- Joined
- Jul 28, 2017
- Messages
- 2,366
I recently bought a pair of igaging DROs with the stainless steel scales, a 6" and a 12" to install on my mini lathe. I made all the mounts and mods needed to install the 12" scale for the Z axis and moved on to thinking about how to attach the 6" to my cross slide. But I noticed that the batteries for the 12" went flat very quickly, in less than 1 week. I thought perhaps the batteries that came with the DRO were old to start with, so I replaced them with some I knew were pretty fresh. Well, they went flat very quickly as well.
Thinking that the problem had to be defective electronics -- either the display unit or the sensor -- I measured the supply current drawn by both units, using the 6" as a reference because it doesn't seem to have a problem. But BOTH units drew about the same amount of current, right around 70 micro-amps! I used a variable lab-style power supply and DVM to measure the current, so the batteries were removed to perform the testing. I examined the battery compartment, thinking that perhaps the problem was related to how the batteries were installed in the DRO -- but I didn't find anything obviously wrong, except that the two batteries are placed side-by-side so closely that they can touch. If the batteries were series-connected (to provide 6V) that would be a problem, but, again using my DVM, I found that the batteries are connected in parallel. So even if the batteries were touching (in this case it would be their two + terminals), that wouldn't be a problem.
BTW, parallel-connecting batteries isn't a great approach to address a capacity problem because you never want to use a fresh/old combination of batteries. The old one could potentially discharge the new one, depending on how old it is.
So at this point I don't know what's going on. Has anyone else experienced this kind of problem? If so, how was it addressed? I'm thinking the 12-incher will likely be going back where it came from, but it still bothers me as to what's wrong with it.
Thinking that the problem had to be defective electronics -- either the display unit or the sensor -- I measured the supply current drawn by both units, using the 6" as a reference because it doesn't seem to have a problem. But BOTH units drew about the same amount of current, right around 70 micro-amps! I used a variable lab-style power supply and DVM to measure the current, so the batteries were removed to perform the testing. I examined the battery compartment, thinking that perhaps the problem was related to how the batteries were installed in the DRO -- but I didn't find anything obviously wrong, except that the two batteries are placed side-by-side so closely that they can touch. If the batteries were series-connected (to provide 6V) that would be a problem, but, again using my DVM, I found that the batteries are connected in parallel. So even if the batteries were touching (in this case it would be their two + terminals), that wouldn't be a problem.
BTW, parallel-connecting batteries isn't a great approach to address a capacity problem because you never want to use a fresh/old combination of batteries. The old one could potentially discharge the new one, depending on how old it is.
So at this point I don't know what's going on. Has anyone else experienced this kind of problem? If so, how was it addressed? I'm thinking the 12-incher will likely be going back where it came from, but it still bothers me as to what's wrong with it.