Highest voltage seen while engine is running

[MacGyverS2000]

Curious as to the highest voltage seen while the engine is running (not talking high voltage at spark plugs)? The suggested value is 13.8V for the average, but I've commonly seen 14.3V.

Anyone seen higher than 14.3V on a production vehicle?

 

[bub579]

Modern american cars(mostly GM)run about 14.4 VDC. I have seen 13.8 VDC on many Bosch units. Where was the lower voltage spec published? bub

 

[MacGyverS2000]

Thanks, bub. I've designed a circuit with a max expected voltage of 15V (meaning it will operate within normal parameters at up to 15V). It can deal with higher voltages for short periods, if necessary, but I wanted to make sure it wouldn't be the norm situation on a typical car. Lower voltage isn't a problem as far as circuit damage is concerned, only that it won't operate in an optimum manner at voltages below around 9-10V...I figure at that point, something is wrong with the system as a whole.

 

[bub579]

You will never see over 15VDC except for voltage regulator or circuit problems. However, you will see 9-10VDC in start mode. good luck, bub

 

[sreid]

There is also a "Load Dump" requirement that allows 40 or 60 VDC (I can't remember which) surges.

 

[MacGyverS2000]

And what exactly is this "load dump", and under what conditions doe sit occur?

 

[sreid]

A load dump occurs when the alternator is charging (possibly at full current) and the battery is disconnected. Search the web for Load Dump for more specifics.

 

[statorwinder]

Specs on Gm go as high as 14.75. With the stop & go driving we see nowdays anything below 14.2 will probably give you short battery life.Even the long haulers are running 14.2/14.5 volt setting. Years back they ran 13.6/13.8,

George

 

[iamyo]

Usually there are several requirements on voltage levels. Normal limits for Ford for example are until 15volts. Then, it exist the jump start (28v 1min), the overvoltage (19v 1hour) and the Load dump (30volts 400ms for centralized protection or even 60volts for not centralized protection)

Iamyo