Coast Resorts Open Roads Forum: Tech Issues: Convert 120V to 12V

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Topic: Convert 120V to 12V

Posted By: mtofell1 on 09/14/17 11:08pm

I Just got a macerator to empty tanks at home and am a bit stumped on powering it. I know I can pull right off the battery but am wanting to run it off my house/shore power. Reasons being I have two tank outlets on my 5th wheel so wiring up to both is a hassle. Also, I mainly bought this thing just to avoid lines at dump stations and so if I use my RV at home I can dump. I may wire up the RV at some point but for now I'm just looking for home use.

Anyway, I'm so familiar with house wiring that I'm embarrassed to even be asking these questions. I've installed electric panels in houses and wired too many things to count (I'm a building inspector by trade so I even got all the permits to ensure I did it right [emoticon]

)

So, what I'd love to find is a simple device I could plug into my outlet at home and wire up the two legs of this macerator to. In searching I'm getting confused by all the terms - transformer, inverter, converter - 12V, 24V.

I've got to think the part I need is simple to find but an internet search seems to just turn up inverters (I know what this is and know it's going the wrong way). From what I do understand I think I need a transformer - like for a doorbell, but the 20A rating and wire size on this macerator tell me I need way more than something for a doorbell.

Thanks for any advice.

Posted By: CA Traveler on 09/14/17 11:32pm

Search on 120v to 12V converter. ie The output is DC. Here's one. A common auto battery charger could also work.

Of course you could just make an extension of 2 wires to run from the battery back to the macerator location. Either permanent wiring or not.

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Posted By: CA Traveler on 09/14/17 11:36pm

BTW A transformer won't work because it has AC output and you need DC.

Posted By: naturist on 09/14/17 11:51pm

Do you have shore power at home? Why not just hook into the fiver's existing 12 volt system like it was designed to do and let the existing converter in the trailer do what it was designed to do, i.e. provide 12 volts off shore power?

Posted By: MrWizard on 09/15/17 12:14am

what is the amp draw on the maceator

buy an RV converter connect the output to the mace
and extension cord on the input,

when you finally get around to wiring the 5vr
you will have a spare converter, IF ever needed

ME i would probably make some long 12v power cord and just connect to the 5vr battery

I can explain it to you.
But I Can Not understand it for you !
....

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Posted By: MEXICOWANDERER on 09/15/17 01:01am

Maybe it's better to start this out easy and ask what the spec sticker says on the macerator for AC power amperage...

Posted By: valhalla360 on 09/15/17 03:02am

I get a little nervous when you claim electrical expertise but don't understand a transformer doesn't convert AC to DC. But anyway...

Looking online most units seem to draw about 20amps (confirm before starting).

Simple solution: Pick up a set of jumper cables long enough to reach from the RV battery or even your truck battery. Attach alligator clips to the leads from the pump motor.

When you use it, connect the alligator clips to one end of the jumper cable and connect the jumper cables to the battery. Quick and easy. Nice thing about jumper cables is even with pretty long distance, 20amps is nothing and they come with easy clamp on connectors for the battery terminals. You could make your own up with smaller wires but if you go with small wires, you have to check voltage drop to make sure the wires can handle the amps.

You could do the same thing with one of the emergency jump start boxes to allow you to shorten the length. Plus you have a jump start backup.

A converter or large battery charger could work but seems kind of complicated for what you are trying to do. If you do go this route, make sure the battery charger doesn't need a battery in the loop. I have a little 6amp one that checks the battery voltage before starting. If you just connect the leads in a circuit, it doesn't do anything.

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Posted By: Bumpyroad on 09/15/17 03:48am

just get a little jump starter battery jobby and your problem is solved. no muss, no fuss.
bumpy

Posted By: Ivylog on 09/15/17 04:05am

Bumpyroad wrote:

just get a little jump starter battery jobby and your problem is solved. no muss, no fuss.
bumpy

X2 or a good battery charger that you need to carry in your RV anyway.

