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12v or 24v battery

You should get yourself a kill-a-watt and plug your devices in to get your real world wattage. Higher volt systems are cheaper overall and less headache. 24V if possible and if you're going dc-dc charger then just get 12v to 24v one.

I'm assuming you're talking about lithium batteries and not lead acid, right? If lead acid you could likely just add a switch/relay and connect them directly into the alternator. Another idea is to add an alternator to your engine then get a wakespeed ws500 type regulator so you can set it to charge the batteries if you have lithium.

If going 12V you might be able to just get a ws500 and connect it to your existing alternator and it has an option for a switch so you could possibly setup a switch where it'll change between charging your van and your inverter batteries. I'm imagining you being able to turn on inverter charge mode then the ws500 switches every 15 minutes between charging the house batteries on a lithium profile then back to the starter battery on a lead acid profile connecting each battery using relays.
 
HarryN said:
I can't think of any downside to a 24 volt system over a 12 volt system.
Click to expand...

I can think of a few right off:

- need to step down to 12V for 12V loads
- potentially more difficult to find 24V replacements quickly

Most van-lifers get by just fine with 12V and some have some pretty high wattage uses.
 
Grimmster said:
I can think of a few right off:

- need to step down to 12V for 12V loads
- potentially more difficult to find 24V replacements quickly

Most van-lifers get by just fine with 12V and some have some pretty high wattage uses.
Click to expand...

The decision to build a 24 volt system means that you also make the decision to mostly use 24 volt loads.

Instead of a 12 volt fridge, you buy a 24 volt version or a dual 12 / 24 like a truck fridge.

Same for water pumps, fuel heaters, USB ports, inverter, LED strip lights, etc.

24 volt appliances are not quite as wide spread as 12 volt but still very common due to it's wide use in marine applications.

You are right that if you still plan to mostly buy 12 volt devices, then it does not make sense to build a 24 volt system.

Somewhat less obvious is that some versions of those 12 volt roof top exhaust fans really struggle with the unregulated voltage range of a 12 volt battery system, so people are having to put in DC - DC regulators anyway for those. Yes there are a few stray 12 volt loads that need a DC - DC converter but usually less than 2- 300 watts.

If there is a load over a 500 watts, it probably should be run through the inverter anyway. At least that is how I build them for customers.

_________

I do realize that this movement toward 24 volt is a break for people, but it is pretty common and safe for DIYers. Pros are increasingly building conversion vans with 48 volt systems.

There can be some very funny conversations with people.

Customer
- "24 volts is too high for a van".

Supplier question / customer response
- "what voltage are you using in your golf cart " - "48 volt and thinking about jacking it up to 72 volts to out pace my buddy "
- "what voltage are you using in your boat" - "24 volt - but I am looking at this new 48 volt trolling motor"
- What voltage is in your electric bike " - " 48 volt"
- What voltage is in your grand mother's wheel chair" - "36 volts but we are thinking about the 48 volt versions"

- You do realize that 24 volt van / marine parts are identical to 12 volt parts - right ? - "oh no - 24 volts is too high for an RV".

:)
 
If you haven't purchased batteries yet, definitely go with 24v. I unknowingly started down the path of 12v, because I was in a bit of a hurry, and never thought I'd expand. Two years later, I'm kicking myself for at least not selling the 12v batteries and jumping to 24v as I expanded out to 6 100ah 12v batteries.
 
justinm001 said:
You should get yourself a kill-a-watt and plug your devices in to get your real world wattage. Higher volt systems are cheaper overall and less headache. 24V if possible and if you're going dc-dc charger then just get 12v to 24v one.

I'm assuming you're talking about lithium batteries and not lead acid, right? If lead acid you could likely just add a switch/relay and connect them directly into the alternator. Another idea is to add an alternator to your engine then get a wakespeed ws500 type regulator so you can set it to charge the batteries if you have lithium.

