Check out this thread:
Does my 2015 have a smart alternator?

 

Thanks, I got my answer but also tased a few more questions. One still being rather or not I can safely use the Li-BIM 225 that BattleBorn recommends with my 150a alt without frying it. It was also nice to find out that a smart alt is also regenerative breaking.

 

You might want to check out the BEMM for that year. I've been reading the 2020, which I'm interpreting to mean that a 240 amp load is their recommended limit for their dual-250-amp alternator with dual batteries--maybe a little conservative, but probably based on long-term use. I would think that a 225 amp load for a single 150 amp alternator is about triple what Ford would recommend.

 

I did find a BEMM printed for 2019 but i got lost pretty fast as to what exactly I was reading, haven't seen one for 2018. According to the spec sheet from Precision Circuits who builds the Li-BIM I have the 160A even though it says 225 on the name. The part number in the sheet and the BIM itself is for the 160a BIM. but that is still higher than my alternators ability. I've tried getting info from them to explain things to me but was told to go to BattleBorn since the BIM was designed to their specs. I've had very little luck with BB service. They didn't return my calls when I was buying their batteries nor did they send me an instruction sheet when I bought the BIM. Personally I don't think its the best design since its all based on time and volts. BB should have more info about it on their website.
Guess its time to just chalk it up to a $200 lesson learned the hard way.

 

It looks like this battery isolation device does not perform any current limiting function, but it does have a duty cycle which means that your alternator has time to cool down between cycles.

LiFePO4 Battery Isolation Manager (BIM)

LiFePO4 Battery Isolation Manager (also known as the BIM) monitors voltage and connects and disconnects batteries when needed. Click here to read more!

battlebornbatteries.com

I just posted something the other day where I read that they recommend charging at a maximum of 0.5C for best lifespan (100 Ah battery at no more than 50 A). It isn't clear to me that this device would ensure this current limiting would take place. You'd charge the battery faster but the lifespan may be shortened if it's accepting more than 50 A for any amount of time.

 

According to Precision Circuits the Li-BIM was built as per requirements from BatttleBorn so I would think it should be the best way to go for their batteries. But I can't find out if it's designed for use with my smaller 150a alt or the HD 250a one is needed. Precision Circuit has a specs sheet that lists two different part numbers, one for a 160a and one for a 225a BIM. My BIM shows the 150a part number even though it has a cable on it saying 225. I'm lost.

 

I asked BattleBorn about the LIBM, specifically about current-limiting. Their reply "The Li-Bim itself will limit the current to 225, it won’t allow more than 225 amps when charging." It sounds to me like it will limit current to the max rating of the device, but I don't think it has the ability to set a lower current than 225 Amps. So, if you want a charge rate other than 225 Amp, this device wouldn't do it by itself.

 

"The Li-Bim itself will limit the current to 225, it won’t allow more than 225 amps when charging."

I suppose that technically, that would be current limiting, but then the same can be said for a fuse. Also for a wire, which turns into a big scary fuse when you put too many angry electrons through it.

"It doesn't control current" would be a more accurate statement.

Regardless, it won't protect your alternator through actual current limiting. Perhaps by duty cycling to limit heat build up, as I mentioned above.

 

Precision Circuits, Inc. also makes a 160A version of the Li-BIM 225 as shown here:

http://precisioncircuitsinc.com/wp-content/uploads/2019/10/00-10041-26x-Li-BIM-Rev1.pdf

 

That's the same spec sheet I have. it wasn't until I had my Li-BIM that I found out who made it so I went to their website hoping for more info. My BIM itself has the part number for the 160a model even though it also shows the same name of Li-BIM 225 on it, i'm confused, plus the spec sheet does not really explain much to me. It shows wire size in relation to continuous amps. Does that mean if I use say 4 AWG I will be pulling 100a from the alt and then 600a intermittently. That would be impossible since my 150a alt couldn't produce it and still maintain running the vehicle. I asked Precision about it and they blew me off and told me to go to BattleBorn.

 

A wire's capability to safely carry a specified amount of current is not directly related to how the wire is sized in a particular use.

The overall capacity (or "ampacity") has to do with the amount of heat created due to the current flow, and the coating of the wire being able to safely withstand that heat. You will find that much smaller wires are rated for the currents that most of us use significantly larger wires for. The reason for this is that wires have resistance. The smaller the wire, the more resistance. Resistance in an electrical circuit (which is what you're creating any time you hook up wires and current is flowing) dissipates power and creates a "voltage drop". There is plenty of reading you can do on the subject beyond what I'm simplifying here.

The reason to oversize (or even supersize) the wire is to minimize voltage drop, and the losses and problems that come with it.

As you have correctly deduced, you can't pull 600A from a device only capable of generating 100A (though if you look at the BEMM and the alternator power curves, you'll see that the 150A can generate more than 150A. Same for the higher current models.). If it's capable of 100A and you hook something up that will draw near to the max, the alternator will do it's best to supply it. While it does so, it will heat up significantly. It simply isn't designed to operate in this range for an extended period of time without some sort of permanent damage occurring. If there's a high temperature cut-off, it will shut down to protect itself. I don't know whether this exists on the Transit, but I would think it should.

Back to your batteries, Battleborn itself says to charge at 0.5C for the best lifespan. This means charging a 100Ah battery at 50A, or 200Ah at 100A - and so forth. Unless you have a good reason to want to charge them faster, why would you risk shortening the lifespan unnecessarily? In order to do this, you will need a device that limits/controls current and keeps it to a maximum of whatever 0.5C is for your chosen battery bank. With presently available options, this narrows it down to a DC-DC (B2B) charger of some sort. Picking a specific brand is probably beyond the scope of this discussion and subject to heated debate.

 

I understand how wire sizing works and why its best to bump up a size but not sure why you included it.

As far as the alt goes, my understanding is that useable output should be figured at 70% of rating. With that I'm limited to 105a max. The Transit apparently can use 70a just to operate its own systems which only leaves me with 35a to work with. I have deduced that I do not have a smart alt by testing with a DVOM as described in another post here. I have no way of knowing if my alt has a built in over heat protection but I doubt it does. I don't think Ford would be that nice to us. And as you say, if I push the alt to max it will fry which is what I'm trying to avoid.

If BB says a 100a battery should charge at 50a then that would mean I need to charge at 150a since I have 3 100ah BB batts, this in itself would be impossible so that makes no sense. It's also something I do not recall seeing on their webpage while looking into both their batteries or the Li-BIM that they recommend using. Maybe I missed it, i'm not the best with finding my way around websites and most times find what info other than a sells pitch by accident. Regardless at this point it's neither here nor there as it sounds like the Li-BIM will not work in my case. I just wish more technical easy to understand facts would have been provided by BB not to mention the manufacture so I could have researched what they had to say also.

I originally started looking into B2B chargers and from what I was understanding that is what the Li-BIM is, guess I was wrong. Like I said above, I learned a $200 lesson. Now I just have to figure out what true B2B system to go with and what size. Sterlings are super high priced and very noisy from what I've heard, plus I don't really have the space for one since I was building for using thermal compact BIM.

thanks for your help