recharging while driving

[pianotuna]

I'm winding my way south and boondocking.

Last power was in Regina, SK

I used a heating pad and lots of computer time last night, powering them from a 400 watt MSW inverter.

Batteries were at 12.3 in the morning.

I drove for about 8 hours in total.

The first two hours, very little in the way of charging happened as I was using the head lights, running the heater fan on high and running the laptop with Microsoft Streets and trips. In fact, at first I was concerned that the alternator was not sending any energy to the house bank.

I stopped about 5 p.m. in Fargo, ND and voltage was back up to 12.9 (under load from the fridge and attempting to recharge a tablet, using a 12 volt adapter.)

I will be using the heating pad and perhaps the tablet tonight. The Tablet is supposed to be able to tether--but it won't. Nor will it do a hotspot. I'm too exhausted to deal with this tonight.

I may or may not have power tomorrow night.

[pianotuna]

The only change was to the AGM jars for the house. I noticed lower charging immediately--but put it down to the old tired Marine jars (9 years old).

[BFL13]

If the starter battery is "suspect" would that not keep the alternator charging at higher amps and voltage? If the battery is good, the alternator should drop to 13.x from 14.x fairly soon after getting going down the road.

The other thing that lowers alternator output is temperature under the hood. Anything new there from before?

[theoldwizard1]

MEXICOWANDERER wrote:
Vehicle wiring harnesses to the chassis battery restrict amperage horribly. The 4 gauge new wire must be dedicated RIGHT FROM THE OUTPUT STUD OF THE ALTERNATOR DIRECT TO BATTERY POSITIVE VIA A CHARGE DIVIDER AND CIRCUIT BREAKER. I don't read this stuff out of a book or put on a propeller beanie and play the part of Gyro Gearloose...I did it and do it for a living. As an engineer not a shoe salesman. Maybe I'm wasting my breath here.

You are 100% correct (except maybe that shoe salesman thing 🙂 )

My only issue is that the standard auto voltage regulator is not optimized to recharge deep discharge batteries, which is why I recommended a DC-to-DC battery charger.

I think I know what you mean by a "charge divider", but Google does not. Got a link to an example.

[pianotuna]

twin 8 gauge

This was done to LIMIT the charge. When I had all Marine batteries (including the starter) I would see up to 70 amps.

But the AGM are a higher voltage.

one is OEM

the other goes from the starter battery not the alternator.

I'm quite suspicious of the starter battery.

[pianotuna]

Got the genny but the cage did not make the time frame.

[MrWizard]

Don I thought you got the replacement generator and built that cage for it

[MEXICOWANDERER]

The difference between slapping 8 gauge wire 15' length from a Ford chassis main buss to the house batteries powered with a Ford 6G alternator versus running a 4AWG wire directly to same house batteries is about f i f t y amperes. Go back and note the word difference. This is from repeated experience testing not speculation.

Now times fifty amps by hours driven and raise your eyebrows. Do not make a fatal error of assumption by calculating theoretical charge curves into batteries alone. The hotel load while driving is not i sigificant.

Single Syllable Simplicity...

Eight

Gauge

Is

Too

Small

[landyacht318]

8awg is too thin for proper recharging a large distant AGM bank via alternator.

Throw out the ampacity charts and the desire to repeat 'just fine' over and over. Thicker copper means the battery can suck more juice from alternator, and perhaps show the voltage regulator that more field current is required to hold 14.x volts, and allow it to stay at 14.x volts for longer rather than the premature reversion to 13.x volts.

As someone with an adjustable voltage regulator with potentiometer on dashboard, and a digital ammeter reading total alternator output, and thick copper between alternator and house battery, soon to be thicker, there is a huge difference in amperage when the depleted battery allowed 13.6v vs 14.7v.

I will be upgrading my 11 feet of doubled 6awg wiring from alternator to AGM with 2 or even 1AWG.

8AWG for such a duty is a JOKE bordering on criminal, and the victim is the depleted battery bank.

[MEXICOWANDERER]

Don do whatever it takes to get to a warm dry climate. The Rio Grande valley of Texas maybe?

Something is baaaaaad wrong. Your data is totally bonkers and you need to troubleshoot with a meter. Do it in comfort. Hurl the heater at a Gila Monster.

Drive during the daylight after outrunning the blizzard. When you get safely ensconced at an RV Park that does not have price delusions pf Trump Tower, send a signal and I will help if I have internet. Usually 2-5AM

[MrWizard]

Don
I do think you need bigger wires to the batteries
But I also think your alternator needs to be replaced
You did not have these charging problems before, 16 amps is pitiful
No Way had lights heater etc.. Is taking 100+ amps
The current voltage level is too low
Mine doesn't do much better on voltage but it puts a lot more amps into my bank from the Delco 10si that is now four years old
Typically 35 amps at idle in the morning and as much as 65 is normal
Rare occasion 95 amps

[time2roll]

So you are consuming all 140 amps near continuous?
Where is that going?
Have you measured the alternator output?

0000 wire will not help an alternator not producing rated power.

[pianotuna]

Mr Wizard,

The generator was taken by thieves. The new front mount carrier did not get completed--so I am sans generator.

I'm also doing the fridge on propane this trip--except if I have shore power

This morning at 3:30 am

house batteries at 12.5

initial charging rate 16 amps

Once I turned on the head lights and fan it dropped back to zero. voltage at dash was 13.1

After driving for 2 hours the house bank was sending 1 to 2 amps to the engine.

[pianotuna]

Mex,

It is the stock Ford 140 amp unit.

The starter battery is nearly 8 years old and is maintained by a Trik-L-Start.

[pianotuna]

I knew I should have put in more dtails.

Dual charging wires, one to each bank #8 wires with Manual control of the solenoids.


What is different is the house jars are AGM and the starter is an old, tired Marine Walmart battery. I think it may be replacement time.

[pianotuna]

Hi all,

I'm currently staying ahead of the snow! In fact, if I'm lucky I won't see it at all.

Overnighting at Harmony, MN or possibly farther south.