Alternator to House Battery Charging Test Results UPDATE

[BFL13]

Update 18 Jan--

This is for my rig with its particular wiring (some changes to original done by me). Has the dreaded Ford 2G alternator.

Testing on a pair of 6s starting at about 55% SOC and 12.2v (so can accept lots of amps--more than from my alternator charging so not a bottleneck for the test) Used Trimetric for house battery voltage and amps, and multimeter for engine battery voltage.

Engine was idling for the test except as noted. Engine hood up, so a bit longer to warm up maybe. Started test at 0925

0925- Cranked engine--immediate 37 amps but tapering fast.
0927- 28 amps/13.3v Engine batt 14.59 volts
0930- 26a/13.3v --14.40v
0935- 24.4a/13.2v--14.35v
0940- 23.0a/13.2v--14.29v Revving made amps go down by about 1 amp
0945- 21.9a/13.2v--14.26v Closed hood to see if more heat matters
0950- 19.1a/13.2v--14.18v engine is warmed up to "normal" Stopped.

Restored 10.7 AH on Trimetric in the 25 minute test.

[MEXICOWANDERER]

No need to use a power rectifier like you've shown, the sensing circuit carries no appreciable current. In my last vehicle, I just used a couple of 3 amp diodes in series to get about a 1.4 V boost, with a switch to bypass as you've done.

With the Ford IAR and 3G regulator the yellow wire serves as both the 100% power supply and the voltage sense lead to the regulator.

Alternators with regulators featuring separate power and voltage sense lead wires are extremely uncommon.

Perhaps you are thinking of voltage regulators that utilize a half phase rectifier off the diode trio, and have a dedicated voltage sense input. Such as the Delco 10, 12, 15, 17 and 27 SI series. With this alternator the regulator plug marked # 2 is a dedicated voltage sense lead, and can be biased not only via rectifier but by resistor. The Delco 27 SI series 200 (truck) alternator even had a square black cap atop a block for the regulator terminals. By rotating the block, various resistances were had changing the regulator set point.

It would take a huge resistor precisely quantified to power the Ford regulator. Which is impractical. The power rectifier is the easiest and most cost effective. If more resolution is need in the voltage setting, a Schottky rectifier can be used alone or in series with a silicon rectifier. A silicon + schottky would amount to a 1.4 to 1.5 volt increase.

[BFL13]

DrewE wrote:
Just out of curiosity, does the class C not have a generator built-in? Or if it does, is it non-functional? I understand the appeal of a quiet inverter generator if one is going to be using it frequently, but for the occasional odd charge of the batteries or running the air conditioner or whatever it's hard to beat the convenience of a built-in generator that can be started without even going outside and has a pretty big fuel tank to draw from.

This one does not have a built- in gen. I could carry a portable, but I don't want to buy one when I already have a Honda 3000. Problem is that gen is so big and heavy. Am hoping it will all work out that no gen is required.

[DrewE]

Just out of curiosity, does the class C not have a generator built-in? Or if it does, is it non-functional? I understand the appeal of a quiet inverter generator if one is going to be using it frequently, but for the occasional odd charge of the batteries or running the air conditioner or whatever it's hard to beat the convenience of a built-in generator that can be started without even going outside and has a pretty big fuel tank to draw from.

[BFL13]

Did another get to know the new rig trip for two days up-Island checking out work done so far.

Turns out the usual driving around plus solar- same driving around as when using the 5er and truck before (library, groceries, dog park, etc), restores about 25 or so AHs a day. Mostly from the alternator charging at 20+ amps.

Was stopped for a while in the bright sun ( was a low sun at 11 am on 22 Jan at 49N) and was getting 5.4 amps from a 255w panel lying flat on roof with MPPT on batts able to accept more than that.

So not much out of solar even mid-day this time of year at this latitude. Which is why I never bothered with solar for camping here before with the 5er until the sunnier half of the year.

With that 25AH info, and knowing our typical AH usage, it looks entirely possible I won't need a generator with this MH.

Boo-hoo--my days of charging the battery bank with 155 amps doing 50-90s with the Honda 3000 may be over! I have the 55 amper on the two AGMs and the 100 amper on the other house bank of four Floodeds, but recharging at home does not need high amps, since there is lots of time. Don't spend more than four or five days away in the dark half, and have enough batteries to get by with that 25 AH assist. Later, staying away longer it will be good solar conditions plus the driving around. Can reduce the other house bank to two Floodeds then too, based on experience with the 5er camping in the same place same time of year.

Scenario is everything.

(This whole Class C thing vs 5er is taking a while to get used to.)

[stevenal]

MEXICOWANDERER wrote:
Simple switch circuit to fool you voltage regulator into charging about eight tenths of a volt higher. I must have installed five dozen of these on Ford and Chevrolet charging systems.

Depending on how fast and easy it is to pass two 16 gauge wires through your firewall and punch a 15/16" hole in your dashboard, this is a simple and bulletproof way to allow your charging system to (example) charge at 14.8 volts rather than 14.0 volts.

