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Old 01-25-2021, 08:32 AM   #21
Bob Bidonde
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Default Re: How difficult would it be to convert this water heater from 12V to 6V?

This is another argument for converting to 12V. All the modern goodies are 12V negative ground.
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Old 01-25-2021, 10:29 AM   #22
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Default Re: How difficult would it be to convert this water heater from 12V to 6V?

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Running it on 6 volts would drop the power of the fans to one quarter of what it was. I would not recommend it. Power is proportional to the square of the voltage so halving the volts reduces the power to 1/4.
Power is proportional to the square of current. Fans will run about 1/2 speed.

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5 Volt fans computer fans are available on eBay. They could probably be run on 6 or 7 volts without any damage.
5V fans can be had, just be sure they're physically the same size. The heavy dimmer switch will keep the speed down at 7V, and they will last longer.
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Old 01-25-2021, 10:31 AM   #23
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Default Re: How difficult would it be to convert this water heater from 12V to 6V?

I was addressing the request in post #1 for a switch.
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Old 01-25-2021, 11:19 AM   #24
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Default Re: How difficult would it be to convert this water heater from 12V to 6V?

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This rheostat or another that is billed for auto fans would be better than an LED controller. https://www.amazon.com/Controller-Un...571361&sr=8-10

Thanks for the link.


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Old 01-25-2021, 01:17 PM   #25
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Default Re: How difficult would it be to convert this water heater from 12V to 6V?

This one rated to 6V -

https://www.amazon.com/RioRandTM-Upg..._t3_B07T35JDTR

The fans in post #9 have plastic housings, which are probably insulative, but check with an ohmmeter to make sure.

Fans don't draw much current; their labels will specify.
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Old 01-25-2021, 01:44 PM   #26
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Default Re: How difficult would it be to convert this water heater from 12V to 6V?

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Up to this point, I haven’t seen much of a compelling reason to convert to 12V. (My car normally starts on first crank on 6V.) But, I can see how 12V would be tempting. You are correct. Virtually everything I’ve found is for 12V.


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I stay current on the latest in electrical control for mobile equipment. Isolation of circuits and reducing switch load through the use of relays provides a method of controlling a wide variety of functions without running high amperage circuits throughout the car.
Its not that 6v cant do the job, its the availability of components that limits you. heat, AC, music, seat heaters, lighting, GPS, just about any addition you want to do is available in 12v. As you add components you raise your ampacity requirements, the model a generator is good to 30a,most off the shelf 12v alternators are under 100 bucks and provide 60a at the minimum..
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Old 01-25-2021, 01:51 PM   #27
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Default Re: How difficult would it be to convert this water heater from 12V to 6V?

A solution that you might consider: I have a 12 V power brick with both 12V and USB outputs that I carry with me to power my 12V accessories (like charge my phone) rather than mess around with trying to convert accessories. No reason you could not rig an SAE adapter to the 12V input of the fans and connect to the brick. Not elegantly wired in, granted, but you'd only need your heater part of the season and it might be acceptable to just run a pigtail down to the floorboard. You can also jump the battery using the 12V in a pinch.

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Old 01-25-2021, 06:04 PM   #28
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Default Re: How difficult would it be to convert this water heater from 12V to 6V?

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Originally Posted by Badpuppy View Post
This one rated to 6V -

https://www.amazon.com/RioRandTM-Upg..._t3_B07T35JDTR

The fans in post #9 have plastic housings, which are probably insulative, but check with an ohmmeter to make sure.

Fans don't draw much current; their labels will specify.

Thanks for the link.


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Old 01-25-2021, 06:11 PM   #29
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Default Re: How difficult would it be to convert this water heater from 12V to 6V?

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I stay current on the latest in electrical control for mobile equipment. Isolation of circuits and reducing switch load through the use of relays provides a method of controlling a wide variety of functions without running high amperage circuits throughout the car.
Its not that 6v cant do the job, its the availability of components that limits you. heat, AC, music, seat heaters, lighting, GPS, just about any addition you want to do is available in 12v. As you add components you raise your ampacity requirements, the model a generator is good to 30a,most off the shelf 12v alternators are under 100 bucks and provide 60a at the minimum..

