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Promasters (and most new vehicles) have significant phantom power drain when the key is off so, especially if it isn’t driven on a regular basis, I assume that’s the reason for the large battery. RAM isn’t giving away large batteries because they are just "nice" guys.
 
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Discussion Starter · #42 ·
"Fault tolerant"??? Were you formerly in the computer industry? I LOVE fault tolerance. And I'm glad you understand that concept. Separate units is my preference for that reason and others. I even have 2 inverters! Talk about fault tolerance! Similarly, my solar panels are wired in parallel too, partly for fault tolerance. :D
Yep, I was a cyber security officer in a small federal agency 🤓. I was on the compliance side, not the technical, so a lot of my knowledge is more conceptual than practical, but yeah, as a principle, fault tolerance makes a lot of sense for me. And since the van will be my home and I have the resources right now to go a ways beyond bare bones, I'm looking for components that will give me a reasonable measure of peace of mind throughout my system.

2 inverters might be a little much at this point...but I'm not ruling it out!
Re: Renogy 40A. I am a traveler and my trips, all in 2019 (2020 was a dud year for a lot of us), had been in sunny areas, so most of the time I was using my pretty beefy solar array (600W). However there were a few times I charged up my, at the time, single 100A Li battery with the Renogy. It seemed to work well. --"seemed" because, at that time, I didn't yet put in any battery monitoring. I was in prototype mode and I was itching to give things a try. So I was flying by the seat of my pants (though I did have a voltmeter but those aren't that accurate with Lithium batteries) and so I'd fire up my DC-DC charging whenever I felt I had an opportunity or should (driving and it had been cloudy).

Re: happiness with it. Realistically, there's not much to it. I just turned it on and it did its thing like a black box (though the Renogy is "green" in colour). So I'm quite happy with it. But do note that I'm a part-timer (traveler) and so it really hasn't been used much. Time will tell if it's reliable but I don't have any reason to doubt it.

It was a lot cheaper than the Sterling was at the time (it may still be, like I said, I'm out of date). My only regret was that I was a bit bleeding edge and didn't wait for Renogy's 60A unit to come out; there was only a 20A and 40A unit available at the time. I have the bigger alternator (225A?) and my now-upgraded battery bank can take all 60A if I had the 60A version and thus be charged faster if needed.
Thanks. Good information.
 

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Discussion Starter · #43 ·
...

I have changed alternators multiple times in truck stop parking lots. It’s not a difficult or messy job, and if like you can practice it at home and get comfortable with it.

Seems to me armed with a spare alternator, you could confidently boondock with any custom power system you decide to build.
Filing this away for future reference, thanks!
 

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Discussion Starter · #44 ·
Don’t you worry, lil’ miss. I’ll get this all sorted out for you..,,
Yeah, thanks 😬
Seriously, here’s another vote for lead-acid with isolator. They’re cheap and effective and the sealed ones require less babysitting.

Just don’t drain leads past 50% to max out their cycles. That’s it. If you have enough solar on your roof to handle your loads and keep your batteries full then you just need to plan your capacity for overnight loads to stay above 50% SoC.

Lithium’s hate heat and charging over 80%. They also hate extreme cold too but for charge speed reasons as mentioned.

If you’re living in your van that might be a better use case for lithium or your batteries are going to spend a lot of time subjected to extreme temperatures. Teslas and iPhones have special software to control battery temperature and to prevent full charging on normal occasions. Maybe your charge controller can do the latter but there’s no battery temp management inside a parked hot van.
And seriously also, thanks for your thoughts. I will be living in the van full time and it's not my intention to spend much time in the cold or extreme heat (although if this last year has taught me anything, it's that planning is overrated...). And I will be insulated and heated, so hopefully that will somewhat mitigate those odd moments when I find myself in an unexpected climate that the batteries wouldn't like.
 

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If the starter battery was only designed to start the vehicle it would have very low capacity, less than 5ah would be plenty. Why are they using such a large batteries (100ish ah) for the starter battery if it's not designed to be discharged and recharged?
I assume that’s the reason for the large battery.
It is about cold cranking amps and reserve capacity. You can google it.

