Lithium upgrade to 2023 5.0 with twin 6V + solar panel

[alanmalk]

The entire Maxx Fan issue is perplexing. The original Maxx fan in my 2014 15A hasn't cared about the higher voltage ala my LFP system for the past 5-years; no blown control boards.

Yet, later model year Maxx fan production seem to be a different animal and their intolerance of anything 13-ish volts and higher.

Keeping with the perplexing theme: Prior to Lithium systems, doing an occasional "equalization" charge (on Flooded Lead-Acid batteries) would bring the system voltage over 15 Volts. It seems reasonable to design RV electronics to withstand that higher voltage also.

 

[BritCanuck]

12.6

Thanks Alan!

Some more questions on your design if you don't mind.

Why did you decide to put the Fridge/Freezer DC circuits on a breaker instead of just a fuse? So you can isolate them easier? (i.e. don't have to pull a fuse)

You've put a fuse on the 12V break away cable. That seems to be a contentious design question in the RV community. Standards say no fuse? Also where did you put the break away cable test LED?

Also what panel are you using for the DC breakers?

Thanks!

 

[BobG-ESC]

You've put a fuse on the 12V break away cable. That seems to be a contentious design question in the RV community. Standards say no fuse? Also where did you put the break away cable test LED?

I believe the Federal Regulations require the electrical circuit for electric breaks emergency breakaway not be switched or fused. A self-resetting breaker (thermal breaker) is ok. You can research this if you want to confirm this yourself. I think you can have a fuse at the battery.

It might be easier to ask ChatGPT: "Can a trailer's emergency breakaway circuit for electric brakes have a fuse?" But you can find the federal regulations and read them. I have read them several times over the years. Sometimes it is difficult to find the pertinent regulation for electric brakes.

 

[BritCanuck]

I believe the Federal Regulations require the electrical circuit for electric breaks emergency breakaway not be switched or fused. A self-resetting breaker (thermal breaker) is ok. You can research this if you want to confirm this yourself. I think you can have a fuse at the battery.

It might be easier to ask ChatGPT: "Can a trailer's emergency breakaway circuit for electric brakes have a fuse?" But you can find the federal regulations and read them. I have read them several times over the years. Sometimes it is difficult to find the pertinent regulation for electric brakes.

I've done a search for Canadian regs. Looks like no fuse. Alan has a big 60A fuse in-line to protect against short circuits by the looks of it. So it shouldn't affect actual operation in an emergency.

Just for reference here's what Grok came up with :-

CSA Standards for Wiring and Electrical SystemsThe key reference for trailer electrical wiring, including breakaway switches, is CSA Z240.6.2-14/C22.2 No. 148-14 (Electrical Requirements for Recreational Vehicles), part of the broader CSA Z240 series for RVs and trailers.

• Breakaway Switch Wiring: Figure 3 in the standard illustrates the brake wiring diagram, showing a direct connection from the trailer battery to the breakaway switch without a fuse or circuit breaker in the breakaway circuit. This is explicitly permitted, as low-voltage (6-12V) brake wiring is exempt from certain overcurrent protection rules if it doesn't contact higher-voltage conductors (Section 1.2).
• Overcurrent Protection: General battery circuits require protection (e.g., fuses) within 1.5 m of the battery, but the breakaway circuit is treated as an exempt "vehicular brake wiring system" under CSA Z240.1.2. No dedicated fuse is required for the breakaway cable itself to ensure uninterrupted emergency operation.

 

[BobG-ESC]

I've done a search for Canadian regs. Looks like no fuse. Alan has a big 60A fuse in-line to protect against short circuits by the looks of it. So it shouldn't affect actual operation in an emergency.

I hadn't looked at Canadian regs. They are similar to U.S. regs. requiring no fuse or manual switch in the circuit. This being separate from the battery fuse located near the battery. Except it sounds like the Canadian regs also prohibit self-re-setting breaker?

