Another solar/battery/ 12 volt question.

[Sleep]

Hi all,  I have almost gotten my solar plans done. Going with a 100 watt kit from Renogy and 2- 6 volt deep cycle batteries (due to my ability to lift), I know the controller comes with. I thought I needed an inverter, but then I read this:

[font=Verdana, Arial, sans-serif]Inverters have been known to consume 20%, 5% is being generous.  [/font]


[font=Verdana, Arial, sans-serif]Most of what is used does not need to be processed by an inverter.  For efficiency you want to get 12 volt devices.  Phone chargers that use 12 volts typically require less power than an inverter running a 120 volt charger.  For laptop computers you can get a power supply brick that makes the 19 volts the computer uses directly from 12 volts.  That is more efficient than making 120 volts from 12 and then making 19 volts from the 120.  Fans, led lights, [/font][font=Verdana, Arial, sans-serif]refrigerator[/font][font=Verdana, Arial, sans-serif]s, etc are available in models that use 12 volts directly.  Some things like microwave ovens and electric shavers are typically used with inverters. [/font]

[font=Verdana, Arial, sans-serif]My question is, if I don't have an inverter how/what do I use to plug in 12 volt devices? I plan on charging my phone, fire tablet, computer, fantastic fan, small fan, 12 volt fridge (Dometic), a few lights and would like to use a 12 volt tv/dvd sometimes. Will get 12 volt chargers for tablet and laptop. (Although my fire/tablet gets used the most.) [/font]

[font=Verdana, Arial, sans-serif]Please feel free to offer your opinions or recommendations.[/font]

[font=Verdana, Arial, sans-serif]Thank you all so very much![/font]

 

[Almost There]

An inverter is simply a device that changes 12V to 120V.

12V devices need to be plugged in to a 12V outlet that looks like this:

http://www.marinco.com/en/12vrc

If you're wiring up a van you will want to install a fuse block like this one between the outlets that you wire in and the battery.

https://www.bluesea.com/products/5026/ST_Blade_Fuse_Block_-_12_Circuits_with_Negative_Bus_and_Cover

If you've nothing that needs 120V to run then there is no point in installing an inverter that you will never use.

 

[Sleep]

Thank you Almost, I can always count on you! So the batteries are connected to the fuse block and then I can use several of the 12 volt outlets in various areas and connect them to the fuse block? Right so far?

 

[Almost There]

Yes, you run one fused wire to positive , one to ground. Then run a pair of wires to each of the outlets wherever you want to install them in the van. Pairs of wire are preferable although if you're being cheap you could just run a short wire off each to a ground but you're taking your chances on ground failure that's hidden behind walls etc.

I ended up using 300' of each of red and black 10 gauge wire to do my van. I bought all my wire off of Amazon in 100' rolls.

I did a bit of overkill in my van - I used up all 12 circuits but I have a roof fan vent, 3 LED lights, and  8 12 V  outlets scattered throughout the living area of the van, 2 of which I removed the outlets and hard wired in my fridge and freezer. BUT I have power wherever I need it including being able to sit outside with stuff plugged in because I put 2 right near the side doors.

The plug ends of the 12V cords that come with most of the 12V compressor fridges aren't worth a damn. One of mine was unusable after only a couple of months and the other failed within the year. I also spent most of that year double checking all the time that I had power to the freezer because the plug would vibrate under travel and come loose. I should have just cut the cords and hard wired them way sooner than I did. If I ever need to remove either of them I can just unplug them at the fridge end.

 

[deadwood]

My van is 12v power only. I have a few 12v / usb outlets around the van. All my electrical devices are wired directly to a blue sea fuse block. Fan, fridge, lights, 12v outlets, etc.

I think the main reason people hook up an inverter is when they have something that consumes more power then the 12v can handle. Something like a microwave, coffee pot or toaster. These items use so much power that they need to be plugged into a 110 outlet to run.

When I originally did my electrical diagram I had an inverter in there. But as I thought about it I realized that for me I just don't have any of those items that need the 110 power. So I deleted it and everything is 12v only. If it has a 12v plug like my portable fan I can plug it right in. If it needs dedicated 12v power then it is run to a fuse block.

Everyone has different needs. And if mine ever changed I could always add an inverter. But for now I don't have a need for one. I do have a little cheap inverter that plugs into the outlet if needed. I have one of those portable vac's to keep things clean and that is 110 power. So I plug in the little adapter and charge it when needed.

 

[Weight]

If you are not going to have many circuits, i have used these fuse blocks. less money than the big jobbies. But still Blue Sea quality.
https://www.bluesea.com/products/5024/ST_Blade_Battery_Terminal_Mount_Fuse_Block_Kit
I use the above mounted to a positive buss bar.
The following can be mounted with screws to a flat surface.
https://www.bluesea.com/products/5045/ST_Blade_Compact_Fuse_Blocks_-_4_Circuits

These are great for the big fuse you need to feed a buss bar from the battery. You select and order the fuse separate with the block.
https://www.bluesea.com/products/5191/MRBF_Terminal_Fuse_Block_-_30_to_300A

 

[John61CT]

I'd recommend Blue Sea for the better-than-a ciggie ports and plugs also.

Don't use for draws over 10-12A, that's what Andersons are for.

Or just standardize on Andersons for flexibility, only put the round ports where guests might have something to plug in.

