Locating the 7 pin alternator power wire

[Cate&Rob]

TucsonJim

I understand the higher voltage = lower current relationship. After all, this is why electric cars operate at hundreds of volts. But, to integrate doubling the storage voltage into an otherwise 12V vehicle and RV matrix . . . seems (to me) unnecessarily complex. Just an observation from the sidelines .

Rob

[TucsonJim]

TucsonJim

I understand the higher voltage = lower current relationship. After all, this is why electric cars operate at hundreds of volts. But, to integrate doubling the storage voltage into an otherwise 12V vehicle and RV matrix . . . seems (to me) unnecessarily complex. Just an observation from the sidelines .

Rob

It's actually not that complicated, and the cost savings can be significant. Half the current for the same wattage means smaller wire and lugs. The solar controllers are rated in amps. So you can purchase a lower priced controller. Of course, you still need to purchase and install a 24V to 12V converter, but they are inexpensive when compared to a high current MPPT controller. Here's a great video that discusses the pros and some of the cons.

https://www.youtube.com/watch?v=Vi7eswWwosk&t=170s

Jim

[Cate&Rob]

TucsonJim


An interesting video. It seems that (other than reduced current) a key driver for going to 24V is less expensive components. Is this just a function of supply/demand with 12V being more popular and thus more expensive?

This does raise the question of . . . why stop at 24V? Golf carts and electric scooters have been running 48V systems for years with batteries in series to reduce electrical current (and improve motor efficiency).

Rob

[howson]

. . . why stop at 24V?

• The ratings of the other components (switches, etc) is one reason 24V is the "sweet spot" for an RV IMHO.
• You'd have to have quite a robust series solar array if the PV minimum (to start charging) was 53V (48+5).
• At least in the Victron product range, going 24V means an owner could choose to install a 5000VA inverter vs the 3000VA upper limit in a 12V system.

From Victron's Wiring Unlimited a safety reason: Between AC and DC: reinforced isolation. Once the chassis has been grounded the DC is therefore considered safe to touch if the nominal voltage is 48 V or lower.

[Dgrothen]

I sure hope you not using the Victron Multiplus in your picture 2x120 12V (12/3000/120-50) as it is not comparable with your 24 v battery system There is a Multiplus 2x120 24V (24/3000/70-50) https://www.victronenergy.com/invert...lus-ii-2x-120v so you may want to double check.. With this set up you will still need to disable your stock 12V converter and utilize the Multiplus and solar for charging. To charge the 24V you will need a high amperage 12v to 24V dc-dc battery charger (with lithium profile) and I don't
know if that is even made, so it may not be possible for your truck to even charge your batterys. I did find this from Victron, but it low amperage Orion-Tr Smart DC-DC charger,but it might work with you normal charge line.

Is going 24V worth needing the extra equipment,- I am guessing it is saving battery space, but a 24V 200AH battery can be replaced with 2-200AH 12v and there are some nice 270AH and larger 12v batterys out there such as SOK and others that could be cheaper. I suggest you look at Will Prowse videos https://www.youtube.com/c/WillProwse on the batterys he has taken apart. Besides 12V solar parts are a lot easier to find on the road over 24V systems.

Trying to learn here - hope this helps

Keith

Yoda good catch on the inverter model in the diagram. I did order the 24 volt model but forgot about updating the diagram. As for why I'm going 24-volt, you are correct it is for battery space and secondly is for the ability to increase batteries if I need to. I'm starting with the two 24-volt 200 amp batteries and may, if needed, add another within the first year. At this point, after my basement wall remodel, the two batteries fit nicely in the basement under the stairs if a third is added it just gets a little tighter, but can be done.

[Dgrothen]

Ok folks, my saga continues on the 7-pin wiring. I. The pin box where the 7-pin wire comes in, the black wire (power wire) connects to two other black wires that go into the RV. One of them was what I was looking for and it connects to the battery bus bar to charge the battery. I've disconnected it which was my intention. But now I have this second wire and I can't for the life of me figure out what it's for or where it goes. Can anyone guide me please?

[Yoda]

Ok folks, my saga continues on the 7-pin wiring. I. The pin box where the 7-pin wire comes in, the black wire (power wire) connects to two other black wires that go into the RV. One of them was what I was looking for and it connects to the battery bus bar to charge the battery. I've disconnected it which was my intention. But now I have this second wire and I can't for the life of me figure out what it's for or where it goes. Can anyone guide me please?

howson

Doug I tagged Howard. I believe that other black wire goes to the emergency break away switch , which means it still must be connected to the trailer 12V power somehow.

But I could be wrong. You probably need to leave the black wire connected to the buss bar as your connecting that to the 12v side on your 24/12 dc-dc converter off your 24V batterys correct? If so leaving it connected should not cause any issues. The break away switch must have 12v power from the trailer. to work properly in case of the trailer disconnect that pulls the plug.

Keith

[Jlawles2]

3 wires in the pig tail from the TV.