This post is my opinion (free advice). It is not intended to influence anyone's judgment nor do I advocate anyone do what I propose.
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Posted By: 2112 on 09/15/17 04:14am

This and This if you already have a charger

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Posted By: Bumpyroad on 09/15/17 04:47am

2112 wrote:

This and This if you already have a charger

a portable jump starter would be preferable IMHO in that there are no posts exposed in storage, can tip it over with no issues, already has battery cables attached, and has a 12 volt port that can take a hookup.
bumpy

Posted By: 2112 on 09/15/17 05:07am

Bumpyroad wrote:

2112 wrote:

This and This if you already have a charger

Agreed, until you find yourself replacing the $50 sealed AGM battery every year. I gave up on mine and parted it out.

Posted By: Pipeman on 09/15/17 05:14am

I made up a longer set of wires and attach them to the macerator wires with alligator clips. I hook them up to my 12 volt batteries in the trailer and pump into the 35 gallon black water tote that I have or into the house when at home. When dry camping I usually have the gennys running and at home the 5er is hooked up to a 30 amp plug to keep batteries charged. Simple.

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Posted By: DutchmenSport on 09/15/17 05:41am

Why not get a cigarette type plug, add extra length of wire to it with the appropriate plug at the end for your pump. Then, just plug into your camper at the television booster (If you have a 12 volt receptacle there)??? Simple, and no "real" extra wiring to do.

Posted By: Dutch_12078 on 09/15/17 06:08am

DutchmenSport wrote:

The TV booster outlet will not supply the amperage needed without blowing a fuse or melting the socket. They're usually marked for 5 amps max as I recall.

Dutch
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Posted By: SoundGuy on 09/15/17 06:13am

mtofell1 wrote:

Why in the world are you making this so complicated when it's SO simple? [emoticon]

You haven't told us just which macerator you have but assuming it's a 12 vdc powered FloJet Waste Macerator just connect it to your rig's battery, whether plugged into shore power or not. Since I use my own FloJet frequently for exactly the same purpose I wired switched 12 vdc using 12 gauge zip cord from the battery back to the waste gate location where I installed a standard Bargman connector. If you want to run the macerator in 2 different locations either install a Bargman at each location OR just one midway between the 2 locations and extend the macerator's cable so it will reach either. The FloJet has a 20 amp fuse in the handle switch so 12 gauge is fine - been using mine for years with no issues at all. This is too simple, no need to over complicate it. [emoticon]

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Posted By: wa8yxm on 09/15/17 06:27am

Can you do it (run the device off 120 volts using a converter)

YES. but.. (Oh that BUT)...

THe macerator can draw 20 amps or more (Stalled rotor is blows a 20 amp fuse nicely) So you need a heavy converter. I would suggest a Progressive Dynamics 9145 or whatever the smallest 9100 is. or equal. A plug in stand along single stage converter.

Or you can do what I did.

I ran 10 ga from the fuse block (30 amp fuse) in the RV (NOTE the fuse block is very handily located for this job) to a "jack" on the outside and I sue an extension cord for the remote tank. also 10ga, matching connectors.

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Posted By: SoundGuy on 09/15/17 06:51am

wa8yxm wrote:

Again - WHY all the complication? [emoticon]

Pretty well every rig has a battery, the OP's certainly does, so just power the macerator with it as it was designed for. Whether the rig is also plugged into shore power or not is irrelevant as the battery, unless it's flat dead, will easily supply the necessary power to run the macerator. I've never bothered ever running my own FloJet with my stock WFCO 8955 converter with the battery switched off as I've never had a reason to but certainly it would power it just fine, just as it powers my slide or awning just fine if I happen to have the battery switched off - which I have done. [emoticon]

Posted By: 2oldman on 09/15/17 07:37am

I use a garden battery to power mine. Easy to carry. Short wires have a couple alligator clips on them. Lotta current for those guys.

Posted By: Sprink-Fitter on 09/15/17 08:08am

naturist wrote:

They said there are two outlets on the RV so they would have to wire it in two places and they do not want to do that.

