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Old 09-07-2006
dave.verry dave.verry is offline
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OK, boys and girls, here’s what I propose for the experiment on current between paralleled batteries.

I have two AGM 92 AH batteries, one at 90% capacity and one at 55% capacity. I had finished a load test on them a couple of weeks ago so I know this is empirical data, not theoretical or estimated. Both batteries are Douglas Battery DGS12-100F and are eight years old.

Both batteries have spent the last several days on a charger and are fully charged as defined by the float current (both batteries where drawings less them 100 mA). They will sit disconnected from each other (and anything else) for the next 48 hours. At that point I will measure and record the open cell voltage of each battery.

I will then hard wire the negative terminals together using 8 AWG cable. At the start of the test I will connect a Fluke 8060A 5 ˝ digit (three decimal places, at the 12 V range. It will measure 1/1000 of a volt) DMM in current mode (measuring in the 2A to 1 milliamp range) between both positive terminals. I will record the current every 15 seconds (using a camera as my automated equipment will be in my lab, not my garage). The data point time interval will be modified as the change in current dictates (no use recording a lot of points of the same level. If the slope is flat I will modify the time between photographs, but that time interval will be recorded.) The temperature of the batteries will also be recorded.

Results will be graphically represented in this thread when completed.

This should answer any questions about current flow between paralleled batteries.

Comments? Suggestions? Hellosailor, you asked for this. Now is the time for comment.
Attached Images
File Type: jpg Test Bat.JPG (45.4 KB, 101 views)
File Type: jpg Bat Lable.JPG (72.7 KB, 96 views)
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