charging batteries with truck

[pinesman]

Several years ago when the fifth wheel that I had at the time only had room for one battery, I carried 2 more in the back of my truck. I used 2 sets of good jumper cables with ring terminals on one end and winch connectors on the other end to supply extra battery power when dry camping. Fast forward a few years and my current trailer has room for 4 batteries so I do not use the cables like I used to. However, I got to thinking about using those same cables to charge my batteries using the truck. I would not be using it for hours to run everything
but just a little while to top off the batteries in the trailer. Has anyone done anything like this?

[time2roll]

landyacht318 wrote:

time2roll wrote:


And I don't buy that alternator story dropping to 13.2v within a few minutes.

Doesn't matter what you 'buy'. You have no data proving otherwise, on any vehicle but perhaps your own, but you are of course welcome to your opinion..

That is fine. Please use the DC-DC charger if you have confirmed your alternator is regulated at a low voltage level. (that is the part you cut out when you quoted me)
See how that works.... you are covered both ways.

https://www.renogy.com/renogy-12v-dc-to-dc-on-board-battery-charger/

[MEXICOWANDERER]

The ECU not only triggers a code if the voltage reaches out of range but if the FIELD REPORT which is a measurement of the alternator rotor current disagrees with voltage by sending a "help-help-help my current has risen but the voltage has not" to the ECU also generates a fault code. Open loop limp home occurs, the ignition timing remains cemented, the air-fuel ratio enriches, top gear cannot be reached and life becomes miserable. Like all automobile design employees, the thick glasses and eat seaweed programmers have to justify their paycheck. The ride-sharing engineers do a dog and pony show for management and like the save one gallon of gasoline in ten thousand designers of expensive SMART ALTERNATOR PULLEYS that cause owners to spend twenty dollars in fuel taking the car back to the dealer for repairs. STUFF THOSE REPAIR BAYS! Meanwhile, those useless US government employees who monitor this **** collect 80K/yr in salary-benefits and produce exactly NOTHING.

Look up the word masochism.

This is the insanity that is bankrupting the country and its citizens.

A country that cannot manufacture its own high voltage transformers for powerlines*. That has to buy GERMAN MRI machines and CAT SCAN machines from GERMANY. I just came out of the hospital and yeah I turned around all of the equipment and none of it was made in the USA except the pacemaker adjustment "laptop" with the attached transmitter-receiver loop that is laid over the implanted device.


*98% are manufactured in Mexico.

Like India and China, the USA is primarily a service-oriented economy. Manufacturing very little, exporting raw materials via desk-bound executives. Don't believe it, start auditing everyone around you at work and your home. They do not manufacture squat. They sell, maintain, change out, or do the paperwork for it all. I have two masters degrees you know about the one, the 2nd is in business administration. Specifically forensic analysis.

My thesis was on Latin American economies. And our economy has changed to a degree of an utter reversal in 50 years. We are now more like Mexico and Nicaragua than the USA of old.

The idiots are running the zoo and the ticket takers are not about to reduce the entry fee.

[pianotuna]

DrewE,

One reason I ran a second charging line was that I blew 3 60 amp fuses on the OEM charging path. The isolation solenoid had burned contacts withing the first year. That's also why I went to automatic circuit breakers, and dual solenoids rated for 200 amps.

[DrewE]

Does Phil perhaps have a lower impedance (i.e. heavier gauge and/or shorter) connection between the two batteries?

If the electronics are looking to determine when the battery is more or less recharged to lower the system voltage, a good low-impedance connection woudl be essential to getting the house battery to charge most or all of the way in a reasonable amount of time. Otherwise, the voltage drop in the interconnection will allow the chassis battery to work its way up to what the ECM thinks is "full" well before the house battery, and the charge rate then drops.

It might be helpful to measure the voltage drop under charging conditions, either directly or indirectly (by simultaneously monitoring both battery votlages). If there's little charge current flowing over the connection, there will of course be little voltage drop per Ohm's law.

I could be all wrong, too, and maybe there's some other difference.

[pianotuna]

I wonder if the ECM may be tweaked by a repair shop to run at a higher voltage. Phil's ride and mine are more or less identical. Why does he get great charging--and I get lousy results?

[landyacht318]

time2roll wrote:


And I don't buy that alternator story dropping to 13.2v within a few minutes.

Doesn't matter what you 'buy'. You have no data proving otherwise, on any vehicle but perhaps your own, but you are of course welcome to your opinion.

I've personally seen 2 GMs, 2014 and newer, decide 12.7v cruising down the highway was fine and dandy with very occassional times above that, usually when braking or coasting.

