12v electrical upgrade to inverter possibly?

outbound

06/2500/140
Thanks again, outbound. Your above advice makes even more sense now reading it a second time. Mainly because it happened again.....
....
..........
I think a big part of the problem is the fuse holder. It's not keeping the fuse tight on the lugs and I'm heating up the lug and wire.

edit: By the way, this is the wire size chart from my inverter manual. Mine is model 2007-2
2nd what Mwd mentioned about having the lug in direct contact with the fuse - that way stud metal isnt a concern.

but that first fuse holder isnt - by any stretch - suitable for something that can pull 200amps, more like 50 max.
(it looks like something sold with/for high-output car stereo amplifiers)
the give-away clue being the allen screw fasteners - vs a 5/16 or better yet, a 3/8 stud with hexnuts and lock washers.
simply because it's unlikely one could get an allen screw tight enough - as harry points out - to withstand the thermal cycling

and - noting the suggested wire chart, see where they show that with an add'l foot beyond 4, they saying to up size to 1/0 (or 0 as they put it)?
thats TWO sizes larger, for just one lil ole measly foot of add'l length...

so please 'trust me' when i tell you that #2 is way too under sized for something that can pull 200amps, even IF the run is only 2+2=4feet,
but from the other comments, sounds like it's quite a bit longer than that - to the battery?

would also 2nd harry on his suggestion of a class-T type fuse, it's whats typically spec'd for large inverters on boats,
due to the suggested/REQUIRED number of amphours of the bank it's pulling from..

with the class-T suggested because of their VERY HIGH (ampacity) INTERRUPT RATING.
what this means is the ability of the fuse (the fusible/burnable link within its housing) to burn completely away
without it's housing melting and creating an inadvertent secondary/after-the-burn path which
would allow current to continue flowing,
AFTER the fusible link burns,
but the housing gets so hot it melts into a blob, thus NOT INTERRUPTING current flow...

implication being, that once you go above a couple100 amphours of battery (which would be abs minimum for your inverter)
you result in multiples of the batteries amphours in TOTAL CRANKING AMPS.
and (right off the top, IIRC) class-T's are 20,000 amp rated interrupt capacity - something one quickly reaches
when connecting HUNDREDS of amphours of batts, which = THOUSANDS of cranking amps.

:2cents:
(and i get paid, or used-to anyway - upwards of $80/hour to tell people this stuff... but just sayin.)
 
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outbound

06/2500/140
and one other comment, jackie - the class-T fuse holders are MUCH BEEFIER than that one shown above,
and made such that if the fuse/connections get VERY HOT, the plastic wont crump on it, melting away when you need it the most.

just sayin....
 

Jackies Dog Grooming

2016 NCV3 144" 4 banger
2nd what Mwd mentioned about having the lug in direct contact with the fuse - that way stud metal isnt a concern.

but that first fuse holder isnt - by any stretch - suitable for something that can pull 200amps, more like 50 max.
(it looks like something sold with/for high-output car stereo amplifiers)
the give-away clue being the allen screw fasteners - vs a 5/16 or better yet, a 3/8 stud with hexnuts and lock washers.
simply because it's unlikely one could get an allen screw tight enough - as harry points out - to withstand the thermal cycling

and - noting the suggested wire chart, see where they show that with an add'l foot beyond 4, they saying to up size to 1/0 (or 0 as they put it)?
thats TWO sizes larger, for just one lil ole measly foot of add'l length...

so please 'trust me' when i tell you that #2 is way too under sized for something that can pull 200amps, even IF the run is only 2+2=4feet,
but from the other comments, sounds like it's quite a bit longer than that - to the battery?

would also 2nd harry on his suggestion of a class-T type fuse, it's whats typically spec'd for large inverters on boats,
due to the suggested/REQUIRED number of amphours of the bank it's pulling from..

with the class-T suggested because of their VERY HIGH (ampacity) INTERRUPT RATING.
what this means is the ability of the fuse (the fusible/burnable link within its housing) to burn completely away
without it's housing melting and creating an inadvertent secondary/after-the-burn path which
would allow current to continue flowing,
AFTER the fusible link burns,
but the housing gets so hot it melts into a blob, thus NOT INTERRUPTING current flow...

implication being, that once you go above a couple100 amphours of battery (which would be abs minimum for your inverter)
you result in multiples of the batteries amphours in TOTAL CRANKING AMPS.
and (right off the top, IIRC) class-T's are 20,000 amp rated interrupt capacity - something one quickly reaches
when connecting HUNDREDS of amphours of batts, which = THOUSANDS of cranking amps.

