DC to DC charger size questions

[Mike Jordan]

DC to DC charger size questions

Looking for info before I install a DC to DC charger for my travel trailer. Bigger may be better for quickly charging the batteries. But my concerns are over taxing the alternator or tow vehicle systems. Where can I find info on amperages safe for my tow vehicle?

diysolarforum.com

Read that.... the first time you posted. With smart alternators, they have the capability of much higher output of the dumb alternators of the past for short time durations. But if you tax the smart alternator with high amperage requirements from a DC/DC charger for long durations, things might not go so well. The days of measuring and amperage needs and finding ratings disappeared a decade or more ago. I am looking for a place to find the output duration and other protection specs

 

[Mike Jordan]

OK some of the details were missing..... such as the make and model of the vehicle. Maybe even the part number for the alternator.
My old Mustang was 35 amps and some trucks go over 200 amps.

Or did I miss this? Or search for a replacement as the specs will often be given. Walk into the dealer parts dept and ask. Google is probably easier.
There is no resource that will tell the maximum accessories that you can add to a vehicle. Going to be a bit of a guess.

That info was left out purposely, as I did not ask for my specific specs, I asked where I can find the specs.

But if you can give me the link with the info, it is a 2020 F150 EB 3.5, max tow

 

[Mike Jordan]

You never gave any information that is needed. Kinda hard to answer or help with limited information. I gave you the generic version, if you want to load an alternator to 100% of output, have at it.

Your vehicle could have a 50 amp alternator or it could have a 250 amp. You are the one responsible for telling us whether you have a Yugo and you are really responsible for looking up the rating for it's alternator. If you want the duty cycle of an alternator, then contact the manufacturer of the Yugo alternator.

Once that information is related to those attempting to help you, then possibly an answer may be forthcoming.

If you want specs, contact the local parts store for the specs for the Yugo alternator. That is the easiest. You might be required to look at the Yugo build specs (little sticker somewhere which lists the equipped option codes) if asked.

If you want to play guessing games, what color is the shirt I'm wearing? It's not the same color I had on yesterday..........

That info was left out purposely, as I did not ask for my specific specs, I asked where I can find the specs.

But if you can give me the link with the info, it is a 2020 F150 EB 3.5, max tow

 

[moonlitsouls]

That info was left out purposely, as I did not ask for my specific specs, I asked where I can find the specs.

But if you can give me the link with the info, it is a 2020 F150 EB 3.5, max tow

you're awfully rude for someone asking for help

 

[Zwy]

That info was left out purposely, as I did not ask for my specific specs, I asked where I can find the specs.

But if you can give me the link with the info, it is a 2020 F150 EB 3.5, max tow

If it has AC power, you might be better served by running ac power to travel trailer and using an AC to DC charger instead of a DC to DC.

If you do go DC to DC, you will need to run a heavier wire than the factory wire.

Why didn't you just ask the Ford dealer to run the VIN for the alternator size?

 

[grizzzman]

That info was left out purposely, as I did not ask for my specific specs, I asked where I can find the specs.

But if you can give me the link with the info, it is a 2020 F150 EB 3.5, max tow

My 2019 with the same specs is rated at 220 amps. Just wait for the fun "smart charging" issues..... be sure your DC to DC has Buck/Boost capability....

 

[corn18]

My 2015 Chevy 2500HD 6.0L gasser has a 150A dumb alternator and I just measured the amperage with the headlights on and it's 34 amps. Am I ok with my 18A DC-DC smart charger I have? The line running back to the 7 pin is 10ga with a 30A fuse. Voltage at the connector is 13.6. I have the smart charger (Victron) set for 14.4V output, so it seems like it would draw about 22A at full load. That would put me at 56A on a 150A dumb alternator.

 

[John Frum]

My 2015 Chevy 2500HD 6.0L gasser has a 150A dumb alternator and I just measured the amperage with the headlights on and it's 34 amps. Am I ok with my 18V DC-DC smart charger I have? The line running back to the 7 pin is 10ga with a 30A fuse. Voltage at the connector is 13.6. I have the smart charger (Victron) set for 14.4V output, so it seems like it would draw about 22A at full load. That would put me at 56A on a 150A dumb alternator.

