Alternator wear and tear

[hatjohan]

Does a second battery place additional load and thus additional wear and tear on a vehicle (smart) alternator?

[Chris8d]

I wouldn't say so, it is working the whole time, doesn't matter if there is one or two batteries connected, it's running.

But I'm by no measure an auto electrician, just a guess.

[Ama-newbie]

I look forward to this discussion as I have the same question.

I believe it does place some additional load which is why I have completely separated my second battery from my vehicle electrics and only plan to charge it from solar panels.

My analogy would be that if you had a trailer permanently hanging off your tow bar, that must place some extra load on your engine and gearbox over time?

[Gothan]

As mentioned before. It’s running the whole time, so don’t really think a second battery wears on the alternator. What’s does is driving short distances. So be kind to your alternator , keep that crank battery charged up

[hunter26]

Not an expert but when having a dual battery system, you install one of those fancy solinoid systems that switches over from primary to secondary battery when traveling. What kills an alternator is excessive continuous heavy current draw off the battery.

[Olyfboer]

Does a second battery place additional load and thus additional wear and tear on a vehicle (smart) alternator?

Hi Hatjohan, any extra load placed on any machinery results in more wear. Extra load on an alternator will result in more heat generated as well. The components that will wear faster due to extra load will be the brushes, slip rings, bearings and belts. The diodes and windings can be affected if overloaded.

[jelo]

As mentioned before. It’s running the whole time, so don’t really think a second battery wears on the alternator. What’s does is driving short distances. So be kind to your alternator , keep that crank battery charged up

Not so true on the new ones I think.

[ekkekan]

I have zero knowledge on smart alternators. Old style I would say it is no problem as the windings in rotor and stator as well as diodes are designed to provide the output. With many alternators now providing 120A it would not take a long time of high current to charge both batteries and then the load is small.
To think about extra wear on engine and gearbox because one might be using 1.5kW (when 100kW+ is produced by the engine) via the alternator to me is pie in the sky. Alternators have a cooling fan via the pulley to assist heat generated. Further the multi groove v belts should also not suffer too much due to the short term nature of charging.
As already said if one had to draw 100A all the time to power a load then one can consider higher wear rates.

[Pieterk]

As the amperage demand increases the mechanical load increases. More rotational force is then needed. Thus, more kilowatts is drawn off the engine, increasing fuel consumption. If the amperage demand is higher than the designed output, damage will occur (burnt windings/rotor) The higher the Mechanical load on the alternator, the more the wear on bearings and brushes etc.
Then contrary to all my statements above. There are thousands of vehicle out there with dual battery systems, some with fancy thingamajigs, and lots with a solenoid and a switch, which are happily serving their owners without a problem.

[hatjohan]

As the amperage demand increases the mechanical load increases. More rotational force is then needed. Thus, more kilowatts is drawn off the engine, increasing fuel consumption. If the amperage demand is higher than the designed output, damage will occur (burnt windings/rotor) The higher the Mechanical load on the alternator, the more the wear on bearings and brushes etc.
Then contrary to all my statements above. There are thousands of vehicle out there with dual battery systems, some with fancy thingamajigs, and lots with a solenoid and a switch, which are happily serving their owners without a problem.

Yes, I am not concerned about and my question was not related to wear and tear on the engine/gearbox.

But you confirmed my suspicion about the additional work load on the alternator

Like all vehicle components, it also only has a certain service life (think water pumps and timing belts). So the reason to my question was that should an alternator not receive additional attention, given the extra load imposed by an additional 2nd (or even 3rd) battery. Given the fact that if that component packs up in the bundus, you are stuffed in more than one way? And also given the fact that it can be reconditioned quite easily and cheaply (by yourself if you are able), say at 100k? as a preventative measure.

[hunter26]

Yes, I am not concerned about and my question was not related to wear and tear on the engine/gearbox.

But you confirmed my suspicion about the additional work load on the alternator

Like all vehicle components, it also only has a certain service life (think water pumps and timing belts). So the reason to my question was that should an alternator not receive additional attention, given the extra load imposed by an additional 2nd (or even 3rd) battery. Given the fact that if that component packs up in the bundus, you are stuffed in more than one way? And also given the fact that it can be reconditioned quite easily and cheaply (by yourself if you are able), say at 100k? as a preventative measure.

To lessen the load and help prevent premature wear and tear, use a solinoid to switch charging from primary to 2nd battery ie alternator only charges one battery at a time.

IMHO if going on a long far away adventure and you worried about parts breaking or failing. I would get the starter and alternator serviced before the trip.

[Peter1949]

From own experience more than once, alternators do and can fail even using a solenoid system when powering dual aux. batteries as well as the crank battery up front.
To be fair though we have two 100 AH batteries in the back as well as the 90 AH crank.
Probably a good idea (although I never did) to carry a rebuilt alternator with you as spare if overlanding in remote areas.
You might never need it, but when you do ........
See my Kokerboom report from 2018 where McGyver (Forum member travelling with us at the time) utilised out solar panel on the Isuzu canopy to power the vehicle when the alternator failed totally.
We drove all the way from Keetmanshoop back to Pinetown on solar power - the first and maybe only, Isuzu Prius.
EISH !

[Ama-newbie]

Yes, I am not concerned about and my question was not related to wear and tear on the engine/gearbox.

