6 replies to this topic

[MountainSufi]

Howdy from Jackson Hole! 2012 Tacoma here.

 

I'm considering getting a heavy duty alternator for more oomph charging my solar battery while driving. At 127,000 miles it might also be good "ounce of  prevention" for boonie camping.

 

I considered the Mean Green alternator but scathing online reviews show longevity issues. And $400 is a lot of scratch to experiment with.

 

I welcome your suggestions.

[ntsqd]

There's a direct relationship between longevity at some specific amperage and the case size of the alternator. Increase the output, decrease the life-span. This is the reason that the monster output alternators used in ambulances etc. are so huge.

 

I would look to see if there is a higher output transplant alternator that can be used. For instance, someone figured out that the ~100A stock alternator from a '92 MR2 fits on my '88 4rnnr's 3.0L V6 with just a few minor mods. That's 15 or 20 amp increase from a stock alternator. Similarly, my '96 Bronco only was offered with a 95A alternator, but the same engine in the same year 3/4t van had a 130A alternator and it fits the Bronco's alternator mount.

[Jon R]

You might consider getting a dc to dc charger instead of a larger alternator. The capacity of your existing alternator is probably adequate for a 30 amp camper charging current in addition to normal loads. The exception might be right after starting the truck, when the truck battery draws a lot of current to replenish its charge. That’s where a dc to dc converter with a charging start delay function can help. You can set it to delay starting the camper battery charging for a few minutes after truck start. That way the alternator isn’t ever overloaded. You would also get all the other advantages of a dc to dc charger that have been discussed extensively on this forum.

Edited by Jon R, 07 March 2022 - 03:46 AM.

[ntsqd]

I've never bothered to total it up, but I've long wondered how much average "Overhead" is built into a stock charging system. While I do think that DC-DC chargers are a good option, if the stock alternator does have the capacity to run it then it won't make much difference. One thing that you don't want to do is run an alternator, of any size, at or near it's max rating for extended periods of time.

[Jon R]

A dc to dc charger limits the current that the camper can draw, allowing an electrical load analysis to be performed. It also allows you to delay the beginning of charging so that its load does not need to be accommodated during the oeak current demanded by truck battery recovery from engine starting.

I agree that you don’t want to run an alternator right at its rating for long periods, but the above load relief factors may allow one to decide their existing alternator is acceptable after analyzing the loads against whatever alternator capacity margin they want to apply.

How do you know what the basic truck loads actually are? Measure it with an inductive current probe.

Edited by Jon R, 07 March 2022 - 03:44 PM.

[ntsqd]

The delay in charging the camper battery is not exclusive to a DC-DC charger. Other charging connection options also have this feature.

 

It has been mentioned here before, but since it doesn't affect me I have not retained when Toyota moved to the so-called "smart alternator". I would suspect that a 2012 Tacoma does not have one, and if so the available options for charging the camper battery(ies) are quite a bit wider than if it were a later truck that is inhibited in those choices by it's alternator.

 

In a car I would expect that the capacity of the alternator is set such that the worst case scenario leaves the alternator operating at it's ideal constant duty maximum. In a truck there is probably (I hope!) some overhead left before the alt. reaches that point.

[Jon R]

Howdy from Jackson Hole! 2012 Tacoma here.

I'm considering getting a heavy duty alternator for more oomph charging my solar battery while driving. At 127,000 miles it might also be good "ounce of prevention" for boonie camping.

I considered the Mean Green alternator but scathing online reviews show longevity issues. And $400 is a lot of scratch to experiment with.

I welcome your suggestions.

OP: which OEM alternator does your truck have? It appears the base alternator was 100 amps and the towing package alternator was 130 amps

If you have the towing package alternator you already have an extra 30 amps of capacity, with whatever longevity margin Toyota included in the design. That extra capacity was intended for use by a trailer for brakes and battery charging.

If you are wondering how close you are to the alternator rating it is easy to measure if you have an ammeter with an inductive current probe. If you don’t have one a friend or a shop near you may have one. Electricians normally have them. I’d try to find out my alternator rating and understand my loads before investing in a modification.