How many amps is the charger rated for?
How long is the round trip distance from the battery to the input side of the dc2dc charger?
What is the voltage at the battery terminals when the alternator is running?

 

[Short_Shot]

My 2015 Chevy 2500HD 6.0L gasser has a 150A dumb alternator and I just measured the amperage with the headlights on and it's 34 amps. Am I ok with my 18V DC-DC smart charger I have? The line running back to the 7 pin is 10ga with a 30A fuse. Voltage at the connector is 13.6. I have the smart charger (Victron) set for 14.4V output, so it seems like it would draw about 22A at full load. That would put me at 56A on a 150A dumb alternator.

You'll be fine. Might be a bit more than 22a with some efficiency and voltage loss on the line but it shouldn't be a big issue.

 

[eXodus]

My 2015 Chevy 2500HD 6.0L gasser has a 150A dumb alternator and I just measured the amperage with the headlights on and it's 34 amps. Am I ok with my 18A DC-DC smart charger I have? The line running back to the 7 pin is 10ga with a 30A fuse. Voltage at the connector is 13.6. I have the smart charger (Victron) set for 14.4V output, so it seems like it would draw about 22A at full load. That would put me at 56A on a 150A dumb alternator.

The 2015 has a "smart" alternator, it has control plug - so it's "smart" I think they introduced those in the 90s

I've got a 2000 Chevy Express 3500 tow package 5.7L Vortec with a smart 180A alternator. (Heavy Duty A/C unit included)

I'm charging a 450ah battery bank - with the help of a stupid relay. The highest load on the cable going to the battery bank I've ever observed was 60A.
I got a resettable 100A breaker to protect the alternator. It tripped once in 5 years.

Disclaimer - I'm using the vehicle frame as ground for the batteries - there are about 25ft of 0/2 going from the alternator to the battery bank all the way in the back of the Van. This setup is introducing ample of resistance into the circuit. The 13.8 - 14.4V coming from the alternator are actually not very good to charge a LFP battery fast. You need like 14.8V to do that, below that - it's slow - just what we want to protect the alternator.

 

[Mike Jordan]

you're awfully rude for someone asking for help

If you read through all of the comments, not one comment has supplied the info I asked for. Thats ok, I guess I have stumped the hive.

I appreciate the bump, so that someone that know might the answer has a better chance to see the question.

Rude is not intended. Just trying to redirect folks that are supplying info that I did not ask for, and not supplying the info I did ask for, so I do not get more of the same

 

[Mike Jordan]

If it has AC power, you might be better served by running ac power to travel trailer and using an AC to DC charger instead of a DC to DC.

If you do go DC to DC, you will need to run a heavier wire than the factory wire.

Why didn't you just ask the Ford dealer to run the VIN for the alternator size?

How do I do this AC to DC charger while running down the road?

I already understand wiring sizes, I did not ask about wire size

I do not need to know the alternator size. Thats why I did not ask about alternator size. Since the advent of smart alternators, charging capacities have gone way up. But that high capacity is greatly limited by time. My question is.... where to find that "charge profile" type info for my alternator

 

[Mike Jordan]

My 2019 with the same specs is rated at 220 amps. Just wait for the fun "smart charging" issues..... be sure your DC to DC has Buck/Boost capability....

Do you have anymore info on the charge profile for the alternator, or know where I can find it?

 

[Short_Shot]

How do I do this AC to DC charger while running down the road?

I already understand wiring sizes, I did not ask about wire size

I do not need to know the alternator size. Thats why I did not ask about alternator size. Since the advent of smart alternators, charging capacities have gone way up. But that high capacity is greatly limited by time. My question is.... where to find that "charge profile" type info for my alternator

Not sure where you got the idea that a smart alt inherently has higher output, but they're just regular alts with a variable output regulator module. In some vehicles you'll have an electric clutch on the alt but most just use an electronic regulator these days.

Further, the information on their "charge profile" isn't really posted information as it's not fixed.
The goal of a smart alternator is to maintain a lower battery state of charge to reduce fuel consumption. Normally this soc is about 80%.