 

[Centex]

Why did you decide to put the Fridge/Freezer DC circuits on a breaker instead of just a fuse?

No good reason?

EDIT - Wait, on recall it's because my DC fuse panel is on the limited-capacity 'house' voltage regulator and the Isotherm dual-compressor fridge has its own internal voltage regulators good for up to 24V (the DC breakers are on an 'un-regulated' bus, so the fridge / freezer doesn't take 'capacity' from my 'house' voltage regulator as would be the case if fused through my DC fuse panel). The Isotherm specifies 15ADC external circuit protection for each compressor.

You've put a fuse on the 12V break away cable.

First, note that 'legal' or not, incorrect assembly or not, as delivered by ETI my trailer had a 50A auto-reset breaker between the battery and the breakaway switch (a circuit which also served for charging from the tow-vehicle). I meticulously studied and documented my entire "As-Delivered" electrical system before undertaking any mods.

As I've explained in other posts (here and here), I do not like auto-reset breakers.

As modified, I now have a 30A manual-reset toggle breaker (not a fuse) in the dedicated breakaway circuit. The brakes will activate in a breakaway situation as long as the circuit is intact. IF not to some 'code', so be it. Do what makes you happiest!

Also where did you put the break away cable test LED?

In a sealed hole in my umbilical cord junction box, visible when I do a breakaway 'pull-pin test'. It's a bare LED from Amazon, I have gobs of them for various fun projects.

Also what panel are you using for the DC breakers?

A DIY 1/8" aluminum panel for the DC breakers and Master Battery Disconnect. A pic after fabricating on the vertical mill but before mounting (breakers are not the final installed):

 

[BritCanuck]

No good reason?

EDIT - Wait, on recall it's because my DC fuse panel is on the limited-capacity 'house' voltage regulator and the Isotherm dual-compressor fridge has its own internal voltage regulators good for up to 24V (the DC breakers are on an 'un-regulated' bus, so the fridge / freezer doesn't take 'capacity' from my 'house' voltage regulator as would be the case if fused through my DC fuse panel). The Isotherm specifies 15ADC external circuit protection for each compressor.

First, note that 'legal' or not, incorrect assembly or not, as delivered by ETI my trailer had a 50A auto-reset breaker between the battery and the breakaway switch (a circuit which also served for charging from the tow-vehicle). I meticulously studied and documented my entire "As-Delivered" electrical system before undertaking any mods.

As I've explained in other posts (here and here), I do not like auto-reset breakers.

As modified, I now have a 30A manual-reset toggle breaker (not a fuse) in the dedicated breakaway circuit. The brakes will activate in a breakaway situation as long as the circuit is intact. IF not to some 'code', so be it. Do what makes you happiest!

In a sealed hole in my umbilical cord junction box, visible when I do a breakaway 'pull-pin test'. It's a bare LED from Amazon, I have gobs of them for various fun projects.

A DIY 1/8" aluminum panel for the DC breakers and Master Battery Disconnect. A pic after fabricating on the vertical mill but before mounting (breakers are not the final installed):
View attachment 1944786

VERY nice!

 

[Centex]

I believe the Federal Regulations require the electrical circuit for electric breaks emergency breakaway not be switched or fused. A self-resetting breaker (thermal breaker) is ok. You can research this if you want to confirm this yourself. I think you can have a fuse at the battery.

I hadn't looked at Canadian regs. They are similar to U.S. regs. requiring no fuse or manual switch in the circuit. This being separate from the battery fuse located near the battery. Except it sounds like the Canadian regs also prohibit self-re-setting breaker?

So, these 'regs' apparently promote connection of a wire to a low-resistance / high-capacity lithium battery with no more wire-overload / short-circuit protection than the battery master fuse (which is inevitably rated very much higher than the ampacity of said wire); or maybe with 'protection' which constantly cycles 'on/off' in the face of an arcing fault?