Thanks for posting that picture. I think you posted it in the past on another thread, and I was thinking about hunting for it.

By any chance, would you have an Amazon link to it?


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Old 01-25-2021, 06:12 PM   #30
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Default Re: How difficult would it be to convert this water heater from 12V to 6V?

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A solution that you might consider: I have a 12 V power brick with both 12V and USB outputs that I carry with me to power my 12V accessories (like charge my phone) rather than mess around with trying to convert accessories. No reason you could not rig an SAE adapter to the 12V input of the fans and connect to the brick. Not elegantly wired in, granted, but you'd only need your heater part of the season and it might be acceptable to just run a pigtail down to the floorboard. You can also jump the battery using the 12V in a pinch.

JayJay

That’s an interesting thought.


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Old 01-25-2021, 06:25 PM   #31
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Default Re: How difficult would it be to convert this water heater from 12V to 6V?

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Thanks for posting that picture. I think you posted it in the past on another thread, and I was thinking about hunting for it.

By any chance, would you have an Amazon link to it?


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That's a custom design brother, I bought the pieces and figured the rest. The concept is simple, though in some places I ran multiple function off of one relay, for instance ignition, fuel pump and main relay to fire the fuse panel
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Old 01-25-2021, 08:03 PM   #32
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Default Re: How difficult would it be to convert this water heater from 12V to 6V?

Many of the parts I have found are advertised as 12V parts. However, for now, I think I'd like to stay with a 6V positive ground system and make smaller changes rather than make all of the bigger changes that would be required to convert to 12V. I'm not necessarily opposed to 12V in the future, but I recently purchased a new 6V horn, my 6V alternator works fine, my battery works fine, and my headlights work fine. For now, it doesn't make sense to replace a bunch of hardware that is working.

Based on the various responses to this thread, I think I have two viable paths to pursue when I purchase this heater (https://smile.amazon.com/dp/B08CZTND...v_ov_lig_dp_it) in the next couple of days or so. Please help me validate these ideas. I'm not very skilled with amps, wire gauges, etc., and I don't want start a wiring fire in my car.

Plan A (run everything at 6V):
  1. Hook up the heater fans "on the bench" to see how much air output is created by the 12V fans running on a 6V battery.
  2. If the 12V heater does not have satisfactory air output, proceed with Plan B.
  3. If the air output is satisfactory, proceed with the following steps.
  4. Add wire of my own to make the heater connections. Would 12 gauge wire be what I'll want to use?
  5. Add a dedicated fuse or circuit breaker between the battery and the heater. (I have a fuse on the starter, but I'm thinking that this heater should be separated from the starter fuse. Can someone help me find a suitable fuse or circuit breaker that will work with 6V systems? This https://smile.amazon.com/dp/B07QJ2T2...v_ov_lig_dp_it is the closest I have found so far, and it's 20A. I'm thinking 10A would be what I want, but I haven't found anything 6V rated at 10A.)
  6. Possibly add a potentiometer (https://smile.amazon.com/dp/B07T35JD...v_ov_lig_dp_it) for fan speed control. This is rated at 10A.

Plan B (add a 6V to 12V step up converter):
  1. As in Plan A, I'll have to add some wire of my own. Would 12 gauge wire be what I'll want to use?
  2. Add a 6V to 12V step up converter (https://smile.amazon.com/dp/B019GY2F...v_ov_lig_dp_it). This is rated at 10A.
  3. Add a dedicated fuse or circuit breaker between the battery and the 6V to 12V step up converter. (This is similar to what is in Plan A. I need help finding the right hardware.)
  4. Add a 12V fuse block (https://smile.amazon.com/dp/B07GBV2M...v_ov_lig_dp_it) to the 12V output side of the step up converter.
  5. Route the heater fan connection through the fuse block.
  6. Possibly route a 12V cigarette lighter outlet through the fuse block for phone charging.
  7. Possibly add a potentiometer (https://smile.amazon.com/dp/B07T35JD...v_ov_lig_dp_it) for fan speed control. This is rated at 10A.

