Questions about VAN solar build 800Watts, 8 LIFEPO4 280Amps 12V - reliability and modular configurations

SteveCA

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Feb 22, 2020
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49
@SteveCA - I agree with you 100%. The only drawback for me for 24V build - is the lack of efficient charging 24v from my vehicle alternator. I live and mostly travel in the geographical region where sun may not be there for weeks during the fall to spring for sufficient solar recharge. Boondocking mostly in remote areas without being able to recharge from a grid, leaves me not much choice. Anyway, I already obtain all the 12v equipment for my build, its already here. Thanks for the input anyway.
I run dual Victron Orion 12/24 smart chargers in my van. Even in a 12 volt system, you need dc to dc chargers so it is not an added cost. My dual Orions output 850 watts of charging even at idle.
 

SteveCA

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Feb 22, 2020
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49
These days, I try to keep my systems draw under full load to under 150 amps. Even that is high for me. Strange challenges crop up when you start pulling higher amperages in my experience. I know it can be done, and I've done it, but not preferable in my book
 

geolboy

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Feb 24, 2021
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I was concern about the load on the alternator with 12v to 24v converter. Maybe I am wrong but read somewhere that efficiency converting goes down and alternator risk of wearing out quickly increases. Again, I am a newbie so maybe read that info incorrectly. As it sits now, I doubt I could swap my multiplus 3000/12v to 24v. And also dc-to-dc 12v charger. and the REC BMS. Anyway, just too late in the game to make a big cost swap. :( Have to work with what I have.
 

synergicity

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Nov 29, 2020
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I was concern about the load on the alternator with 12v to 24v converter. Maybe I am wrong but read somewhere that efficiency converting goes down and alternator risk of wearing out quickly increases. Again, I am a newbie so maybe read that info incorrectly. As it sits now, I doubt I could swap my multiplus 3000/12v to 24v. And also dc-to-dc 12v charger. and the REC BMS. Anyway, just too late in the game to make a big cost swap. :( Have to work with what I have.
I am a little confused by how worried you are over the alternator. Is this a vehicle with a marginal alternator or does your vehicle have a huge amount of DC load while you are driving? Surely the alternator can spare 30-50 amps while at highway speeds? If you have a DC/DC convertor (which you will need for sure due to the two different battery chemistries) it will not charge the house battery until the starter battery is above a certain voltage. If you have reason to worry that I am missing, then continue onward, but I think it would be reasonable to have the alternator do a fair share of the work.
 

geolboy

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Feb 24, 2021
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There are a number of youtube videos I watched warning about premature alternator wear out when task with charging house batteries. It can happen two ways, one when the alternator is forced to provide higher amperage over longer periods of time, and typically dc-dc chargers and isolators do that (as I understand). And two, due to a heat generation at lower alternator rpms, when alternator fan has to work at a lesser speed while charging Lithium batts. Victron actually has a video that shows how the alternator will overheat and burn out when the speed of the alternator dropped to 1500rpm from 3000rpm, as oppose to higher rpm when the fan was also working at higher speeds. Frankly, driving slower on various mountain service roads for days - I just don't know how this type of driving affects the alternator, and since I have only one, I wanted to build an alternator charging system that I would use only when no other option would be available and absolutely necessary. Without house batteries, I still can get by. With a burnout alternator in the mountains, I would be really screwed.
 

synergicity

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Nov 29, 2020
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That certainly sounds reasonable. I appreciate the explanation of where you are coming from.

There are a lot of people doing alternator charging daily in a variety of vehicles of a variety of ages every day all over. I have a 92 subaru engine in an 87 Vanagon. I upgraded the alternator to 120 amps and have merrily charged my LiFePO4 batteries at 30 amps for years. My point was that of so many single points of failure to worry about on remote roads, this one seems maybe a little unreasonable. For example, do you have a spare water pump when you are out there, and know how to replace the failed one (and carry the tools to do that)? What about a selection of hoses for your cooling system? I am not trying to be an asshole, but maybe trying to put things in perspective. Also, a spare alternator is small and not that expensive and easy to replace. You can also install two if you want. Many boats (where things can't fail) have two. Or install one that is more bombproof. Alternator charging is a really nice thing to be able to do and it is what many/most people depend on in addition to solar.
 

geolboy

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Feb 24, 2021
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11
That is all true. Me, being a newbie in the whole VAN build the thing and not possessing good auto mechanical skills, I just err on side of caution, to minimize a chance of getting stuck in remote places. The cost adding of a second alternator to my Transit 2020 in a way that does not violates my van warranty is huge, to me, even it would be a preferred option. In any case, I do have a dc-dc charger that I'll be using when needed. As is the rest of my equipment that is currently all set at 12v build. With time and experience, I'll be making changes as needed and budget permits :).
 
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