That strikes me as the height of folly and hubris. Do what you will but there's no way I'm going to have a ~10AWG wire that's essentially directly connected to my lithium battery running through my trailer without proper wire-ampacity overload / short-circuit protection.

 

[CE Vogel]

So, these 'regs' apparently promote connection of a wire to a low-resistance / high-capacity lithium battery with no more wire-overload / short-circuit protection than the battery master fuse (which is inevitably rated very much higher than the ampacity of said wire); or maybe with 'protection' which constantly cycles 'on/off' in the face of an arcing fault?

That strikes me as the height of folly and hubris. Do what you will but there's no way I'm going to have a ~10AWG wire that's essentially directly connected to my lithium battery running through my trailer without proper wire-ampacity overload / short-circuit protection.

Centex's concern is valid, and this is especially true with lithium batteries. But there is another option besides a fuse or circuit breaker: a low resistance resistor. According to the Dexter website, four brakes draw 12 amps, which is equivalent to one ohm resistance at 12 volts. An in-line resistor significantly less than one ohm will protect the circuit, while also limiting the power to the brakes when the breakaway switch is pulled. For example, a 1/2 ohm resistor will limit current to 24 amps into a dead short, while limiting the brakes to eight volts from the breakaway switch. A 1/4 ohm resistor will limit short circuit current to 48 amps, while limiting the brakes to 9.6 volts from the breakaway switch. The resistors will dissipate a lot of heat in a short circuit condition, 288 watts for the 1/2 ohm resistor, 576 watts for the 1/4 ohm resistor. Not an ideal solution, but perhaps better than a wire catching fire in a random location. Suitable resistors can be found at DigiKey and Mouser Electronics.

 

[hghsl]

I don't know how long it would take. I suppose it depends on wiring and alternator, but if wiring and fusing was good for 30 amps, then I think an hour or two would be good for a day of energy as long as energy use was held to a minimum. Adding a DC-DC charger to the charging circuit and rewiring the breakaway switch and power jack would be relatively easy.

A generator is an option but not for everyone. In any case, if tow vehicle charging eliminates some generator use, that would be a plus.

I did a dc to dc charger on a 5.0ta. I mounted the charger to the inside panel of the lefthand landing gear compartment. I opened the 7 way junction block. Since there are no backup lights on the 5.0ta, I removed the backup light wire from the 7way block and taped this wire back. Next I located the aux power wire coming from the 7way plug and moved wire to the now empty stud. Next I ran two 10gauge copper stranded wires to the landing gear area. Connected wires to these two studs on the 7way junction block. Wired to dc to dc charger with the proper wires. I used a landing gear mounting bolt to connect the ground wire or wires, depending on the dc to dc charger. This will allow power to the breakaway brakes and also the landing gear from the house batteries, without a lot of rewiring

 

[Chamberman]

Centex's concern is valid, and this is especially true with lithium batteries. But there is another option besides a fuse or circuit breaker: a low resistance resistor. According to the Dexter website, four brakes draw 12 amps, which is equivalent to one ohm resistance at 12 volts. An in-line resistor significantly less than one ohm will protect the circuit, while also limiting the power to the brakes when the breakaway switch is pulled. For example, a 1/2 ohm resistor will limit current to 24 amps into a dead short, while limiting the brakes to eight volts from the breakaway switch. A 1/4 ohm resistor will limit short circuit current to 48 amps, while limiting the brakes to 9.6 volts from the breakaway switch. The resistors will dissipate a lot of heat in a short circuit condition, 288 watts for the 1/2 ohm resistor, 576 watts for the 1/4 ohm resistor. Not an ideal solution, but perhaps better than a wire catching fire in a random location. Suitable resistors can be found at DigiKey and Mouser Electronics.