The principle is easy to understand. The 2G and 3G Ford alternator voltage regulator to provide power to the alternator field. Not only does it supply a max of around 5 amperes at full load this wire is also the -voltage sensing lead-

"Magic" will make this wire have about .8 lower voltage. The regulator sees the lower voltage and says "I have to charge .8 of a volt higher to meet my goal".

A switch in or out rectifier is placed in the feed wire that gets cut. The yellow wire see the picture below.

The switch is an ON/ON switch with no ability to switch completely off. If you want to get fancy an LED pilot light can poke through the dash announcing when the regulator has been switched to pass field current through the rectifier.

The rectifier itself it neat with it's own heat sink. It has four terminals but only two will be used. Push on terminals without wire can cap the two unused terminals. The rectifier is insulated so there is no exposed voltage points to short.

Yep, it costs money for the parts. Yep it costs money for gasoline too. Less run time means less fuel.









See the yellow wire that's the wire that will be severed and extensions to the cab will be put on both ends.






https://www.delcity.net/catalogdetails?item=73247

No need to use a power rectifier like you've shown, the sensing circuit carries no appreciable current. In my last vehicle, I just used a couple of 3 amp diodes in series to get about a 1.4 V boost, with a switch to bypass as you've done.

[MEXICOWANDERER]

Ah yes. Old proverb.
Easier to raise roof than lower floor.

If a person want to use their intelligence to transmit alternator power to remote batteries, consideration should be given to installation of a three phase AC remote rectifier. This is an intermediate range solution and it works wonderfully up to around fifty feet line distance.

Three ten gauge wires will pass a hundred amps with ease. And because it is AC there is a lot less loss than doing it with DC.

BUT!

I am leery of suitability with some of the more sophisticated Engine Control Unit voltage regulators.

With newer trucks, the ideal way is to do this with a second alternator. All the brackets and pulleys are available over the counter. There's nothing like charging 100 amps at idle. Couple the 2nd alternator with a remote rectifier and a decent voltage regulator and then engine charging would become rational.

An hour spent jamming 200 amp hours into the batteries makes it worthwhile.

Solar is great until it isn't. Compromises, compromises. Restrictions on running a generator, no sun, there seems to always be some kind of fly in the ointment.

[landyacht318]

Other than the issue of stacking another ring terminal on the Alternator (+) output stud, I am unsure why everybody seems to think they have to pull power from starting battery to charge house battery

The OEM alternator circuit was never intended to pass the additional depleted house battery current, and acts as a bottle neck, and the OEM fuse might blow, and this load dump might take out the alternator diodes. No to mention the always undersized and problematic OEM grounds. If all thisthe OEM circuit has to be upgraded, why not bypass the OEM circuit, use a dedicated new shorter fatter less resistive circuit instead?

Also if one takes power from the engine battery, there should be a fuse on that circuit, close to the battery, adding even more resistance, and more voltage drop, inhibiting amperage flow into depleted house battery even further.

Take power right from the Alternator output stud and bypass the too thin OEM wiring, and the engine battery, the extra fuse, have a likely much shorter circuit as well.

Another consideration is the usual frame grounds. How many engines actually have a Stock frame to engine ground? Few is my bet, and then house battery current then has to flow through firewall to engine battery ground then engine battery to engine OEM ground. How much longer is that circuit, compared to running a physically parallel ground cable back to alternator mounting bolt? At the minimum ground the frame to the engine rather that relying on stock grounds for passing house battery current.

With a thick pipe to depleted house battery, perhaps the voltage regulator might allow higher voltages for longer, if thermally based perhaps much shorter before it drops to a rather disgusting 13.6ish.

Seems to me the whole DC to DC booster or the inverter to converter could be, depending on vehicle platform, as much, or more work as modifying alternator voltage regulation, and tricking engine computer, to seek and hold 14.7v whenever house bank is still less than 100%.

My alternator temp data shows as long as vehicle is moving 65mph the alternator case when maxed out will not get above 140f, but idling maxed out and temp skyrockets to 200F quickly. Since i can twist a dial to seek any dang voltage I choose, I can almost always max out my alternator, making this data valid, at least for my engine and underhood airflow idling vs as speed.

I'll soon be installing a secondary battery system in a 95 chevy g20 conversion van. I am using the Colehersee 200 amp silver tungsten contact solenoid and 4AWG, back and forth from alternator to house battery. I do not trust frame grounds, an no way will I take power from engine battery unless access to alternator output stud(+) requires hours of labor.
I am not sure what the chevy's VR will allow, and for how long, but I am also putting 200 watts of solar on the roof, and they are getting a PD9245 for a single G31 AGM and an easy way to plug in to the grid, when that is an option.

[babock]

BFL13 wrote:
The issue then is to get "enough" AH into the house batteries with any alternator charging going. How much is "enough"? How long is a length of string?

I agree. Using the TV to charge the TT batteries is the worst option.

