Disconnect at 11.8V HOW? Please help

  • Thread starter trulka
  • Start date
In summary, Tom is constructing an electric racecar and is having trouble with running on only one battery at a time. He is looking for advice on how to switch batteries mid-race. If this is for a contest, how will he convince the judges that only one battery is being used at a time?
  • #1
trulka
1
0
Hey guys,

I am building an electric racecar for university and I'm stuck!. It has to be run on car batteries and it can only use one at a time... many people are just using an excellent battery with a great amp-hour rating... but I'd like to switch batteries halfway through...

I want to disconnect a car battery when it reaches 11.8V and possibly using an adjustable voltmeter/detector?

Please help, any advice would be great!

Thank you!
-Tom
 
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  • #2
You're not going to build much of a race car with only one 12V battery at a time. A single 12V battery, even at 100 amperes of current, is only providing 1,200 watts of power. This is about the same amount of power generated by a lawnmower engine.

- Warren
 
  • #3
There are plenty of battery voltage detector chips about.

Maxim make a shedload.

Combined with suitably zonky Power mosfets, then bob's yer uncle.
 
  • #4
zeitghost said:
Maxim make a shedload.

Combined with suitably zonky Power mosfets, then bob's yer uncle.

You Brits sure talk funny :rofl:
 
  • #5
berkeman said:
You Brits sure talk funny :rofl:

We've had centuries to practice... :biggrin:

Zonky, by the by, means "large" as in >100A Id(on).
 
  • #6
One way for a warning system would be to setup a diode with a resistor (or trim pot) combination that switches at 11.8V.
 
  • #7
What the heck does "then bob's your uncle" mean?

CS
 
  • #8
stewartcs said:
What the heck does "then bob's your uncle" mean?
It means you're problems are solved

Historical note:
Robert Gascoyne-Cecil,was prime minister in the 1890 and was a big fan of nepotism - appointing his nephew as minister, so if Robert (bob) was your uncle you didn't have any problems getting a job.

Interestingly neptosim is from the Italian for nephew and comes from Pope's giving appointments to their (cough) nephews (cough)
 
  • #9
mgb_phys said:
It means you're problems are solved

Historical note:
Robert Gascoyne-Cecil,was prime minister in the 1890 and was a big fan of nepotism - appointing his nephew as minister, so if Robert (bob) was your uncle you didn't have any problems getting a job.

Interestingly neptosim is from the Italian for nephew and comes from Pope's giving appointments to their (cough) nephews (cough)

Ah...Thanks.

CS
 
  • #11
trulka said:
I want to disconnect a car battery when it reaches 11.8V and possibly using an adjustable voltmeter/detector?

Do I understand that both batteries will be in the car at all times, and you want a circuit that electrically switches over to battery #2 when battery #1 reaches 11.8V?

If this is for a contest, how will you convince the judges that only one battery is being used at a time?
 

1. How does a disconnect occur at 11.8V?

A disconnect at 11.8V occurs when the voltage drops below the threshold of 11.8V, causing the electrical circuit to break or open, resulting in a loss of power.

2. What causes a disconnect at 11.8V?

There are several potential causes for a disconnect at 11.8V. It could be due to a faulty battery, a malfunctioning charging system, or an overloaded circuit.

3. How can I prevent a disconnect at 11.8V?

To prevent a disconnect at 11.8V, it is important to regularly check and maintain your battery and charging system. You can also avoid overloading circuits by distributing power usage evenly.

4. What are the potential consequences of a disconnect at 11.8V?

The consequences of a disconnect at 11.8V depend on the context in which it occurs. It could result in a loss of power to a device or system, potentially causing malfunctions or disruptions. In certain situations, it could also be a safety hazard.

5. Can a disconnect at 11.8V be fixed?

In most cases, a disconnect at 11.8V can be fixed by addressing the underlying issue. This could involve replacing a faulty battery, repairing a charging system, or redistributing power usage. However, if the disconnect is due to a safety issue, it is important to seek professional help to ensure proper and safe repairs are made.

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