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Mean Time Moderator
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I was browsing eBay looking for a T4R 130A alternator as if I’m towing I’m now charging four batteries... came across this, anyone have any experiences?

 

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Personally, I'd go with a 130A Denso rather than any aftermarket "high output" unit.

Is there any reason that you believe that a 130A alternator would not be able to keep your battery bank charged during the "typical" driving you would do in whatever type of expedition(s) you are planning?

You mentioned that the alternator will have to charge 4 batteries - is this battery bank configured as the FJ primary starting battery, a secondary starting battery, plus 2 additional "house" batteries in the trailer?

What capacity are the house batteries?

Would all four batteries be charging simultaneously the instant the engine started? I might be inclined to provide some means of isolating (via switches, or manually switched relays) the house batteries from the charging system until the starting batteries were at full voltage.

Going to a 250A alternator would require additional changes to the electrical system (much larger alternator output fuse, plus larger gage wire everywhere in the alternator output circuit).

When the trailer is not in use, make sure to keep the house batteries continuously connected to battery tenders so they will always be at 100% charge level at the beginning of every trip.

I'd be inclined to start with a reliable, moderate-cost Denso 130 and see if it meets your needs. You may still want to install a slightly larger alt output fuse to provide additional current-carrying margin.
 

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I bought this for my 2007. It’s the same than Tacoma w/towing package (130A).
Looks good, like OEM. There was some testing result also included (charges over 160A).

Pictures are in my old phone, I download later today.
2772B9D3-A257-4B0A-875A-8AA07664C613.jpeg


EB630C15-5269-4B2D-80EB-E6AC86D3238C.jpeg
 

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Mean Time Moderator
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Discussion Starter #5
@FJtest Thanks for the input. Nope no reason at all a 130A won’t be plenty good enough and I’d shy away from something so high anyhow as it leads to other issues/complications I was just curious really while I looked for a 130A to add to my next shipment of bits.

my vehicle aux battery is connected via a Blue Sea ML ACR. The trailer batteries are on a DC to DC charger, the trailer is fitted with a complete battery management system which does mains hook up, solar and DCtoDC. They connect to the vehicle feed via an Anderson plug on which I have a 30A circuit breaker as a switch.
 

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I've been using the Mean Green HO alternator since June 2013 (over 6 yrs now) with no issues.

Others have had issues but I'm doing good (knock on wood).

It still doesn't do a great job charging my dual battery in parallel though.... as I believe it takes it's cue on how much to output from the first battery in the parallel group.

Yeah, those DC to DC chargers seem like they'd be great.... you have something similar to this then?

I have installed a waterproof Noco dual bank battery charger.... for when I have shore power.... or when I use my generator camping.
It's great for keeping things topped up every once in a while even if I'm not going anywhere. I believe this is the reason I've had good luck with my alternator and also my Optima batteries - topping them up every once in a while (not to mention the alternator voltage booster)

 

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Winterpeg said:
"...I believe it takes it's cue on how much to output from the first battery in the parallel group."

The alternator has no way of knowing which battery is "first" ... parallel loads are parallel loads, and the charging current will be divided according to load resistance.

The battery which has the lowest internal resistance and the lowest resistance wiring will always draw the most current. No two batteries will ever have exactly the same internal resistance, even if they are the same make, model and age.

When using your Noco dual charger, do you isolate the batteries from each other with some kind of disconnect switch?
 

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Winterpeg said:
"...I believe it takes it's cue on how much to output from the first battery in the parallel group."

The alternator has no way of knowing which battery is "first" ... parallel loads are parallel loads, and the charging current will be divided according to load resistance.

The battery which has the lowest internal resistance and the lowest resistance wiring will always draw the most current. No two batteries will ever have exactly the same internal resistance, even if they are the same make, model and age.

When using your Noco dual charger, do you isolate the batteries from each other with some kind of disconnect switch?
Yep
 
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