I would use a battery charger

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2012 Can Am Commander XT 1000

Posted By: CA Traveler on 09/15/17 08:18am

Sprink-Fitter wrote:

naturist wrote:

They said there are two outlets on the RV so they would have to wire it in two places and they do not want to do that.

I would use a battery charger

A single 12V plug and short extension on the macerator would eliminate wiring to 2 plugs.

Posted By: CA Traveler on 09/15/17 08:24am

OP,

Why not just go ahead and wire the rig? You can use frame ground and one positive wire. Depending upon existing rig wiring the new wire length may be short.

Now no matter where you dump you have the option of taking and using the macerator.

Posted By: Bumpyroad on 09/15/17 08:27am

my dump station was adjacent to my generator and the 12 volt starter wires were front and center on the gen set and I just ran wire from there back. I use MinKota trolling motor connectors to plug the macerator to the gen set leads.
bumpy

Posted By: mtofell1 on 09/15/17 08:55am

Thanks everyone.... auto jump starter makes total sense. I will likely wire this thing into my trailer at some point but just want to be sure it all works the way I want before doing that.

Posted By: SoundGuy on 09/15/17 09:03am

mtofell1 wrote:

I will likely wire this thing into my trailer at some point but just want to be sure it all works the way I want before doing that.

If we're talking about a FloJet Waste Macerator it works just fine for all the rest of us who own one, why wouldn't it work for you? [emoticon]

Posted By: MrWizard on 09/15/17 10:28am

Hi I'm not sure a jump box would work
This is not a (2) minutes rapid drain
The mace grinds and pumps, it has a set Max flow rate
20 amps * minutes equal amp minutes
A (9) amp hr battery pack would have 270 amp minutes to 50% soc
How long to empty one 40 gal tank?
He has (2) tanks
10 minutes per tank would equal 400 amp minutes
Using 400 out of 540 total equal way below 50% soc
At that level will a jump box even keep the pump running to completely empty the second tank

Posted By: SoundGuy on 09/15/17 10:42am

So, to the OP ... why not tell us just which "macerator" you bought so rather than have us all continue to guess we can intelligently discuss how to best power it? [emoticon]

Posted By: Byrogie on 09/15/17 11:00am

I 2 wired a 7 pin plug ($10) and connect to the umbilical. Make it as long as you need to hit both outlets.

Posted By: MEXICOWANDERER on 09/15/17 11:05am

SoundGuy wrote:

So, to the OP ... why not tell us just which "macerator" you bought so rather than have us all continue to guess we can intelligently discuss how to best power it? [emoticon]

I tend to lose interest after 21 replies go by and this simple question remains ignored.

Posted By: Bumpyroad on 09/15/17 12:52pm

are these two outlets both black tanks or one is grey. with a bypass feature, you could let the grey drain by gravity, depending on how the home set up is.
bumpy

Posted By: valhalla360 on 09/15/17 12:55pm

MrWizard wrote:

Interesting, I was going to question the battery size considering a jump box rated at 400amp would eat more than 50% in under a minute of cranking but then looked it up and yes, they are that small.

Considering the price, I could buy an extra battery for the truck and a set of jumper cables for less money and have more power available.

Posted By: mtofell1 on 09/15/17 01:59pm

MEXICOWANDERER wrote:

SoundGuy wrote:

So, to the OP ... why not tell us just which "macerator" you bought so rather than have us all continue to guess we can intelligently discuss how to best power it? [emoticon]

I tend to lose interest after 21 replies go by and this simple question remains ignored.

FloJet Model 18555-000. It's been about 12 hours since I posted the original question. Sorry to keep you waiting for sooooooooo long.

I love the way I get flammed for over-complicating something then get 8 answers and an argument about how I should do it.

Thank you to those that gave reasonable and on-point answers. The rest of you need to get a hobby or something to occupy your time.

Posted By: SoundGuy on 09/15/17 03:00pm

SoundGuy wrote:

So, to the OP ... why not tell us just which "macerator" you bought so rather than have us all continue to guess we can intelligently discuss how to best power it?

