Help dealing with voltage drop

[Freep]

I'm having trouble finding a DC-DC voltage booster that will go from 12v to 60v. I've searched for days.

In our off grid fishing cabin we have a water pump that is 50 feet from the house, which is where the battery is. The pump runs 12v and tops out at 19amps. The line we are installing is 8 gauge copper.

Going from 12v to 60v drops my loss from ~10% to .5%. So it's definitely worth doing since we already have a weak/sluggish pump running 12v over 12 gauge.

Since this is a remote fishing cabin, the booster needs to be reliable. I keep finding some products that seem OK but then I see the reviews which mention a lot of failures.

For example

https://www.amazon.com/Voltage-Converter-Supply-Module-10-60V/dp/B07N6BJWXH

This would be ideal if it were reliable, had an enclosure and could run continuously for 30 minutes in summer heat. If you know of a great product for this, please let me know.

 

[MisterSandals]

The line we are installing is 8 gauge copper.

Going from 12v to 60v drops my loss from ~10% to .5%. So it's definitely worth doing since we already have a weak/sluggish pump running 12v over 10 gauge.

Have you considered running both the existing 10AWG as well as the 8AWG you mentioned, together? A little more wire would be a lot more reliable than 2 voltage converters.

 

[DThames]

Where is your 12v source coming from? Would starting with a 48v source be an option?

I just bought one of those boost converters that you referenced. I have tested it a little but only a little. Made it pull 20amps at 25v on the input, to make 12amps, 40v on the output.

 

[rmaddy]

If you use 2AWG wire for the 12V 20A run to the pump you will be under 3% voltage drop.
If you go to 48V then 8AWG will keep the drop just under 3%. 6AWG will keep it under 2%.

You will likely have more luck finding 12V-48V and 48V-12V converters than 60V.

 

[Freep]

Have you considered running both the existing 10AWG as well as the 8AWG you mentioned, together? A little more wire would be a lot more reliable than 2 voltage converters.

That's an interesting idea. Do you have any idea how much of a deviation in length you can have for a run like that? How would I calculate the gauge?

 

[Freep]

Where is your 12v source coming from? Would starting with a 48v source be an option?

I just bought one of those boost converters that you referenced. I have tested it a little but only a little. Made it pull 20amps at 25v on the input, to make 12amps, 40v on the output.

It's coming from a 12V AGM battery that runs lights and radio in the house. 48V source isn't an option.

 

[MisterSandals]

How would I calculate the gauge?

I would get the AWG cross section area in mm^2, add them, and then reverse lookup mm^2 to AWG.

 

[DThames]

If you could put your power switching (remote) at the pump site and could put a small 12v battery at the site, in parallel with your main battery, during pump operations the local battery could keep the voltage up. It would then "recharge" when the pump was off. Your main power run wouldn't need to be more than 14ga or something just heavy enough to allow the current to recharge the local battery.

 

[Freep]

If you could put your power switching (remote) at the pump site and could put a small 12v battery at the site, in parallel with your main battery, during pump operations the local battery could keep the voltage up. It would then "recharge" when the pump was off. Your main power run wouldn't need to be more than 14ga or something just heavy enough to allow the current to recharge the local battery.

Is it as simple as wiring up the pump battery to the house battery? Are there any issues if the house battery is AGM and the pump is a smaller FLA?

 

[DThames]

Is it as simple as wiring up the pump battery to the house battery? Are there any issues if the house battery is AGM and the pump is a smaller FLA?

Somewhere, you have a switch that turns on the pump. To use this approach, you need to,
1. put a battery at the pump location
2. put a relay at the pump location to turn on the pump, connecting it to the pump battery
3. put control wiring in from where you control the pump to the relay at the pump location
4. run some wires to the pump battery so that it will charge off of the main battery. You might want to put a series diode or two in the charge circuit to drop the voltage to your FLA battery so it doesn't see the higher voltage of the AGM.

Your pump "on" circuit will turn on the relay at the pump and the pump will run off of that battery, draining it a bit, while at the same time, it will be taking some power via your charging wiring. If you drop a volt or two over that wire, not a problem. After the pump is off, the pump battery will go back to the resting voltage after some amount of power has flowed into it, replacing what the pump pulled. That way your wire run doesn't have to be large wires. But you will need a local battery that will carry the pump load for that time that it is normally on.

 

[Freep]

Somewhere, you have a switch that turns on the pump. To use this approach, you need to,
1. put a battery at the pump location
2. put a relay at the pump location to turn on the pump, connecting it to the pump battery
3. put control wiring in from where you control the pump to the relay at the pump location
4. run some wires to the pump battery so that it will charge off of the main battery. You might want to put a series diode or two in the charge circuit to drop the voltage to your FLA battery so it doesn't see the higher voltage of the AGM.

