32 replies to this topic

[Defulmmt]

I have the marine cable gland installed.  I used a hole saw to slightly enlarge the original entry point that ATC made when they installed the 10 awg.  I also installed the cable gland pictured above to the cable entry hole to protect the cables from the bed metal.  It appears to be a good solution although it was very difficult to access.  Vic’s solution described above would have been much simpler and, as it turns out, that area appears to be well protected from road spray, mud etc. (2019 f250).

 

Next step is running the cables to the engine compartment.  I have one question on grounding  …..ATC terminated the ve- cable at the chassis where the battery ve- cable is terminated.  Is it a better practical to run the ve- to the battery ve- post?  This maybe a newbie question and perhaps there is absolutely no difference, but I want to get it right before I terminate the cable.  Thx.

[Jon R]

… I have one question on grounding …..ATC terminated the ve- cable at the chassis where the battery ve- cable is terminated. Is it a better practical to run the ve- to the battery ve- post? This maybe a newbie question and perhaps there is absolutely no difference, but I want to get it right before I terminate the cable. Thx.

Either termination point is fine for the amount of current you are talking about as long as good practices are followed.

[K7MDL]

The F-150 uses a hall effect current sensor the negative battery lead for the internal battery monitoring system (BMS) which in turn controls the alternator output among other things.  Connecting to the battery neg post would bypass that sensor and not let it see the actual state of the battery current draw thus altering the calculated battery SOC. The F-250 may also have a BMS from what I can see.  I would use the chassis connection.  They will both work though.

Edited by K7MDL, 04 October 2023 - 07:21 AM.

[Vic Harder]

The F-150 uses a hall effect current sensor the negative battery lead for the internal battery monitoring system (BMS) which in turn controls the alternator output among other things. Connecting to the battery neg post would bypass that sensor and not let it see the actual state of the battery current draw thus altering the calculated battery SOC. The F-250 may also have a BMS from what I can see. I would use the chassis connection. They will both work though.

That’s a new one for me… really good to know!

[Wandering Sagebrush]

The F-150 uses a hall effect current sensor the negative battery lead for the internal battery monitoring system (BMS) which in turn controls the alternator output among other things.  Connecting to the battery neg post would bypass that sensor and not let it see the actual state of the battery current draw thus altering the calculated battery SOC. The F-250 may also have a BMS from what I can see.  I would use the chassis connection.  They will both work though.

Thanks for sharing, I had to look that one up.

[Defulmmt]

I terminated the ve- cable in the engine compartment at the chassis ground point, ve+ at the Blue Sea CB.

 

Do smart alternators use the Hall effect sensor to manage alternator output?  

[K7MDL]

I do not know what other vehicles use myself, but hall effect sensors are small and popular.  I use one for my main 70A 12V ham radio shack power supply current meter.  They are also used for charge and discharge current sensing in large 150VDC oil-filled pressure tolerant lithium batteries I work on used for deep submersibles.  They are very reliable but I did have to replace one buried inside of one battery.

[Defulmmt]

I’m making progress inside the camper with a new battery box (16 inch square footprint).  It’s a tight fit, but I have the components installed.  A little larger box would have probably been a good idea.

 

A couple of wiring issues have come up:

 

1) IIRC Tacoma Austin has a Blue Sea circuit breaker in the solar input line.  Seems like a good idea particularly with the Renogy dcdc. I think if the circuit is open the dcdc wouldn’t sense a solar input and could deliver the rated charge from the alternator.  Do I understand this correctly?

 

2) There are 10 awg wires from the battery compartment to the dc fuse panel.  I don’t recall seeing a fuse on this line during the disassembly of the stock system.  The loads on the panel are all fused but shouldn’t the 10 awg cable be fused.  I believe 30 amps is the maximum current for a 10 awg cable.  Is an in line fuse or a circuit breaker a best practice for this cable?

[TacomaAustin]

1) IIRC Tacoma Austin has a Blue Sea circuit breaker in the solar input line.  Seems like a good idea particularly with the Renogy dcdc. I think if the circuit is open the dcdc wouldn’t sense a solar input and could deliver the rated charge from the alternator.  Do I understand this correctly?

 

The breaker for my solar panel is for when I disconnect the house battery for storage.  It lets me isolate the solar panels BEFORE switching off the house battery. 

 

I haven't used this feature remove the solar panel from the equation when driving down the road for the purpose of bumping up the charging amps from the Renogy DC to DC charger.  I may do this later on in the year when the solar panel is next to useless on a dreary winter day.

[K7MDL]

2) There are 10 awg wires from the battery compartment to the dc fuse panel.  I don’t recall seeing a fuse on this line during the disassembly of the stock system.  The loads on the panel are all fused but shouldn’t the 10 awg cable be fused.  I believe 30 amps is the maximum current for a 10 awg cable.  Is an in line fuse or a circuit breaker a best practice for this cable?

 

 

Generally you want a fuse and/or battery disconnect as close to the battery as you can get.  There are standards (RVIA for RVs, ABYC/NMEA for marine) that specify max distances allowed.  Also wire size guides for current in a length of wire for specified voltage drops and insulation temperature ratings.  For marine it can vary, if cable is jacketed or in conduit it is allowed to go further from the battery. 

 

It comes down to a risk calculation - what is the chance of the wire from the battery to the first fuse or load point getting damaged and shorting, thus unleashing massive current and burning your wire and perhaps your vehicle with it?

 

I believe the RVIA magic number is 18 inches but I do not have the standard in front of me.  In our campers the battery to fuse block wire may be close, though it seems like a bit longer in mine.  Given that the wire is reasonably protected in sheathing and/or in cable harnesses in backs of cabinets, the risk of going a few inches longer seems low and I suspect FWC thinks so also.  Of my 3 FWC campers, none use battery fuses or a switch.

 

When I get around to upgrading to LI batteries, it will get rewired and I plan to install a switch and fuse near the battery.  For my portable batteries I use a MAXI fuse within a few inches of the positive post.