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Battery capacity tester ?

Larry DeCamp

Well Known Member
Yes,yes many threads on this. B&C agrees that buss voltage is the important thing to monitor in flight. So, I did not incorporate the Garmin shunt in my E system.

I would like to use it to make a battery capacity checker for EI back-up battery.
My question is, what is the easiest load to build ? Parallel light bulbs, series lightbulbs, carbon variable resistor ? Advice appreciated.
 
Look around here .. http://www.aeroelectric.com/ Bob had a battery load tester / charger somewhere on his site.

Basically it would time a discharge down to a set minimum, and then charge it back up ready for use. This is done in the hangar. You would know the health of the battery before your flight.
 
Yes,yes many threads on this. B&C agrees that buss voltage is the important thing to monitor in flight. So, I did not incorporate the Garmin shunt in my E system.

So... you won't have an Ammeter?
The B&C low voltage light will tell you if there is an immediate problem with the Alternator, but it won't tell you how hard it is working at any given time. An Ammeter gives you an indication of health ofall the other components in the system, such as batteries, or anything else that might start showing unusual power drain.
Installing a shunt is easy & you get an Ammeter that's already there.

Not filling the tool box with all the basic tools that's available doesn't make sense (to me).

As an alternate way to test the EI backup battery, I installed a momentary 2 way switch wired directly to each battery & an independent cheap (Amazon) volt meter which is easily accessible while doing the preflight walk around. A quick flip of the switch both ways gives the voltage readings of both batteries. If they don't agree - I don't go flying.
 
Yes,yes many threads on this. B&C agrees that buss voltage is the important thing to monitor in flight. So, I did not incorporate the Garmin shunt in my E system.

I would like to use it to make a battery capacity checker for EI back-up battery.
My question is, what is the easiest load to build ? Parallel light bulbs, series lightbulbs, carbon variable resistor ? Advice appreciated.

There are many different ways to test battery capacity.

I recently started using a new fangled battery tester that was not very expensive. I purchased mine a year ago for less than $20 before tax with free shipping.
 
Larry,

Battery Capacity is usually spec'd at a specified current. If you want to test a battery against its rated specs you need to create a load equal to that current. Then you can measure the time it takes to discharge. Again there is normally a rated voltage spec'd for the low end of the voltage measurement. So you have a fully charged battery, the required load and you start measuring the time until you reach the rated voltage. Then you multiply the current times the number hours to get the capacity in Ampere-Hours. That is technically how you measure the actual capacity of a battery. Now if you just want to test the battery then that is a different measurement.
 
I test my back up by measuring voltage via G3X and a stop watch on my phone. Although, the data card will also record the data. It works for the back up and the main battery. My panel has a back up switch, and for main, I just switch to main and set amps across the shunt.

My Dyson back up attitude has an internal battery and do the same thing as it has a voltage readout.

All this allows plotting volts vs time and with amps allows energy calculation. Total capacity is another matter.


Gary, that battery test tool looks very good!! I might want to have a more secure attachment, but it may not matter with the internal electronics.
 
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Many cheaper 300 to 500 watt inverters have an audible alarm and cut out just above where one loses a master relay solenoid, 10.5 ish volts.

Plug in one or 2 100 watt fans and time a 10 or 20 amp draw- your choice. 10 or 20 amps at 12 volts should be shed or no shed loads for many on battery only with a pad.

Recharge, reinstall if it passes. Recondition or replace if it does not.
 
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larry, There are carbon piles with variable resistance, but leaves you with an analog test apparatus.

Here is a $20 unit with either 10-100-300AMP shunt you could even use with the carbon pile to yield the data you might want. Download the manual and it will show you the schematics. Either fixed or adjustable resistors or a carbon pile can be used I would use a cell phone video to record a several minute event then can be played to get the data without missing it.

A little assembly and you could test any size battery to the voltage you want.

Good luck, Bill
 
Yes,yes many threads on this. B&C agrees that buss voltage is the important thing to monitor in flight. So, I did not incorporate the Garmin shunt in my E system.

I would like to use it to make a battery capacity checker for EI back-up battery.
My question is, what is the easiest load to build ? Parallel light bulbs, series lightbulbs, carbon variable resistor ? Advice appreciated.

I calculated how much wire I'd need to make it work--turns out a 100 foot roll (or was it two rolls?) of 14 gauge solid copper household wiring was perfect. I shorted the battery across that with an ammeter in series and voltmeter in parallel and it worked great.

Edit:

now, I remember. I think it was one 100 foot roll of two-conductor-with-ground. I wired the three conductors together to make one long 300 foot conductor with the instruments as described above.
 
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