I don't see this as being a viable alternative due to the fact it limits brake current in an emergency to less than the manufacturers design. In some older trailers even with only 0.25ohms of resistance added to the circuit in order to limit max current some of the brakes may not fully engage, especially if the grounds and wiring aren't perfect. Having the full 12.8V available to push current through the magnets helps to displace other mechanical/wiring factors which may hinder brake current in an emergency.

The regulation boards certainly have engineers involved with these rules and those folks are aware that simple high power wirewound resistors could be used to limit current in the direct connected brake circuits, but they didn't offer that as an option.

 

[BobG-ESC]

When I was dealing with the emergency breakaway brake circuit 5 years ago, I had to deal with the issues being discussed. It is possible that a fuse in the line will at some point during a violent breakaway event get blown by a loose brake wire contacting the ground. It could be instantaneous and intermittent. If the accident results in an investigation and there is a blown fuse in the circuit, I am not sure how a plaintiff's attorney would play that.

After thinking about it and not being happy with anything I could think of, I just used the reset breaker that Escape installed, secured all my wires and torqued all the connections to spec and hoped for the best. I don't think Contex's approach is necessarily wrong. I certainly felt uncomfortable not fusing the line.

 

[Centex]

I don't see this as being a viable alternative due to the fact it limits brake current [voltage] in an emergency to less than the manufacturers design .....

My thought, too.

After thinking about it and not being happy with anything I could think of ....

I agree that none of the approaches mentioned for this particular circuit, with its unique purpose, is 'ideal' or 'foolproof', mine included. I certainly understand your final election. Methinks this particular circuit is one where each person just needs to make their own evaluation of risks / pros / cons and upon settling on a solution that makes them comfortable .... head-on down the road, enjoying their travels without further worries!

 

[CE Vogel]

I don't see this as being a viable alternative due to the fact it limits brake current in an emergency to less than the manufacturers design. In some older trailers even with only 0.25ohms of resistance added to the circuit in order to limit max current some of the brakes may not fully engage, especially if the grounds and wiring aren't perfect. Having the full 12.8V available to push current through the magnets helps to displace other mechanical/wiring factors which may hinder brake current in an emergency.

The regulation boards certainly have engineers involved with these rules and those folks are aware that simple high power wirewound resistors could be used to limit current in the direct connected brake circuits, but they didn't offer that as an option.

There appear to be no good ways to guarantee the brakes work in an emergency while providing protection to the wiring. Fuses, self resetting breakers, non-resetting breakers, resistors, no protection, all have their disadvantages.
My current trailer and my previous trailer both came with a small battery used only for the breakaway circuit. The small size of the battery limits available current, thereby operating almost like a resistor. But the wiring is unfused and direct, meeting regulatory requirements. My breakaway switch was accidently activated last summer when I made an unusually tight turn. I could feel the brakes drag, but the trailer wheels were definitely not locked. I also wonder how long the battery could provide 12 amps, and may fail to meet any regulatory time requirements. This is what was factory installed on my trailer: https://www.etrailer.com/Trailer-Breakaway-Kit/Hopkins/20099.html
Having a dedicated breakaway battery carries its own disadvantages. It doesn't fully engage the brakes. There is the cost of periodic battery replacement. Somehow it must be kept charged. It is easily forgotten and neglected. It can fail without any indication to the owner until it is needed in an emergency.
There are no ideal solutions. For now I'm keeping my breakaway battery setup. I do periodically test and replace the battery. It works (as confirmed last summer), even if it doesn't lock up the wheels.

 

[Chamberman]

I think that it would be better on dual axle trailers to have two independent axle brake circuits. Separate wiring and independent fuses or breakers for the front & rear axle. In the event one axle has an overcurrent event and opens the protection device then the second axle brakes will still be operable. It would be similar to a vehicles braking system in which front & rear have independent hydraulic circuits. It wouldn't add that much cost to wire up two separate circuits. Of course this still doesn't help those with a single axle trailer.

 

[BritCanuck]

Well started tracing out pertinent wiring today and it looks like my breakaway cable is fused through the battery 50a thermal breaker. It’s connected on the 50a fuse terminal before the disconnect switch.

