Looking for a large current adjustable circuit

Thread Starter

LAOADAM

Joined Nov 21, 2018
518
Hi,
I am looking for a large current adjustable circuit, 48V at about 200A, no matter what components used.
Need help please.
Thanks
Adam
 

Papabravo

Joined Feb 24, 2006
16,107
Hi,
I am looking for a large current adjustable circuit, 48V at about 200A, no matter what components used.
Need help please.
Thanks
Adam
I'm not sure what that is. Can you elaborate on the phrase "current adjustable circuit"? Are you looking for a variable load that can dissipate up to 10 kW? If so good luck. If you are going to dissipate that amount of power I don't want to be responsible for your electric bill and you may as well do something useful like run motors. Maybe you just want to be the first kid on your block to make the lights go dim. A good radial arm saw will do that for you. Better yet a whole bank of them and switch them on in sequence.
 

Thread Starter

LAOADAM

Joined Nov 21, 2018
518
I'm not sure what that is. Can you elaborate on the phrase "current adjustable circuit"? Are you looking for a variable load that can dissipate up to 10 kW? If so good luck. If you are going to dissipate that amount of power I don't want to be responsible for your electric bill and you may as well do something useful like run motors. Maybe you just want to be the first kid on your block to make the lights go dim. A good radial arm saw will do that for you. Better yet a whole bank of them and switch them on in sequence.
Thanks.
I have two 24V SLA batteries, and I try to use them series connection for testing Resistance heaters. I like the station be able to test different value of resistance at as less as the V charges.
 

sparky 1

Joined Nov 3, 2018
541
The batteries CCA will change. In order to test you need to record %CCA
A meter like foxwell could measure 24V battery. With new batteries the %CCA does not present problem at first.
When you charge the batteries and keep getting low % cold cranking amps your seal lead acids will limit your ability.

With a data logger the chart reveals voltage drop on your resistive load along with the test ID and %CCA and temperature. The file from the data logger uploads to a spreadsheet. Because you have different loads that would be an AC equivalent of this using PWM with large heatsinks the spreadsheet would give the DC equivalent.

Last year my new battery's percentage CCA dropped an average of 5% each month. In 9 months it would retain only 45% CCA
Dependability, service life, return date are far less than years past while the cost have sharply increased.
 
Last edited:

Thread Starter

LAOADAM

Joined Nov 21, 2018
518
The batteries CCA will change. In order to test you need to record %CCA
A meter like foxwell could measure 24V battery. With new batteries the %CCA does not present problem at first.
When you charge the batteries and keep getting low % cold cranking amps your seal lead acids will limit your ability.

With a data logger the chart reveals voltage drop on your resistive load along with the test ID and %CCA and temperature. The file from the data logger uploads to a spreadsheet. Because you have different loads that would be an AC equivalent of this using PWM with large heatsinks the spreadsheet would give the DC equivalent.

Last year my new battery's percentage CCA dropped an average of 5% each month. In 9 months it would retain only 45% CCA
Dependability, service life, return date are far less than years past while the cost have sharply increased.
Thanks for good advice.
My testing is simple, just record the relation chart between: I/V/T/t (Current/Voltage/Temperature/time).
 

Thread Starter

LAOADAM

Joined Nov 21, 2018
518
What are the test specifications ?
What exactly are you trying to find out about the Heaters you are testing ?
All of the small details are very important.
.
.
.
Thanks.
I don't have much detail yet, just in Preparation Phase。
 

LowQCab

Joined Nov 6, 2012
517
Specifically, how much Time do you think will be necessary to obtain the required Temperature ?

This can be calculated, and extrapolated, once the initial start-up behavior is established.
The start-up behavior can also be an indicator of Life-Expectancy.

If the Heating-Element is not attached to its normal Heat-Sink, the results may not be 100% valid.

You also need to take into consideration whether the Batteries can repeatedly withstand the abuse.

I believe I know what you want, and have almost finished the design,
but I want to make sure of what you expect to happen, especially the Duty-Cycle.
.
.
.
 

Thread Starter

LAOADAM

Joined Nov 21, 2018
518
Specifically, how much Time do you think will be necessary to obtain the required Temperature ?

This can be calculated, and extrapolated, once the initial start-up behavior is established.
The start-up behavior can also be an indicator of Life-Expectancy.

If the Heating-Element is not attached to its normal Heat-Sink, the results may not be 100% valid.

You also need to take into consideration whether the Batteries can repeatedly withstand the abuse.

I believe I know what you want, and have almost finished the design,
but I want to make sure of what you expect to happen, especially the Duty-Cycle.
.
.
.
Thanks.
1. the Testing Time Cycle need be set after a Tentative test;
2. the Heating-Element will be tested with and without Heat-Sink.
3. the battery group may not be a good choose, especially the test need be conducted time by time.
 

LowQCab

Joined Nov 6, 2012
517
OK, lets try again, how about a general, roundabout, sorta-kinda, amount of time ?
0.5-Seconds ?
1-Second ?
10-Seconds ?
30-Seconds ?
5-minutes ?
30-minutes ?

And, at approximately what variable Voltage and Current ?
.
.
.
 

Thread Starter

LAOADAM

Joined Nov 21, 2018
518
OK, lets try again, how about a general, roundabout, sorta-kinda, amount of time ?
0.5-Seconds ?
1-Second ?
10-Seconds ?
30-Seconds ?
5-minutes ?
30-minutes ?

And, at approximately what variable Voltage and Current ?
.
.
.
Thanks.
I'll put these in my design plan after I collect as much information as I can.
 
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