24v Lifepo4 & solar set up

[Madoxen]

Might this be an easier way? A lot depends on the availability of 24v vs. 12v appliances, etc.

Yes a 24/24 dcdc charger is what i would link up to the Alt i think the issue is that the parallel charger size to do such a big bank would use more than the alt can put out and would quickly kill the alternator. Hence the thoughts of 2nd dedicated Alt or enen an alt that runs off of the live pto / or selectable pto for that matter, turning the pto into a generator with on off ability. The live pto can be used while driving but cant turn off the other only when stationarry and not in gear.

 

[Madoxen]

I very strongly believe it is stupid to let a BMS dictate your use case.

Buy the BMS that accommodates what you want to do.

Do u have any suggestions for a bms that would cope with a bank and charge set up like this ? Dealing with the rate from solar charge and also the faster large alternator charge if i can make it happen?

It will most likely fall into the too expencive basket butif i can make it happen it would be nice to do it properly

 

[DiploStrat]

Just how big a bank are you planning? Mine is 600Ah @ 12v and I do the stove/microwave/espresso/induction/diesel heat/etc. all day long, on AGM.

Since I can't make my own LiFePO4 battery bank, I am looking at charge of around 100A @ 12v from a combination of 80A from the alternator (40A @ 24v) and 30A+ solar when the sun is good.

That comes out to a typical overnight draw restored in two hours drive or less. I looked at second alternators, etc., but the answers all came back "too hard/expensive" for what you get.

Of course, YMMV and NZ can be cloudy.

As noted, a single BMS and proper cell balancing should give you better performance than I will get with two drop-ins in parallel.

 

[Madoxen]

Just how big a bank are you planning? Mine is 600Ah @ 12v and I do the stove/microwave/espresso/induction/diesel heat/etc. all day long, on AGM.

1 - 32 x 3.2V @ 280 Ah lifepo4 cells ( I am not sure I will need to use all 32 cells I could or might use just the 16 to make a 24v system), what are your thoughts. The surplus cells will be used on equipment at work so not wasted either way.

I have 2 options with the Lifpo4 bats that i have 560 AH or 1120AH @ 24V

 

[DiploStrat]

While it is none of my business, I gotta ask. What are you planning to drive with over 500Ah of lithium. I'm struggling with air conditioning and I'm not getting those numbers.

 

[Madoxen]

While it is none of my business, I gotta ask. What are you planning to drive with over 500Ah of lithium. I'm struggling with air conditioning and I'm not getting those numbers.

It is not so much a case of driving a lot of gear, but more a case of NZ weather and the amount of time we stay put in one spot playing/hunting roaming the mountains that we wanted to know even with a week of bad weather we will have power for the important stuff with out needing to drive. we will also be running a large chest style freezer.

we do not stop in camp grounds etc where shore power or hookups are available we are almost always in very out of the way places.

lol I did kind of make it your business when I posted it up on a public forum ;-)

 

[Peter_n_Margaret]

One controller per panel will provide best redundancy and best shade tolerance.
Cheers,
Peter
OKA106 motorhome

 

[DiploStrat]

Random Thotz:

-- In the US, 24v appliances are rare, hence a 12v camper battery and 12v refrigerator, etc. If on the other hand, you are running a 240v appliance(s) through an inverter, then a 24v battery bank might be fine, using a Victron or similar converter to produce enough 12v for whatever you have left over. See: https://www.victronenergy.com/uploa...nd-12-24-DC-DC-converters-non-Isolated-EN.pdf

-- For a lithium bank, I would think that a B2B is almost essential with a lead acid starter bank. REDARC and Sterling make 30-50A models with various features. I believe both can be paralleled to get you up to 80-100A.

-- Victron have an MPPT calculator with which you can play to your heart's content: https://www.victronenergy.com/mppt-calculator Slide out panels may be an option/requirement in your case. Jason, of Everlanders, has the most sophisticated set up I have seen: https://www.youtube.com/channel/UC76GYXW3j9z5g3OdW--Sf5g Scholars love to debate series/parallel, etc., but for as big an set up as you are contemplating, series is usually indicated in weak sun and a series/parallel set up might give you better shade protection - the best of both worlds. (Unless you plan to travel in Oz, in which case, they can't even spell "shade!"

-- I have to stop agreeing with John, but everything I have read/seen, including three vehicles with which I am familiar, agrees with his comment that you can achieve better results if you can assemble your own lithium bank. This assumes, of course, that you do a good job and produce a system that is physically and electrically sound.

Final thought, my longest rainy siege was a tropical storm at Overland EXPO in Carolina. After three days we idled the engine while cooking, not because we had to, but simply to spare the AGM bank. Note this simply adds current for the immediate load, with lead acid, at least, it does not provide any meaningful charge.

Final, final thought. Assuming a monster battery bank, providing 100Ah a day for a rainy week, your recharge is going to be something fierce. It is not impossible that that might offer a demand greater than 500A, so do make sure that all of your charge sources are healthy and protected.

Offered in the belief that all is correct and that there are no id skids, typos, or simple tech errors.

 

[dreadlocks]

Any High Output inverter that has good efficiency uses 24v, my Engel is 12v/24v, all my Victron Gear is 12/24.. its not that big of a problem going 24v outright from the get go, I could switch and have little issue, the remaining 12v circuits for lights and stuff could be easily fed w/a small and efficient step down converter, any losses of converting to 12v wont be larger than the gains in cabling and efficiency of 24v.

*edit* forgot to mention he can hookup much more solar power to the same chargers at 24v

 

[Wyuna]

I’d be looking at 24 volts, almost all options are available in 24 volts in NZ and Aus

Diesel heaters, fans, fridges, air compressors, Victron gear, Hafele do 24 volt versions of their loox lighting range (cabinetmaking suppliers)

I’d be using all the cells, I know what the weather is like back home, I wouldn’t rely on 560ah as while solar is helpful, i Find the best spots also come with shading issues from trees

 

[DiploStrat]

If you can get most of your appliances in 24v, then with a 24v truck, that is a no brainer. Especially as once you get down to 10-15a, 24>12v converters are cheap.

 

[Madoxen]

Helli all sorry for not replying sooner have been on the road collecting a new cutain sider for work.

One controller per panel will provide best redundancy and best shade tolerance.
Cheers,
Peter
OKA106 motorhome

Sounds good but alot of cable to go through the roof

Offered in the belief that all is correct and that there are no id skids, typos, or simple tech errors.

Thanks will have a play with links . Here we can get weeks on end of sun but we can also get a week or so of clowd and rain so extra battery is always good.

I’d be using all the cells, I know what the weather is like back home, I wouldn’t rely on 560ah as while solar is helpful, i Find the best spots also come with shading issues from trees

This was my original thinking but i am worried about never getting it charged to full again and also space. I guess it is unusual not to need to woory about buying them lol as i already did that.

If you can get most of your appliances in 24v, then with a 24v truck, that is a no brainer. Especially as once you get down to 10-15a, 24>12v converters are cheap.

Agreed and i already have a heap of 24 to 12 convertrs from the big red donor truck think they are an 18 amp and 30 amp from cab. Good merc gear

 

[Madoxen]

Slide out panels may be an option/requirement in your case. Jason, of Everlanders, has the most sophisticated set up I have seen:

Yes i had alrwady watched this and have been thinking on it. But i do think i will get the truck on the road then start the pretty ugly 2.0

 

[DiploStrat]

Best wishes! After much agonizing and some serious hand holding by one of our brighter members here, I am in the process of ordering the same cells for a 12v battery bank.

 

[Madoxen]

If you say you came to them from " the Forum" they will give you free double bussbars and screws for each battery free