Originally Posted by Raz
We disagree here. These monitors were designed with large solar
in mind. The smallest shunt is 100 amp. For folks using s single battery you are operating in the bottom 10% of the range. With a 1 millivolt per amp resolution accuracy at fractions of an amp, is doubtful. Unfortunately, when folks spend $200 on a battery monitor they wish to believe. Now folks that run an inverter, that's a different story. Still, spending $200 to get every ounce out of a $100 battery. There is a lot of snake oil on those solar sites.
While I do respect your opinion (because it is apparent that your really know this stuff), I think there is more science behind the Bogart Engineering products than most so I would not lump them in with the solar snake oil crowd.
But you got me wondering so I just now ran a little experiment. I put a digital multi-meter in series with a LED bulb, powered by a 12 VDC outlet in the Scamp
The digital meter read 102.5 mA with the LED on.
The TM-2030 readings showed an increase of .09 (90 mA) filtered* and .11 (110 mA) instantaneous with the LED on.
Perhaps this margin of error at very low levels will add up, but will also be less with things like a 1.5 – 3 amp draw from a fan. Bogart makes this claim: “With 100A/100mV shunt 0.00-300 Amps, resolution 0.01 Amp. ±1% ± least significant digit.”
But accuracy and cost effectiveness aside, the thing I really like about is the convenience. Just push a button a few times and get all sorts of readings. I don’t regret buying it at all. It would be a good test to compare the TM-2030 value of percent battery charge against a hydrometer reading, but since I like convenience and hate acid burns
, I will leave that for another time.
Second would be the knowledge that its about impossible for me to unexpectedly end up with a dead battery, especially while boondocking
in the middle of nowhere.
Maybe I like it so much because I paired it with the SC-2030 solar charger. Just one of the things I like is that in this config it tells you when there is spare solar power
available, and you know that you can charge phones, etc. without even drawing from the battery (or at least drawing less because it is supplemented with solar).
Actually I do have a issue with my setup. I cannot for the life of me get a good spec sheet on the battery. I had to take a sawg at the capacity and more than any other variable, that one probably limits the accuracy for me. The next battery will be from a manufacturer who provided decent documentation.
Everything in the camper was off except for a propane
detector (rated at 75 mA but not measured) and the TM-2030 which uses about 30 mA when display is on (according the published specs).
The TM-2030 readings with the LED on were .21 and .20 (with the two values alternating but more often on .21). The filtered value was .20 (200 mA). With the LED off the reading was .10 but the filtered value was .11.
* Filtered values are an “average value” taken over 140 seconds and the figure used by the monitor to avoid monetary fluctuations in the data. For my measuring I allowed for five minutes with the LED both on and off before reading the filtered value.