Am I at risk of overloading anything with either of these plans? Do I have circuit protection in the correct places?
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Old 01-25-2021, 08:10 PM   #33
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Default Re: How difficult would it be to convert this water heater from 12V to 6V?

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That's a custom design brother, I bought the pieces and figured the rest. The concept is simple, though in some places I ran multiple function off of one relay, for instance ignition, fuel pump and main relay to fire the fuse panel
Thanks. You are WAY more skilled than I. :-)
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Old 01-25-2021, 08:18 PM   #34
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Default Re: How difficult would it be to convert this water heater from 12V to 6V?

I may be wrong, it has been many decades since I took electrical theory classes, but if the voltage is cut in half the fan speed will be cut by 1/4. Power is volts times current. I think the current is cut in half because the voltage is half and the voltage is half. So 1/2 times 1/2 is 1/4.
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Old 01-26-2021, 03:59 PM   #35
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Default Re: How difficult would it be to convert this water heater from 12V to 6V?

[QUOTE=Badpuppy;1977827]Power is proportional to the square of current. Fans will run about 1/2 speed.


See nkaminar's post at #34.
Yes, power is proportional to current squared but consider this.
Resistance is volts divided by current and remains constant. Power is voltage multiplied by current.
Halve the voltage and the current is also halved (constant resistance). Looking at power in terms of current only, it is resistance by current squared. One half multiplied by one half is one quarter. The fan runs at 1/4 power.
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Old 01-26-2021, 09:56 PM   #36
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Default Re: How difficult would it be to convert this water heater from 12V to 6V?

Power = Amps X Volts (remember P=IE, it is a piece of pie!)
The minor disagreement with Synchro909 is that you are usually trying to maintain a given level of power, like a 5 watt light bulb. So, if you are trying to provide the same level of power at 6 volts instead of 12 volts, you must double the current. This is why the wire gauge in a 6 volt car is bigger than in a 12 volt car. The age old rule is that if you want to switch to 12 volts, your wiring is not a problem but all your light bulbs, etc must be changed.
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Old 01-27-2021, 12:26 AM   #37
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Default Re: How difficult would it be to convert this water heater from 12V to 6V?

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Power = Amps X Volts (remember P=IE, it is a piece of pie!)
The minor disagreement with Synchro909 is that you are usually trying to maintain a given level of power, like a 5 watt light bulb. So, if you are trying to provide the same level of power at 6 volts instead of 12 volts, you must double the current. The only way to do that is either increase the voltage back to 12 volts or halve the resistance and that would require the motor in the fan to be rewound for 6 volts. This is why the wire gauge in a 6 volt car is bigger than in a 12 volt car. The age old rule is that if you want to switch to 12 volts, your wiring is not a problem but all your light bulbs, etc must be changed.
I see no disagreement at all. As you say, P=IE. Resistance (R) is E/I. R is constant. That is, it is unchanged regardless of what voltage is supplied to it so if the voltage is halved, the current is also halved. That makes the new current and voltage I/2 and E/2. Now, to put those figures back into the power formula, we have P=I/2 X E/2=IE/4. That is, the power is reduced to 1/4 what it was.
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Old 01-28-2021, 11:02 AM   #38
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Default Re: How difficult would it be to convert this water heater from 12V to 6V?

I stand corrected for my fuzzy thinking: V/2 ~ P/4.

In my defense, (somewhat) axle friction and wind resistance will be reduced, and the motor will spin rather faster than expected.
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Old 02-01-2021, 10:04 AM   #39
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Default Re: How difficult would it be to convert this water heater from 12V to 6V?

I love LED lights how about a red LED next to the heater control switch make a small polished stainless plate and hang it from the bottom screws on the dash.
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Old 02-01-2021, 05:47 PM   #40
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Default Re: How difficult would it be to convert this water heater from 12V to 6V?

The heater arrived over the weekend, but I’m going to wait for warmer temperatures before I start working with it.


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