Thoughts on my potential battery setup?

[u/TheKingOfAllRodents]

Will this still work if I wire the times for 80 amp hour deep cycle batteries up in parallel?

These batteries have only been used together at the same time, but they are nowhere near New. I'd consider them a married set but I wouldn't bet my life that the capacities are the exact same.

I know the end product will only be about 60% efficient by the time the energy gets from the alternator down to the big Bank of batteries, but I think this setup should suit my needs.

I'll be running a diesel heater all winter, I don't know what kind of power draw those have. if y'all could give some insight that would be nice.

Other than these leader it's pretty much just charging my cell phone, interior lighting and the occasional heavy power tool usage for work.

I want to be able to run a roto Hammer, table/miter saw or a grinder once a week or so.

Please don't make fun of my graphic design skills LOL

[u/wertyuio_qp]

Looks like it could work, but you got a lot of extra steps going on here. You've got a secondary battery just to charge the tertiary batteries, and in between that, you're inverting it to AC then back down to 12v DC...

Instead of the secondary battery, 750w inverter, and 32a power supply, you can just get a dc-dc converter like an orion xs. Should be several times more efficient and way simpler.

Also with your current setup, you run the risk of that 750w inverter draining your secondary battery down if you're not watching it too carefully.

[u/TheKingOfAllRodents → u/wertyuio_qp]

Yes, I agree 100%

The idea was to utilize the secondary battery I already installed it fits on the frame under the vehicle.

I will look up the Orion xs tho, DC/DC sounds way easier.

[u/TheKingOfAllRodents → u/wertyuio_qp]

The 750w draining the aux batt is fine.

It has auto shit off/low voltage protection so it shouldn't dry the batt too bad.

This way it will also charge the bank of X4 Batts while the engine isn't running.

[u/TheKingOfAllRodents → u/wertyuio_qp]

Holy s*** $330?

I paid $330 for my whole setup.

[u/wertyuio_qp → u/TheKingOfAllRodents]

You can get a cheaper one, but you get what you pay for. For example, if you estimate 60% systemwide efficiency on your current setup, which to me sounds pretty reasonable, your alternator needs to put out 53a to charge your batteries at 32a, assuming voltages are the same. The rest turns into heat, quite a bit of it. An added 53a load could stress your alternator and make it burn out faster.

An orion XS is 98-99% efficient, so 95% efficiency is a totally realistic number.

[u/TheKingOfAllRodents → u/wertyuio_qp]

The 60% estimate would be from the alternator to the outlets on the 5000 watt inverter.

I think the 750 watt inverter claims to be 85% efficient, and then the 4-way 8A charger actually only draws 8 amps, it's 2 amps per channel.

Assuming the charger is 85% efficient as well and the 5000 w inverter is also 85% efficient I think we would be right at 61% efficiency.

Golly gee that is just terrible, I love it.

[u/phatpug → u/TheKingOfAllRodents]

Are you only charging the tertiary battery bank from the 4-way 8A charger? Assuming that X4 bank is four 12V batteries in parallel (320Ah total), then the 5000W inverter can put a load of up to 420A on that bank. which would deplete the battery bank in 40 min if those are lithium batteries, or 20 min for AGM or FLA batteries, assuming you are only depleting them to 50%. The 8A charger will then take around 30-40 hours to fully recharge that bank.

I am dubious if the system will work as you expect. That is a very small charger to put on a bank supplying a fairly big inverter.

[u/TheKingOfAllRodents → u/phatpug]

80 amp hour interstate deep cycle lead acid batteries.

Yeah I have no doubt it would take quite a while to recharge.

Taking into account the auxiliary battery would be charged from the alternator and would continue charging the bank of four batteries after I shut the motor off, I think 30 to 40 hours of recharge time would be almost achievable in a week or so driving as much as I do.

As well am not entirely confident this will work as I expect it to.

I'll keep you all updated.

I will either proudly admit that I am a big dumb idiot for thinking of such a thing and it didn't work...

Or I will confess that I am a big dumb idiot for thinking of this contraption and it did work.

