![]() ![]() Im using MickroC,i can send u the code but it would be pointless because in my testes i redused the code to just reading the ADC and truning ON or OFF a led and a couple of delays,and the scheamtics its just a voltage divider and a low pass filter basicly a very simple circut. ![]() Your cable could be causing some of the problem if current draw is too much have your tried this way measure you voltage at the battery then at your UPS end see what the difference then subtract that from the reading or just calibrate what your reading at the battery end with your meter, Let’s say if your meter reads 12.01V on the battery terminals then at the load end it reads 11.67V then you can take that of in the software or just get your LCD or raw value to what your meter reads, Why not try a 1-5 seconds delay before sounding alarm, you could try and take several samples over 1 or 2 minutes then work out the average from that before sounding alarm Other factors where are you measuring your voltage from at the battery terminals or at the load end, even if your current draw was 60amps it still would take 1hr before flat. ![]() So carrying on from above you need to check if your battery is capable of supplying the required current for the hours you require, So if your load was drawing a continuous load of 15 amps the 100/15=6.66hrs before flat, This is not strictly true the battery will only last 5.30hrs and if it was 30amps then it would only last 2.3 hours. 12V 100AH at the 20hr rate will only supply 5amps for when 20 hours before 100% discharge but only 80% recommend (again depends on battery) Car batteries are not meant for heavy discharging, these work by cold cranking amps, The battery I would say you need is a deep cycle type. There are lots of factors you have to look at and take into consideration.ĮG. Last edited by Andy Wood - 29th June 2008 at 08:05.This also depends on your battery capacity as well and what type of battery it is When it cools down again, operation will resume as normal. This way, if the transorb conducts due to overvoltage, the polyfuse will trip and go open circuit. The 10ohm resistor could be replaced with a resettable polyfuse. Also ensure the capacitors on the input of the regulator have a voltage rating of at least 35volts. If there is a possibility of the input being connected to a 24volt system, I would use a 33v transorb. The transorb is there to protect the input of the regulator from these spikes. I would use a Transorb, not a zener for this task.Ī 12volt automotive system can contain many voltage spikes much higher than the 12 volt battery. For a 12 volt system, a value of 18volts would be more appropriate. ThanksThe value of the zener diode is incorrect. Thanks again guys, why would i need to put a reverse diode between the in and out of my reg, every time i add a diode i lose 0.7 v is it really needed also, what is the purpose of that 5.1 volt zener in their on my opinion that no good my reg needs minimum 6.5v to work. Also is their a way to protect my ADCIN if someone would ever use two batteries and would connect them in series which would give me 24 v and 8 v at the output of my ADCIN, so for that to never happen, how can have no more then 5 v output into my ADCIN to protect it i'm trying to make it as dummy proof as possible. This will give me a wattage of 20 mW for the 5k and 10 mW for the 2.5 k now all this to ask my resistors should not get very hot but would this be enough to change resistance values as they get hotter, so as my resistors get hotter i would lose more and more accuracy or is the wattage so low i should not worry about it. With a peak voltage of 15v which the battery should never get that high the out of my voltage divider will be 5 v. For my voltage divider i want to build it with a 10k var in series with a 2.5K, and set the 10k at 5k, this will give me accuracy to tweak out the 5% tolerances. Thanks for your replies again guys, you've all been very helpful, what would the 5.1v zener do i know its for protection, it will start conducting around 3.3 v only when D1 as blown what is the purpose of that.
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