Thread: Trying to figure out Livescope mounting with limited options

A quick online search says that Livescope can run on 10-32V.

If that is the case, I have two 9AH AGM batteries that start out around 13V. I want to run them together for longer use during the day.

Would it be best to:

1. Run them in parallel, starting out @13V? (12V nominal)
2. Run them in series, starting out @26V? (24V nominal)

Is there any benefit or detriment to running them at the higher voltage, or will it run the same either way?

Thanks.

Originally Posted by thill

A quick online search says that Livescope can run on 10-32V.

If that is the case, I have two 9AH AGM batteries that start out around 13V. I want to run them together for longer use during the day.

Would it be best to:

1. Run them in parallel, starting out @13V? (12V nominal)
2. Run them in series, starting out @26V? (24V nominal)

Is there any benefit or detriment to running them at the higher voltage, or will it run the same either way?

Thanks.

Run in parallel. The run time is actually the same but easier to recharge and you won’t forget it’s wire for 24v and fry something else down the road.

Volts x amps = watts

Watts / volts = amps

Ah in parallel is Ah + Ah, volts stay the same
Ah in series is volts + volts, Ah stays the same.

Parallel will double the amp capacity/run time.


Sent from my iPhone using Tapatalk

First, thanks for the quick replies and good reasoning. And I agree with everything said. But I'm curious about one thing in particular.

Both methods produce the same AH, but one is at a higher voltage, and I keep hearing that the Livescope doesn't like low voltage.

Run in parallel, full charge is @ 13V. At 50% charge, it's down to say, 12.0V.
Run in series, full charge is @ 26V. At 50% charge, it's only down to 24.0V.

In parallel, at 25% charge, is probably down to 11.5V, and flashing low voltage warnings.
In series, at 25% charge, it's still giving 23V.

Of course, both are going to die at the same time, but is staying higher in the voltage range a good thing? I guess that's the big question.

Does this make sense?

Trying to avoid having to buy more/better batteries.

Thanks again.

Ok I'm on my computer so this is a little easier. Two identical batteries doubles your runtime in any configuration. Since the GLS10 can operate in a range of voltages you get to pick that configuration. A device that can not run at ~24v limits you to running the batteries in parallel.

Here's the science behind it. While an engineer or troll could pick this apart because nothing is a perfect apples to apples comparison and precise math would have bell curves and powers and blah blah blah. The simple math is this.

A device (like a lightbulb) consumes a pretty constant amount of power.
A Battery has a relatively known capacity, though manufactures pick and choose how they want to declare this, Amp Hours or Ah is a common way.
An amp hour is a 1 amp draw for 1 hour.
Since our batteries are 12v, let's assume we have a 12v 1 amp light bulb. The energy consumed would be measured in Watts. 12v * 1a = 12watts.
The batteries in question are 9Ah. Each fully charged battery could support that lightbulb for 9 hours each.
BUT, let's double the batteries. 2 9ah batteries in parallel produce 12v, but the capacity is doubled so now together in parallel you get an 18ah battery(configuration). The same light bulb can now be run for 18 hours.

Now lets say that lightbulb can safely operate at 24v. It's still a 12 Watt bulb so now it only draws .5 amps (12w/24v=.5a).
In order to produce 24 volts you need to wire the 9ah batteries in series. This time the voltage is doubled, not the capacity. This is now a 24v 9ah battery. Since the bulb now uses half the amperage. 9ah / .5a = 18 hours run time.

The GLS10 peaks at 58 Watts.
58w / 24v = 2.42A. 2 in series runs this for 3.72 hours. (9ah/2.42a=3.72hours)
58w / 12v = 4.84A. 2 in parallel runs this for 3.72 hours. (18ah/4.84a=3.72hours)

You can use smaller gauge wires on a 24v system, so that's one advantage.

The RMS however is 21 watts so you could probably run about twice as long in reality.
The graph(fish finder) itself is not considered in this illustration.

On my boat I have 4 20ah batteries in parallel (1 charger bank this way). All of my graphs etc. are connected to it. I don't have any strange grounding issues, motor noise, etc. I had the batteries leftover from doing solar array experiments.

Something else to note is that a battery could be 80ah but might only support a 20 amp load for 2 hours rather than 4 hours (more bell curves and crap that makes my head hurt). Every battery is different in this regard, and for our electronics, understanding that is not really necessary.
Temperature is also a factor in capacity plus, if you fish sub freezing, you don't want lead acid (over drawing will make it freeze and ruin it). If you recharge below 35-40 degrees you don't want lithium (they won't recharge or might get damaged, but you can overdraw them without issue).

Well I had typed out a formula and came up to 36 hours but I think I’m way off. And after reading the above I’ll be quiet so no one knows I’m a fool but me. Lol. Lol.

Originally Posted by thill

First, thanks for the quick replies and good reasoning. And I agree with everything said. But I'm curious about one thing in particular.

Both methods produce the same AH, but one is at a higher voltage, and I keep hearing that the Livescope doesn't like low voltage.

Run in parallel, full charge is @ 13V. At 50% charge, it's down to say, 12.0V.
Run in series, full charge is @ 26V. At 50% charge, it's only down to 24.0V.

In parallel, at 25% charge, is probably down to 11.5V, and flashing low voltage warnings.
In series, at 25% charge, it's still giving 23V.

Of course, both are going to die at the same time, but is staying higher in the voltage range a good thing? I guess that's the big question.

Does this make sense?

Trying to avoid having to buy more/better batteries.

Thanks again.

Now that I think about it, the 9ah may not support a 5 amp load. Connecting it in series won't improve that, but by connecting them in parallel you have better chances.
Your batteries shouldn't be drawn down to 10v, at least not for a while, but if you can't provide the 5 amps when it wants, that's a problem. It's like having jumper cables that are too small, sure it's 12 volt, but the car aint gonna start.

Originally Posted by thill

A quick online search says that Livescope can run on 10-32V.

If that is the case, I have two 9AH AGM batteries that start out around 13V. I want to run them together for longer use during the day.

Would it be best to:

1. Run them in parallel, starting out @13V? (12V nominal)
2. Run them in series, starting out @26V? (24V nominal)

Is there any benefit or detriment to running them at the higher voltage, or will it run the same either way?

Thanks.

The only thing you are avoiding there is the potential low voltage from a 12v battery that's getting into the lower operating range. Livescope really works best in the mid 12s and up.

As mentioned, from a runtime standpoint you are not gaining anything, 6 of one, half dozen of another.