Power System for Winter Use

[DiploStrat]

... And I’m not sure what it is but I too am drawn to REDARC. I saw one in person at the local overland shop the other day and it just seems like a solid unit, and the more I’ve read about it the more I think they’re cool.

I have used both REDARC and Sterling Products. Both work, depending on your circumstances, one may be a better fit for your rig.

 

[SteevsyWeevsy92]

I have used both REDARC and Sterling Products. Both work, depending on your circumstances, one may be a better fit for your rig.

Ive read that the sterling can distinguish between an actual ignition as opposed to just a key in then “on” position, which is something apparently not all DC-DC chargers can distinguish. Do you know if the redark has this ability?

 

[SteevsyWeevsy92]

How long will you be stationary in the winter? I am working on planning a similar winter primary system. Solar is near useless for a PNW/BC ski weekender rig.

Does the 2020 Transit have a smart alternator circuit? I am looking at doing a 48v - 12v hybrid solution in order to be able to maximize the alternator charge and to future proof my electrical system. It looks like more new vehicles are adding a 48v secondary system into them (Ram e-torque).

Charge the 48v battery via a bidirectional boost buck converter. Try and set up as many of the items to run off 48v or do point of load conversion to 12v as needed.

https://www.safiery.com/3kw-12-48v-canbus-integrated-buck-boost-power-chard

From my current research I think this is about the fastest way to recharge your lithium based house bank off the alternator.

I found this a good read.

https://www.t6forum.com/threads/guide-dc-dc-charger-for-leisure-battery-how-i-done-it.15066/

How long we will be stationary ultimately depends on our ability to keep the lights on, so to speak. We will also be spending lots of time in the PNW and BC, and even further north. I would say it’s within the realm of possibility, if we can pull it off that we could be parked for a week at a time. More than that and we’d probably be looking to plug into a generator anyway. But I guess the idea would be to be able to keep the batteries charged with short practical drives every 3-4 days, more realistically. We can always just drive for the sake of charging though if we have to and it doesn’t work out that way.

That looks like it would make for one hell of a power setup, possibly beyond our needs at the moment but I will do some more research on it. I can always appreciate future proofing, though I have to wonder for my own budgeting reasons if it might make more sense for us to wait until we find we are naturally being pushed towards a 48v system, hoping that then cost would have come down on parts like that by then. We really have quite modest power needs at the moment. I’m glad to know kit like that exists though.

 

[skyfree]

The Renogy 100ah 12v lithium batteries only take 50A charging. I wouldn't charge them at full capacity like that. A 40A DC-DC charger is just fine. If you want to, you can wire up 3 DC-DC 40A chargers off your very powerful alternator for maximum speed, but I don't see the point of that personally unless you are doing very short drives.

BTW, let's say you want to run 120A of current charging your batteries. You will need some really stout wire for that. 1 or 2 AWG. Pretty expensive stuff. Get the pure copper welding wire.

 

[SteevsyWeevsy92]

The Renogy 100ah 12v lithium batteries only take 50A charging. I wouldn't charge them at full capacity like that. A 40A DC-DC charger is just fine. If you want to, you can wire up 3 DC-DC 40A chargers off your very powerful alternator for maximum speed, but I don't see the point of that personally unless you are doing very short drives.

BTW, let's say you want to run 120A of current charging your batteries. You will need some really stout wire for that. 1 or 2 AWG. Pretty expensive stuff. Get the pure copper welding wire.

So maybe I’m operating on bad information here, seems critical so I’m glad you brought it up, but I thought that charging amperage for the batteries was additive when they are wired together in parallel. So theoretically my bank would be able to handle up to 150a? Or does the single battery limit of 50 have a greater impact than I realized? Thanks for the reply.

Edit: maybe I’ve conflated that with max continuous discharge rate?

 

[Chuck1]

A LiPo 12v 100a battery can charged at 50A or .5C , as your bank grows you can put in more amps and stay at .5C (charge rate)

150a into a 100a battery will kill it faster, stay at .5C or below, low C rates in and out will lengthen the life span

Yes you add up parallel charges from all sources.

 

[SteevsyWeevsy92]

A LiPo 12v 100a battery can charged at 50A or .5C , as your bank grows you can put in more amps and stay at .5C (charge rate)

150a into a 100a battery will kill it faster, stay at .5C or below, low C rates in and out will lengthen the life span

Yes you add up parallel charges from all sources.