:2cents:
(and i get paid, or used-to anyway - upwards of $80/hour to tell people this stuff... but just sayin.)
At $80 bux an hour, I feel like I'm robbing a bank. ........Martha, start the car! go go go! :bounce:

I've looked locally for 2/0 welding cable with no luck. I'm going just order it on Amazon. As mentioned, I wasn't taking the distance from the alt nor the aux bat into consideration. So realistically I'm closer to 8 ft round trip.

Also, as mentioned, I want to get rid of the fuse entirely and go with this Blue Sea breaker. https://www.amazon.com/Blue-Systems-187-Circuit-Breakers/dp/B007P5UNNW?th=1

It'll be easier for my wife to reset if she does over tax the system accidentally.

My only concern is something that midwest drifter mention a while back when I mentioned it. The circuit breakers tend to have hair trigger and trip easy. If it does it every time she turns on the blow dryer, that would suck, but easy to reset. I guess the only way to know will be to try it.

If I decide to stay with a fuse, I'll switch to a T-Class. You guys are right, it just makes better sense in design.
 
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Jackies Dog Grooming

2016 NCV3 144" 4 banger
Speaking of breakers instead of fuses, anyone have experience and opinions?

I have the Blue Sea 200amp breaker in my shopping cart. https://www.amazon.com/Blue-Systems-187-Circuit-Breakers/dp/B007P5UNNW?th=1

I'm ordering 2/0 welding cable, 2/0 eyelets and a new crimping tool because mine only goes to 1 awg.

I have two thoughts before I click the order button.
1. Now that I'm going to 2/0 awg wire, should I go to a 250 or 300 amp breaker? 2/0 awg can go to 400 amps at 25 ft.
2. The Blue Sea breaker is $87 bux and other brands are under $20 bux. IE: https://www.amazon.com/dp/B00MR1LVZ...TF8&colid=35LKB1XNSHS68&coliid=I2XA93SCBH39FG
Why? The only thing I know is that I've had great luck with everything I have from Blue Sea. But that's a big price difference.

Also, I do know I can't install a breaker/fuse larger than the smallest awg wire in the run. I really need to find the awg size of the Sprinter's factory wire gauge.
 

DieselFumes

2015 4x4 2500 170 Crew
I really need to find the awg size of the Sprinter's factory wire gauge.
The 2007 Sprinter wiring diagram shows it as 1 gauge.

So you probably need to replace the whole run from the aux battery location through to the inverter with the higher rated cable. Otherwise, this 1 gauge cable is going to act as your fuse, and maybe take the whole van with it when it bursts into flame.

This is one reason why the aux battery location isn't so great for house batteries.

It should be pretty easy to get the 2/0 welding cable to conform to the bends it needs to get from the aux location through to the seat base.

Another thing to bear in mind is that now you have this upgraded system, do you also need to upgrade the battery isolator relay that takes the aux battery in/out of the charging circuit? It was only designed to handle the 100Ah battery and associated low draw.
 

Jackies Dog Grooming

2016 NCV3 144" 4 banger
I didn't think about the factory isolator relay. I should see if I can get the specs on it.

As far as my factory aux battery wire becoming the fuse, that won't happen as long as my breaker/fuse is gauged no bigger than the factory wire allows. IE: 1 awg/250 amps.
 

GrayGhost

New member
Speaking of breakers instead of fuses, anyone have experience and opinions?

I have the Blue Sea 200amp breaker in my shopping cart. https://www.amazon.com/Blue-Systems-187-Circuit-Breakers/dp/B007P5UNNW?th=1

I'm ordering 2/0 welding cable, 2/0 eyelets and a new crimping tool because mine only goes to 1 awg.

I have two thoughts before I click the order button.
1. Now that I'm going to 2/0 awg wire, should I go to a 250 or 300 amp breaker? 2/0 awg can go to 400 amps at 25 ft.
2. The Blue Sea breaker is $87 bux and other brands are under $20 bux. IE: https://www.amazon.com/dp/B00MR1LVZ...TF8&colid=35LKB1XNSHS68&coliid=I2XA93SCBH39FG
Why? The only thing I know is that I've had great luck with everything I have from Blue Sea. But that's a big price difference.

Also, I do know I can't install a breaker/fuse larger than the smallest awg wire in the run. I really need to find the awg size of the Sprinter's factory wire gauge.