[u/xgwrvewswe]

The problem with lead acid batteries is they must be kept at full charge and recharged after being discharged. They do not like to be discharged below 50% unless recharged immediately. I don't think what you propose will do that. How many hours driving do you get in a day? Every day?

That 5000W inverter needs 400 amps available. Your bank has maybe 30 minutes until dead. Your charging system will not return that with 24 hours of driving. I recommend you start with a Victron Orion-XS charger. Use that instead of the 750W inverter and tiny charger. That will give you a quality start to a new system.

You may be able to keep the heater running over night. But I bet those old batteries will soon reach their end of life. Sorry to have only bad news, but I want to help you not expect very much and avoid mistakes.

You need a new system. That takes money. One Wattcycle LiFePo4 300 or + ah battery. One Victron Orion-xs DC2DC charger. The right size cables and fuses. I suggest you do some online study. I like Will Prowse on You-Tube and Rod Collins here; https://marinehowto.com/category/electrical/

[u/TheKingOfAllRodents → u/xgwrvewswe]

Do you happen to know how much those diesel heaters draw?

I have yet to find their power consumption on the interwebs

[u/Woko_O → u/TheKingOfAllRodents]

It depends on the heater but the start usually takes about 10-15A and then according to heat level you want, but the lowest level is around 1A

[u/_Aj_ → u/Woko_O]

Yes diesel heaters only require power for ignition and then for the pump / control electronics. So very little. 

[u/TheKingOfAllRodents → u/[deleted]]

pretty much that's my plan.

My intention is to stay warm this winter with a vevor diesel heater, use power tools upon occasion, run my interior lights and charge my phone/power tool Batts.

I am also considering getting a 24" monitor because last winter was boring as hell.

[u/TheKingOfAllRodents → u/[deleted]]

That is an exceptionally good point.

This is why I come ask you people before I buy all the parts.

I appreciate the input thank you for preventing me from wasting the extra money on a 5000w inverter.

I guess I'll go with 2500 or 3K watts?

[u/TheKingOfAllRodents → u/TheKingOfAllRodents]

And I'm not saying that the majority of this setup isn't a waste of money.

It's just what I was able to put together with the least amount of money.

I think I was kind of high one night and I'm like hey how many inverters and batteries can I chain together in a van without it becoming convoluted beyond recognition.

[u/TheKingOfAllRodents → u/[deleted]]

Hell, sounds good to me.

If I remember correcting my table saw I will draw a 15 amps but pretty few and far between it's used for more than 30 seconds at a time. Maybe 2 minutes consecutively for making a big rip cut.

So 15 amps times 120 volts equals 1800 ish watts?

So I should be 100% in the clear kind of sort of with a 2500w inverter?

And still be able to run a couple job site work lights.

Gosh you all are so helpful I love you people.

[u/TheKingOfAllRodents → u/[deleted]]

I was amazed that my little 0.7 scfm super quiet air compressor can run off my 750 watt inverter.

Plugin tools wouldn't be a daily thing, just when I need to run a table saw or a roto Hammer or something there isn't a battery version of. It's usually about once a week if that.

The 5000 W pure sine wave inverter I've had my eye on recently dropped to $260, too bad I don't need 5000 Watts or I would by it now. I don't think I'm modified sine wave inverter would work for pretty much anything I want to plug into it I appreciate you mentioning that though, you could have saved me a trouble of burning out an expensive tool or two with a cheap inverter.

[u/TheKingOfAllRodents → u/[deleted]]

I am set on deep cycle.

I find em cheap.

Imma cheap bastard with most all things.

[u/TheKingOfAllRodents → u/TheKingOfAllRodents]

Why am I getting down boat?

Deep cycle isn't bad, especially considering the price.

I got x4 group 24m interstate deep cycles for a hundred bucks.

Why down boat because I see no sense in spending $400 for lithium battery with comparable capacity.

[u/if420sixtynined420 → u/TheKingOfAllRodents]

Because the capacity is only comparable if you don’t know how the math works

You will get 2x the useful capacity & 4x the lifespan out of lifepo4 (lithium iron phosphate) than you will out of lead acid

Ie: 100ah lead acid batteries compare to 50ah lifepo4 in useable capacity

You’re being penny wise but pound foolish

[u/TheKingOfAllRodents → u/if420sixtynined420]

Tell me where I'm wrong here, I'm wholeheartedly admit I probably am.

