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Author Topic: Crude looping setup  (Read 10323 times)

Offline penno64

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Crude looping setup
« on: May 08, 2011, 02:14:01 AM »
Hi all,

Would someone be kind enought to replicate this test.

You will require -

A "smart" charger
12v Car battery
25watt Incandescent light bulb
600watt 12v inverter

The test :

I charged the "OLD" car battery from mains power
Let it rest overnight - measured voltage 12.7
Connected the 600watt inverter with light and charger - down to 12.3
Switched on the "SMART" charger and selected 2amp charge - voltage stabilises at 12.10

Has now been running six hours  - battery voltage steady at 12.10
                                              and charge rate fluctuates between 1.9 and 2.0 amps

Comments appreciated

Is all we really need a "SMART" charger ?

Kindest Regards, Penno

Offline gotoluc

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Re: Crude looping setup
« Reply #1 on: May 14, 2011, 07:34:55 PM »
Hi Penno,

thanks for sharing your experiment.

I was wondering if your battery in your setup is still maintaining 12.10 vdc?

If not, what was the total amout of hours it was able to maintain 12.10 vdc?



Offline e2matrix

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Re: Crude looping setup
« Reply #2 on: May 15, 2011, 05:03:58 AM »
Which 'smart charger' are you using?  If I understand correctly you are running an inverter off the battery and have the charger running from the inverter charging back to the battery.  And in addition have a 25 watt bulb running?  Big car batteries have a lot of wattage available and it can take a long time to get below around 12 volts.  But if it runs this way for a week or more straight than I'm thinking you may have something interesting. 

Offline forest

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Re: Crude looping setup
« Reply #3 on: May 15, 2011, 11:04:50 AM »
how is bulb connected ? parallel to charger or in series ?

Offline FatBird

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Re: Crude looping setup
« Reply #4 on: May 15, 2011, 09:53:43 PM »
@ Penno,   Thank you for sharing your circuit.

Please try leaving your circuit on all night, because a 25 watt bulb is only a 2 Amp draw from the 12 V car battery.
Most car batteries can deliver 2 or 3 Amps for several hours without much change in voltage.

Please try letting it run all night & let us know what you find.

Thanks again,


Offline DreamThinkBuild

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Re: Crude looping setup
« Reply #5 on: May 15, 2011, 10:53:53 PM »
Hi Penno,

What is the wattage rating on the smart charger? Find the closest inverter to the wattage rating to reduce switching amps.

Offline ibpointless2

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Re: Crude looping setup
« Reply #6 on: May 16, 2011, 04:34:06 AM »
I've tried it but I didn't have the 25 watt light bulb, figured it was not needed.

I used a 400Watt black and decker square wave inverter and a BatteryMinder smart charger that pulse charges when the battery is fully charged. I hooked it all up to feed back to the battery, the battery read 12.09 volts when everything was hooked up. The battery is a size 16 jet ski battery. It held at 12.09 for about 10 minutes until it went to 12.08 volts. It kept on dropping after that.

This for me doesn't not work, you have too many losses in the system. But It did seem to slow down the consumption of power being used doing it this way.

Offline FatBird

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Re: Crude looping setup
« Reply #7 on: May 16, 2011, 10:38:51 PM »
Any further results Penno?