I was just throwing out options. Being blasted for not "getting it" is laughable. Been an EE for 35 years so I do indeed get it.

Curious why this forum tends to have way more "know it all" posters that get their panties in such a bind compared to other forums when someone has a contrarian opinion.

[BFL13]

Scenario is being forgotten here.

Yes, batteries need 14.8 to be properly charged, but all we want here it to put some AH back in, not to properly charge the batteries. That is done elsewhere by other means.

With generator recharging we do 50-90s and not even try to do the 90-100 on generator. You do the 90-100 on shore power or with solar.

Alternator charging is done on an opportunity basis if driving around anyway, or else when parked as a desperate way to restore some AH when the batts get too low and you don't have a generator. You would have to be crazy to try to properly charge your batteries with alternator charging.

The issue then is to get "enough" AH into the house batteries with any alternator charging going. How much is "enough"? How long is a length of string?

[babock]

Gdetrailer wrote:
The real charging workhorse for HOUSE BATTERIES IS the CONVERTER when you are plugged into shore power..

So why not take advantage of what is already there?

Just add the 120V inverter and you ARE done.

To run most converters, you will need at least a 1000W inverter.

Better off just buying a dedicated 15A charger and a much smaller inverter.

[babock]

Better yet...just spend the money on solar.

[Gdetrailer]

Mex, you and I "get it" and understand the short comings, the problem is it seems that lots of others just don't "get it".

While technology has advanced with much more efficient switching power supply type of DC - DC boost/buck systems, you simply end up with wasting a lot of the energy in heat due to the line losses.

The end result is putting much more stress (and heat) on your most critical must run part of the system (your vehicles battery and charging system).. Which really was never designed or intended for high current charging over LONG periods of time.

Sure, a 300 HP engine could produce up to 222 Kw of energy, but why in the world would one wish to beat the darn thing up is beyond my comprehension..

High current auto alternators are not cheap, towing is not cheap..

So, if one REALLY insists on using a "cannon" to swat a "flee" then you should consider doing it with the LEAST harmful impact.. That amounts to using a MORE efficient conversion process.

12V to 120V inverters are cheap and plentiful and extremely easy to find, DC-DC not so much.

14ga-12Ga wire is cheap, 2ga-1/0 not so much.

Boosting DC will result in a heavier load on the starting battery and alternator with only marginal gain, wasting a lot of power over the resistance of the wire in heat..

If you want heat, I am sure there ARE better ways to go about that..

In motorhomes and even trailers, the house battery charging is not meant for fully replenishing a totally dead house battery. It is there to help keep the house battery which is nearly or fully charged TOPPED OFF WHILE TRAVELING.

The real charging workhorse for HOUSE BATTERIES IS the CONVERTER when you are plugged into shore power..

So why not take advantage of what is already there?

Just add the 120V inverter and you ARE done.

[babock]

Gdetrailer wrote:
No, that is not the way it works.

Yes it is the way it works.

The problem is that if you are drawing 20A, you would get a voltage drop between the TV and the TT. The drop may be as little as 0.5V but that is enough to not be able to charge your battery. Its the same issue in many RVs where the converter is too far from the battery.

These chargers sits close to the battery and eliminate the issue of that 0.5V voltage drop. DC-DC converters of this type are 98% efficient so don't know where you get this 40A cause a draw of 60A.

You can do the inverter method as well if you wish. A DC-DC converter does the same exact thing as an inverter but at much lower AC voltages.

Its the users choice to use the charger's built in inout voltage cutout or an ignition controlled relay. That's a minor issue.

[MEXICOWANDERER]

I learned this subject from Lisle Bruney at Sure Power in the early nineties. I contracted to build a multi-voltage single alternator system for the US Air Force at Edwards Dry Lake.

Twenty eight years ago, boosters did not exist so I had to settle for a bucker. 100 amperes capacity. A 4875 Leece Neville 24 volt alternator, and a DC to DC bucker the size of a 2,000 watt inverter. Because the efficiency of this device was so poor, I had to over-kill on the capacity of the charging system. It indeed had a electromechanical interrupt.

Let's say a person wants to boost voltage electronically from 13.2 volts to 14.3 volts. Because of dropout voltage limitations of voltage management devices, the voltage would first have to be boosted to beyond device dropout limits then bucked with another circuit.

Efficient? Access eBay. Peruse their selection of DC to DC boosters and buckers.

See the large heat sinks? They are there for a reason as are the warnings to use fan cooling enhancements if an amperage threshold has been breached.

Bottom Line? AWFUL efficiency.
AWFUL efficiency times TWO. Booster + Bucker.

Then read the part about quiescent milliamp draw.

Then realize the successful merchandise that uses voltage threshold switching (battery combiners, BIRDS) switch mechanical relays. And the value of the action cannot be tweaked.

Few things in this area are wonders. Most have drawbacks. Pluses and Minuses. They have to be weighed before choosing. The school of hard knocks (user reviews) is one way to display shortcomings of a device.