If going 12V you might be able to just get a ws500 and connect it to your existing alternator and it has an option for a switch so you could possibly setup a switch where it'll change between charging your van and your inverter batteries. I'm imagining you being able to turn on inverter charge mode then the ws500 switches every 15 minutes between charging the house batteries on a lithium profile then back to the starter battery on a lead acid profile connecting each battery using relays.
Click to expand...

I will be honest - that sounds like a recipe for disaster.

An alternator is a large inductive type generator. If there is even the slightest moment in time when it is not connected to a battery, the output voltage will skyrocket. If you happen to be pushing on the gas pedal to accelerate up a ramp - the rpm will be high and that alternator will be just flying for output.

That same company is better known for selling alternator controllers and I have experience with them. I can tell you that even under ideal conditions, alternators are not so easy to keep under control when the engine rpms are changing and there are multiple stories about Li BMS trips blowing out alternators, inverters and everything attached to them.

I am not saying that their stuff does not work, but I will say that the power system needs to be able to handle > 100% of the full rating of the alternator because it will experience it under normal driving conditions no matter what settings are put in the controller.

If there were to ever be a failure of the controller or relays - you are going to blow out every item attached to that alternator and controller.
 
HarryN said:
I will be honest - that sounds like a recipe for disaster.

An alternator is a large inductive type generator. If there is even the slightest moment in time when it is not connected to a battery, the output voltage will skyrocket. If you happen to be pushing on the gas pedal to accelerate up a ramp - the rpm will be high and that alternator will be just flying for output.

That same company is better known for selling alternator controllers and I have experience with them. I can tell you that even under ideal conditions, alternators are not so easy to keep under control when the engine rpms are changing and there are multiple stories about Li BMS trips blowing out alternators, inverters and everything attached to them.

I am not saying that their stuff does not work, but I will say that the power system needs to be able to handle > 100% of the full rating of the alternator because it will experience it under normal driving conditions no matter what settings are put in the controller.

If there were to ever be a failure of the controller or relays - you are going to blow out every item attached to that alternator and controller.
Click to expand...
I believe this type of system is very popular in boating community where you might have 2 engines and multiple electrical systems. I've seen it setup for RVs too. Actually battleborn has a bim that basically connects/disconnects lithium to start every x minutes.

I'm not saying the switch controls the relays. The ws500 has an input and I believe output relay so you would have the switch tell WS500 to turn off the alternator, flip the relay then ramp it back up.

No it won't use 100% of the rating of the alternator. You set the output amperage with multiple charging profiles. For example I have my 300amp alt setup to delay 3 minutes then charge based on battery SoC it gets from Victron. Then ramp down based on alt temp so when it's 200degs it'll slowly ramp down all the way to 0 output if needed. Most times my alternator is off or on a trickle float charge since I have solar and usually use when topped off
 
HarryN said:
I will be honest - that sounds like a recipe for disaster.

An alternator is a large inductive type generator. If there is even the slightest moment in time when it is not connected to a battery, the output voltage will skyrocket. If you happen to be pushing on the gas pedal to accelerate up a ramp - the rpm will be high and that alternator will be just flying for output.

That same company is better known for selling alternator controllers and I have experience with them. I can tell you that even under ideal conditions, alternators are not so easy to keep under control when the engine rpms are changing and there are multiple stories about Li BMS trips blowing out alternators, inverters and everything attached to them.

I am not saying that their stuff does not work, but I will say that the power system needs to be able to handle > 100% of the full rating of the alternator because it will experience it under normal driving conditions no matter what settings are put in the controller.

If there were to ever be a failure of the controller or relays - you are going to blow out every item attached to that alternator and controller.
Click to expand...
Also the ws500 seems very sensitive to voltage spikes. I have an issue where a system where it'll turn off causing voltage to spike .5V above its charging rate and it faults then alerts my Victron and I need to restart my coach to turn alternator back on. There's also another device that you can get to protect against voltage spikes
 
You have to be really careful with the assumptions of what will really happen.

I have a post in the "up in smoke" section with more info.

In a marine application, the engine rpms don't change all that quickly or very often. In a van, they do.

