Alternator size?

Have a 2023 Tundra SR5 TRD sport DC 6.5ft bed with tow package. What is the amp size of the (stock) alternator?

 

I believe 180 amps. That seems big to me for a non hybrid. Makes sense for the hybrid. On my Scangauge, the percentage of alternator capacity is generally no greater than 27%. That would be around 47 amps which seems a lot DC current demands on a non hybrid if the output is truly 180 amps on my truck. But then we have electric fans, electric assisted steering, and a lot more electronics watching everything.

 

Mine has a power inverter for the hybrid instead of an alternator.

 

Parts catalog lists the alternator as 180 Amps as @tbrady mentioned. That’s a fair size alternator. I believe 2nd Gen was 150 amp; must be a lot more Nannie’s on the 3rd gen..

A 47 amp nominal load isn’t all that much considering a blower motor can consume 30 amps by itself. Add all of the computers to run the vehicle, dash, lights, radio, etc and 47 amps isn’t bad, IMO. Most vehicles come with 80-100 amp alternators with headlights and HVAC typically being the largest power consumers.

 

Looking at installing a 40 amp DC-DC charger to charge camper batteries while driving. Article said make sure alternator was large enough to handle it. Is it as simple as saying I will have 180 - 40 = 140 amps still available for the truck, ie, the 180 amp alternator is big enough?

 

Your camper batteries should already be charging from the tow vehicle via the 7 pin trailer plug - part of why tow package equipped vehicles have a larger alternator to begin with.

 

With most modern vehicles transitioning to electric power steering vs conventional hydraulic power steering, 175-200+ amp alternators are becoming the norm to keep up with the current demands while maintaining the ability for quick state of charge recovery for the battery from starting loads coupled with frequent short trip driving of some owners driving habits.

 

This

 

Yes, I agree battery will charge via 7-pin plug. That's fine for an 80-100ah flooded battery, but that battery died and we are upgrading camper electrical system to inverter and probably 300ah lithium batteries. These will need a different charging regiment and present wiring to 7-pin plug can't carry enough amps to be effective or efficient. Hence the DC-DC charger.

 

The charger should be built in to the camper end and turn on whenever voltage is present at the plug. It will still charge your lithium batteries, just not at MAX charge rate.

You are welcome to spend the money and install the additional charger if you please; we are just saying that it should already have power present (30A if memory serves).

 

Exactly. And to circle back to alternator size, I have asked Service at the dealership to confirm what's been said here, which looks like the 180 amp alt has enough capacity.

 

VERY NICE set-up! Ours is celestial silver. We camped in Algonquin as kids many, many decades ago - beautiful place. How are you using the portable solar?

 

If I recall correctly, the DC power in the 7 pin connector is fused at 30 amps. Next the gauge of the wire providing the power is probably 10 or 12 gauge so a little small to carry 40 amps. 10 gauge is rated at around 30 amps but not for the distance from the alternator to the RV battery. If you are going to put in a DC-DC charger I would limit it to 15 amps. Most DC wiring guides recommend using 10 gauge wire for carrying up to 15 amps 20 ft. LFP batteries have a very high charge acceptance rate, and if you offer them 40 amps they will take it. One way to limit the current flowing to the battery is to limit the capacity of the charger.

 

Gotcha. I know Lithium batteries need a different charger but I was under the impression that the charger took whatever power was available and metered it out to the batteries similar to MPPT solar chargers, but it looks like I got my wires crossed. Good to know.

 

It's not so much the amperage capacity coming from the 7 pin, rather lithium chemistry batteries need a completely different and critical charge algorithms to safely recharge them compared to lead acid deep cycle chemistry. Lithium batteries are much more subject to damage or even fire hazard if proper charge/discharge processes are not used. Therefore a dedicated charger must be used.

Now standard lead acid type deep cycles can be charged directly from the B+ output of the 7 pin.

 

Trailer wire from plug back gets sketchy on trailers. Size-type-insulation. I’d keep charging system separate. Start at truck battery back. Use separate plug. Wire sized and protected.

 

tbrady I believe you nailed it with "One way to limit the current flowing to the battery is to limit the capacity of the charger". I've read the lithium will take all that you give it, so I think I might use a 20amp charger, better for the alternator as well. What I've read and watched supports what bonefish says as well. Also, watched a Will Prowse video where he confirmed 40 amps coming out of a 40 amp charger to a lithium battery. And I have confirmed with the dealer I have a 180 amp alternator (tow package on truck). My question now, folks, is to ask if anyone has actually installed a DC-DC charger on a 2022 or 23 Tundra. What size charger installed? What are your experiences? Any problems caused with the alternator or anything else? The dealer's service shop has not seen these installed on such new models so they have little to no experiences to offer. Thanks.

 

Nice TT!

 

Back to - I confirmed the truck has a 180 amp alternator. I need to know the "rated output current" for this alternator. I assume it is not 180 amps because that's too easy. Does anyone know? Sent this question to the dealer but have not heard back.