75021
 

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Discussion Starter · #46 ·
We often 're-hear' the argument that one shouldn't use a combo unit because you don't want to 'put all your eggs into one basket'. Maybe it's our 'single engine' private pilot heritage that makes us smile a bit at this argument. Years and thousands of hours ago we had to confront the likelihood of engine failure and its corresponding consequences and concluded that the chances of the former were insignificant enough that we could accept the risk of the latter. If an internal combustion engine (with its hundreds of very quickly moving and reciprocating parts) can be made reliable enough to place our lives upon it, surely a modern electronic device with only a fan and on/off switch as its moving parts can be relied upon. And if it does fail, well, you're already on the ground.
Great perspective, Winston, thanks. Working in federal cyber security might have pushed my natural risk-aversion a little bit over the edge, so a reminder to moderate that a bit is welcome!
Seriously, though . . . the 'smoothness' of combo units should not be ignored. Yank the shore power plug and inside the ProMaster the transition from shore to inverter power is so seamless that the lights don't even flicker. Computers (even those without batteries) continue uninterrupted as if connected to a UPS (uninterruptable power supply). All 120VAC outlets are treated the same. They are either connected to shore power or to inverter power. And then there's the issue of neutral bonding/grounding (where the neutral must be connected to ground/chassis when operating on inverter power and disconnected from ground/chassis when supplied by shore power) - - just another of the functions that combo units do 'for you'.

Settle those nerves - - go combo!
Very good information, added to my notes. Especially the bit about the neutral, that is an excellent reminder. Thank you so much!
 

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I don't think there is an answer as to why we need 900 CCAs for a V6 vs the 500-600 CCAs cheapest batteries I used on big block Chevys.
 

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I don't think there is an answer as to why we need 900 CCAs for a V6 vs the 500-600 CCAs cheapest batteries I used on big block Chevys.
maybe its because the PM has so many components which draw power from the battery, even when engine is off?

I have one of those Li starter battery packs, it is 24wh and starts the PM and v8's no problem, I know its not a direct comparison from CCA's to Watt hours/amp hours but if the starter battery were not meant to be discharged and recharged it would be small fraction of the size/capacity. the large capacity is not needed for the big short amp draw needed to turn the starter.
 

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The battery is likely oversized to handle cases where the PM is used as a delivery vehicle, and will be need to be started many times driving around a neighborhood without sufficient time between restarts to recharge the battery.
 

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Gee, I guess Lithium vs. Lead-Acid discussions have achieved the passion and fervency level comparable to that of insulation! :D

I think it's a good thing as it has become more popular and no longer in the realm of the exotic. I for one am happy as I recently upgraded my battery back with more batteries for cheap(er) and should there be a version 2 of my van (a la a few members here), maybe I can put in even more capacity and greater capability for even less money.

Not an expert but I'll comment on a couple of the topics mentioned:

1) redundancy vis-a-vis aircraft engines.

It's a valid point but it may not be 100% relatable to the consumer Li battery and support systems market, especially when combined with the DIY campervan building community.
a) the design of aircraft engines leaves a big margin for safety. I suspect engines aren't run anywhere near max and the load is fairly well understood.
b) the designers of the "system" are professional engineers working from 100+ years of hard-won experience (2 world wars for example)
c) the "people involved" are highly trained (the manufacturers, the pilots, maintenance crews, ground crew--passengers don't count; they're just cargo)
d) I don't know if this is true exactly, but I suspect there are regulatory bodies that enforce certain safety aspects such as regular maintenance with logs, or at least there's an understanding from everyone involved that maintenance is important

Contrast this with the electrical systems for campervan builders:

a) a lot of this stuff is sometimes made with questionable based on designs inspired by or cloned or stolen from others, often with an eye to cheapening the cost. Safety margins are (I suspect) very low if not outright "negative" in that claimed wattages are not as advertised as and/or cannot be safely run at the claimed specs for extended periods of time. My "3000W" inverter (claimed to be "6000W peak" --Wow!) is likely nowhere close to even the 3000W sustained. I suspect its components are second rate and assembly is so-so.
b) users have a hodgepodge of experience. A few have some relevant experience. Most others have limited experience and are reading blogs or relying on forum comments written by unqualified people--like me (not only am I unqualified, but I also have NO relevant experience, AND I'm writing a comment! :p)
c) some are not only building systems out incorrectly (components of inadequate capacity, insufficient wire thickness, poor quality crimping) but are also not using them correctly (too much current draw at once, running down batteries beyond safe levels for longevity), etc.

So...redundancy may not be such a bad idea. :D [Hmm...I might just go to a junkyard and retrieve a working alternator as a spare! (thanks for the idea, Kip!)]

2) capacity of Promaster starter battery

I think one of the reasons we have such a large battery is that the PM is a commercial vehicle. Unlike a passenger car, it might have to run some emergency lights or other electrical equipment for long periods with the engine off. It might have to reliably start the PM in really cold climates. Possibly after having sat for a while as a crew listens to the radio (think ambulance).