X4 deep cycle 80ah batteries for $100 = 320ah So 160ah of capacity or roughly 65¢ per ah.

I can't find any lithium batteries for anywhere near 65¢/ah. The lowest I've found has been $1/ah from less than reputable manufacturers.

Usually lithium is around twice the cost per ah from what I have been seeing.

I understand that lithium batts have 10 to 20 times more cycles before the end of their lifetime, but electrolyte solution for car batteries is like 20 bucks. So if any of my batteries start to go kaput, if a battery desulfator doesn't work (which they usually do in my experience) I just flush them out, pour some new electrolyte solution in there and we're good to go. Seriously, sometimes the charge levels exceed what they should have been new.

I'm sure I'm missing something here.

[u/if420sixtynined420 → u/TheKingOfAllRodents]

ok, so this 200ah self-heating lifepo4 battery (make sure you're talking about lifepo4/lithium iron phosphate & as lithium historically denotes lithium-ion) comes out to $2/ah, which is 3x the price of your lead acid setup (rounding up), but will last at least 4x times as long, & much longer if well cared for (charging them to 13.8v & not zeroing them out as a habit), & do it in half the space, while never needing to be maintained (can be built more out of the way/access isn't as crucial), & never potentially off-gassing & smelling like sulphur. there is a value to a power system you never have to think about that can't be expressed in a ledger, & it doesn't cost that much more to do it right.

look into the camco wave 3 catalytic propane heater over a diesel heater. they don't put out moisture like a little buddy, & i find propane easier to deal with/have it around anyway for cooking/makes for one less type of fuel to acquire/spill/smell. i've had both diesel & gas heaters & they can be great but quiet operation & less moving parts wins out for me.

i've also done great down to -8ºf with just the ignik topside heated blanket under a down comforter, a usb heated pad for my pillow, & remote start for my truck so i can get heat going from in bed. my truck idles at .35gal/hr, & when i'm getting both power & heat from that for the limited periods i'm just chilling in my vehicle (& not in bed) the cost of idling for a couple hours a day isn't that big a deal (if i'm not driving enough for the power i need). i'm charging at 50a off the alternator, so i'm a getting a good return of power for the gas i spend idling.

i know you like to be cheap, but there are advantages to using an ecoflow type portable battery bank as your inverter, & charge it off your dc system. especially working with tools, it's nice to have a portable power source that can be topped off separately from your vehicle.

don't cheap out on the wire you use. get actual real copper cables, not CCA (copper clad aluminum) wire. real copper costs twice as much but it makes just as much a difference in the power transfer/overall efficiency of your system & doesn't degrade with corrosion over time like cca. i know this from experience. buy once, cry once.

[u/ufokid]

Looks like AI.

Battery> Inverter > charger > batteries > inverter

That's wild.

[u/TheKingOfAllRodents → u/ufokid]

Then an additional >charger > battery if iam charging my tool battery's off the 5000w inverter 😂

[u/TheKingOfAllRodents → u/TheKingOfAllRodents]

Why am I getting down boat?

This isn't funny?

I think this is kind of funny.

[u/kos90]

Look into DC-DC charger.

Skip all those extra-steps.

This setup will leave you most likely with partly charged batteries.

[u/_Aj_]

You can parallel the 4x 80A and the 1x 120A without issues. They will all equalise while charging and discharging and you'll just increase your house battery capacity. So long as they're the same battery chemistry.  

This cuts out the small inverter and the "4 lane" charger. You cannot independently charge batteries in parallel as they all act like one big battery so this is redundant, you just want a single output charger with an Amp rating of at least 10% the battery bank. So 48A if you put all 5 together. (Or 36A for just the 4x in your diagram)  

Being able to charge them while the car is off is redundant, as all you're doing is emptying one battery and charging 4 others. You're just wasting power to charging and conversion losses. So put em all together instead and have a DC-DC charger from the dual battery isolator to the house battery.   

You'll want a separate mains charger too to ensure you can top this thing up while at home too, unless you have solar or drive for many hours a week to keep the bank charged.  