Okay thanks, that’s what I was thinking. So just to be sure, I don’t plan on putting this much into it at once anyway, but since my bank is 300ah (3 batteries that will be wired in parallel), it could take 150a and maintain .5c?

 

[Chuck1]

yes in general, AGM, Lead, Some different AGM, some lead, Lipo, lithium Tanerate, all have different rates that are good

i would read the battery manufacturers specifications and follow what they say.

 

[DiploStrat]

Ive read that the sterling can distinguish between an actual ignition as opposed to just a key in then “on” position, which is something apparently not all DC-DC chargers can distinguish. Do you know if the redark has this ability?

Can't say, but it would appear to me that the issue is where you sense, not the B2B. It just wants to see more than 0v. So if you tap at some point that comes live when the key is "on" it will react. Tap at a point that is only live when the engine is actually running and only then will the B2B switch on. In my case, my cab air conditioner is wired to ignore the key position and only run when the alternator is actually putting out amps. john61ct is the in house guru of all things Sterling.

 

[Joe917]

What does key position have to do with it. The Stirling B2B will not start drawing current until it detects sufficient voltage for a sufficient time at the starter battery .
I would assume that is how all B2Bs work?

 

[SteevsyWeevsy92]

What does key position have to do with it. The Stirling B2B will not start drawing current until it detects sufficient voltage for a sufficient time at the starter battery .
I would assume that is how all B2Bs work?

it could be a weakness that’s totally unique to the renogy DC-DC, but apparently rather than activating based on voltage, it’s connected to the ignition signal and will when the ignition is set to on, draining the starter battery. If that’s the only one that suffers from that problem, all the better and easier to avoid.

 

[broncobowsher]

I keep seeing the alternator for charging the battery. Are you actually planning on driving and charging? Or are you thinking of just starting the engine and idling the engine to charge the battery?

This might be one of those times where you just need to get a generator.

 

[Chuck1]

I just assume different models and brands work different, good ole RTFM stuff.

Alternators seem to be vastly over rated, a solid 50A+ draw i think will kill the life span on most of them

Instruction Manuals (Older Models)

Battery Chargers Pro Charge Ultra Aquanautic 8-20A PFC Pro Sport 5_5/5 Global Smart Battery Chemistry Module Pro Charge Digital CED - discontinued range Pro Charge International - discontinued range Pro Charge C - discontinued range Alternator to Battery Chargers Pro Alt C (AB1280 + AB12130)...

sterling-power.com

 

[SteevsyWeevsy92]

I keep seeing the alternator for charging the battery. Are you actually planning on driving and charging? Or are you thinking of just starting the engine and idling the engine to charge the battery?

This might be one of those times where you just need to get a generator.

All depends, but generally I expect to be doing enough sporadic driving. I’d plan to use a generator in cases where I wasn’t. It won’t be long term parked anywhere, but it will be in places where solar will probably provide very little input, so I’m just looking for solutions that will be most efficient for sporadic drives into town or whatever. Again though, it’s not like I’m planning to park for a season or anything, I can just foresee storm cycles where we will be parked more than we will be driving. But if I have to turn it on and drive around for a bit every few days to top the batteries off, I have no problem doing that.

edit: we’ll be in this more or less full time in the winter, going out of our way to find the deepest snow in North America (within reason). So it’s not a single, particular use case, rather a set of eventualities we’re trying to prepare for.

 

[skyfree]

Okay thanks, that’s what I was thinking. So just to be sure, I don’t plan on putting this much into it at once anyway, but since my bank is 300ah (3 batteries that will be wired in parallel), it could take 150a and maintain .5c?

So maybe I’m operating on bad information here, seems critical so I’m glad you brought it up, but I thought that charging amperage for the batteries was additive when they are wired together in parallel. So theoretically my bank would be able to handle up to 150a? Or does the single battery limit of 50 have a greater impact than I realized? Thanks for the reply.

Edit: maybe I’ve conflated that with max continuous discharge rate?

Yes, you could of course charge at 50A X 3 or 150A, but the biggest 12V dc-dc charger I've ever seen is 120A, and it was $$$. I've never seen a single charger that could put out 150A. Maybe for Marine applications but a lot of those are 24V. You could do 3 40A chargers which would give you some redundancy in case one fails.