How to burn out your alternator while direct charging LiFePo4

[Gr8ful]

When I was in high school I had a job rebuilding altenators, starters & electric motors. Then we were always building bHot Rods, dune buggies etc. We used these alot. !!) amp 1 wire altenators which are cheaper norw, This is from Amazon & new not rebuilt or remaned & they're dozens more choices with more amps, pulleys, etc. Probably easy to add one of these just to run the house batteries & up the output if Li-On batts. You can add a diode or use a external alternator controller or make your own . Many you tubes showing how.

110A CHROME STREET ROD GM HIGH OUTPUT ALTERNATOR FITS 1-ONE WIRE SELF EXCITING ENERGIZING
110A CHROME STREET ROD GM HIGH OUTPUT ALTERNATOR FITS 1-ONE WIRE SELF EXCITING ENERGIZING
4.3 out of 5 stars 119
$67.58
New High Output 100 AMP Alternator Chrome 1 or 3 Wire, Self Exciting, GM Chevy 10 SI 10SI DELCO BBC SBC 1965-1986 1100125
New High Output 100 AMP Alternator Chrome 1 or 3 Wire, Self Exciting, GM Chevy 10 SI 10SI DELCO BBC SBC 1965-1986 1100125
4.3 out of 5 stars 20
$67.95

[Roadtripp]

Thanks! What fountain of useful information this thread turned into. Well, I’ve never been good at burning out my alternator. Last one I remember replacing came bad in the vehicle when I bought it. But Ive never charged deep cycle house batteries with my alternator. My vehicles have been stock electrical. Engines, transmissions, rear ends, suspension, paint, Ive changed those. 
 I read the alternatorparts.com site and learned a lot. Those Transpo external regulators are a bit spendy but worth it imho. 
 Today I got to see the inside of a Harris Hydro alternator. It took some looking to figure out what I was seeing. These are Ford Motorcraft 1970s externally regulated alternators. But essentially only the case is original. The stator and rotor are all different. Adjustable magnets and all. He said they were getting close to 80% efficient. 
 It’s a dilemma deciding what to do with the vehicle charging system. I like a lot of the ideas in this thread. The stock charging systems work very well for what they are designed for. So far I use solar/mppt and if needed a Honda eu2200i inverter generator to a power factor corrected charger. I’ll probably just do the minimum to boost the stock charging system. Leaning towards a Victron Smart Battery Combiner, only $45, and a Renogy 40 amp DC to DC Charger. If the house battery is Lithium the stock lower alternator charging  voltage is ok the way it is. I think?? If I read the AM Solar website correctly.

[sternwake]

I got my transpo 540HD regulator for 25$ several years ago, and just checked and it is still the same price on Ebay

One can really go nuts optimizing things. Its good to draw a line....... somewhere. My goal was to rid myself of the insane voltage regulator inside my engine computer. 13.7v when the battery is well below 80% charged was infuriating, as was the occassional 14.9v spike, when it was.

I Don't have much money tied up in my modifications. I was just looking a bit into theoretical alternators which would fit my rig just now, and quickly X'ed out all the links before I started really considering expending any time or money towards them, as I simply do not need any additional improvement in alternator charging. Sometimes at hot idle at night, I could charge a bit faster, and perhaps have one or two more AH that night to use, or just use less lights fans and laptop and think about other things instead.



I do not like voltage sensing relays/ solenoids with pure lead acid systems, especially with solar present. Surface charge retention after stopping the engine, will keep the battery voltage above the setpoint for a while after shutting off the engine, before falling below the separation threshold, and if solar is present, it will keep both batteries above that voltage and remain in parallel till afternoon/evening, depending on loads. The engine battery might not need any additional charging, yet it would still be eating some solar wattage the house battery would be all to happy to feed upon instead.

In dual battery systems I feel (opinion!) the engine starting battery should always be brought to and kept at 100% charged and saved for engine starting, and ALL parked loads should be on house battery. It therefore should not need any voltage sensing relay to impart some charging current to it from solar panels or plug in charging sources. These might very well overcharge it and with solar present it will allow them to remain in parallel long after engine shutdown, even if it is a single sense relay and not a dual. Duals sense combine batteries whenever either battery sees charging voltages, singles sense parallel when only one sees charging voltages.

It is not always easy to transfer all parked DC house loads, like a stock stereo system, or dome/map lights to the house batteries so the engine battery getting charged in parallel anytime the house batteries are charging , can certainly be desirable on such vehicles.

The keeping of batteries in parallel longer than necessary after engine shutdown is not a huge factor, it is just a preference I would prefer to avoid, and pretty much irrelevant to my current personal one battery for house and engine starting system which I don't plan on changing anytime soon.
If I needed more capacity I would likely still not have separate batteries, just two or more dual purpose AGMS in parallel always for engine starting and houseloads, with a small jumper pack battery in case of emergency overdischarge. But mine is hardly the only 'right' way to do it.



Does the renogy dc to dc unit come with an alternator temp sensor?

[Gr8ful]

Temp & amp adjustment seem to be options. The only problems with batteries I've every had were with AGMs by Optima. Here's a you tube on Renergy DC-DC chargers

[Roadtripp]

Yes, after watching the Renogy review video I see only temperature compensation for the batteries and nothing for the alternator. Some smart regulators like Balmar have all the bells and whistles. I like what  Sternwake suggests by adding instrumentation and controls then the operator is the “smart” regulator. 
 Phew! There is to be a lot of ways to do charging these days. FLA are more forgiving in some ways. One of the simplest I saw was a 10 hp Diesel engine with a 100 amp Motorcraft alternator simply full field charging directly to a large FLA battery bank for 1 hour. Then the solar was used to finish the charge. Apparently the alternators were not damaged and the battery bank large enough to absorb the high voltage. I forget exactly how large but it was a residential off grid system so probably 800 AH or so. 
 If the vehicle doesn’t get driven much other these options get more interesting.

[Gr8ful]

My buddy built one like that 40 years ago only gas. The one wire 110 amp alt would work great.