Lithium battery charging in FW of truck

[Slownsy]

Can someone please explain. 2015 F350 alternator 200-220A, wire to rear of truck not clear on gage but about 20’, wire from plug to FW batteries 15’ or more supposedly protected by 30A fuse. I se people say batteries can draw power and fry alternator, and are installing dc to dc charger in FW to limit the charging. Also people are installing dc to dc chargers because of voltage drop in wire and smart alternators not supplying sufficiently. So how is all this happening,or is it. Please be gentle as I am no electric genus.
Thanks Frank.

[Slownsy]

The trailer charging fuse in truck is 40A, in FW wire is 10 avg to a 30A fuse before batteries, the V from truck to FW is 14.1V to the 30A fuse before the batteries. ? Any way that batteries can damage the alternator,or will the fuse blow if to much amp are getting called for by batteries.
I can easily pull the 30A fuse in FW if necessary.
Thanks Frank

[StirCrazy]

pianotuna wrote:
Steve,

The 40 amp has a jumper that may be removed to allow it to work at 20 amps. I would go with the 40 because of that feature.

thats good to know, I do have the 220 amp alt so I can handle the 40, but if I ever transfer it to somthing new that might be a good feature to have.

Steve

[StirCrazy]

BFL13 wrote:


PT says 1/3 for running so 220/3 = 73 amps and the 60 will pull 90, so the 40 pulling 60 seems right. But that needs a wire upgrade from the 7-pin's.

I put an on /off switch on the "ignition" wire that goes to a 12v source in the camper, not the truck. I have the 20 amp DC-DC with 7-pin input. It does great with constant 20 amps, and pulls maybe 30 amps which the 7-pin can handle ok, and also the alternator at 1/3.

ya I am planing on runing a couple of 2 or 4ga wires to a special plug in with a signal wire hooked to my upfitter switch so I can turn it off or on from the cab of the truck. what I am trying to figure out is if I can just buy one and mount it un the truck and use it for both the 5th wheel and camper or if I have to buy two. I know it should be as simple as going to a larger wire size to reduce voltage drop. if I go 2ga that should be less than a 1% voltage drop over 20 feet if I am dealing with the 40 amp output rather than the 60 amp input. I am trying to find a voltage drop chart that shows less than 1% but having a hard time.

Steve

[MEXICOWANDERER]

Just for reference the 4890 Leece-Neville Alternator is about the physically smallest unit that would put out massive amps reliably for extended periods under hood. And it's a moose. The only way I would task a high amperage ND alternator would be if it had an external rectifier bridge. It would be a money in the bank burnout otherwise. It takes x number of c2x to heatsink rectifiers and the NDs aren't even close.

[Grit_dog]

Bottom line, your alternator isn’t going to be damaged by charging through the factory system. It’s also not going to do the “best” job of charging your house batteries.
But you can keep rolling without doing anything.
Too many theories by others that are also not electrical geniuses.
I’ve heard some new vehicles will limit out put more than they could put out , but I heard that here. And it doesn’t have a lot of plausibility, as trucks are designed to pull accessory loads or they would not be set up with factory up fitter switches and alternators larger than needed for normal daily use. Think about it.

You “could” theoretically cook an alternator if you wired large gauge direct to alt output and to a Lifepo4 battery as it would pull more charging amps than available.
But in practicality I doubt that too.

Now if you want or need to optimize charging house batteries off of your truck, then a DC DC charger will accomplish that.

Remember believe nothing you hear and only half of what you see....and always take a look around and judge what you heard based on what you see.
Do you see new trucks with the hood up and smoking alternators that are hooked to campers? Ever? Nuff said....

[BFL13]

No, I meant pin 4 in the 7 pin which is the 12v wire. Maybe #10 gauge . Your 200a alt can take
the amps of the 40 , but you need fatter wire and fuse maybe the winch wire.

[pianotuna]

Frank,

The 7 pin does not have 4 gauge wire.