Most of them will stop doing this when the headlights are turned on, the vehicle is placed into a "tow mode" or the battery is in poor condition.

Quite simply, the information you're asking for doesn't exist and is utterly nonsense to even look for.

The only thing you need to know for a DC to DC charger is what the max output is and whether your wiring will handle the chargers current demands.

Further still you did not ask for this information in the first place. You asked what "safe amperages" are for your tow vehicle.

 

[Mike Jordan]

Further, the information on their "charge profile" isn't really posted information as it's not fixed.
The goal of a smart alternator is to maintain a lower battery state of charge to reduce fuel consumption. Normally this soc is about 80%.



Quite simply, the information you're asking for doesn't exist and is utterly nonsense to even look for.

I detect a contradiction in statements.

"A charge profile is not posted, as it isn't fixed".... is EGGGGGGGZACTLY why it should be, and probably is posted. If it was fixed, you would just look at the alternators amp rating, like so many folks have (wrongly) suggested. The fact that it is not fixed, it the reason why I would like to find the profile. I would like to find the parameters that change the variability of.... "it isn't fixed"

So... since its not fixed as you so eloquently described, then why is it such nonsense to look for the parameters of the changes that make it "not fixed"?

 

[Short_Shot]

I detect a contradiction in statements.

"A charge profile is not posted, as it isn't fixed".... is EGGGGGGGZACTLY why it should be, and probably is posted. If it was fixed, you would just look at the alternators amp rating, like so many folks have (wrongly) suggested. The fact that it is not fixed, it the reason why I would like to find the profile. I would like to find the parameters that change the variability of.... "it isn't fixed"

So... since its not fixed as you so eloquently described, then why is it such nonsense to look for the parameters of the changes that make it "not fixed"?

As stated the "charge profile" isn't of a fixed nature. The "parameters" are "don't charge the battery all the way to save fuel" and "enable full output when the lights are on or in towing mode". This, you might recognize, is not a "charge profile".

Some vehicles will provide additional reasons to go to high output depending on other loads, like if you have a fancy built in inverter, and some will detect any high load and enable.

That's it. That's what you get.
That's what any of us gets.

For all practical purposes your alternator is either on, or off. Sure you'll get a bit of voltage regulation in there but when it kicks "on" your able to pull whatever maximum current it can provide at that RPM.

So you would do well to understand the output limit at idle as well which should be a phone call to the dealer. I'd find that out then find my vehicle's maximum idle demand and make sure my charger is slightly under that limit when added up.

I have a smart alt and use a dc to dc charger and I'm confused as to why you need more than that.

You can't do anything about it except understand that the output fluctuates and how to force it "on". I've given you this information.

All you can do is enable or disable the charger depending on alternator output condition and this is built into any good dc to dc charger, such as victrons.

 

[Zwy]

How do I do this AC to DC charger while running down the road?

By using a cord, duh!



The only one stumped in this thread is yourself, certainly not the hive.

This article refers to the 2021 model F150 with Pro Power Onboard, but it still applies. Let me make it simple for you as you don't understand how to plug a cord into an outlet to get AC power. From the article, https://news.pickuptrucks.com/2020/06/5-fun-facts-about-the-2021-f-150s-onboard-generator.html

The 2.0-kW system can be added to any F-150 equipped with the 2.7-liter V-6, 3.5-liter V-6 or 5.0-liter V-8 engine. When activated, the system runs the engine to provide power to the inverter and two 120-volt, 20-amp three-prong outlets in the bed of the truck. It operates while the vehicle is parked or while it’s in motion, enabling you to keep items plugged into the outlets in the bed that might need recharging as you’re driving to a worksite or campsite. It provides up to 2,000 watts of power for whatever you want to plug in. This is a considerable upgrade from what most 120-volt outlets presented in trucks currently are usually limited to 400 watts, which is enough to power portable speakers or maybe a small television at a tailgate party. But now with 2,000 watts to play with, you can theoretically power some speakers, a TV, an electric heater, a mini-fridge and a blender, perhaps all at the same time.

Now if you don't have this option, then it doesn't apply. But with the tow package on your 3.5L, it should have been equipped.

