I was almost done installing a 2nd battery on my 2009 F350 when I traded it in for my new XLT EcoBoost. I kept all the 1/0 cable, PAC 200 Solenoid, 200Amp Fuses and Circuit Breakers.
Now I am scratching my head and wondering how am I going to do the install on my new ride.

The alternator puts out 220Amps. And the truck has
1) Electric assisted power steering
2) A sophisticated charging systems that detects hi amp output and will shut the charging system down when detected. Which requires going to the dealer to reset
Here are some questions :
1) When I engage the aux battery into the charging system after running it down, will the resulting spike in alternator output shut down my charging system?
2) Can I do the big three upgrade and circumvent the existing trucking wiring and just go to the solenoid directly from the alternator?
3) If I can go from alternator to solenoid, will the amp draw that the aux battery pulls from the alternator also run through the existing wiring and the hi amp output detection system?
These are my unknowns I am hoping the experts here can provide some advice

FYI I am doing this to power a 2000w Inverter. The battery and inverter will be mounted on the inside truck bed sidewall. I also plan on putting the solenoid on a switch so I can control when I want the aux battery inserted into the charging system. The bummer is I don’t think I can install the Upfitter switches in this truck. Not enough spaces in the fuse box

 

How many total battery amps do you need to power the 2000w Inverter?

 

I wouldnt use the charging system to power the inverter. I have a Optima Yellow Top Battery for that. I would only use the charging system to recharge the Yellow Top.

But to answer your question a 10" saw uses about 1350 watts and my output is about 300Ah at 2000 watts ~1hour discharge time
This is also a useful solution for those wanting to add a winch or Boom Boom speakers. Hope some one has already tackled this

 

I would think this is something others are looking to do as a mod. Cant believe I am the only one

 

The Battery Management System (BMS for short) doesn't shut the charging system down when alternator puts out high current - wouldn't that kind of defeat the purpose of the 220A machine in there. BMS operates of the hall sensor coming off the battery negative post. You'll see a round item around battery negative wiring before it is grounded and split off to other parts of the truck. The main purpose is to measure the current coming into and out of the battery.

Why would you want to measure battery current - mainly to monitor the battery state of charge. If your battery begins to have a low SOC, then the system, can raise the system voltage and load shed consumerable items to reduce draw (such as heated/cooled seats). It will also shut off the battery saver in Key in Accessory mode.

BMS also uses a hall sensor coming off the alternator. With both sensors it helps to balance the charging system, improves fuel economy and mainly protects the battery from ever dying or getting too low (extends battery life).

With that said, you could do away with the sensors and upgrade the wiring as normal. Unplugging the sensors will trip a DTC but not an error light on the dash - "Check Charging System" would be the error message. If you wanted to keep the BMS operating correctly, you'll need to pass all the upgraded wiring thru these sensors and I know they are not big enough for a 1/0 cable plus the OEM wiring. You could remove the OEM wiring and pass a single 1/0 cable thru it. Once thru the sensor, can splice off as needed - this is what I would perform.

So to answer your questions with that in mind:

1 - No it won't shut the system down. If the aux battery is wired directly to the OEM battery (not thru the sensor) then nothing happens but the system will not be able to protect the battery from a low SOC. If the aux battery is wired thru the sensor, then system actually will help to promote charging of the second battery. One of the first things it may do is increase idle speed to help pump more alternator current if it is in full field already.

2. - No and yes. You can do the big 3 upgrade but still keep the battery and alternator current sensors if possible. When you disconnect the alt/battery wiring, the wire end connectors was designed so they could be slipped thru the current sensor w/o being cut. Then route your new wiring as needed.

However, do not run the alternator output directly to the solenoid. It shoud be run to the OEM battery first, then all connections made from there. Depending on the system, you may be bypassing the pre-fuse box connected to battery B+ terminal which protects the alternator wiring.

I would connect your solenoid from the OEM battery.