I am not talking about 0.5 volt spikes - think of 100 - 200 x that number.
 
I appreciate everyone's advice! Considering my needs, I think a 24v system is the best bet for me.

I haven't yet purchase anything but here's my plan. For a battery I like the https://signaturesolar.com/eg4-ll-lithium-battery-v2-24v-200ah-server-rack-battery/. Many reviews I've watched/read suggest it has the best build quality, features and price point at the moment. With it, I was thinking about using the https://signaturesolar.com/growatt-24v-3kw-150vdc-stackable-off-grid-inverter/. The Growatt looks great, 3000watt inverter with a 80ah mppt charge controller and the ability to charge by a generator or grid. In addition to those two, I'm hoping to use the https://www.sterling-power-usa.com/SterlingPower12volt-to-24volt-70ampbatterytobatterycharger.aspx.

This week I was able to install a roof rack on my van so I'd like to put two 100 watt solar panels on it permanently. Thanks for showing an example HarryN. In addition to the solar on the roof, I was hoping to tie in some folding panels for times when I'm parked and able to put panels on the ground. I like the https://www.amazon.com/ALLPOWERS-Po...dable-Generator/dp/B0BGXJWYPG?ref_=ast_sto_dp and I also currently own an older model of this panel: https://www.amazon.com/Renogy-Monocrystalline-Kickstand-Extension-connectors/dp/B09134RLZR/ref=sr_1_6crid=3CH4879GXZJJ9&keywords=renogy+folding+solar+panel&qid=1685742514&sprefix=renongy+folding+solar+pane,aps,230&sr=8-6 Although, I'm not sure yet if those two folding panels will work with the EG4 server rack battery. If anyone can think of a reason why it won't work, let me know.

What do you think of my plan so far (I haven't yet worked out the wires / fuses etc. yet, just trying to determine the big components first). Would using a server rack battery in a van build will be a bad idea? I generally see everyone using sealed lithium batteries like Weize, Redodo or Battle Born. Coud a bumpy ride or potentially unstable temps be worse for a server rack battery than for a sealed lithium battery? Thanks for the help!
 
Check the idle consumption of that Growatt compared to a inverter/charger like the Victron Multiplus. Some all-in-one units have rather high idle consumption.

The AllPowers panels aren't going to work. The voltage is only 20 volts. You need at to have a voltage of +5 volts higher than the system voltage for charging to start.

Where are you going to put all this? A server rack battery is rather large. I would rather use a smaller battery that can fit in the footwell.
 
EG4 batteries have great build quality and no issues with them in a van setup. They're metal and very solid so are ideal and easy to mount as if you have a slot under a bed or cabinet you can just cut out and place in there. So much easier since everythings on the front panel. Also since they're metal you can simply put a tank heater pad underneath for when cold to heat them and it'll keep the cells warm.

I cant imagine going anything but Victron. Their system is amazing and you can slowly add components.
 
HRTKD said:
Check the idle consumption of that Growatt compared to a inverter/charger like the Victron Multiplus. Some all-in-one units have rather high idle consumption.

The AllPowers panels aren't going to work. The voltage is only 20 volts. You need at to have a voltage of +5 volts higher than the system voltage for charging to start.

Where are you going to put all this? A server rack battery is rather large. I would rather use a smaller battery that can fit in the footwell.
Click to expand...
I read somewhere that the Growatt uses about 1.5amps at idle, so around 35watts (does that sound about right). I saw that a comparable Victron unit uses 100watts so seems the Growatt is pretty low for all it does. I may be off though, so if anyone knows otherwise let me know.

I saw on the Allpowers link that it has a maximum power outage of 37.4v so I assumed it would work. Did I read it wrong or am I missing something?

