DC-DC battery charger under hood?

[CampStewart]

Ambulances used to have external adjustable voltage regulators, wouldn't that solve the low voltage issues you guys are bickering about? No one here seems to be giving out solid concrete numbers A to Z to support their arguments, without them this just sounds like a ********** fest of those trying to prove they are the smartest. Back up your arguments so we can learn something

 

[DiploStrat]

... Standard automotive-type alternators rarely offer the construction required to meet the demands of large marine charging systems.
...

Absolutely true. But, at the same time, the real world charging needs of a lead acid camper battery bank rarely exceed 100A and even that for only a limited period of time.

Most Big Three US pickups are available with 200A+ alternators and even if derated by 50% can handle those loads.

For those who need more, Adam Nations offers many options, some rated for a 100% duty cycle. https://www.nationsstarteralternator.com

A thought - might some of this be better placed in the thread on charging batteries, rather than in which is really about the temperature sensitivity of B2B? https://www.expeditionportal.com/forum/threads/how-to-charge-a-lead-acid-battery.192038/

 

[martnH]

Use a alternator to charge a battery has no current limitation.

I don't know what that means. Limiting current is very important to protect the alt from burning out

> For example optima battery.
Optimas are not proper deep cycling batts, just robust Starters. Very poor value since Enersys spun them off.

> Anyway maybe you should watch this sterling videos.

I did, and obviously it's all in support of his (very fine) DCDC chargers. Nothing he states is in conflict with my statements, he's talking at an elementary level about the horrifying lack of quality design across the whole RV industry, very valid points but not relevant to the topics here.

Just have a read.

From optima battery
"Recommended charging information: Alternator: 13.65 to 15.0 volts, no amperage limit.

Battery Charger: 13.8 to 15.0 volts, 10 amps maximum"

View attachment RedTop_English.pdf

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[martnH]

Use a alternator to charge a battery has no current limitation.

I don't know what that means. Limiting current is very important to protect the alt from burning out

> For example optima battery.
Optimas are not proper deep cycling batts, just robust Starters. Very poor value since Enersys spun them off.

> Anyway maybe you should watch this sterling videos.

I did, and obviously it's all in support of his (very fine) DCDC chargers. Nothing he states is in conflict with my statements, he's talking at an elementary level about the horrifying lack of quality design across the whole RV industry, very valid points but not relevant to the topics here.

Interesting to hear what do you think about optimal battery
And what you regard as proper deep cycle battery



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[restorationrides]

This has been an interesting thread what with the talk about B2B Chargers and A2BChargers, VR's, etc.

As I read through the threads I see there's still a lot of misinformation, or lack of understanding of how some of the underlying technologies work. There are people out there who are genuinely curious and want to understand better so they can get the best solution for their particular needs.

I am wondering if participants would like to start a new discussion on a different thread and explore more fundamental discussions of the underlying Technologies? I would like to explore basic battery technologies, how an alternator and a voltage regulator really work, the purposes for things like battery switches battery banks, isolators, wire sizes, termination, etc.

There really is a lot to talk about but it'll have to be done in a more planned and supportive environment than was experienced here...and no sales pitches please.

Regards,
RestorationRides

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[DiploStrat]

...
I am wondering if participants would like to start a new discussion on a different thread and explore more fundamental discussions of the underlying Technologies? I would like to explore basic battery technologies, how an alternator and a voltage regulator really work, the purposes for things like battery switches battery banks, isolators, wire sizes, termination, etc.
...

Your wish is my command. And, as noted, your comments are welcome. (Please do provide sources, as I try to assure that whatever I post is correct.)
https://www.expeditionportal.com/forum/threads/how-to-charge-a-lead-acid-battery.192038/

I try to avoid sales pitches, but I use, or have used, products from these companies, among others:

-- Blue Sea
-- Blue Sky
-- Magnum Energy
-- Lifeline Batteries
-- Go Power
-- REDARC
-- Chevrolet
-- Mercedes Benz

 

[dwh]

I am wondering if participants would like to start a new discussion on a different thread and explore more fundamental discussions of the underlying Technologies?

Have you seen the electrical section of this site? It's "uuge". Most all of this stuff has been hashed out and/or explained in excruciating detail for years now.

But feel free to start another thread if you like. There will no doubt be lots of posts.

 

[john61ct]

The nuanced details that they go into are just not a factor in the real world.

There are different use cases and levels of care.

> It seems, to me, like they're just trying to push a sales agenda.

Some may, I sell nothing.

> I see little value in using the vehicle alternator or any other source to charge the STARTING battery and then use a DC DC (12v to 12v) charger to tap into the STARTING battery and use it to charge the HOUSE bank. As I said before you're not going to get away without losing energy through inefficiencies.

Yes the ideal is a proper regulator and output to House, but if that costs $1500 while the DCDC only $800, latter gives more flexibility. All depends.

> And the idea that most alternators can't even sustain an output when they get hot, is ridiculous. They're rated output is what's listed on them and that is good up through some very high engine compartment temperatures.

Only in some, IME very rare, cases. Easy enough to test for any given vehicle, if rated at 120A, put a 100A load on for two hours of high enough rpm and watch V, A and temps.