Also I’ve come to realise (obvious from the wiring diagram) that if you have solar the battery disconnect does not completely disconnect the battery, it just disconnects the DC fuse panel from the battery. The battery is still connected and being charged from solar.

So think when I rewire everything I’ll keep the break away feed on the 50A thermal fuse.

Again I presume this design is to ensure the emergency brakes work even If you accidentally activate that switch as it’s connected on the battery side of disconnect switch.

To be a complete disconnect the switch needs to be on battery negative, which is what Centex/Alan has done on his design.

 

[BritCanuck]

So another question if anyone is still reading this thread.

I've decided to keep it simple and not put an inverter in. I am switching out my WFCO for the PD4655V though.

How concerned do I need to be about higher lithium battery voltages being fed directly to all my DC appliances? I'm assuming it's not a major issue and RV appliances can deal with the slightly higher voltages.

As fast as as I can tell I don't have an easy way of regulating the DC voltage from the battery without blocking charging from the PD6455? From my research none of the Victron DC/DC controllers allow reverse current flow.

Attached is my draft layout.

 

[Ron in BC]

I've decided to keep it simple and not put an inverter in.

How concerned do I need to be about higher lithium battery voltages being fed directly to all my DC appliances?

I've had inverters since they first became economically feasible about 1989. Well, a 400W for the cost of a much more powerful one today. I've gone back and forth on the need for one and have retro-fitted 4 of them. It's a pretty easy DIY add-on later if you decide you want one.

Some folks have had fan problems and thought the voltage was to blame. I've never had a problem with the voltage from my lithium batteries. Probably mixed opinions on that issue.

Ron

 

[Centex]

Just to be clear, this is installing a PD4655V converter upgrade within your existing WFCO 8955 Power Center, retaining the WFCO AC and DC Fuse Panels, is that correct?

Hmmm, I'm not sure that as depicted your shunt will properly / accurately account for trailer loads and charging.

Methinks that rather than routing the DC fuse panel ground to chassis it would be better to route that ground to the shunt "loads" terminal (or a negative bus between the "loads" terminal and the chassis ground).

^edited upon further reflection, misplaced / needless concern^

Also curious, why is there a 30A fuse on the ground-cable between the DC Fuse Panel and the chassis (or shunt / negative bus if routed as suggested above)? IMO it's not appropriate to limit the current on a ground cable.

Again curious, why are you limiting the battery input / output at the DC fuse panel (and thereby charging amps from the PD4655V) with a 30A fuse? Your 8955 panel is rated for 55A isn't it? I note that the PD4655V is rated to output up to 55A; if the battery condition demands a charging rate over 30A, that fuse would blow.

 

[BritCanuck]

Hmmm, I'm not sure that as depicted your shunt will properly account for trailer loads and charging.

Methinks that rather than routing the DC fuse panel ground to chassis it would be better to route that ground to the shunt "loads" terminal (or a negative bus between the "loads" terminal and the chassis ground).

Also curious, why is there a 30A fuse on the ground-cable between the DC Fuse Panel and the chassis (or shunt / negative bus if routed as suggested above)?

Again curious, why are you limiting the battery input / output at the DC fuse panel (and thereby charging amps from the PD4655V) with a 30A fuse? Your 8955 panel is rated for 55A isn't it? I note that the PD4655V is rated to output up to 55A; if the battery condition demands a charging rate over 30A, that fuse would blow.

Yes you’re correct, those 2 x 30A fuses are the ones included on the DC panel to protect against reverse polarity. I’ve mis-drawn where the fuses are on the internal converter circuit. Having done some more research i believe those 2 30A fuses are in parallel on the positive leg providing 60A capacity. So 55a charging isn’t an issue.

Can you expand on the shunt location? That’s where Escape installed it. On the negative battery cable which goes down thru the floor to the frame bolt.