Yes, this will take up a lot of space but I'm hoping to make it fit. Even the regular sealed lithium batteries are big. I gutted the van so far and figuring the power will take up about 1/4 of the space, lol. As I mentioned before, I don't plan on being in a minivan for too long I should be moving the system to a piece of land or a larger vehicle at some point.
 
justinm001 said:
EG4 batteries have great build quality and no issues with them in a van setup. They're metal and very solid so are ideal and easy to mount as if you have a slot under a bed or cabinet you can just cut out and place in there. So much easier since everythings on the front panel. Also since they're metal you can simply put a tank heater pad underneath for when cold to heat them and it'll keep the cells warm.

I cant imagine going anything but Victron. Their system is amazing and you can slowly add components.
Click to expand...
Thanks for the info! I was checking out the https://signaturesolar.com/phoenix-inverter-24-1200-120v-ve-direct-nema-gfci/ as well but the Growatt seemed to have more features. What Victron model would you suggest? The Victron brand seems to be one of the most popular for charge controllers / inverters. To be honest I'm not a huge fan of having to rely on bluetooth though, that's why I'm considering other brands over them. Although, I haven't heard much about Growatt. Does anyone know if they are considered to be a reliable brand? Any other brands/models to check out?
 
CampLife said:
To be honest I'm not a huge fan of having to rely on bluetooth though, that's why I'm considering other brands over them.
Click to expand...
Buy a CerboGX, the inverter plugs into it and everything works over wifi/internet through the VRM app or website anywhere as long as you have wifi for the Cerbo. The inverter doesn't have bluetooth (other ones do though). Whatever Multiplus size fits your needs would work. I use the Quattro's because they have 2 inputs so it'll autotransfer for me and start genny along with a couple other things.
 
CampLife said:
I appreciate everyone's advice! Considering my needs, I think a 24v system is the best bet for me.

I haven't yet purchase anything but here's my plan. For a battery I like the https://signaturesolar.com/eg4-ll-lithium-battery-v2-24v-200ah-server-rack-battery/. Many reviews I've watched/read suggest it has the best build quality, features and price point at the moment. With it, I was thinking about using the https://signaturesolar.com/growatt-24v-3kw-150vdc-stackable-off-grid-inverter/. The Growatt looks great, 3000watt inverter with a 80ah mppt charge controller and the ability to charge by a generator or grid. In addition to those two, I'm hoping to use the https://www.sterling-power-usa.com/SterlingPower12volt-to-24volt-70ampbatterytobatterycharger.aspx.

This week I was able to install a roof rack on my van so I'd like to put two 100 watt solar panels on it permanently. Thanks for showing an example HarryN. In addition to the solar on the roof, I was hoping to tie in some folding panels for times when I'm parked and able to put panels on the ground. I like the https://www.amazon.com/ALLPOWERS-Po...dable-Generator/dp/B0BGXJWYPG?ref_=ast_sto_dp and I also currently own an older model of this panel: https://www.amazon.com/Renogy-Monocrystalline-Kickstand-Extension-connectors/dp/B09134RLZR/ref=sr_1_6crid=3CH4879GXZJJ9&keywords=renogy+folding+solar+panel&qid=1685742514&sprefix=renongy+folding+solar+pane,aps,230&sr=8-6 Although, I'm not sure yet if those two folding panels will work with the EG4 server rack battery. If anyone can think of a reason why it won't work, let me know.

What do you think of my plan so far (I haven't yet worked out the wires / fuses etc. yet, just trying to determine the big components first). Would using a server rack battery in a van build will be a bad idea? I generally see everyone using sealed lithium batteries like Weize, Redodo or Battle Born. Coud a bumpy ride or potentially unstable temps be worse for a server rack battery than for a sealed lithium battery? Thanks for the help!
Click to expand...

For a van/RV setup, I would pass on the Growatt, due to it's very high idle draw. A slightly different model, but this thread says it draws 115W!! In perspective, that high of an idle draw would drain your 24v 200Ah battery (4800Wh), without powering a thing but simply being on, in about 41 hours.

