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Automotive/Current draw
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I have just followed your Q and A regarding current draw because it pertains to a problem I am trying to solve. We have a situation where 2 Chev 2500 Express vans are suffering dead battery over night. The original complaint is that is was the GPS units installed causing the problem. upon trouble shooting, with the GPS units removed there is still a 1 Amp current draw on both vehicles. (doors closed, lights off, key off), then I checked my own 2500 Express and it too has a 1 A current draw, but I do not suffer dead battery syndrom. Checked current with 2 different meters etc... What is the standby current spec of a 2500 Express, 1 A sounds too high? Thanks Ken]
I have no specs whatsoever on your vehicle, not having that particular one, but I DO have all the documentation on all the vehicles I DO have - highly recommended! No matter - I can concur that a 1 Amp parasitic draw is on the high side. While this likely would not be noticeably problematic with on a vehicle which is started every day, it is very probable that a vehicle that is left for say, a week, could not be started.
Inasmuch as vehicles are not intentionally designed to require that a charger be present if one is simply not driving one's car for a few days, I would suggest that there is an unintended drain somewhere, due either to a faulty component or to some accessory that should be on the keyed-activated accessory circuit but which is, in fact, on an always-powered bus.
Finding any problem of this type is best done following the following simple rules: assume nothing, and check everything! Be systematic so that nothing is missed.
In the unlikely event that all IS in order, then check the vehicle's owner's manual to see what it recommends when one contemplates storing the vehicle for any length of time. It may well be that keeping a battery on charge is recommended if the cars is to be left unused for as little as one week!
If that is the case, then I would recommend that you buy a sealed underhood automatic charger. These are low-cost, about twenty-five dollars or so (less if you have trade discounts#, and provide 1.5 A of charge top-up whenever the battery voltage drops below 12.4 to 12.5 volts #12.39 volts is 90% charge at 80F) or so. The important thing is that they shut down again once the battery has maintained 14 volts for a few minutes. After that, they will not cycle on again until the battery is again at or below 12.5 volts.
Keeping a battery between 90 and 100 percent charge is optimum. Deep discharge causes sulfation and ultimate battery failure, and so does OVERcharging, the latter due to gassing and boiling out of electrolyte - while this is a problem with "flooded" (wet) batteries predominantly, even sealed lead-acid (maintenance-"free") batteries are abused by this. The sealed automatic charger limits sulfation admirably by keeping the voltage in the optimum range. (If your battery happens to be a flooded type, then please do check the electrolyte level, and top up with distilled water as required! Most modern starting batteries are sealed, but RV deep-cycle batteries usually are flooded type.)
Regards ... EGK
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Answers by Expert:
Ernest (Ernie) Kenward
Expertise
The challenges I most enjoy are thoughtful technical questions of a trouble-shooting nature in both electrical, power electronic and mechanical systems, mainly automotive but also machine control and small-machine PLC applications. Please note, however, that I am NOT a walking shop manual! I DO, however, make it a point to have those manuals and other service literature for those vehicles I DO own, and highly recommend that anyone serious about maintenance or modification of their vehicles do the same; MOST of your answers WILL be found there. For that matter, I do NOT go out of my way to acquire shop manuals for any vehicle I do NOT own! That being the case, any general query to me along the lines of "What is the meaning of this code read from the ECU of my 2015 XYZ?" or "Where is the fuse for the windshield washer pump found?" (try your car's electrical distribution panel for a start!) will not go far. What I do offer is a pretty good collection of literature, insights and hands-on experience with 1950s to 1980's Ford products (plus a developing database of information and practice with the Mercedes diesel cars), along with an engineering perspective and the ability to design and implement custom control, electrical and mechanical subsystems for vehicles. For that reason, I am happy to make my thoughts and efforts available to those who are of like mind and/or are seriously making a point of learning about their vehicles. Use the Opportunity to Learn!
Experience
A key skill in my work and hobby pursuits both is STRATEGIC TROUBLESHOOTING. I am a senior instructor in Electrical Engineering Technology at a leading Canadian polytechnic, my areas being Electrical Power and Industrial Control, electrical and electronics design and manufacturing, and AutoCAD and related CAD/CAE software - plus equipment problem-solving and new equipment design and prototyping.
Hobby-wise, I have 30-plus years of experience in auto restoration, mostly in electrical and mechanical systems. Ongoing projects include a 1959 Edsel Corsair, my 1978 Ford E250 class-B motorhome conversion, and the care and upkeep of my Mercedes 300CD.
My vehicles become engineering test beds for electrical and mechanical upgrades as ideas present themselves. This includes the design and production of circuit boards to restore or enhance features for which no OEM replacement parts are obtainable, or where better specifications or reliability can be had via newer concepts. Regarding the E250 RV conversion, I designed and continue to revise a custom power distribution system, managed by a Programmable Controller (PLC); this has made most revisions as easy as uploading new firmware as I develop it.
The "mini" PLC is a powerful device for custom automotive control systems. One good example (there are many) would be the Moeller "Easy Relay"; these offer a wealth of control, monitoring and variable-and-status display options for such projects. A good example project which has worked well is that one for my RV noted above, which has been on the job - revised in firmware only - for a decade now. It is a load management and charging control system to avoid the sulfation-induced early failure that often befalls deep-cycle batteries used in RV power applications. The battery installed in 2003 lasted long enough to more tnan pay for the PLC that contributed to its longer life ... and the PLC will be there for the next battery as well!
Organizations
IEEE - senior member ... past WCC Student Activities;
SME - senior member ... past chair, greater Vancouver chapter chair 318;
Edsel Owners' Club - have served in various capacities on chapter executive during seventies;
have been Power and Driveline resource on the Edsel Owners' Club "E-team" for more than a decade.
Education/Credentials
Graduate of UBC
Awards and Honors
Certificates of appreciation from IEEE and SME for work in student and chapter activities
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