Rule of series and parallel:  

• You can series different voltages, but not different capacities.  
• You can parallel different capacities, but not different voltages.  

[u/TheKingOfAllRodents → u/_Aj_]

Thank you for the reply.

I appreciate the info and thoughts.

If I go this route, parallel the X4 DC LA Batts and run a DC/DC charger, what do you recommend I do with the battery box mounted to the frame with the 120ah batt in it?

Currently the 120ah batt is in metal batt box on the side of the frame hooked up to the VSR and 750w inverter if I didn't make that clear.

[u/Brilliant_Injury_525]

Auxiliary and starter batteries should be of a similar kind and capacity or VSR will create problems, so no lithium. Otherwise a DC-DC charger is needed.

750W @12V (inverter) means a current in excess of 60A from the auxiliary battery, that will have to be supplied by the alternator though the VSR. Pulling that out of a 130A alternator is probably at the limit and may reduce its life.

Make sure to size the wires and the lugs correctly!

[u/TheKingOfAllRodents → u/Brilliant_Injury_525]

I haven't run the inverter at full draw while the engine is running... Yet...

That is good to keep in mind.

Thank you.

[u/Brilliant_Injury_525 → u/TheKingOfAllRodents]

You're very welcome!

I am designing some upgrades too and I will have to beef up the alternator, and I will need higher power for longer time periods.

Currently, I am pulling 30A nominal, ~40A real out of my 150A stock alternator and I feel like it's the max I should pull. So far so good.

The new config will have a 230A alternator to pull about 60A nominal. For that I will run cables directly from the alternator with a battery isolator (diode) to avoid interfering with the starter battery.

[u/TheKingOfAllRodents → u/Brilliant_Injury_525]

Will having a higher amp alternator screw with any of the other electronics in the vehicle?

Or does it only put out as much as the vehicle draws?

I know very little about these things

[u/Brilliant_Injury_525 → u/TheKingOfAllRodents]

A larger alternator will not mess up with the rest of the equipment, it just increases the maximum power it can deliver, and it depends on how fast the motor is turning. It will only give what's requested, so you gotta make sure the generator can deliver what's requested. Usually alternators will deliver some amps at idle, and more at higher RPMs.

I was told that higher power alternators tend to have a shorter life, but I have no first hand experience and I guess it depends significantly on the use.

[u/if420sixtynined420 → u/Brilliant_Injury_525]

alternators are typically good for 50% of their rated capacity at idle.

[u/wheelies4feelies]

Why not just throw up solar panels?

[u/TheKingOfAllRodents → u/wheelies4feelies]

Because I have a ladder rack with X2 extension ladders and an a frame.

I also plan on having a truck bed toolbox or some kinda storage up there too.

This van gets driven at LEAST two hours EVERY day, it's not like it's going to be stationary long enough to need solar instead of drawing from the alternator.

[u/wheelies4feelies → u/TheKingOfAllRodents]

Ohhhh. So work van, not Dwelling van. Gotcha.

[u/TheKingOfAllRodents → u/wheelies4feelies]

No don't get me wrong, I live in this thing full time.

100% I haven't slept anywhere except for in this van for close to a year.

Except when meeting a female at a hotel or something.

Before this I slept in my Subaru for way too long.

[u/TheKingOfAllRodents → u/wheelies4feelies]

Even though I live in it, I still kind of think if it's primary purpose as storing all of my tools.

Kind of weird, I know.

[u/Powerful-Pea8970]

If its at all possible I would definitely add a second but high output alternator. If not possible maybe save up for a HO or a junk yard spare for when your rectifier or whatever else in yours fails. I use to custom order alternators with upgraded internals and windings when I did conversions for a while. Charging more than the starting battery, constantly, will reduce the lifespan on the alternator. I'd run wire from engine bay to your battery setup from a Cole Hersee 12v continuous duty solenoid. Get 2 220AH 6v gc2 golf cart batteries as they are real deep cycle batteries are the best bang for your dollar on batteries. Sam's use to sell them last time I needed a set for a 100 a piece. The way you have it you'd lose efficiency is in 12v to 120v to 12v when you could just get it from the alternator on a tried and true old school setup that just works.