Lots of newer cars' voltage regulators will seek to keep the battery at only 12.7v, asking for higher voltages seldomly. They shiv not one git, about battery longevity, but meeting C.A.F.E, means more profit, for them.
A battery kept intentionally discharged, can accept much higher amperage alternator amperage when the system asks for 14.5+ volts.
Each 25 amps the alternator makes is said to eat up one engine HP.
Ask for those higher voltages seldomly and when most advantageous for increasing measurable MPG as the EPA tests vehicles mileage, and manufacturers can some closer to meeting fuel economy standards across their fleets.



People should measure their voltage at different times with an actual guage on the battery terminals. This forum could use more data as to which vehicle's voltage regulation needs no assist from a DC to DC charger for their house batteries, and those whose depleted batteries are doomed to see too little electrical pressure to ever do much charging going down the road.

[philh]

MEXICOWANDERER wrote:
all this **** must be what Americans lust for.

DING DING DING

I get to drive a lot of new vehicles, usually in advance of their release. I enjoy "most" of the technology advancements. However, I did not enjoy collision avoidance notification the first time it lit up the windshield with flashing red and horns going off... especially since there was no impending collision. I was driving a bit spirited on an off ramp, and a sign on the ramp set it off.

[MEXICOWANDERER]

Most vehicles start off with higher voltage and ambient temp plays a big role in how fast and how much the volts will drop. Common to see 13.8 - 13.9, on a hot morning down here the Mopar ECU may decide a 13.9 startup and 13.5 after 10 miles of warmup is appropriate. The voltage is always hunting .3 to .4 volts. That's what drove Landyacht nuts. I think the engineers had a hooka in the lunchroom.

When I was rebuilding I kept an assortment of voltage regulators. Most were adjustable with no thermistor in the voltage divider. Unchanging voltage is called FLAT COMPENSATING.

Detroit Engineers now

"Lemmee atit lemme atit"
Bluetooth, houndstooth, it has to have a catchy name and end up as an obstruction, not an aid. The more worthless **** we pack into the car, the more days the POS will spend in our dealer's bays. How can we control the rugs and the glove box by Alexa? The ashtray?

"Ding! Ding! Ding!"

WE HAVE DETECTED DRINKS IN THE CUPHOLDERS FOR THREE HOURS
THE WINDSHIELD HAS DETECTED RAIN, SELECT ONE, LOW, MEDIUM. HIGH?

"DING! DING DING!"
Detector senses right rear power window has detected excessive pressure without full window closure. Check your children.

"DING DING DING"

"Detectors have sensed pedestrian beneath the chassis"


all this **** must be what Americans lust for.

DING DING DING

[time2roll]

+1 for a dc-dc charger in the oem connection.

And I don't buy that alternator story dropping to 13.2v within a few minutes.

[MEXICOWANDERER]

Unless you have a digital gauge on the dash your gauge cost thirteen cents. According to experience with my factory temperature gauge if it ever went to "H" the engine would be around 2,000 C

Dollar for dollar nothing can touch the cost, ease of installation and fuel cost of a Harbor Freight 2-cycle engine and a Megawatt 36-amp charger. Not even close. Don't bother to compare. Not good for campgrounds with generator bans or national parks where employees pray for an outbreak of Lyme disease because their pay does not change whether there is a thousand campers or zero.

[S_Davis]

theoldwizard1 wrote:

pinesman wrote:
I got to thinking about using those same cables to charge my batteries using the truck. I would not be using it for hours to run everything but just a little while to top off the batteries in the trailer.

Modern vehicle (after about 2000) charging system work TOTALLY DIFFERENT than the past. They drop the voltage down to about 13.2V within a few minutes of starting. That is much TOO LOW to charge such a large battery bank !

This is not true at lest on my 2013 Chevy 2500HD, my voltage after starting goes to 14.7 volts for a few minutes and then settles at 14.4. I can drive for hours and it never goes below 14.4 volts.

[MEXICOWANDERER]

Amass 10 Pair XT60H Bullet Connector Plug Upgraded of XT60 Sheath Female & Male Gold Plated For RC ...

These are good for 50 amps @ 16 volts because I tested them and found only very modest warmth after a few hours.

The wires need to be soldered onto the mini-lugs on the other end. I would not hesitate to use 8 AWG with these plugs and sockets. Terminals are gold plated and the male bullets are X sliced so a thin screwdriver can spread apart the bullet to the point of making an insanely tight fit.

SEE (!) what you're missing by not taking a moment to learn how to solder?

[2oldman]

pianotuna wrote:
If there is a decent converter, consider powering it from an inverter connected to the battery of the tow vehicle.

Nice idea.

[pianotuna]

If there is a decent converter, consider powering it from an inverter connected to the battery of the tow vehicle.