3. If all wiring from the alternator and battery pass thru the hall sensors, then the system will be able to monitor the charging system performance. If you realize it is there to protect the battery and not to shut down the charging system you'll be better off in the long run and possibly be not stranded out in the boonies.

Note - Worse case though, if you left the OEM wiring in place and connected additional wiring from the alt to the solenoid (make sure it is protected/fused) would throw off the system. If you don't utilize your aux battery that much then the balance of the system won't be off very much and likely not know the difference. However, used every weekend and the system will not know how to react and might cause some undesirable results.

I quickly typed this and didn't have time to proof it so hopefully it made some sense and don't be afraid to ask questions. There are guys who put sound systems with a second battery and following above advice have had no adverse affect. The BMS system isn't like what Honda does and drop the system voltage so low that the sound system performs lousy, but will actually raise it when needed.

 

P = V * I * cos(theta) (which is 1 when voltage and current are in phase like in DC).

Therefore I = 167 Amps, plus losses in the inverter process. Assume 200A required.

 

I hope I'm not hijacking this thread, but I have some questions about this topic.

I have a 2011 F-150 5.0. I would like to install an auxiliary battery to run the ham radio gear that I plan to put in the truck. Max current draw of all equipment will be in the 25-30 amp range. All of the equipment I'm adding will draw power from the aux battery. I can get Optima batteries at a discount through my employer, so I'm thinking about a yellow-top mounted in a truck-bed tool box. I had figured on getting a garden-variety dual battery isolator that will keep the aux battery charged, but not let loads attached to the aux battery run down the OEM starting battery.

Is this feasible in my truck? Where would you suggest I tap power for charging the aux battery?

Also, I think I figured out what you mean by "big three upgrade". Are kits available for doing this or am I on my own?

 

Great posts
I am also installing a second battery. All I will do, is charge my travel trailer battery when I leave camp.
.
Questions.

1) I have not been able to locate the 'hall' sensor on the Pos. side where is it and what does it look like?


2)If I want to connect this second battery through the sensors, where exactly should I make the Pos. connection? There are 3 the cables coming off the pos. battery terminal. . 2 of these cables seem to be fused. Is the connection supposed to be made to one of these 2 cables? Which one? And on which side of the fuse. I have fused both sides of my wiring but since I can't tell what is the amperage on the 2 car fuses, I am concerned that if I connect on the wrong side, I could damage them. That is why I had planned to connect directly to the battery.


3) Do I have to also connect the negative terminal through the Neg. hall sensor? Or can I just connect the second battery Neg. to a ground? Since I will only be charging the battery, it is not likely that I would discharge the OE battery.

4) Originally I had just planned to connect straight to the Pos. and Neg. terminals. If I do that, will the truck's charge regulator still deliver a good charge cycle?

Thanks ,
SJM

 

If you've got the tow package, why not just charge your TT battery through the 7-pin plug? That's what's happening when the TT is attached anyway.

Don't know how much current it can provide but it should be a fair amount. And there may be some trailer detection circuits that need to be "tricked" before the current will flow ... not sure.

The advantage would be that the 7-pin trailer socket is designed to work with rest of the truck's electricals.

 

That was my first thought. Actually that is what I did initially. Then I thought that it might not be the best way to do it.
.
That system works well as long as the trailer is hooked up. Then, power from the truck goes through the travel trailer's charge regulator, and that charges the battery. The trailer plug circuit is protected by a couple of 30A relays, and fuse #37 ( only 10A) in the fuse box. As far as I can tell, the trailer plug does not have a charge regulator. So hooking up a discharged battery might be problematic. The wire to the trailer plug looks to be #12 gauge, The instruction pamphlet that Ford provides with the trailer brake wiring shows that the max amperage there is 12.5A. not enough to use as a charger. As far as I can tell, the trailer plug does not have a charge regulator. So hooking up a discharged battery might overtax that circuit and not provide the discharged battery a proper charging cycle.

I wanted to charge spare batteries when I am away from the trailer. I figured that as long as I am driving, might as well use the available alternator power to charge my spare batteries.
SJM