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Hi guys anybody know of a good make of battery tester

I recently bought a BA-101 Ancel battery tester. Seems to give good results when direct connected to a range of batteries that I know are good or bad. Does not give accurate results when connected to the Battery in my Touareg via the remote jump start connections under the bonnet ( Hood) for the battery under the seat.

cheers
Rohan

rgh0 wrote:I recently bought a BA-101 Ancel battery tester. Seems to give good results when direct connected to a range of batteries that I know are good or bad. Does not give accurate results when connected to the Battery in my Touareg via the remote jump start connections under the bonnet ( Hood) for the battery under the seat.

cheers
Rohan

I thought vehicle-battery testers were generally designed with sharp points intended to be pressed firmly directly onto the output terminals of the battery itself.

Otherwise the (low) resistance of whatever cables you use will cause erroneous readings.
Very high currents are used during battery testing as low currents won't 'say' much about the internal resistance of the battery.

billwill wrote:

rgh0 wrote:I recently bought a BA-101 Ancel battery tester. Seems to give good results when direct connected to a range of batteries that I know are good or bad. Does not give accurate results when connected to the Battery in my Touareg via the remote jump start connections under the bonnet ( Hood) for the battery under the seat.

cheers
Rohan

I thought vehicle-battery testers were generally designed with sharp points intended to be pressed firmly directly onto the output terminals of the battery itself.

Otherwise the (low) resistance of whatever cables you use will cause erroneous readings.
Very high currents are used during battery testing as low currents won't 'say' much about the internal resistance of the battery.

These modern testers send a small high frequency alternating current through the battery to measure the "conductance" this can apparently be directly correlated to battery condition once information is input into the measuring device of type of battery and its original capacity. This is why direct connection to the battery is required as the vehicle wiring has its own conductance which can then give erroneous results.

The Ancel BA-101 is a basic device, fancy professional devices cost 10 times more but do the test across a range of frequencies which apparently gives a more reliable result.

When battery testing of the type you are referring to is done a high current is discharged for a short period through a resistor for a short period and measurements made of current and voltage drop to similarly determine battery condition. Thus they need a direct connection using high current capacity cables.

cheers
Rohan