# Battery load test question

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#### carnage

##### Enlightened
What size resistors do I need to do a load test with AAA,AA,D size batteries?

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#### TinderBox (UK)

##### Flashlight Enthusiast
Do you know how accurate they are? Have you tried it against a DMM reading?

A DMM does not load a battery while testing, Also you cannot disable the load on this battery tester, So i cannot compare like for like.

My DMM shows an Eneloop AA at 1.3305v

The battery tester with low load = 1.33v
med load = 1.33v
high load = 1.31v

John.

C

#### carnage

##### Enlightened
A DMM does not load a battery while testing, Also you cannot disable the load on this battery tester, So i cannot compare like for like.

My DMM shows an Eneloop AA at 1.3305v

The battery tester with low load = 1.33v
med load = 1.33v
high load = 1.31v

John.

I was watching a Youtube video where a guy was using a resistor to put a load on the battery to measure the draw. People was replying that he was using a resistor that was to low to measure current drain.

#### TinderBox (UK)

##### Flashlight Enthusiast
I was watching a Youtube video where a guy was using a resistor to put a load on the battery to measure the draw. People was replying that he was using a resistor that was to low to measure current drain.

CPF member HKJ will most likely know.

John.
[h=1][/h]

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#### carnage

##### Enlightened
CPF member HKJ will most likely know.

John.

Thanks for the replies!

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#### terjee

##### Enlightened
Quick note: it's probably be really fiddly, but you could use both the battery tester and DMM at the same time. The load from the battery tester would drag the voltage down for the DMM as well, allowing for comparison.

It would however be a bit surprising if the battery tested is way off however. Even \$2 DMMs off of eBay usually get the voltage reading in this range somewhat right, with decent margins.

What you're paying for with a more expensive DMM are things like safety, features, getting the hard readings (small and large values) right, a more accuracy than you really need.

Using a resistor is also entirely possible, just a bit of work to get everything just right.

W

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#### carnage

##### Enlightened
Thanks for the replies!