24 VDC and 12 VDC brakes in Fifth Wheel

[John Frum]

So, when you run your electric kettle on solar power, do you have a battery monitor that will watch how quick the battery % goes down?

I guess what is getting me is watt hours is one measurement and should work well for things close to a C20 draw, but for my 478 Amp Hour System at the C20 rate, once I draw amps much quicker than 24 amps per hour, like the 141 amps per hour rate, the math I’m doing says that when I run my kettle for 5 minutes, that will cost me 8% of my battery power If the C1 rate of the battery is 143 amps. Between some of this amperage coming from the panels in the daytime (in my favor), and system losses (not in my favor), this 8% should at least be a ball part number.



I was convinced before I came to this forum that going with a 2000 watt inverter was a bad and dangerous idea on a 12 VDC system. I’m trying to use some math to see with proper sized wires like 2/0 and flooded lead acid batteries, this could be done.

If we got a 2000 watt inverter, the other people in my family would appreciate The switch to solar, but with a 1000 watt inverter, they’d miss some things. My idea of camping is a little more rustic than there’s.

I don't ever plan to use lead acid batteries so I'm not well versed on the peukert effect.
For lifepo4 its not a significant issue nor is round trip efficiency.

 

[John Frum]

I was convinced before I came to this forum that going with a 2000 watt inverter was a bad and dangerous idea on a 12 VDC system. I’m trying to use some math to see with proper sized wires like 2/0 and flooded lead acid batteries, this could be done.

I thought I already showed you the math for wire size.
Maybe I didn't, I do it so much I could have given it a miss.

 

[chrisski]

I thought I already showed you the math for wire size.
Maybe I didn't, I do it so much I could have given it a miss.

Thanks for that. I’ve got no doubt the wires are the right size for the amps. It’s just whether 440 amp hours of lead acid batteries are strong enough.

I did not want to make the plunge into lithium right off at 4 times the price of my FLAs, but from what I’ve seen it would make things easier. Watched a YouTUbe video of a system very similar to mine where the guy started off with AGM batteries and showed the voltage drop off a blow dryer and went from in the 12s to low 11s or high 10s, and then switched to lithium batteries and turned on the same device, and the lithium’s had far less voltage loss.

That Peukert Effect is supposed to be far less on lithiums and they can handle those large amperage draws better than FLAs.

 

[bpal]

I had a pull trailer previously where I installed a 3000w Magnum hybrid inverter. I had 520ah of Crown lead acid batteries. It was a bit of overkill but i could actually start the A/C on battery only, mostly just as a test. It had no problem being plugged in to a 15a outlet and supplementing with battery and running the A/C for several hours as well as other electrical needs. I had 4/0 welding cable between the battery box and the inverter. I had 450w of solar on the roof.

 

[John Frum]

That Peukert Effect is supposed to be far less on lithiums and they can handle those large amperage draws better than FLAs.

That and the cost per lifetime watt hours is why I prefer lifepo4.

 

[chrisski]

That and the cost per lifetime watt hours is why I prefer lifepo4.

When this system is built, one thing I’m afraid to do is calculate cost per watt hour used. If I do, I will never share that info with my wife!

 

[piciu1982]

Battery is only for break away switch. Actual electric brakes r still from 7 pin trailer plug and your brake controller !!

 

[chrisski]

Battery is only for break away switch. Actual electric brakes r still from 7 pin trailer plug and your brake controller !!

Maybe be size of the trailer matters, but if I have no battery, I have no brakes. My trailer is 12k.

 

[eXodus]

First: all the break power is coming from the Truck for normal operations. If this is not the case - then something is incorrect wired at your trailer.

The only time you use the trailer battery is when the fail safe switch is triggered.

So basically when you loose the trailer of the hitch and the cable is pulled out. The breaks on the trailer are big ole magnets.
Your lithium battery is not a single battery ? Can't you just grab 12V in the middle of it?

 

[John Frum]

This is post #50.

 

[eXodus]

Maybe be size of the trailer matters, but if I have no battery, I have no brakes. My trailer is 12k.

No battery is fairly common. But no breaks at at 12K trailer? WT? Are you sure that it doesn't have a integrated electric break or a surge break?

Depending on which state you are - 1500lbs or 3000lbs may be driven without a trailer break. Everything over this is not legal my friend.

 

[chrisski]

No battery is fairly common. But no breaks at at 12K trailer? WT? Are you sure that it doesn't have a integrated electric break or a surge break?

Depending on which state you are - 1500lbs or 3000lbs may be driven without a trailer break. Everything over this is not legal my friend.

That is exactly how I thought the breaking system worked off the 12 volt only through the seven pin until I got the no connection fault when I picked the trailer up from the shop who had killed my battery, and on when I hooked the trailer up, there was a no connection fault. After putting a new battery in, the brakes worked fine. This dead battery happened twice, so my assumption is that the brakes need the battery to function.

The only other thing I think it could be is bad wiring or the seven pin not plugged in completely.

There's plenty of flatbed trailers like car haulers as heavy or heavier than mine, and if there's no batteries on those trailers, must have just been a coincidence about my dead batteries. I would think that a battery is in the system at least for the brake away. I'm hooking this RV up in a couple of weeks, and I will see in my brake controller displays a no trailer fault while my battery is out of the trailer.

If I don't need the trailer 12 volt battery, this makes my problem a bit easier.

 

[eXodus]

That is exactly how I thought the breaking system worked off the 12 volt only through the seven pin until I got the no connection fault when I picked the trailer up from the shop who had killed my battery, and on when I hooked the trailer up, there was a no connection fault. After putting a new battery in, the brakes worked fine. This dead battery happened twice, so my assumption is that the brakes need the battery to function.