And a bigger battery could provide a longer service life (e.g. a big battery at 50% capacity due to age could still function whereas a smaller one at 50% would not start the PM in cold weather and commercial vehicle operators would not be happy--a whole fleet's worth of sales could be in jeopardy) and thus Ram was wise to have specified this big a battery.

If campervan builders want to save weight, they could always swap in a smaller battery. In my sporty car days, one of them came with a huge OEM battery. Aggressive owners would swap that out for a much smaller one. But they're not trying to start them in Alaska in January.
 
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Oh and re: smoothness (in my previous life, I might have used the word "seamless"), I can also yank shorepower and have AC systems continue to run. However, being a nerd, I've run parallel systems for AC power so if I want to, I can switch some AC items to strictly shorepower. Why would I want to do that? My power converter can supply 50A. By switching a power-hungry item to using shorepower directly (e.g. my induction burner stove), I can use all 50A of my power converter's output to charging my battery bank.

I can mix and match too, leaving things that wouldn't be good to "reboot" on the coach electrics system even when on shorepower (e.g. a dreamt-of future raspberry pi video surveillance system or maybe a wifi hotspot or cellphone booster thing-a-ma-bob).

The downside to all this is that there are multiple devices and the wiring is much more complex. It's possible that I've spent more money than had I bought an all-in-one unit too.

So I'm not advocating that my approach is correct. (see my previous comment about my own qualifications!) But I found it kind of cool to design and build and my nerdy side felt fulfilled. (Fulfillment is a good thing! :D )
 
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Gee, I guess Lithium vs. Lead-Acid discussions have achieved the passion and fervency level comparable to that of insulation! :D

I think it's a good thing as it has become more popular and no longer in the realm of the exotic. I for one am happy as I recently upgraded my battery back with more batteries for cheap(er) and should there be a version 2 of my van (a la a few members here), maybe I can put in even more capacity and greater capability for even less money.

Not an expert but I'll comment on a couple of the topics mentioned:

1) redundancy vis-a-vis aircraft engines.

It's a valid point but it may not be 100% relatable to the consumer Li battery and support systems market, especially when combined with the DIY campervan building community.
a) the design of aircraft engines leaves a big margin for safety. I suspect engines aren't run anywhere near max and the load is fairly well understood.
b) the designers of the "system" are professional engineers working from 100+ years of hard-won experience (2 world wars for example)
c) the "people involved" are highly trained (the manufacturers, the pilots, maintenance crews, ground crew--passengers don't count; they're just cargo)
d) I don't know if this is true exactly, but I suspect there are regulatory bodies that enforce certain safety aspects such as regular maintenance with logs, or at least there's an understanding from everyone involved that maintenance is important

Contrast this with the electrical systems for campervan builders:

a) a lot of this stuff is sometimes made with questionable based on designs inspired by or cloned or stolen from others, often with an eye to cheapening the cost. Safety margins are (I suspect) very low if not outright "negative" in that claimed wattages are not as advertised as and/or cannot be safely run at the claimed specs for extended periods of time. My "3000W" inverter (claimed to be "6000W peak" --Wow!) is likely nowhere close to even the 3000W sustained. I suspect its components are second rate and assembly is so-so.
b) users have a hodgepodge of experience. A few have some relevant experience. Most others have limited experience and are reading blogs or relying on forum comments written by unqualified people--like me (not only am I unqualified, but I also have NO relevant experience, AND I'm writing a comment! :p)
c) some are not only building systems out incorrectly (components of inadequate capacity, insufficient wire thickness, poor quality crimping) but are also not using them correctly (too much current draw at once, running down batteries beyond safe levels for longevity), etc.

So...redundancy may not be such a bad idea. :D [Hmm...I might just go to a junkyard and retrieve a working alternator as a spare! (thanks for the idea, Kip!)]

2) capacity of Promaster starter battery

I think one of the reasons we have such a large battery is that the PM is a commercial vehicle. Unlike a passenger car, it might have to run some emergency lights or other electrical equipment for long periods with the engine off. It might have to reliably start the PM in really cold climates. Possibly after having sat for a while as a crew listens to the radio (think ambulance).

And a bigger battery could provide a longer service life (e.g. a big battery at 50% capacity due to age could still function whereas a smaller one at 50% would not start the PM in cold weather and commercial vehicle operators would not be happy--a whole fleet's worth of sales could be in jeopardy) and thus Ram was wise to have specified this big a battery.

If campervan builders want to save weight, they could always swap in a smaller battery. In my sporty car days, one of them came with a huge OEM battery. Aggressive owners would swap that out for a much smaller one. But they're not trying to start them in Alaska in January.
Actually, I didnt see this discussion as a debate over Li or LA being better or worse. I think everyone would agree that both have their place in modern van builds. Advantages and disadvantages to both. Even the battery experts selling expensive Li system like @HarryN here recommend LA batteries over Li for some van builds.

