Modules dying when 24V vehicles are jump started
in [Design]
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From: JosephKK on 5 Jul 2010 18:12 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.
From: Joerg on 5 Jul 2010 18:25 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. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Tom Gootee on 5 Jul 2010 23:00 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
From: JosephKK on 6 Jul 2010 05:23 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.
From: dcaster on 6 Jul 2010 09:01
On Jul 3, 3:52 pm, Tom Gootee <t...(a)fullnet.com> wrote: > Something available off-the-shelf would be ideal. If > nothing already exists, what might work? 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. Dan |