Alternator spare amp capacity at idle.

[Kdburns]

Hi All, new here writing from southern Chile. I have what might be a simple question.
I have a 2016 2.4L diesel double cab Hilux Gun125. (I believe comes stock with a 80amp maybe 90? alternator)

I’m looking to use a inverter to use up any spare amp capacity from the alternator in case of a real extended power cut. (In my house)

So the question consists of this:
1: How many amps does it really produce at idle speed? (Without overheating)
2: How many amps does the truck use idling if all lights etc are off?

My guess is it’s capable of making 60amps idling and uses about 10amps idling. Leaving me a safe max of about 40amps (with 10amps for the angels share)
But I would love some facts before I overload it and have a camp fire in my alternator…
Thanks in advance from the green Patagonia!

[Kdburns]

I have seen 25amp dcdc charge controls on this model Hilux. But I would love to know if 40amps is reasonable?

[Family_Dog]

I cannot really answer your question but I do not think the alternator is built for sustained high-amperage output. A car battery is usually charged at high amperage for only a few minutes and then the charge rate tapers off as it reaches full charge.

I would recommend buying a smallish pure sine-wave inverter - 1500 - 3000w depending on your requirements, run it from one or two 100A batteries in series or parallel depending on the inverter DC input and then charging the batteries again once the AC mains returns. Ideally, a Smart charger so that the batteries are always kept in good condition.


-F_D

[Kdburns]

I cannot really answer your question but I do not think the alternator is built for sustained high-amperage output. A car battery is usually charged at high amperage for only a few minutes and then the charge rate tapers off as it reaches full charge.

I would recommend buying a smallish pure sine-wave inverter - 1500 - 3000w depending on your requirements, run it from one or two 100A batteries in series or parallel depending on the inverter DC input and then charging the batteries again once the AC mains returns. Ideally, a Smart charger so that the batteries are always kept in good condition.


-F_D

Thanks for the suggestion. I was thinking another way of getting at the safe amp draw of the alternator at idle speed would be to idle the truck with all the stock accessories AC, lights etc. and put a clamp amp reader on the alternator wire. Then turn off all accessories and take a second reading. The difference in the 2 readings would be what Toyota engineered the alternator to safely supply at idle indefinitely in theory.

[dax021]

I'm not talking from experience, rather just my assumption, which is that if your batteries are low on charge, your car alt won't handle the draw at idle and it will just stall. Also quite an expensive way to charge batteries. Do as Eric says, or get a cheap PWM controller and a couple of solar panels.

[Kdburns]

Thanks guys for your thoughts. I will go I to the use case a little more deeply (mostly for your entertainment)
Here in Chile Patagonia we get about 8 months of rain and 6 months of heating season. Winter low night temp around 0c, daytime high temp about 7c. 20 days straight of 0 sun shine. I use a wood pellet stove for heat. Which requires 100w per hour to operate. Our grid is generally stable rarely more then 12 hours down. And on those days not having a heater for 12 hours isn’t a problem. But one day I’m sure we will get a week or 2 grind down situation. (Earthquakes and volcanos are our game here)
But the situation is very rare maybe once a decade. But without notice…
So in the winter solar is not practical, and maintaining a generator and 2 weeks worth of fuel (80Liter+) seems like a waste of space and the fuel will go bad so frequently. Since a few hundred watts per hour will get me by in a once a decade situation. I can maintain a fairly full fuel tank and have my mini generator/truck on hand ready to plug in. (Australians tend to us 25amp dc to dc chargers on there trucks for second batteries I assume they could idle it to charge the battery without burning it up, they also sell a high amp alternator 250amp! 170 at idle. But the are pricey as they are Australian built)

Anyhow, thanks again for your thoughts! I have gotten to visit South Africa a few times (the usual tourist stops) I and really fell in love with some many aspects of the place. Although I never did a massive truck camping trip… stay well!