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Author Topic: An Idiots battery tester  (Read 2485 times)

ddraigmor

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An Idiots battery tester
« on: September 07, 2008, 05:08:11 PM »

Being the simple man that I am, can any of you experienced gents recommend a battery tester (by brand name, seller etc) that will work happily on 6v 3ah batteries but could also be used to test other types of SLA batteries? One that even an idiot (such as I) am able to use.....?

I look forward to the wealth of knowledge about to pour down upon me!

Jonty
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barriew

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Re: An Idiots battery tester
« Reply #1 on: September 07, 2008, 05:29:07 PM »

As long as you don't want to go above 6volts, I don't see why the Rx battery testers that Model Power and others sell wouldn't work. They are switchable between 4.8 and 6 volts and display the 'reading' via coloured LEDs. They are designed to plug into receivers, so you would have to remove the plug and put croc. clips or similar on. Otherwise you are probably into a digital multi-meter - read Footski's thread for that {-)

Barrie
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barryfoote

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Re: An Idiots battery tester
« Reply #2 on: September 07, 2008, 06:58:15 PM »

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sheerline

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Re: An Idiots battery tester
« Reply #3 on: September 07, 2008, 11:47:29 PM »

Barriew, Jonty's idea is a good one, its a very basic bit of kit but it will certainly tell you when your battery is getting low. You should be able to pick one up fairly cheaply and a model shop will probably stock them.
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FullLeatherJacket

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Re: An Idiots battery tester
« Reply #4 on: September 08, 2008, 08:27:56 AM »

Here's a suitable gizmo with a familiar name attached......... I've built one and it works a treat; so much so that it's now an essential part of my workshop test equipment. Thanks, dude!

http://www.pm.keirle.com/ESV/ESV.HTM

FLJ
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barry park

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Re: An Idiots battery tester
« Reply #5 on: September 08, 2008, 09:38:44 AM »

Gizmos are easy to fit inside boats.
It takes a voltmeter(a battery tester) to calibrate one.

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barriew

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Re: An Idiots battery tester
« Reply #6 on: September 08, 2008, 10:57:59 AM »

Barriew, Jonty's idea is a good one, its a very basic bit of kit but it will certainly tell you when your battery is getting low. You should be able to pick one up fairly cheaply and a model shop will probably stock them.

I think you meant " Jonty, Barriew's idea is a good one" ;D

Barrie
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sheerline

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Re: An Idiots battery tester
« Reply #7 on: September 08, 2008, 12:33:29 PM »

Its an age thing Barrie...well thats my excuse anyway! :'(
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ddraigmor

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Re: An Idiots battery tester
« Reply #8 on: September 08, 2008, 05:36:45 PM »

 :D What's that song by ELO? Oh yes, 'Confusion....'  :D

The multimeter idea looks good - but again, is very confusing (yup, I read the thread....)

I just want something I can stick the prongs on to the terminals and it will tell me - by flashing, lighting up LED's or simply showing the voltage on a screen - what I have got.

I told you that you were working with an idiot!  ::)

Ta for the replies so far!

Jonty
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barriew

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Re: An Idiots battery tester
« Reply #9 on: September 08, 2008, 05:45:42 PM »

Jonty,

This is what I was talking about - 4.95 from Model Power. As I said you would need to remove the plug and fit croc clips. If you don't feel confident doing that I have one of these which I will modify and sell to you for 7.50 including postage.

Barrie

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ddraigmor

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Re: An Idiots battery tester
« Reply #10 on: September 12, 2008, 10:41:25 AM »

Barrie,

I'll look it up at Model Power but I can fit the clips on - thanks for the offer!

Looks ideal - simple, for a simple man!

Jonty
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malcolmfrary

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Re: An Idiots battery tester
« Reply #11 on: September 12, 2008, 11:40:02 AM »

The big problem with simple battery testers is that they can only tell you what the voltage available is.  This is useful, but can also be misleading, as you can never actually know how much is in there and whether it can be delivered.  With a lot of note taking, you can know how much WAS in there.
The LED unit is a good easily read item, the meter will tell you the voltage in numbers with more detail, but neither will tell what can be delivered by the battery.  Its a bit like having a depth gauge on a fuel tank without knowing what the size of the tank is, or if the outlet filter is blocked.
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"With the right tool, you can break anything" - Garfield

catengineman

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Re: An Idiots battery tester
« Reply #12 on: September 12, 2008, 07:25:11 PM »

True,

I had a 12 volt SLA which showed 12.8 volts on the meter but connect a light up and it lasted all of about 1 second

R,
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sheerline

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Re: An Idiots battery tester
« Reply #13 on: September 12, 2008, 08:52:47 PM »

Any meter reading a voltage direct from a battery will invariably show you an indicated off load voltage... and thats it! It will never tell you how much current capacity is left in the pack. Using a water analogy, you know there is water in a tank because it comes out of the tap but you can't see in it so you don't know how much. Different batteries behave differently during discharge, for instance, nicads will keep going and then drop off suddenly whereas dry cells will slowly keel over from the moment you start using them. A battery's vlotage is best checked when it is being put to work and current is being drawn, then the voltage will drop and if the thing is virtually flat the voltage will start dropping off fairly rapidly. Another indication might also be the voltage recovery time when the load is removed but as with all things, a bit of experience with meters and batteries is usually called for before any of it gives you a feel for whats going on.
If you have doubts about a battery's condition this can easily be verified by first knowing what your boats maximum current drain was when you first installed your new fully charged battery, theoretical run time should have been calculated against the battery's current capacity. An initial run on the pond can be used to verify this and may actually exceed it. When run times begin to fall off, a quick current reading at max throttle will tell you if the current has increased due to tight proshaft bearings, faulty motor etc and if they are much the same as they were when you first tested them, your battery is probably stuffed so it's off to Maplins with you!

 Current readings should be considered the God of the model boater, they tell you all you need to know about the health and efficiency of your setup, it can prevent you from burning out motors prematurely, wasting battery run times and cooking speed controllers.... and stop you wasting money on a battery you didn't need. This is so very true for the model submariners where we consider minimum current drain to be the ultimate goal and I think most of us are familiar with current readings... or should be!
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