But you confirmed my suspicion about the additional work load on the alternator

Like all vehicle components, it also only has a certain service life (think water pumps and timing belts). So the reason to my question was that should an alternator not receive additional attention, given the extra load imposed by an additional 2nd (or even 3rd) battery. Given the fact that if that component packs up in the bundus, you are stuffed in more than one way? And also given the fact that it can be reconditioned quite easily and cheaply (by yourself if you are able), say at 100k? as a preventative measure.

Which reinforces my decision to use only solar to maintain my aux battery. I can plug my fridge in to the 12 V port in the load bin and drive on days when there is not enough sun for charging.

OTT? Maybe, but that’s just me...

[jelo]

Does a second battery place additional load and thus additional wear and tear on a vehicle (smart) alternator?

I reckon in my limited electrical logic brain, that it depends on the Amp rating of the system. If your alternator is a low amp rating, it will work its bum off to charge 2 batteries. In which case, yes, it will experience more load hence more wear.

[Dungbeetle]

Excessive heat kills an alternator. The cooling fan inside the alternator needs to be able to do its job. For that it needs revs. So drawing high amps is not really an issue at decent cruising speeds. BUT, if you are crawling difficult terrain or driving very slow on game drives you are in potential danger burning it. On most vehicles the alternator runs at approx twice the engine revs.

Many moons ago I have burnt my stock alternator on my 4.2D Patrol when it was directly connected to a total of 300Ah batteries during a long slow speed crawl (6 hours in 1st and second gear! up in Northern Moz). Luckily got hold of an el cheapo 2nd hand Lucas universal 60A off a scrapped farm tractor.

That tought me a lesson.

Since then I use decent DC-DC chargers which limits the peak amps drawn.

[kavirondo]

As far as I understand it the following is true for alternators:

• They will only output the current that is demanded by the load. I.e. the load sucks power, the alternator doesn't push it. (This is true for all charges/MPPT/alternators)
• Alternator will really only provide half its rated output amps due to inefficiencies in the form of heat.
• Extended high loads (i.e. drawing 50% of the rating continuously) for long periods will toast the alternator. Beware charging lithium batteries, see https://www.youtube.com/watch?v=jgoIocPgOug
• The higher the load, the more heat. The more heat, the shorter the lifespan

Alex

[BushNomad]

Charging a second battery and all other electrical junk in your vehicle all contribute to the net load call on your alternator ... all energy that has to be generated.
I think the relevant aspect is the load call relative to the amp rating of your alternator ... where the former approaches the latter tolerances are tested and I would expect it to manifest esp in winding temp.
Copper windings make alternators expensive items and manufacturers
continually economise ... use thinner windings and fit lower rated alternators as they can get away with for
point of sale.
As for alternators breaking down ...
it helps if you can crank start your
motor ( pushing or even with a rope on your wheel etc!) and if you have a mechanical fuel pump ...
... say no more ... !!!

[ekkekan]

Interesting topic. Although I doubt the 2nd battery will affect the alternator to worry about. The copper and laminated core of rotor and stator will not degrade purely because it is working. If concerned then just use a DC - DC charger that limits the current to 20-30A and you go. Essential as pointed out when using lithium.
The weak points on the alternator is rectifier. It goes clamps when welding on the vehicle without disconnecting the battery. Vibration due to loose mounting bolts. Regulator as the components have a shorter life than copper. Bearings and more so on higher revving petrol engines as the alternator spins 2 to 3 times the speed of the engine. Brushes can also wear out but cheap to replace.
I would guess the alt works harder after starting a car than it would when a 2nd lead acid battery is connected that is at 50% DOD.
Many alternators work for 20years and may just need a regulator and bearings replaced. Then on tractors they vibrate a lot due to loose bolts and can give problems within 6 months. My experience years ago.

[dewets]

Interesting topic. Although I doubt the 2nd battery will affect the alternator to worry about. The copper and laminated core of rotor and stator will not degrade purely because it is working. If concerned then just use a DC - DC charger that limits the current to 20-30A and you go. Essential as pointed out when using lithium.
The weak points on the alternator is rectifier. It goes clamps when welding on the vehicle without disconnecting the battery. Vibration due to loose mounting bolts. Regulator as the components have a shorter life than copper. Bearings and more so on higher revving petrol engines as the alternator spins 2 to 3 times the speed of the engine. Brushes can also wear out but cheap to replace.
I would guess the alt works harder after starting a car than it would when a 2nd lead acid battery is connected that is at 50% DOD.
Many alternators work for 20years and may just need a regulator and bearings replaced. Then on tractors they vibrate a lot due to loose bolts and can give problems within 6 months. My experience years ago.

I totally agree with this.
Weak points on alternators are the rectifiers , brushes, voltage regulator and bearings. Heat from overcharging or alternator being on the "hot" side (close to exhaust manifold) can also kill alternators. I've replaced all at times, and within a relative short time too. Getting the pulley off is usually the biggest issue.

If you always have the dual batteries connected, I'd recommend that you use a DC-DC charger between the alternator and aux batteries as others have also noted.

[Chris8d]

To lessen the load and help prevent premature wear and tear, use a solinoid to switch charging from primary to 2nd battery

Or just don't drive your vehicle, don't even start it, that way nothing will wear.