We're really just trying to increase the collective understanding to fill in the gaps of knowledge to make better decisions. Question at hand: is charging LA batteries via alternator/single stage charging really harmful to the batteries? Id love to know. I suspect that the answer is somewhere in the middle, that 3 stage charging specific to the exact battery chemistry is "better" but "better" can be meaningless if its an insignificant improvement. Of course battery manufacturers will recommend whatever works "best" in a lab and their recommendations will be based on what makes them the most money either by selling chargers or lengthening to life of their batteries. Manufacturers of chargers obviously will say that anything but using their chargers is battery murder. One must think that engineers designing a car and its battery system have looked at the options and put whatever is cost effective and works in the vehicles. They certainly could have designed the PM with multi stage starter battery charging for a very small increase in cost. I wonder if other vehicle manufacturers use multi stage charging.
 

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A Note on Redundancy,,,


#12 Engine Just Quit !!! ,,,,, Which Side ???

75037




When an engine quits on a twin - The running engine is only there to take the plane to the crash scene 😜

70's Statistics,,,

75038





The Insurance industry changed there perspectives on twins once faced with "Real World"Statistics or "Real World" Safety. After all a twin should be safer right. 🤔



I believe in redundancy and think it is a good thing/design. Real World use & the user has to be considered. Sometimes redundancy does not work out - sometimes it does.




Most of us DIYers are not Electronics Engineers. We only know what we have been told & sometimes the things we are told are not correct. There are Pros & Cons to all battery designs and chemistries. We all have our reasons for picking the batteries we picked or designing the systems we design. What is right for us (or so we think) may not be right for someone else.

For me I pick the type of battery I want based upon as simple and inexpensive as possible with delivering stored power for my needs and the ability to get them recharged. When they fail (& they will), I will report it like @MsNomer did. Much like "experimental aviation" we are "experimental van builders" and the more truthful data / information we share with each other the more we help each other.

@CParks

Short answer is "NO" Alternator charging is not too complex for the Novice. Especially if you are willing to use the collective knowledge of the forum members here to help get you educated. You will get different opinions that you will have to parse thru, but you will get information (some of it will even be correct 😜).







 

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Actually, I didnt see this discussion as a debate over Li or LA being better or worse. I think everyone would agree that both have their place in modern van builds. Advantages and disadvantages to both. Even the battery experts selling expensive Li system like @HarryN here recommend LA batteries over Li for some van builds.

We're really just trying to increase the collective understanding to fill in the gaps of knowledge to make better decisions. Question at hand: is charging LA batteries via alternator/single stage charging really harmful to the batteries? Id love to know. I suspect that the answer is somewhere in the middle, that 3 stage charging specific to the exact battery chemistry is "better" but "better" can be meaningless if its an insignificant improvement. Of course battery manufacturers will recommend whatever works "best" in a lab and their recommendations will be based on what makes them the most money either by selling chargers or lengthening to life of their batteries. Manufacturers of chargers obviously will say that anything but using their chargers is battery murder. One must think that engineers designing a car and its battery system have looked at the options and put whatever is cost effective and works in the vehicles. They certainly could have designed the PM with multi stage starter battery charging for a very small increase in cost. I wonder if other vehicle manufacturers use multi stage charging.
I am not an expert, but I have read a little about batteries and had pretty detailed discussions with charger companies.

There are definitely a range of opinions.

As a practical matter:
- If you are going to charge an AGM battery, then even just over the narrow temperature range of 30 - 100 F, doing this "correctly' requires temperature compensation. (which most chargers don't have). Probably this is more important than any other factor for AGM. (I don't use flooded batteries inside of a van)

- If you turn off the temperature compensation, then the charge profile of a typical LiFe is remarkably similar to an AGM at room temperature. Perhaps close enough for most van applications.

- If you have a 400 amp-hr @ 12 volt AGM battery pack, (example Lifeline, Northern, etc) then very few vehicles can muster the power to charge the battery pack at specs suggested by the mfg, so really almost no one in a van or RV is properly charging their batteries "correctly". A largely pure 300 watt panel setup like I use isn't even close, but it does have temperature compensation. When the sun can't keep up (a few months a year) I plug in.

- Starter batteries can take really abusive charging and discharging and the on / off again charging that happens in modern vehicles just makes this worse. Not ideal but it is what it is.

- As far as AGM vs LiFe, I build van systems with both types and plan to continue to do so indefinitely. That isn't where I started.

