discretes. And Maxim has a >>> discrete version schematic of something similar in some literature >>> about a similar IC they sell. >>> Does anyone know if there any COTS products (already available) that >>> use something like that? >> Not for 24V but you could ask these guys: >> >> http://www.advancesurgesuppressor.com/#DC >> >> The market is small thouygh because most equipment is properly designed >> to handle those load change surges or, ahem, "unusual" jump-start >> methods. In aircraft it has to or it won't be certified. >> >> -- >> Regards, Joerg >> >> http://www.analogconsultants.com/ >> >> "gmail" domain blocked because of excessive spam. >> Use another domain or send PM.- Hide quoted text - >> >> - Show quoted text - > > This paper has what looks like some really good information: > > http://www.radiocad.com/_downloads/LoadDumpPaper-final.pdf Yes, but don't use the BJT version if the load is fat. Else ... *PHUT* -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Joerg on 6 Jul 2010 09:36 JosephKK wrote: > On Mon, 05 Jul 2010 15:25:50 -0700, Joerg <invalid(a)invalid.invalid> > wrote: > >> JosephKK wrote: >>> On Sun, 04 Jul 2010 18:00:57 -0700, Joerg <invalid(a)invalid.invalid> >>> wrote: >>> >>>> Tom Gootee wrote: >>>> >>>> [...] >>>> >>>>> ... But it seems like a >>>>> TVS or Zener clamping circuit would be a lot cheaper and smaller, and >>>>> maybe more reliable and robust, and should work well-enough. And they >>>>> are available and ready to use as is. There are too many of these >>>>> systems out there to spend a lot of money on each one. >>>> That one you can buy as a COTS module, ready to wire up, at the company >>>> I pointed out in the other post. However, they use MOVs whivh have a >>>> finite number of times they can be hit. It's like an energy bank >>>> account, when the balance is used up ... *PHUT* ... a fuse in the module >>>> blows. >>> That might turn into a good thing. If it changes the maintenance profile >>> it may result in a user behavior change. >> >> Depends. If the competition manages to deploy a system without that >> effect it would increase the "customer pissedness factor". Not a good thing. > > True. OP's current problem of dead modules on a regular basis still > falls far higher on that scale than dead fuses that a regular user might > be expected to replace. In the end it's all about what competitors offer. Changing a long-standing yet "sub-optimal" user behavior is next to impossible. As engineers we have to design around it. Just like engineers had to design anti-lock brakes because people notoriously tailgate during rushhour no matter how often they are told not to (on Wednesday I almost had a septic pumper truck crash into the back of my car ...). -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Jim Thompson on 6 Jul 2010 10:45 On Tue, 06 Jul 2010 06:36:00 -0700, Joerg <invalid(a)invalid.invalid> wrote: >JosephKK wrote: >> On Mon, 05 Jul 2010 15:25:50 -0700, Joerg <invalid(a)invalid.invalid> >> wrote: >> >>> JosephKK wrote: >>>> On Sun, 04 Jul 2010 18:00:57 -0700, Joerg <invalid(a)invalid.invalid> >>>> wrote: >>>> >>>>> Tom Gootee wrote: >>>>> >>>>> [...] >>>>> >>>>>> ... But it seems like a >>>>>> TVS or Zener clamping circuit would be a lot cheaper and smaller, and >>>>>> maybe more reliable and robust, and should work well-enough. And they >>>>>> are available and ready to use as is. There are too many of these >>>>>> systems out there to spend a lot of money on each one. >>>>> That one you can buy as a COTS module, ready to wire up, at the company >>>>> I pointed out in the other post. However, they use MOVs whivh have a >>>>> finite number of times they can be hit. It's like an energy bank >>>>> account, when the balance is used up ... *PHUT* ... a fuse in the module >>>>> blows. >>>> That might turn into a good thing. If it changes the maintenance profile >>>> it may result in a user behavior change. >>> >>> Depends. If the competition manages to deploy a system without that >>> effect it would increase the "customer pissedness factor". Not a good thing. >> >> True. OP's current problem of dead modules on a regular basis still >> falls far higher on that scale than dead fuses that a regular user might >> be expected to replace. > > >In the end it's all about what competitors offer. Changing a >long-standing yet "sub-optimal" user behavior is next to impossible. As >engineers we have to design around it. Just like engineers had to design >anti-lock brakes because people notoriously tailgate during rushhour no >matter how often they are told not to (on Wednesday I almost had a >septic pumper truck crash into the back of my car ...). I guess that would be a *SLOSH* instead of a *PHUT* ?:-) ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | Obama: A reincarnation of Nixon, narcissistically posing in politically-correct black-face, but with fewer scruples.
From: m II on 6 Jul 2010 19:26 dcaster(a)krl.org wrote: > Regardless of the engineering fix, I would put a caution label on both > the batteries and the jumper cables stating that the > 'xxxx" system circuit breaker must be off before jump starting the > vehicle to avoid damaging the " xxxxxx" system. > > That might reduce the failures while you work on the ultimate > solution. In a better world, your caution label WOULD be the sufficient. Unfortunately, too many of the people doing the boosting don't care. Some of the geniuses working in the oil patch come to mind, but they are everywhere. Screwing up the equipment is a life calling for these types. We had one of them zip-tie a bundle of data cables to a tractor drive shaft. He was fired when one of his low life buddies ratted on him. mike
From: Cydrome Leader on 8 Jul 2010 16:47 Tom Gootee <tomg(a)fullnet.com> wrote: > We provide support for a number of systems installed in 24V vehicles. > When the vehicles are not in use, the users like to leave the system's > main power switch and circuit breaker both in the on position. If the > vehicle then needs to be jump started, the users often do not first > turn off the system's circuit breaker or power switch, despite > continuing attempts at training them. Jump starting under those > conditions tends to destroy a very expensive electronic module in the > system. > > Modifying the systems themselves is not a viable option. And we do > not yet understand the exact failure mechanism that is occurring. We > do know that there is an internal SMPS upstream from the at-risk > module, but don't have schematics for the system. The system draws > about 35 Amps continuously, when operating. > > Knowing only that, is there something that could be strapped across > the system's DC power terminals that would prevent damage from jump > starting? Something available off-the-shelf would be ideal. If > nothing already exists, what might work? one cheap thing to at least try is to put a giant diode across the power feeding the equipment, but backwards. motorola mobile radios were protected (against backwards installations, but there may be more to it than just that) this way and rugged beasts.
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