 

[Sleep]

Thank you all for this info. I thought I was starting to get my head wrapped around the electrical. Oh well better now than later!

 

[Weight]

My Blue Sea outlet/plugs are rated for 15 amps. (Not for cigarette lighters with the heat and all.)

 

[everett ruess]

Someone can correct me if I'm wrong, but it sounds like your system description is light on power. One 100 watt panel would have a hard time keeping up with what you want to run- "[font=Verdana, Arial, sans-serif] I plan on charging my phone, fire tablet, computer, fantastic fan, small fan, 12 volt fridge (Dometic), a few lights and would like to use a 12 volt tv/dvd sometimes". A warm shady day and the fridge would be a big drain.[/font]

[font=Verdana, Arial, sans-serif]And it sounds like you are running 2 6v golf cart batteries, the small ones of those are 200 amp hr. The rule of thumb is to match panel watts to batt. amp hrs. You're at half with a 100 watt panel. Another 100 watt panel would put you there. I think you'd be chronically under charged and killing batteries with just one.[/font]

[font=Verdana, Arial, sans-serif]Do you have room for another panel? It'd sure save you on battery replacement.[/font]

 

[John61CT]

Not just a bank longevity issue, simply won't last more than a day or two if a 100w panel is the only input.

IMO two pairs of GCs required, and either 3-400w of panels or supplemental power sources in the morning, either long drives for alt charging or a small gennie.

 

[DLTooley]

I'd like to get some firmer numbers on those inverter efficiency losses.

I'm working on running a 12v fridge off 100 watts.  I wait until after I have 2-3 hours of absorption, full solar charging, to turn it on.  Works fine as a fridge in moderate temps.  I will try as a freezer on this next trip.

This puts zero-minimal load on the battery, but is tricky/risky.  Plan B, which is going to happen some time, is to upgrade the system.

Working on a smaller system without a fridge might well be the best 'learning curve' solution - better to destroy a single battery than two, etc.

You can get cigarette lighter-usb converters easily.  Amazon is good to shop for this sort of stuff, but these are commonly available.

Here's a single battery box that's simpler than setting up a fuse block, etc:

https://www.amazon.com/MinnKota-Trolling-Motor-Power-Center/dp/B001PTHKMG
https://www.amazon.com/MinnKota-Trolling-Motor-Power-Center/dp/B001PTHKMG
Walmart has an okay marine deep cycle, batteries plus also sells a true deep cycle 12v battery.

How soon are you going to want that freezer?  Do you have space for second panel?

(FWIW I actually use 150 watts with the pre-upgrade 50 used as a semi-portable that sits on my windshield when camped.)

 

[John61CT]

10-25% losses are very common, but it varies by power level, % capacity utilization.

5% rating would be at a very specific point, rarely achieved in practice.

The only advantage of using a fridge designed for shore power off an inverter is up front purchase price.

Whether that's worth the headaches and lifetime lower energy efficiency is an individual judgement call.

 

[John61CT]

Walmart only sells Starter style batts falsely labelled as "marine deep cycle"

Batteries+ and Sam's Club sell Duracell flooded 6V GC, x2 = 12v cheapest best value true deep cycle bank available.

It is difficult to find 12V deep cycle, and impossible in automotive or big box retail.

 

[Weight]

It is possible to buy a Golf Cart 12 volt battery at Batteries Plus Bulbs. Also Sam's Club sometimes. These are Duracell made by East Penn. You will get more AH from two series CG2 6 volt battery.

 

[John61CT]

The 12V version are rated by EPM at half the cycles lifetime.

The sealed ones aren't good either.

Flooded 6V are really the only way to get good true deep cycle for around or under $200.

There are lots of more expensive options of course, and some of those are 12V, but only through small specialist mfg authorized dealers, not consumer retail AFAIK.

 

[SoulRaven]

I think the main reason people hook up an inverter is when they have something that consumes more power then the 12v can handle. Something like a microwave, coffee pot or toaster. These items use so much power that they need to be plugged into a 110 outlet to run.

Also one very important reason is that the item you wish to use is 120v.
Like my  charger for my laptop,  my hair clippers, my tiny little hotplate, my hotpad  (for my back ); frankly the list goes on.  Wired power tools.   Even cordless ones generally have chargers that plug into 120v. 

If you brought on the road things you used before,  you may have a lot of items that run off120v.  It's my observation that a lot of us have inverters and not just for high power items.   PLUS,  when I'm not using it, I turn it off. 

I can't imagine not having one.

Pat

 

[SoulRaven]

Since I can't edit the former post,  ,
I'll just post another. 

I don't know if the fact that I'm pulling a cargo trailer makes any difference, but I am. 


I also have a gas generator,  which I almost never use.

 

[SoulRaven]

One more thing. ..


My plan is to EVENTUALLY replace as much 120v stuff with 12v. 

If I think about it, using a device to step up 12v to 120v,  and then back down to 12v seems really stupid.   You will always have some power loss.  Many devices, like rechargers, rely on that process. 

Pat 

 

[John61CT]

Ryobi for one makes native 12V versions of their chargers. Pretty neat for them to standardize on one batt design for all their devices, from drills etc to lights and fans, inflator/compressors.

Lots of hacks to use them to power USB, small portable inverters. . .