You might instead consider (at greater expense), the ultra-efficient Victron devices. The Victron Multiplus 3000 is a combo inverter-charger, delivering 3000VA (equates to 2400W continuous) and 6000W peak. Idle draw is a miserly 20W. In comparison to the Growatt, the Victron would run off your battery (powered on but no loads other than idle draw) for 240 hours (10 days). You would still need a solar charge controller, but the idle draw of SCC's tends to be very low, usually a few watts.

The All-in-Ones like the Growatt tend to have stupid high idle draws. Which is not a big deal if you have a massive panel array...but 2x100W like yours is not going to cut it. At an average of 6 hours a day of good power-producing hours, at say 60% efficiency, better if you angled them to the sun, (2x60w=120W), you would produce 120x6=720Wh per day. Your Growatt would eat 115x24=2460Wh per day! The Victron would eat 20x24=480Wh, meaning you would gain a charge of 240Wh into your battery with the Victron vs zilch with the Growatt. But in any case, you're going to need several more panels unless you only want to charge a phone and a laptop.

We have a mobile setup too and are starting to replace items with Victron gear. What a world of difference. Just got the Phoenix 12/1200 inverter (12v 1000W) and it's a champ. Color me impressed. The idle draw is but 9W and if I can dial in the ECO-mode settings, it will be closer to 2-3W.
 
CampLife said:
Thanks for the info! I was checking out the https://signaturesolar.com/phoenix-inverter-24-1200-120v-ve-direct-nema-gfci/ as well but the Growatt seemed to have more features. What Victron model would you suggest? The Victron brand seems to be one of the most popular for charge controllers / inverters. To be honest I'm not a huge fan of having to rely on bluetooth though, that's why I'm considering other brands over them. Although, I haven't heard much about Growatt. Does anyone know if they are considered to be a reliable brand? Any other brands/models to check out?
Click to expand...
As in my other comment, I just got the Victron Phoenix 1200, but the 12v version. There's no requirement to use bluetooth to use the inverter, it works just fine out of the box. But if you want to get into the advanced features, like change the ECO settings, you need either the bluetooth dongle and an app or the USB cable and a laptop. The app is fantastic - and if you go with other Victron-bluetooth gear, all devices work with the same app. I also have their IP22 12v 30A charger and it's really great to see exactly what is going on with charging the battery.

One other thing about the Phoenix inverter is the power switch is on the back of the unit, same place where the battery cables connect. It's not a convenient place to reach, especially how we have it mounted. But with the app, you can remotely switch the inverter ON/OFF/ECO, which I find priceless and I don't have to buy a separate hard-wired remote switch button.

I think you should dig deeper to find the actual idle draws of the inverters or AIO's you're considering. It makes a huge difference in a mobile setting. I looked up the spec sheet for the Growatt you linked and they do not list the idle draw of the inverter, only of the solar charge controller (2W). I find this deceiving, the idle draw of the inverter should be clearly listed but it's not. Which is why I linked you that thread where someone measured 115W idle draw of their slightly different model.
 
There is nothing wrong with building every component yourself, but if you want to build something that is mobile rated that you can use this summer, my suggestion is to try to buy as many components off the shelf as possible that are actually designed for mobile / marine use.

All of this stuff takes time and there is nothing wrong with that when it is a hobby and there aren't any deadlines.
 
CampLife said:
Thanks for the info! I was checking out the https://signaturesolar.com/phoenix-inverter-24-1200-120v-ve-direct-nema-gfci/ as well but the Growatt seemed to have more features. What Victron model would you suggest? The Victron brand seems to be one of the most popular for charge controllers / inverters. To be honest I'm not a huge fan of having to rely on bluetooth though, that's why I'm considering other brands over them. Although, I haven't heard much about Growatt. Does anyone know if they are considered to be a reliable brand? Any other brands/models to check out?
Click to expand...

I don't know which Victron model you got that rating from. As @Tomthumb62 said, the idle draw for the Multiplus is about 20 watts. Mine seems to come in at about 17 watts and I don't have it on the most efficient option which is "Search Mode".

Here's the data sheet for the Multiplus 12/3000, which is what I use in my RV.

 
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