Gary M Posted July 23, 2021 Share Posted July 23, 2021 (edited) Got my coach out of shop yesterday. Since it sat there for two weeks I decided to just check volts in house and engine batteries with my VOM. First ground lead then positive and got a spark on both sets. Is the problem my VOM or is it something else? Tried testing a truck battery and the VOM did not register. So its now either dead or maybe fuse inside if there is one. Cheap Cen-Tech VOM by the way but dont want to use my good VOM and screw it up too. Any help appreciated. Edited July 23, 2021 by Gary M Link to comment Share on other sites More sharing options...
John Haggard Posted July 23, 2021 Share Posted July 23, 2021 23 minutes ago, Gary M said: Got my coach out of shop yesterday. Since it sat there for two weeks I decided to just check volts in house and engine batteries with my VOM. First ground lead then positive and got a spark on both sets. Is the problem my VOM or is it something else? Tried testing a truck battery and the VOM did not register. So its now either dead or maybe fuse inside if there is one. Cheap Cen-Tech VOM by the way but dont want to use my good VOM and screw it up too. Any help appreciated. So what is your question??? At a hundred to three hundred dollars a batterie, I wouldn't use anything but a decent meter You can make one for a few $$$s with parts from an auto parts store. Or buy real nice ones for not many $$$s Call triple A if you don't want to use your meter Link to comment Share on other sites More sharing options...
Guest Ray Davis Posted July 23, 2021 Share Posted July 23, 2021 (edited) Is it a digital meter with a screen for the numbers? I imagine it is, anyway the only way the meter should spark is if it's on the wrong setting, probably set for amps. If it was, that probably ruined the meter or at least a fuse inside. Edited July 23, 2021 by Ray Davis Link to comment Share on other sites More sharing options...
Gary M Posted July 23, 2021 Author Share Posted July 23, 2021 22 minutes ago, John Haggard said: So what is your question??? At a hundred to three hundred dollars a batterie, I wouldn't use anything but a decent meter You can make one for a few $$$s with parts from an auto parts store. Or buy real nice ones for not many $$$s Call triple A if you don't want to use your meter Sorry my question was in the middle of the post. Could problem be batteries or VOM which is causing spark. It didn’t spark when I tested truck batts. Why would it only spark on coach batts? 4 minutes ago, Ray Davis said: Is it a digital meter with a screen for the numbers? I imagine it is, anyway the only way the meter should spark is if it's on the wrong setting, probably set for amps. If it was, that probably ruined the meter or at least a fuse inside. It was set on 20 DCV. It sparks on coach batts but not truck batteries. Link to comment Share on other sites More sharing options...
John Haggard Posted July 23, 2021 Share Posted July 23, 2021 Turn your battery switches off. Turn your inverter off. Remove the ground wire from the batteries. Let sit for 30 to 60 minutes without any charge. Then re test and see what happens Link to comment Share on other sites More sharing options...
Gary M Posted July 23, 2021 Author Share Posted July 23, 2021 Well not sure what happened but my good VOM doesn’t have a problem with checking batteries. 12.7 engine, 12.4 house. Fixed my own issue I guess. Human error???? Link to comment Share on other sites More sharing options...
Ivan K Posted July 23, 2021 Share Posted July 23, 2021 (edited) Wrong comment removed Edited July 23, 2021 by Ivan K 1 Link to comment Share on other sites More sharing options...
John Haggard Posted July 23, 2021 Share Posted July 23, 2021 33 minutes ago, Gary M said: Well not sure what happened but my good VOM doesn’t have a problem with checking batteries. 12.7 engine, 12.4 house. Fixed my own issue I guess. Human error???? Is that reading during charge 🤔 If so. It won't tell you the health of the batteries. Just the charge they are receiving Link to comment Share on other sites More sharing options...
Gary Cole Posted July 23, 2021 Share Posted July 23, 2021 Gary, the spark indicated that current somehow flowed in your meter test circuit. You probably blew the typical 10 amp fuse in the meter. Easy to replace. The truth about most all handheld digital multimeters is that they all use the same type of transistor which probably cost about a nickel in bulk lots. I once checked a $30.00 Harbor Freight meter against a $5000.00 test bench instrument and found that they agreed to 1 and 2 significant digits ( the resolution limit of the cheap meter) when measuring the 3 basic functions. An insignificant difference giving what most people use a meter for. What one should look for in an inexpensive meter is one with a button, usually labeled REL, which is used to zero out resistance in the internal circuit and the test leads, Which in turn compensates for cheap leads, rotary dials, and other assorted things. I've seen $60.00 meters with this function. Link to comment Share on other sites More sharing options...
Rikadoo Posted July 23, 2021 Share Posted July 23, 2021 (edited) Perhaps, looking at your picture if you had your red lead in the amp hole rather than the voltage hole that could be a issue Edited July 23, 2021 by Rikadoo Link to comment Share on other sites More sharing options...
Gary M Posted July 24, 2021 Author Share Posted July 24, 2021 6 hours ago, Gary Cole said: Gary, the spark indicated that current somehow flowed in your meter test circuit. You probably blew the typical 10 amp fuse in the meter. Easy to replace. The truth about most all handheld digital multimeters is that they all use the same type of transistor which probably cost about a nickel in bulk lots. I once checked a $30.00 Harbor Freight meter against a $5000.00 test bench instrument and found that they agreed to 1 and 2 significant digits ( the resolution limit of the cheap meter) when measuring the 3 basic functions. An insignificant difference giving what most people use a meter for. What one should look for in an inexpensive meter is one with a button, usually labeled REL, which is used to zero out resistance in the internal circuit and the test leads, Which in turn compensates for cheap leads, rotary dials, and other assorted things. I've seen $60.00 meters with this function. Ya know I appreciate all comments but what ever I did all is well including my cheap VOM meter. I checked it with engine running to se out put of alternator. I checked it with gen running to see charge rate. Checked it with all off. 4 hours ago, Rikadoo said: Perhaps, looking at your picture if you had your red lead in the amp hole rather than the voltage hole that could be a issue I agree but what u see is how it was. 4 hours ago, Rikadoo said: Perhaps, looking at your picture if you had your red lead in the amp hole rather than the voltage hole that could be a issue It is in volt hole. Other above is amps. 1 Link to comment Share on other sites More sharing options...
John Haggard Posted July 24, 2021 Share Posted July 24, 2021 11 minutes ago, Gary M said: Ya know I appreciate all comments but what ever I did all is well including my cheap VOM meter. I checked it with engine running to se out put of alternator. I checked it with gen running to see charge rate. Checked it with all off. I agree but what u see is how it was. It is in volt hole. Other above is amps. Right on Gary 1 Link to comment Share on other sites More sharing options...
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