- AGMs continue to have massive benefits for people who live or travel to areas where it snows or gets very hot.

- LiFe's benefit (in my mind) is the ability to tolerate partial charging better and battery powered air conditioning systems.

- There is an obvious difference in weight, but I am not sure if it really matters or not once the batteries are in place for typical battery packs in a van.

I only build 24 and 48 volt systems and need whatever I design to work with all vehicle brand platforms, so an active battery to battery charger is always used when alternator charging is used.

For this area, most people really don't need BTB charging and solar will meet all of their power needs most of the time. For a weekender type use, I probably would skip battery to battery charging and just use solar. It is so easy, you don't really need to think about it or the need to drive to keep the fridge going. The ultimate lazy person's charging method.

Perfect example - right now I am drinking coffee and BSing on the internet while the sun does the hard work of charging my van's battery pack. That is my idea of success.

If I relied on BTB charging for my use, the house battery pack would be dead most of the time. With solar, it is ready to go 98+ % of the time. The other 2% of the time I just plug into the house overnight.
 

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@HarryN - You say you don't use flooded batteries anymore but for me it appears to be just the thing. My needs are miniscule and can easily be scaled back so was thinking just one flooded 12V 100aH RV/Marine battery charging off the alternator w/just an isolator - used to light 1-2 small LED lights, charge phone, small laptop & run a very small vent fan a few hours a day, mainly in the evening to dispel daytime heating before bedtime. I usually move every day or two and wasn't even going to box it or vent it as my van is usually open when stopped, plus it's only going to be charging while driving so any possible fumes should exit out the rear. Thoughts?

Vent fan - MaxxAir 00-03812B MaxxFan Dome Roof Vent With 12V Fan - Manual Lift - Black
 

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@HarryN - You say you don't use flooded batteries anymore but for me it appears to be just the thing. My needs are miniscule and can easily be scaled back so was thinking just one flooded 12V 100aH RV/Marine battery charging off the alternator w/just an isolator - used to light 1-2 small LED lights, charge phone, small laptop & run a very small vent fan a few hours a day, mainly in the evening to dispel daytime heating before bedtime. I usually move every day or two and wasn't even going to box it or vent it as my van is usually open when stopped, plus it's only going to be charging while driving so any possible fumes should exit out the rear. Thoughts?

Vent fan - MaxxAir 00-03812B MaxxFan Dome Roof Vent With 12V Fan - Manual Lift - Black
All of the battery manuals that I have read indicate that a battery like that should be vented to the outside.

My perception is that it has more to do with potential acid fumes from over charging than the small amount of H2 produced.

I am thinking about adding either the same or similar fan to my mini van every day driver.

As far as my thoughts on it?
  • It makes sense for your current planned needs
  • Many people end up ruining their first house battery anyway, so buying a low end one is just fine.
  • Van electrical needs are a moving target.

Once you get the urge to have a compressor refrigerator, everything starts to revolve around keeping that going.
 

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All of the battery manuals that I have read indicate that a battery like that should be vented to the outside.

My perception is that it has more to do with potential acid fumes from over charging than the small amount of H2 produced.

I am thinking about adding either the same or similar fan to my mini van every day driver.

As far as my thoughts on it?
  • It makes sense for your current planned needs
  • Many people end up ruining their first house battery anyway, so buying a low end one is just fine.
  • Van electrical needs are a moving target.

Once you get the urge to have a compressor refrigerator, everything starts to revolve around keeping that going.
Ok, acid fumes don't sound good, will put it in a plastic box and run a tube outside. Yeah, it'll likely evolve over time but for the next couple years I want to keep it as simple as possible. Thanks for your input.
 

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Ok, acid fumes don't sound good, will put it in a plastic box and run a tube outside. Yeah, it'll likely evolve over time but for the next couple years I want to keep it as simple as possible. Thanks for your input.
Hi @h1k3rb


The vent should be at the top of the battery box and can go outside immediately if you want.

This is how a factory unit does it / hardware / etc;

75088


75089
 

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Thanks @RV8R - I see that's way in the back but mine will likely be under the drivers seat to keep the wires short. Should be able to run it out somewhere near the gas filler pipe but will have to poke around a bit, maybe run a thin rubber tube behind one of those triangles and out one of the drain holes below.
 

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Thanks @RV8R - I see that's way in the back but mine will likely be under the drivers seat to keep the wires short. Should be able to run it out somewhere near the gas filler pipe but will have to poke around a bit, maybe run a thin rubber tube behind one of those triangles and out one of the drain holes below.
Why not just run it thru the chassis battery box considering the house batteries are under the drivers seat? Or am I missing something in this scenario?
 
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