The only other thing I think it could be is bad wiring or the seven pin not plugged in completely.

There's plenty of flatbed trailers like car haulers as heavy or heavier than mine, and if there's no batteries on those trailers, must have just been a coincidence about my dead batteries. I would think that a battery is in the system at least for the brake away. I'm hooking this RV up in a couple of weeks, and I will see in my brake controller displays a no trailer fault while my battery is out of the trailer.

If I don't need the trailer 12 volt battery, this makes my problem a bit easier.

there is something wrong with the wiring in your trailer. Get that figured out. The trucks break controller provides all power for everyday breaking.

I had plenty of trailer without a battery which still breaking normal and my horse trailer is still breaking perfectly when the battery died.

For the fail safe switch you can just wire that from the middle your lithium battery. Because it will be hopefully never used.

 

[HRTKD]

That is exactly how I thought the breaking system worked off the 12 volt only through the seven pin until I got the no connection fault when I picked the trailer up from the shop who had killed my battery, and on when I hooked the trailer up, there was a no connection fault. After putting a new battery in, the brakes worked fine. This dead battery happened twice, so my assumption is that the brakes need the battery to function.

Does your trailer have disk brakes? I haven't had a trailer with disk brakes, so I'm not familiar with where a trailer with disk brakes gets the power for the hydraulic system.

 

[chrisski]

Does your trailer have disk brakes? I haven't had a trailer with disk brakes, so I'm not familiar with where a trailer with disk brakes gets the power for the hydraulic system.

The trailer has drum brakes. When I get the connection error without the battery, could have been a coincidence. That part I will get straightened out in A couple weeks

 

[HRTKD]

What truck? As smart as my F-350 is, it would not surprise me at all if it could detect no battery in the trailer. That would be raised as a red flag that the breakaway system lacked power to operation. I don't know that is does, just that it wouldn't surprise me. It's quite good at detecting that a lamp is out on the trailer.

 

[mapguy525]

Does your trailer have disk brakes? I haven't had a trailer with disk brakes, so I'm not familiar with where a trailer with disk brakes gets the power for the hydraulic system.

Same place as drum brakes - brake pin on 7way for normal operation. trailer battery for emergency operation.

No battery is fairly common.

This is clearly bad information. Electric brakes requires a battery on the trailer for emergency activation of brakes.
Surge brakes have no battery, but still have an emergency activation system that full operates the tongue master cylinder.

Depending on which state you are - 1500lbs or 3000lbs may be driven without a trailer break. Everything over this is not legal my friend.

Every state is different on brake requirements. If you are legal in your state of licensing -then you should be legal / able to fight a ticket.
Washington State RCW is here:
http://search.leg.wa.gov/search.aspx#document&searchQuery=&searchBase=RCW&exec=false

That is exactly how I thought the breaking system worked off the 12 volt only through the seven pin until I got the no connection fault when I picked the trailer up from the shop who had killed my battery, and on when I hooked the trailer up, there was a no connection fault. After putting a new battery in, the brakes worked fine. This dead battery happened twice, so my assumption is that the brakes need the battery to function.

Connection fault is just that. Connection is being broken, but is not shorting out. Overload or o/l on most brake controllers is a connection fault that is shorting out.
Need to get this resolved. First place to look for bad wiring is the crossover wire that is run inside the axle tube.

 

[eXodus]

Same place as drum brakes - brake pin on 7way for normal operation. trailer battery for emergency operation.

This is clearly bad information. Electric brakes requires a battery on the trailer for emergency activation of brakes.
Surge brakes have no battery, but still have an emergency activation system that full operates the tongue master cylinder.

Every state is different on brake requirements. If you are legal in your state of licensing -then you should be legal / able to fight a ticket.
Washington State RCW is here:
http://search.leg.wa.gov/search.aspx#document&searchQuery=&searchBase=RCW&exec=false

https://drivinglaws.aaa.com/tag/trailer-brakes/ Most states are between 1500 3000lbs for breaks.
I was referring to those

but you are correct, trailer which require breaks should have a break away with battery. Man comment can be read miss leading I see that now.

Trailer which do not require breaks don't need that feature and thus don't have a battery. Or bigger trailers which have a surge break.

 

[MilkMan]

Thanks. If people are using the 60 amp DC to DC converter safely on a brake system that is rated at 16.3 amps, than I am perfectly happy to purchase it and install to run my brake system without a battery. I just don't want to be the first on my block to try it. Not that brave.

I felt the need to come back to this thread and mention some difficulties I had. The Daygreen converter eventually burnt out and started a fire. I suspect the 13.8v vehicle alternator voltage on the 12v load side of the converter fried it. This lead to the device continuously heating up without tripping any breakers/fuses. Or the device was faulty in an unknown way. Everything was properly fused.

I should have disconnected the vehicle power passthrough to the trailers 12v system. Costly mistake.

 

[chrisski]

I felt the need to come back to this thread and mention some difficulties I had. The Daygreen converter eventually burnt out and started a fire. I suspect the 13.8v vehicle alternator voltage on the 12v load side of the converter fried it. This lead to the device continuously heating up without tripping any breakers/fuses. Or the device was faulty in an unknown way. Everything was properly fused.

I should have disconnected the vehicle power passthrough to the trailers 12v system. Costly mistake

Thank you for sharing.

I am a couple months out from installing a Victron Orion 24 volt to 12 volt 70 amp converter.

I think you may be the only person I’ve read posting on using a high amperage converter to power breaks for a trailer. I also think the 60 amps is for leveling jacks.

I will try to see if what problems there could be on my similar setup. No reason I can’t disconnect the 12 volts you mentioned, especially with the battery and soar panels on the trailer.