I already understand wiring sizes, I did not ask about wire size

It isn't about wire size, it's about transferring the watts from the alternator to the house battery. I understand, you're stumped again unlike the hive. But maybe it will sink in, eventually.

2000w available on the AC inverter on the truck is 150a at 12v. I'd like to see you run 150a thru the factory wires to the trailer connector.

I do not need to know the alternator size.

You asked "Where can I find info on amperages safe for my tow vehicle?"

In order to answer any question similar to that, the rated amperage of your Yugo alternator needs be known. You can't run an alternator at continuous duty at 100% output, it will fry it. You don't seem to grasp the concept that duty cycle is important in any electrical device.

Thats why I did not ask about alternator size. Since the advent of smart alternators, charging capacities have gone way up. But that high capacity is greatly limited by time. My question is.... where to find that "charge profile" type info for my alternator

What you want to know is out there, you need to contact the vehicle manufacturer as they did the testing. However a smart alternator will only produce what is needed to maintain the vehicle battery charge with the current loads, this is done to reduce engine load and increase the fuel economy.

The best method for your particular case is to run an AC power cord to an onboard AC to DC charger with a LFP charging profile. Do what you want, but you will not get that wattage to the house battery using a DC to DC charger. And the DC to DC will cost you way more than a drop cord and AC to DC charger.

 

[grizzzman]

Do you have anymore info on the charge profile for the alternator, or know where I can find it?

The system is capable of14.7 volts. On the freeway the voltage "mostly" stays at 12.9 volts. Climbing a pass (Under a moderate load) the voltage would jump to 13.6 volts (My guess is with the A/C on the voltage under load that the fan voltage would be at the rated fan speed for max cooling if needed) I saw it jump to 14.7 volts once when I first turned on the A/C (lasted for about 2 seconds) On my trip back home. I will turn off the A/C under a load and observe.

 

[Mike Jordan]

As stated the "charge profile" isn't of a fixed nature. The "parameters" are "don't charge the battery all the way to save fuel" and "enable full output when the lights are on or in towing mode". This, you might recognize, is not a "charge profile".

Some vehicles will provide additional reasons to go to high output depending on other loads, like if you have a fancy built in inverter, and some will detect any high load and enable.

That's it. That's what you get.
That's what any of us gets.

For all practical purposes your alternator is either on, or off. Sure you'll get a bit of voltage regulation in there but when it kicks "on" your able to pull whatever maximum current it can provide at that RPM.

So you would do well to understand the output limit at idle as well which should be a phone call to the dealer. I'd find that out then find my vehicle's maximum idle demand and make sure my charger is slightly under that limit when added up.

I have a smart alt and use a dc to dc charger and I'm confused as to why you need more than that.

You can't do anything about it except understand that the output fluctuates and how to force it "on". I've given you this information.

All you can do is enable or disable the charger depending on alternator output condition and this is built into any good dc to dc charger, such as victrons.

You are describing the exact parameters that I would like to quantify, but you don't know what they are either. Thats OK. I don't know, you don't know. But since you have responded to the post. maybe someone will come along that knows. Then we both will know

 

[Zwy]

You don't get it yet, but I will explain this more clearly so maybe you will catch on. On the AC power supply side of this vehicle, there is 2000 watts of power available. This was designed to provide the 2000 watts continuously from all the information I have found including an interview with the Ford On Board Power engineer. This information is out there, you just have to dig for it. As for surge rating, it's probably in your owner's manual.

If you have the optional 7.4kw version like the 2021 model has, then it was designed to provide 7400 watts continuously.

In other words, as long as you use the AC side of the system, you can draw the full amount of watts continuously at 100% duty cycle if you desire. I've tried to steer you in the right direction, it is quite simple, you use the AC side of the On Board Power system to transfer power from the tow vehicle to power accessories and charge the house battery bank. It was designed for it's rated capacity and 2000 watts is plenty of available power compared to attempting to charge with a DC to DC charger at 60 amps (which is about the largest DC to DC I've seen). never mind the cable size needed. You won't need to override the PCM control of the smart alternator either, the PCM will control output based upon what the On Board System demands.

This is the easiest and highest power output and even the cheapest.