1 - Power from the TV
2 - Power wire to the battery / bus bar
3 - Power to the Breakaway switch (IIRC)

So Kieth should be correct.

If you isolate all 3, you should be able to pull the break away and go to one of the hubs with a compass and confirm that there is no power to the magnets. Do not leave the break away pulled for extended times (5 min or less).

[Dgrothen]

Oh, wow, I'm glad I asked.

If l am understanding you guys Jlawles2 and Yoda correctly I must maintain 12v to this second wire to maintain breakaway trailer breaks. And, I can do that by leaving the busbar wire connected to the busbar (yes, I'll be powering it via my 24v - 12v converter) and tying the busbar wire to the breakaway wire at the pinbox. The 7-pin power wire will remain capped or not connected to anything.

I think I understand but please acknowledge

Again, thanks a million?

[Yoda]

Oh, wow, I'm glad I asked.

If l am understanding you guys Jlawles2 and Yoda correctly I must maintain 12v to this second wire to maintain breakaway trailer breaks. And, I can do that by leaving the busbar wire connected to the busbar (yes, I'll be powering it via my 24v - 12v converter) and tying the busbar wire to the breakaway wire at the pinbox. The 7-pin power wire will remain capped or not connected to anything.

I think I understand but please acknowledge

Again, thanks a million?

This is just a thought and hopefully the electrical experts will chime in. You can actually leave the TV charge wire connected. it should not hurt anything and if something goes wrong with your 24/12 converter you can use the TV to operate you jacks in an emergency. I don't think back feeding the 24/12 converter with the charge wire would hurt anything.r any of you other 12v components. You can check with the manufacturer of the 24/12 converter. if there is a concern adding a 50A on more capacity Diode to the 24/12 converter output would solve the issue. A diode only allows power flow in one direction. The experts here like Joseph Jlawles2 can recommend the actual sizing and probably what you need .


Keith

[epearce]

3 wires in the pig tail from the TV.

1 - Power from the TV
2 - Power wire to the battery / bus bar
3 - Power to the Breakaway switch (IIRC)

So Kieth should be correct.

If you isolate all 3, you should be able to pull the break away and go to one of the hubs with a compass and confirm that there is no power to the magnets. Do not leave the break away pulled for extended times (5 min or less).

Shouldn't the e-brake power go directly to the battery? It my OEM wiring on my 200MK it went directly to the battery side of the Bussman Shortstop. In my re-wire, I take it directly to the + terminal on the first battery in the battery bank. Seems like a not so great idea to take the e-power from a wire nut junction in a metal, non-weatherproof box under the trailer. I think you should think of that third wire as the e-brake finding its way to the trailer battery by a convenient route, not the TV power.

Also note that the brakes have a separate ground return for each side, in that giant white bundle in that box,

[Country Campers]

Shouldn't the e-brake power go directly to the battery? It my OEM wiring on my 200MK it went directly to the battery side of the Bussman Shortstop. In my re-wire, I take it directly to the + terminal on the first battery in the battery bank. Seems like a not so great idea to take the e-power from a wire nut junction in a metal, non-weatherproof box under the trailer. I think you should think of that third wire as the e-brake finding its way to the trailer battery by a convenient route, not the TV power.

Also note that the brakes have a separate ground return for each side, in that giant white bundle in that box,

Yes on a TT the emergency break away wire will generally go directly to the battery or bus bar, on a fifth wheel it comes from the pin box as it is shorter and the break away is up on the pin box versus down on the tongue. It all has to do with the close proximity to the hitch.

Brian

[howson]

Shouldn't the e-brake power go directly to the battery?

Normally, yes, but Dgrothen is going to have a 24V battery bank so it's not an option.

What he may consider is an entirely separate 12V battery system for the emergency brake. The tow vehicle can be used to keep that one (small) single-purpose battery charged.

I believe it was Guest that had researched this topic in the past (hopefully Jim will chime in).

[Guest]

Thanks Howard,

Yes I looked into the brake away kits when I moved my battery inside the rig. I struggled with this since in the Imagine's original wiring configuration the brake away switch is directly connected to the battery at the frame mounted breaker. I did not feel comfortable routing an unfused wire from inside the passthrough to the the break away switch. Two solutions were possible.

1) Install a dedicated battery and charger for the brake switch such as the curt brake away kit. The switch could remain directly connected to the battery but the charge wire could be fused.
2) Install a dedicated resettable breaker from the battery to the break away switch. The word I received from eTrailer is its ok as long as the breaker is used only for the break away switch.

https://www.amazon.com/CURT-52028-So...35677463&psc=1

Jim

[Jlawles2]

On one of the diesel sites, a guy was converting a horse trailer to an RV. For the brakes, he did something he called a "super capacitor" to power the brake EOH actuator then a NC valve between the EOH and the calipers so it would stay locked. There is always an option to do something similar with the break away switch. Power it from the TV to a capacitor that will apply and hold the brakes for XX seconds. Based on his studies, the brakes had to hold for 5 minutes (someone may know the exact spec).

If I get the specs on the capacitor, I'll post them.