[Slownsy]

Thanks all, BFL13 thanks I take it you are referring to the wire as 4 gage on plug? Or the nor 4 position. And that this is connected true a 30A fuse that will blow if to large a drain is put on it, that was my thought also, so the lithium batteries will not smoke the alternator and only have to get dc to dc charger if I want higher charging? I have already in the past had to replace a glass fuse in FW a couple of times in the past, I think it was on the supply coming from truck, will check it and it’s rating out.
Frank.

[pianotuna]

Steve,

The 40 amp has a jumper that may be removed to allow it to work at 20 amps. I would go with the 40 because of that feature.

[BFL13]

I have it in the 2003 Chev. Can't remember the amps of the alt--ISTR 105 amps, not sure.

PT says 1/3 for running so 220/3 = 73 amps and the 60 will pull 90, so the 40 pulling 60 seems right. But that needs a wire upgrade from the 7-pin's.

I put an on /off switch on the "ignition" wire that goes to a 12v source in the camper, not the truck. I have the 20 amp DC-DC with 7-pin input. It does great with constant 20 amps, and pulls maybe 30 amps which the 7-pin can handle ok, and also the alternator at 1/3.

Can't carry a gen in the TC/truck so this is the "gen" if no solar. Have to idle the truck for an hour to get 20AH. With the 40 you could get 40AH but needs the better wire for input.

[StirCrazy]

BFL13 wrote:
-The base alternator is still a 157A single unit on the 6.7L.

-Extra Heavy Duty Alternator (220A single unit) is the first possible upgrade:
Required on any truck with the snowplow package
Required on any Lariat and up trim truck with the upfitter switches OR 110v outlet
Required on any XL or XLT truck with the upfitter switches and 110v outlet ordered together

https://www.ford-trucks.com/forums/1503981-2017-alternator-questions-dual-single-extra-heavy-duty-so...

AFAIK, if your LFPs want more amps than what the 7-pin can supply it will just blow the fuse on the pin # 4 wire.

Not clear what you really want for a set-up here. Once that is clear , there will be a number of ways to do it.

BFL13, which altanator did you have and how do you like the preformace of your DC to DC?

I am trying to decide what one to get. I have the 220A alt and I want to wire it to the upfitter switch so I only have it on when I want it to be on, but not sure of I should go with the 40 or the 60Amp

Steve

[StirCrazy]

Lwiddis wrote:
If you get an adequate solar system you’ll never look back. That’s all you need.

thats not always true, I have a solar system that normaly had my batteries at 100% by noon.

last fall I was camping and it was cold, cloudy and overcast for 3 days and I got down to about 50% on my deep cycle GC batteries. a DC to DC charger would have been handy to top up my bateries in thoes types of conditions.

I dont like using the factory wiring as there is voltage drop and so on , but a nice DC to DC that you can turn on or off (I am going to put it on one of the upfitter switches in my truck) seams like a nice back up power supply just for situations like I have quite ofter in spring and fall.

Steve

[pianotuna]

An Ambulance is often dual alternators.

If you still want Li charging from alternator but are afraid of blowing a fuse--then get an auto reset breaker rated 10 amps below the fuse value.

The continuous duty rating for the alternator is 1/3 of the full output.

[BFL13]

-The base alternator is still a 157A single unit on the 6.7L.

-Extra Heavy Duty Alternator (220A single unit) is the first possible upgrade:
Required on any truck with the snowplow package
Required on any Lariat and up trim truck with the upfitter switches OR 110v outlet
Required on any XL or XLT truck with the upfitter switches and 110v outlet ordered together

https://www.ford-trucks.com/forums/1503981-2017-alternator-questions-dual-single-extra-heavy-duty-so...

AFAIK, if your LFPs want more amps than what the 7-pin can supply it will just blow the fuse on the pin # 4 wire.

Not clear what you really want for a set-up here. Once that is clear , there will be a number of ways to do it.

[Slownsy]

Ok thanks all. It appears that I have better disconnect charging from truck or get a dc to dc charger. According to Fords window sticker it is the heavy duty alternator, there are 3 set ups that I am aware of , standard, heavy duty, and dual, don’t know what is used in Ambulance.
Frank.