MEXICOWANDERER wrote:

I tend to lose interest after 21 replies go by and this simple question remains ignored.

mtofell1 wrote:

FloJet Model 18555-000. It's been about 12 hours since I posted the original question. Sorry to keep you waiting for sooooooooo long.

Information that would have simplified and shortened this discussion enormously had you provided it in your original post. [emoticon]

Quote:

I love the way I get flammed for over-complicating something then get 8 answers and an argument about how I should do it.

Thank you to those that gave reasonable and on-point answers. The rest of you need to get a hobby or something to occupy your time.

You're welcome, for my "reasonable and on-point answers". [emoticon]

Posted By: MEXICOWANDERER on 09/15/17 04:11pm

No flaming sir but listing the power draw on the unit's sticker eliminates the need for a person who wishes to help to go on a web Easter egg hunt to track it down.

Help us to help you...at your service...

An OEM PDF download says to use 10 gauge wire for distances to 20'

21' or greater I would use 8 gauge. Nothing is as nasty as fixing a clogged macerator because of a weakened motor.

It's not just the time to pump "water" maceration is slower, then a clear water flush is desired. No twenty dollar booster jumper pack or cigarette lighter connection will survive that.

Helping folks IS my hobby thank you very much...

Posted By: Bumpyroad on 09/15/17 04:25pm

MEXICOWANDERER wrote:

It's not just the time to pump "water" maceration is slower, then a clear water flush is desired. No twenty dollar booster jumper pack or cigarette lighter connection will survive that.

Helping folks IS my hobby thank you very much...

$20?? things must be a lot cheaper in Mexico.
bumpy

Posted By: wa8yxm on 09/15/17 05:05pm

To SoundGuy. THe O/P wants to use a converter.. I don't.

To the O/P.. Now that I recall it. back before I got the wiring and jack installed to make it easier to battery power it off the RV..

I used a JUMP START battery pack. All RVers should have one and keep it charged.. THey are very useful for many things

THe one I have now is operating my main slide out due to a controller failure. Works great.

Heaven forbid I run all the batteries in the RV down again (Did it once) Jump pack has the oomph to fire up ye old ONAN and recharge.

Runs portable battery operated fan

RUns other stuff.

Very nice device.

Posted By: theoldwizard1 on 09/15/17 06:56pm

Pipeman wrote:

Simple ! Elegant !

I would use at least 14 gauge wire, 12 would be better. Also, for heavy DC loads like that, install a set of Anderson PowerPole 45A connectors close to the batter bank with a 30A inline fuse. Couple of bucks on eBay.

Posted By: mtofell1 on 09/15/17 07:57pm

So, if wiring off the battery I'm seeing wire size recommendations from 8 to 14 gauge in the last handful of posts. Online I found some voltage drop tables but they talk about different % (3% table, 10% table, etc.). Does anyone have an opinion as to what table is used for the motor in this macerator? There seems to be a pretty big difference depending what table is used.

Something I did not know from a lack of DC wiring knowledge is the drastic wire size increase necessary when traveling distance. In houses it rarely is an issue unless pulling a feed to an outbuilding. Sometimes, with a very large house you might put a second panel at an opposite end. But I've often suspected the 2nd panel is as much about convenience for the electricians as it is voltage drop due to long runs.

Posted By: MEXICOWANDERER on 09/15/17 08:40pm

With DC it is a real pain to maintain adequate voltage over a long distance. My issue with macerator is this...

With varying loads (don't ask) 17 amps at the motor may be a dream in worst case. I demonstrated this to a fellow in a Crown bus conversion. His bus was 12 volt. At the macerator motor he was getting 10.9 volts while his house batteries were registering 12.7 with the converter charging them up.

I applied 14.8 volts, the macerator speed ramped way up and the fellow got the concept rapidly. He exchanged his 12 gauge wires for 8 gauge (about a 30' run) then checked with me again. "Cuts the time needed about in half".

