How to measure car battery capacity,car battery terminal stuck,best battery for 80 series landcruiser exhaust - Step 1

24.06.2015
Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. I want to measure car battery currents in high resolution and in wide range and both directions (including engine start and charging currents). I have lots of amazing Microchip MCP3424 4 channel ADCs in my workshop, it's my favourite ADC and I want to use it. I figured out, that typical op-amp in differential mode is bad idea, it produces a lot of error (offset voltage error?
There are auto-zero, low noise, low offset amplifiers, dedicated differential amplifiers, but my op-amp knowledge is not enough to make use of them, but I found that there is easier way - dedicated current monitor amplifiers. In a nutshell, I think (and have heard) that an instrumentation amplifier would be better for this for many reasons. As for using an instrumentation amp, yes you can find some that are single supply which would let you power it from USB. For instance, the INA122 is a single supply amp that can be powered by anything from 2.2 to 36V. While it doesn't seem to specifically touch on low-side current sensing, I have read in several places that there are really only 2 disadvantages to low-side compared to high-side.
The first one I don't see being much of a problem in a car, especially given that you've got a fuse box. The second point I also do not see affecting a car too much, especially if your shunt is an extremely low value.


So, if I put it on low side - I need some kind of differential measurement anyway, because after engine starts - charging current will start flowing into battery. Not the answer you're looking for?Browse other questions tagged current-measurement high-current shunt or ask your own question. I just recently had to replace the 12V auxiliary battery in the electric MR2 after almost 2 years of driving. The 12V battery on converted electric cars, serve mostly the same purpose as the 12V battery in a gas car.
Have you ever left the lights on after driving in the rain and come back to a dead battery?
Based on your normal driving pattern, estimate the max downtime you will have between driving the car. Multiply the amp draw result from step 1 by the number of hours representing the time you will not be driving the car on a regular basis from step 2. The electric MR2 uses a 22 amp-hour (AH) deep cycle sealed lead acid battery, which should   give me ample energy to park the car for over 10 days. I don’t, however, recommend doing this because if you ever leave your lights on, you could deplete you main pack battery much quicker. For those of you driving electric cars, how many days can you park your electric car without the 12V battery draining? Related PostsMay 15, 2013 -- Should you install a Battery Management System to protect those expensive Lithium batteries?


Thanks for the numbers, that makes me feel a bit more confident that my amp draw is inline with yours. No, I don’t have an ignition relay between the dc-dc converter output and the 12V battery as your set up shown in the schematic diagram. Thanks to all those that responded with your suggestions (Here’s a thread of discussion that I posted on diyelectric car and the many useful response I got on the post). HOV stickers to be extended for electric cars in California until 2020 but not for conversions yet. No matter what you will need a differential amplifier to measure a differential voltage across a shunt. I think it's about mains powered devices, where you need low impedance ground path for fast circuit breaker turn off in case of short (more current - faster turn off, resistor in path - less current). It's too hard for me to get reasonable precision witch such low resistance shunt and general purpose op-amp.
Current clamp with such precision will be waaay to expensive (if there are clamps with such precision).



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Comments How to measure car battery capacity

  1. never_love
    Adhesive starts to let manufacture of rare or discontinued battery car arrives so that they do not deteriorate.
  2. Shadowstep
    Recommends leaving the machine sound, but your.
  3. 0702464347
    Fill the battery, then drain out, dry, then fill very fast at charging.
  4. SEVGI1
    Level of power for a much stratification can occur when.