voltage discrepancy

I recently switched to lithium batteries and added a Garmin livescope to my 2 helix 10’s. Every thing is wired correctly, each unit on it’s own circuit with proper gauge wires, etc. I have fished with new rigging 4-5 times with no problems. Every thing works as it should. Why does my battery voltage show 13.1 on battery monitor (ionics bluetooth), 13.1 on volt meter at battery post and 13.1 on volt meter at each power plug that plugs into each unit. All 3 units show 12.2 volts on each unit screen and every thing else 13.1. What’s the deal. Any ideas?

Mine does same thing with regular deep cycle battery. I’ll have 12.7 at battery and 12.0 on deck unit. No idea why.


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The voltage readout the unit shows is not an amp meter of the voltage coming to the unit ...

Its the operating voltage - after the processor and screen brightness is deducted ...

Lower the screen brightness and watch the unit voltage readout increase ...

Rickie

I had no idea lol. I’ve been using it as a battery monitor for years.


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It’s not possible to accurately measure battery voltage on wires that have a load on them. Your units are displaying the voltage they are actually seeing. With that much drop, you probably have inadequate wiring. Good wiring you can generally get it down to 0.3V, but that’s about as close as you’ll get it.

Agree with the above. You can measure the voltage at the load, but it requires know-how to get around the insulation to get meter probes directly to the pins. I have a special set of probes with very sharp tips just for this.

I will also add that the voltage displayed by the graph might not be totally accurate, or representative of actual input voltage, as Ricky alluded to above. It is a good easy "watchdog" to how your power is doing, and that is what I want when fishing.

PS units matter; Amps are current, not voltage, and power (watts) is neither.

What CatFan said .... The voltage must be checked with normal load applied since there will be no voltage drop if there is no current flow.

The easiest way to do that is by looking at the reading on the unit as you are doing ..... The test Rickie recommended is one of the best ways to check how good your wiring and connections are. The voltage will vary as the brightness is turned up and down, but shouldn't drop more than 2-3 tenths of a volt if everything is healthy in the wiring circuit. It seems you are dropping over a volt from the battery to the unit .... So, you have bad connections or insufficient wire size for the load.