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Ok here is the how I have gotten to this point. I'm building a overland trailer. It is going to have a Optima Yellow Top in it for power. The idea is to hook it through an Anderson Plug to the FJs electrical system for charging. I'm trying to figure out if I need to run a DCDC charger. I need to know if the 2007 FJ uses a Fixed Voltage, Variable Voltage or Temperature Compensation Alternator. The Red Arc website pull down menu doesn't provide for the 2007-2010 FJs only the 2011-2016 FJ. (Redarc is a Australian company so the FJ was still available down under until 2016). The claim that the alternator for these rigs was a Temperature Compensation Alternator. Since mine is a US model and a 2007 I'm not sure if this is true for it also.....Any help would be grateful.
 

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I have an '07 and the Alternator would put out 13.6v when the battery was fully charged and up to 14.1v when charging the battery after there had been a partial drain. I have since gone to dual AGM batteries and had to mod the sense circuit on the alternator to increase the charging voltage to support them. The range is now 14.2v - 14.7v depending on battery state of charge. What this means to you is that you should change the FJ battery to an AGM type to match the Optima and buy/make a replacement for the sense circuit fuse that forces the voltage regulator to bump up the voltage so the AGM batteries will get fully charged. Then you can use a battery isolator to separate the the trailer from the FJ. This requires some attention to wiring/fusing of the trailer circuit to prevent burning things up. The alternator can put out 100-135 amps, batteries much more. If the FJ battery is charged and the trailer battery is near dead when they are connected together there will be high current flow(think jump starting) and wires should be sized to match. Alternatively you can use DC/DC charging which will limit current to the capacity of the charger and allow smaller wire sizes. The input side should take in 13.6-8v (for wet cell) or 14.2-4v(AGM) and the output should be 14.2-4v for the Optima. The Denso alternators is USA FJs are voltage variable governed through the sense circuit which is fused in the engine bay fuse box.
 

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I have a stock alternator and the Dirty Parts diode. I run a dual battery set up on the vehicle using a Blue Sea MLACR. I now also have an overland trailer to which I have fitted two 110Ah AGM leisure batteries. The trailer came with a battery management system installed and to that I have a DC to DC feed from my vehicle aux battery circuit to Anderson connector on the rear. So far no issues with keeping it all charged.

This is the management system in my trailer


1118913
 

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I'm running a 2015 130A Tacoma alternator. Plug and play. And to answer your question, they are made by Denso. Also running the diode and National Luna Dual Battery system.
 

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I have a 2008, with a DC Power high output alt., older voltage boost diode and use both Redarc and CTEK dual DC-DC chargers. You shouldn't have any problems with either.
I have a Redarc in the Teardrop and a Dual CTek under the hood supplying power to primary and secondary AGM batteries. I switched the battery in the Teardrop from an AGM to Lithium, the dual CTEK can't charge the Lithium properly so I installed the Redarc to handle the Lithium and moved the CTEK dual under the hood. This replaced the Dirty parts dual charging setup as I no longer needed it. Both chargers are also connected to separate solar panel systems and work great.
 

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In answer to OP's original question: "Is the alternator in the '06~'09 FJ a Fixed Voltage, Variable Voltage or Temperature Compensation Alternator?"

It is my understanding that the type of alternator did not change, from the early to the late version of the FJ, and always used the same type as the contemporary 4-Runner/Tacoma using the same engine (there were different current outputs, depending on model, but all were of the same type, as far as how they functioned).

Perhaps that information will help to decipher the Red Arc website on the topic?
It might be wise to also discuss this directly with Red Arc, as they should be able to provide you guidance, as to how to answer their question.

Norm
 

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Sorry but it was a little late when I responded and I didn't read the post thoroughly.
From OP: "I'm trying to figure out if I need to run a DCDC charger. I need to know if the 2007 FJ uses a Fixed Voltage, Variable Voltage or Temperature Compensation Alternator."

I did a bunch of research quite a while ago before I bought my voltage booster from Austrailia a few years back. We have Variable Voltage, which is controlled through the ECU. Manufactures started to lower and vary voltage to help fuel economy. Less voltage, less load on the engine at idle, less fuel consumption. Higher voltage keeps the AGM type batteries happy. I had and have expensive battereis that I want to keep for as long as possible. This is the reasoning for voltage booster. Using this knowledge also led me to purchasing DC-DC chargers. I also contacted both companies,Redarc and CTEK, roughly 1-2 years ago

Redarc replied: " BCDC1225D is compatible with any alternator type."
CTEK: I deleted email and don't have a copy, but do recall, that it's compatible.

Also, you don't have to run a DC-DC charger that is entirely up to you. There are other ways to charge your secondary battery. However, a DC-DC charger is one of the most efficient.
 

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Sorry but it was a little late when I responded and I didn't read the post thoroughly.
From OP: "I'm trying to figure out if I need to run a DCDC charger. I need to know if the 2007 FJ uses a Fixed Voltage, Variable Voltage or Temperature Compensation Alternator."

I did a bunch of research quite a while ago before I bought my voltage booster from Austrailia a few years back. We have Variable Voltage, which is controlled through the ECU. Manufactures started to lower and vary voltage to help fuel economy. Less voltage, less load on the engine at idle, less fuel consumption. Higher voltage keeps the AGM type batteries happy. I had and have expensive battereis that I want to keep for as long as possible. This is the reasoning for voltage booster. Using this knowledge also led me to purchasing DC-DC chargers. I also contacted both companies,Redarc and CTEK, roughly 1-2 years ago

Redarc replied: " BCDC1225D is compatible with any alternator type."
CTEK: I deleted email and don't have a copy, but do recall, that it's compatible.

Also, you don't have to run a DC-DC charger that is entirely up to you. There are other ways to charge your secondary battery. However, a DC-DC charger is one of the most efficient.
1119078
 

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Some clarifications:
1. The OEM Denso alternator is temperature compensated, and it varies its output voltage as a function of ambient temperature. Therefore, it is BOTH temperature compensated and variable voltage.

2. The FJC alternator is NOT controlled by any ECU, other than its internal voltage regulator. The internal regulator senses the battery voltage at the battery's + terminal, and adjusts output voltage to keep the battery voltage within a narrow range, depending on ambient temperature.

3. The preferred solution to your multi-battery setup is to use a DC-DC charger. This will prevent the high peak current that may occur if you switch a discharged "house" battery directly across a fully charged starting battery.
 

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All model year FJs have essentially the same basic charging system circuitry.

2010 and later have slight changes to the alternator mounts, and ‘13/‘14 alternators have an over-running clutch on the pulley.
 

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Thanks, it's been a while since I did my research and I guess my recollection was a little flawed on the alternator. However, I do remember that I absolutely, positively, certifiably could run a DC-DC charging system on my 2008 FJC. Hence spending the big bucks for the batteries, DC-DC chargers and posting a picture as proof.
Would you be so kind as to share where your getting your info.
Thanks again
 

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A DC-DC charging system can be implemented on just about any kind of electrical system with two or more batteries ... automotive, marine, backup auxiliary power generation system, etc.
 

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Hello,
Your absolutely correct, that's why I installed 2 different brands of DC/DC chargers Unfortunately or fortunately, the battery chemistry for my trailer battery (LiPo) neccesitated a 2nd different DC/DC charger, Redarc. CTEK has yet to develop and market a DC/DC charger for LiPo.
 
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