> manufacturers have designed these alternator to operate in extremes of temperatures in most places that you would ever find a vehicle.

Yes but only handling propulsion and Starter bat, a tiny fraction of large-bank deep cycling, especially high-CAR recharging.

LFP is famous for burning out alts.


> With regards to voltage versus amps...it's the AMPS that create the heat and losses. it is important to remember that INCREASING the VOLTAGE allows us to DECREASE the AMPERAGE required of a particular power transfer scheme.

> which will have an alternator restricted Max voltage of around 13.8 to 14.2v

We don't have choices here. The expensive House bank has a spec charging profile which must be matched for longevity. If the spec is 14.8V IMO you'd be stupid to accept less, measured at the bank posts.

> If you want to use a DC to DC (12v to 12v) charger, put the charger closest to the SOURCE battery

Fine if you can afford the huge wire gauge to eliminate voltage drop, or your regulator has a dedicated voltage sense wire. Usually next to Target bank makes more sense.

> But as I said before, I don't think a DC DC (12v to 12v) charger is a necessity for the cost and scarce real estate available in most vehicles.

True, most owners don't even care if they only get 3-4 years from their bank rather than 8-10.

> I think your money would be better spent on an isolator (separating STARTING from HOUSE batteries)

That's usually assumed, not an either/or choice in many cases

> and a sophisticated external regulator to drive your alternator.

But costs do come into it too. The DCDC can travel with the bank, service various different charge sources, very often Alternator is hardly even a significant source overall anyway.

In many cases a sophisticated VR and a DCDC unit are both required.

All depends on the requirements of a given rig and usage patterns.

 

[teotwaki]

OP's original question:

Anyone know of a DC-DC battery charger that can be mounted under the hood? The ones I've looked at from Ctek, Redarc, and Sterling don't appear to be able to do this because it would be to hot for the charger.

Thanks
Matt

I previously had a 4th Gen 4Runner and now have a 5th Gen 4Runner. A convenient spot to mount a CTEK 250 is right on top of the plastic fuse box by the starter battery. Fits perfectly and if you set up the cables well it will be easy to open the fuse cover if you ever need to. Be sure to run a big enough cable to your second battery to minimize voltage drop at max current. The CTEK's temp sense probe can be run all the way to the other side of the engine bay if needed.

I had mine in the 4th Gen for 5 years and it never had a heat issue so I will install it in the sae spot on the 5th Gen. The only problem I ever encountered with the CTEK was a blown fuse and 2 MOSFETs (Internal) due to overvoltage on the solar panel input and that was my fault.

 

[john61ct]

>> For example optima battery.
> Optimas are not proper deep cycling batts, just robust Starters. Very poor value since Enersys spun them off.

Interesting to hear what do you think about optimal battery

I guess you mean Optima as a brand. I think above is clear enough.

> And what you regard as proper deep cycle battery

My definition is **minimum** 800 cycles at 50% average DoD. And that's only for super-cheap 6V FLA GCs, about $1/AH @12V.

Once paying premium pricing 1200+.

Each market has their own well trusted brands, very few here come from China, which I understand dominate there.

There are only 2-3 vendors in each sub-category whose detailed tech specs and support resources I trust.

People full-time living on boats cruising off-grid are the best reference sources.

 

[john61ct]

Just have a read.

I did, and see nothing of note; as I said, I have no interest in that marque.

Or did I miss the point you were trying to make?

 

[john61ct]

And the idea that most alternators can't even sustain an output when they get hot, is ridiculous. They're rated output is what's listed on them and that is good up through some very high engine compartment temperatures.

Fwiw, Ford publishes data on what their alternators produce at different temperatures.
I expect others publish similar info.Their alternators loose around 25-40% toward the higher temperatures.

The user needs to verify exactly how they handle the overtemp.

Those that reduce Voltage in effect stop useful charging.

I have yet to see a stock setup that intelligently holds V high but derates Amps output.

For those vehicles using the ECU as VR, if the actual charging profile is inadequate, an appropriate DCDC/B2B unit is really the only option.

Unless there's room for fitting a second Alt completely independent of the vehicle's circuitry. A huge investment, and rarely possible.

Better IMO to just carry a Honda inverter gen and a powerful mains charger.

 

[teotwaki]

From optima battery
"Recommended charging information: Alternator: 13.65 to 15.0 volts, no amperage limit.

Note the clearly stated battery temp limit from Optima.

".......as long as battery temperature remains below 125°F (51.7°C)"

A typical alternator has no way of measuring battery temperature.

Engine compartments can easily reach 200 degrees F and thermal soak after engine shut down can push a battery past that peak.

 

[john61ct]

I agree, but in a general discussion. . .

Plus many trucks on the small side no matter how real, just don't have room for a nice large-frame LN.

 

[john61ct]

A typical alternator has no way of measuring battery temperature.

Exactly.

A dedicated temp sensor wire direct to the bank is basic equipment for a proper VR, in fact any high-end charge source designed for charging deep-cycling banks. Plus sensors at the alt diodes.

Not only for regulating overtemp conditions, but adjusting compensation voltage as needed in normal operation.