Your pump on circuit will turn on the relay at the pump and the pump will run off of that battery, draining it a bit, while at the same time, it will be taking some power via your charging wiring. If you drop a volt or two over that wire, not a problem. After the pump is off, the pump battery will go back to the resting voltage after some amount of power has flowed into it, replacing what the pump pulled. That way your wire run doesn't have to be large wires. But you will need a local battery that will carry the pump load for that time that it is normally on.

I should have mentioned that the pump is triggered by a drop in water pressure. So it's remotely switched.

I don't know anything about series diodes, I'll have to look into that.

Thanks!

 

[DThames]

I should have mentioned that the pump is triggered by a drop in water pressure. So it's remotely switched.

I don't know anything about series diodes, I'll have to look into that.

Thanks!

A normal diode will drop 0.6v. If charge your AGM to 14.4v, minus 0.6, your FLA would see 13.8, or with 2 diodes in series, 13.2. Germanium diodes (from memory) drop 0.3v maybe. Anyway, you can tweak the voltage with diodes.

 

[krfish]

I believe rmaddy had it right, it will be cheaper to just run 2AWG wire...

 

[MisterSandals]

it will be cheaper to just run 2AWG wire...

I did a quick search for 2AWG and found $2.59-$2.75 /ft.... lets call it easily $3/ft taxed and shipped. 100' = $300.

That sounds like the most expensive option mentioned. But probably the easiest and most reliable (which is worth something too!)

 

[Freep]

A normal diode will drop 0.6v. If charge your AGM to 14.4v, minus 0.6, your FLA would see 13.8, or with 2 diodes in series, 13.2. Germanium diodes (from memory) drop 0.3v maybe. Anyway, you can tweak the voltage with diodes.

But since I am already running across 50 feet of 12 gauge from the house battery I should be getting a voltage drop to begin with. So no need for a diode, right?

 

[Zwy]

I'm having trouble finding a DC-DC voltage booster that will go from 12v to 60v. I've searched for days.

In our off grid fishing cabin we have a water pump that is 50 feet from the house, which is where the battery is. The pump runs 12v and tops out at 19amps. The line we are installing is 8 gauge copper.

Going from 12v to 60v drops my loss from ~10% to .5%. So it's definitely worth doing since we already have a weak/sluggish pump running 12v over 12 gauge.

Since this is a remote fishing cabin, the booster needs to be reliable. I keep finding some products that seem OK but then I see the reviews which mention a lot of failures.

For example

https://www.amazon.com/Voltage-Converter-Supply-Module-10-60V/dp/B07N6BJWXH

This would be ideal if it were reliable, had an enclosure and could run continuously for 30 minutes in summer heat. If you know of a great product for this, please let me know.

Just a thought, wouldn't it be easier to just use an inverter and AC powered pump?

How often and how long does this pump run?

One more option, battery at the pump location and use a DC to DC charger from the house to charge it. The voltage drop will not really affect the DC to DC charger.

 

[DThames]

But since I am already running across 50 feet of 12 gauge from the house battery I should be getting a voltage drop to begin with. So no need for a diode, right?

What you call "voltage drop" is really I*R voltage drop. It approaches zero as the current approaches zero. If you have an AGM battery at the house and you add an AGM battery at the pump location, no need for anything else. The 12ga wire that you have will do fine. I mentioned the diode because you said something about a FLA battery at the pump. If you hold a higher voltage on that battery after it is charged, it will use the charging current to remove the water from the battery (over time). Two AGMs would be ideal, since you already have an AGM.

 

[12VoltInstalls]

50’ has voltage drop, sure. But it’s not that far. I’d just add a couple conductors and be done with it- nothing to break or get moisture damaged or buy twice.

 

[Freep]

What you call "voltage drop" is really I*R voltage drop. It approaches zero as the current approaches zero. If you have an AGM battery at the house and you add an AGM battery at the pump location, no need for anything else. The 12ga wire that you have will do fine. I mentioned the diode because you said something about a FLA battery at the pump. If you hold a higher voltage on that battery after it is charged, it will use the charging current to remove the water from the battery (over time). Two AGMs would be ideal, since you already have an AGM.

I'm having trouble finding the right diodes. The highest rated amperage I've seen is one amp and I know there could be up to 20 amps going through the line when it's under load.

 

[DThames]

Here is one.

Note, if you have a battery at the pump, the current between the batteries will be pretty low while the pump is running. Likely less than 50% of the pump load.