Info only: 2021 Tacoma amp draw and alternator loads tested

This thread is just for reference for those looking to use excess alternator capacity to charge a battery. Other cars should have similar loads to this Tacoma for lights, airco, radio, etc.

21 Tacoma OffRoad, 130A alternator, 9k miles, running perfect, zero issues battery or alternator. I decided to test how much of my alternator output capability was being used, before I came up with a plan for a dcdc charger off the alternator to charge a 2nd house battery.

I used a Klein tools clamp ammeter, the one Will Prowse recommends. It has been tested and verified for good calibration, using Kill A watt meter and cross checking ac and dc amps for devices both.

I tested on the main negative battery cable. The positive starter battery terminal has 2 cables to it, one from alternator and one to fuse box. At idle, alternator charging tested on alternator to battery positive was only 4 to 5 A. I was surprised the positive to the fusebox showed -4A, which I didn't understand, thought all the power from battery would flow through that to fusebox. However, the main negative battery cable was the highest readings and seemed correct, and I know the SmartShunts go there also, so... The battery negative to chassis ground cable was about 4A less than the main negative. I was able to get ammeter around all return wires right at terminal, for what I believe are accurate readings.

Truck running idle, nothing on, 11.2A
+ lowbeam 55w ea +11.1A 22.3A
+ door open light and dome +1.2A 23.5A
+ air-co full cold and fan +10A 33.5A
+ fog lights, only avail on lowbeam 19w +3.4A 36.9A
+ turn signal, 21w x 2 +1.6A 38.5A
+ highbeam headlights, 65w ea 45.5A
(+7A from lowbeam&fog to Hibeam)
+ Qi pho e charger +0.2A
+ radio full loud +3A
Bed lights +0.4A

Likely driving setup Snapshots:
Truck alone 11.2A
Lowbeams 22.3A
Full draw: Hibeams, full airco, turn signal, full radio 46.5A

With Inverter: 125v measured, supposedly 400w in park and 100w in gear. Should be 31.2A of 12.8v at battery. However, tested way lower.
+ 465w pull on 400w inverter, +22A
--- In Lowbeam, dome, full airco, 33.5A without inverter, 465w on inverter 55.0A
--- In Full Draw (hibeam, full airco, full radio) 46.5, with 465w on inverter 65.5A

Conclusions: test was done parked in idle, normal driving 2500rpm load unknown.
130A alternator appears able to support 400w inverter full time. With all loads off but inverter, amps are 33.2A. Driving with lowbeams and turn signal gives +12.7A for approx 55A. This is a safe setup for driving, at 42% alternator stated max.

Most I could load truck in idle WITH inverter, 65.5A. This is 50% of alternator stated max.
If running full 400w while driving, can reduce alternator load by turning off devices, 11A for lights, 10A airco, 3A radio.

 

Thanks. I have been looking for some info like this. Much appreciated.

 

I’m curious of draw on battery while cranking the starter?

How about draw if it were raining - wipers, fan, lights, fogs, and radio.

 

Wipers!! Gahhh, I knew I forgot something.

 

How about with the electric heating element on? Sure that is a big power draw.

 

What electric heating element? Maybe you have a seat heater? I don't have one in 21 OR. Are you talking about somethng else?

The point of this testing for me, is to see if I can run the 400watt anytime mod while driving to charge a power station, or add a dcdc battery charger. That's 30A. So I'm not going to run power hungry things like an electric element anyways, just the things like light, turn signal, airco for defrost, and wipers, I guess.

In any case, if I had tested that I would have posted it, I posted all the items I tested.

 

https://www.tacomaworld.com/threads/electric-heater-element.523097/

 

Thanks for the info. Very helpful. This is a sticky note worthy.
Now I'm not anymore worried turning on my victron 12/24 20amps dc to dc converter to charge my ecoflow delta2 at idle . Seems the alternator is more than capable.

 

So, I did some calcs for bulalo. Here are my thoughts on his setup. The short answer is, even a 12/24 20A converter probably pulls too much amps at idle. It is going to come down to having some sort of input amp limiter in your specific power station. Using their solar input, most have both a watts limit and an amps limit.

Question: Im safe to run this to charge my ecofliw delta 2cwhile in idle right? Trd off road with same 130a alternator. This is the one installed. .

1. answer:
   The specs on that from their sheet say 20A continuous OUTPUT, but it will deliver 30A max, just don't do that continuous. So, at 26.4v or so (it is adjustable 20-30v, comes factory set at 26.4v) that is 44A to 66 A of 12v power demand from your alternator. Well, it will demand 66A if your power station will take it. Here is how that stacks up for alternator: in IDLE, the alternator can't deliver 130A, maybe only half that? I haven't seen a power curve for it, but that is normal. At idle is when it works the hardest and will get the hottest, low rpm means low cooling. Since it self cools via car movement and internal vanes. However, you dont need to run ANY OTHER loads when in idle either, so truck should only use 11.2A, if you have nothing on--no lights or airco fans or audio. So, that is 55A to 77A on the alternator... Hmm seems pretty sketchy to run that, the 130A alternator at idle probably maxes out at 65A to 70A, that means you're pulling 100% available power? I don't really know how the thing will heat up in that situation.
   
   The thing you need to look at, is the input power limiting on your ecoflow. I assume you are running this 24v into its solar charge dc port? Most of them have a watts limit and an amp limit at which they won't take more power. So long as the input voltage isnt too high, you can put 2000A available at the input and it will just use say 15A. If yours does this, then it may be ok and self limit the power pulled from alternator.
   
   I am going to run mine at the 400w inverter bed power, using the 400w anytime mod, then plug in a power supply I can control both amps and voltage to limit it to 400w actual, then plug that into my powerstation.
   
   Just looked at your ecoflow delta2 specs:

Solar Charging
11-60V, 15A, 500W max

Car Charging
Support 12V/24V battery, 8A

DC Charging
1100W, <====this is using the ecoflow Smart generator in place of the expansion battery, using the expansion battery port.

So, if you ran the 24v power supply to the solar input, it SHOULD only take 500W max, which is 19A at 26.4v. But it also says 15A, so it should limit itself there, which is 15A x 26.4v == 396W, which is 33A demand on your 12v alternator. This seems OK, the alternator should support 44A total in idle. That is what I'd do.

Teat the power station input to be sure it is only pulling around 400w, and then really the big sanity check is see how hot the alternator gets doing this.
Good luck, I was thinking about this method so all good .

 

Thank you so much. Yes, the ecoflow treats it as solar . Max run time maybe 2 hours while driving or maybe an hour idling when there's no sun and my solar rooftop solar setup can't be used . Thank you so much for clarifying this . Again thank you @Roadkill69 .

 

I also have a eco flow. Based on this information, will the eco flow alternator charger work to charge their delta 2 max battery with out damaging anything. I imagine I'd have to tone the out put down from the full 800w?