There are 2 pin high amperage sockets and plugs in case you wish to have a macerator with a short DC pigtail.

Posted By: CA Traveler on 09/15/17 08:41pm

Use 3%, 20A, 12.7V, copper wire, wire length and what does the calculator indicated for gauge?

Yes, use a online calculator.

Posted By: mtofell1 on 09/15/17 08:59pm

25' run, 20A

3% is telling me 8 gauge
10% is telling me 12 gauge

Seems like a pretty big difference. I bought a 12 gauge cord today but am not sure it's the right one for the job.

Posted By: CA Traveler on 09/15/17 09:09pm

At 12.7V 10% drops the motor voltage to 11.4V.

Use 8 ga.

Posted By: mtofell1 on 09/15/17 09:10pm

Also, just noticed the amp rating stamped on the motor is 16A but the manual lists everything for 20A.

Posted By: time2roll on 09/15/17 09:52pm

I would have #6. Marginal cost is very small.

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Posted By: valhalla360 on 09/16/17 02:33am

mtofell1 wrote:

It's not an AC vs DC thing.

It's an amperage thing. The higher the amperage, the more losses. Since 12v is 1/10th of 120v, for the same power, you are pulling 10 times the amperage. This results in much shorter runs before voltage drop becomes an issue and you have to up-size the cable.

This is a big part of why many other countries run 240v household AC. It allows smaller cheaper wires to be used. 120v or 240v, if you lick the live ends, it's not a good thing, so not much safety difference. Only reason the USA doesn't switch is everything is set up for 120v.

Remember to take the full round trip when using the tables to calculate the length (If you coil up 50' of cable in the circuit, that counts towards the length)

I wouldn't use the 10% table. If you are fully charged it can work OK but if the battery is down, it tends to compound. Say you use 10AWG copper.
- 12.7v (fully charged battery) @ 20 amps = 254w with 9.45% voltage drop with 11.5v at the motor. The motor will run a little warm but likely will survive if you don't use it a lot.
- 12.0v (45% charged) with 10% voltage drop results in 24amps and 12% drop end result 10.56v at the motor and that will be hard on the motor and being weaker, may result in greater likelihood of jamming on solids.

The site below has a nice explaination:
https://www.westmarine.com/WestAdvisor/Marine-Wire-Size-And-Ampacity

Edit: My calculations assumed 30' roundtrip, so 15' from battery to motor and I see you just posted 20' w/ 12AWG. That should result in around 12.5% voltage drop or 10.48v at the motor if the battery is at 12.0v. Bump up to 8AWG and that gets you 5% drop or 11.4v at the motor.

I would jump up at least to 8AWG and might even consider 6AWG but that does get pretty big and costly.

* This post was edited 09/16/17 02:42am by valhalla360 *

Posted By: mtofell1 on 09/16/17 10:55pm

I think I ended up with a pretty good setup - 25' 10 gauge "generator" cord at Lowes for $46. It's a pack of 4 conductors so combining 2 each side gives me approximately 7 gauge (per an online calculator for combining conductors).

Posted By: MEXICOWANDERER on 09/17/17 01:36am

And it will be flexible and easy to roll up. Good tip about Lowes.

Posted By: SoundGuy on 09/17/17 07:07am

mtofell1 wrote:

Since you've now purchased cable the point is moot for you but may be of use to others ... I've been using a 20' run of 12 gauge zip cord to power my own FloJet for 10 yrs now with no issues at all, speed isn't any different than it would be when connected directly to the battery, works just fine. Yes I know, the manufacturer specs 12 gauge for 10' runs and 10 gauge for 20' but I had some 12 gauge on hand so that's what I used - no motor overheating, just works as it should. [emoticon]

Posted By: MEXICOWANDERER on 09/17/17 12:32pm

Ummm, with direct current is it not the rule the fewer the watts, the less the heat?

What does, and does not (Ewwww) make it successfully through the grinder makes required watts an issue. Overkill versus (Ewwwwwwwwwwwwwwwwwwwwww) clogging is therefore heavily biased in my book.

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