I've had a bad experience trying to use a circuit breaker where a fuse is better suited. My system has a 255ah battery , then a 300 amp circuit breaker , then a 2000 watt inverter. My 1400 watt Keurig ( verified with a kill a watt) will throw the breaker. I'm hoping to remedy that with a class t fuse.
 

HarryN

Well-known member
To be honest, the most valuable lesson here is that 12 volts is marginal for this type of application.

It wasn't available to you back when you started, but now there are 48 volt, LiFe based systems out there which would make this project much easier to do. (sorry for the self promotion, I make these now)

Instead of pulling 200 amps at 12 volts, it would be more like 50 amps at 48 volts, which is easy to wire for.

A LiFe battery pack could probably do an entire grooming session, maybe two, including running the air conditioning. Even a lead acid based system running 48 volts would actually help a lot.

Battery to battery charging, using managed current draw from the auxiliary system could be used to recharge - over time, rather than pulling it all at once during peak use.

I am not saying that you should change your system, but just letting you know that there are other options for the future if interested.
 

Jackies Dog Grooming

2016 NCV3 144" 4 banger
@Grayghost, good to know. That is my concern.

@HarryN, I have no problem making a "next" plan. I want to stay up with the next best thing I can do. How much would a 48v LiFe battery pack cost that is equal to around 12v 750ah?

I've never actually calculated my battery requirements because I idle the engine as my generator. Can you link me to an easy calculator?
Also, I have plenty of room in the back for a battery pack that is independent from the vehicle. Other than a charger that is powered from the inverter.
 
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Nightpanda

2016 4x4 144 premie
To be honest, the most valuable lesson here is that 12 volts is marginal for this type of application.



It wasn't available to you back when you started, but now there are 48 volt, LiFe based systems out there which would make this project much easier to do. (sorry for the self promotion, I make these now)



Instead of pulling 200 amps at 12 volts, it would be more like 50 amps at 48 volts, which is easy to wire for.



A LiFe battery pack could probably do an entire grooming session, maybe two, including running the air conditioning. Even a lead acid based system running 48 volts would actually help a lot.



Battery to battery charging, using managed current draw from the auxiliary system could be used to recharge - over time, rather than pulling it all at once during peak use.



I am not saying that you should change your system, but just letting you know that there are other options for the future if interested.


The theory is good and sounds attractive. When I work the numbers though, we seem to loose capacity.
Ex:
12 v 400 ah battery bank =(100 ah @3.2vpc)x4 parallel
48v 100ah battery bank= (100ah@3.2vpc) series

A 400ah LifePo bank weighs 116 lbs. to maintain the same capacity (ah) it would weigh 448 lbs.

48v seems more practical in stationary applications?


Sent from my iPhone using Tapatalk
 

HarryN

Well-known member
The theory is good and sounds attractive. When I work the numbers though, we seem to loose capacity.
Ex:
12 v 400 ah battery bank =(100 ah @3.2vpc)x4 parallel
48v 100ah battery bank= (100ah@3.2vpc) series

A 400ah LifePo bank weighs 116 lbs. to maintain the same capacity (ah) it would weigh 448 lbs.

48v seems more practical in stationary applications?


Sent from my iPhone using Tapatalk
The key is to think in KW and KW-Hr rather than amp-hours.

Example (from what I use)
- 130 amp - hour battery, 12 volt ,LiFe, size 27

- 4 each x 12 volt x 130 amp - hours = 6.2 KW-Hrs

It doesn't matter if they are in series or parallel, they will supply the same amount of KW-Hrs.

LiFe battery life depends somewhat on depth of discharge. The ones I use are rated at 3 000 cycles at 100% charge / discharge, which if you think about it is 10 years at 1 cycle per day.

In order to be completely sure that my customers are happy, I de rate this to 4 KW-Hrs usable, but it is more for how I choose to market them rather than a technical reason

LiFe batteries like that weigh about 50 Lbs each. (Li ion are lighter but less stable) For ultimate performance, people use Li Ion or Li Co. For substantial improvements in safety, people use the slightly lower performing LiFe.

When you add in a heavy duty protective case, mounting, BMS, wiring, auto protections, battery to battery charging, etc, the package is more like 300 Lbs.
 
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HarryN

Well-known member
@Grayghost, good to know. That is my concern.

@HarryN, I have no problem making a "next" plan. I want to stay up with the next best thing I can do. How much would a 48v LiFe battery pack cost that is equal to around 12v 750ah?

.
Implementing 48 volt has some non trivial integration aspects, so I tend to sell it as a system. I will contact you privately to discuss more details of your needs and put some options together to consider.

Just up front, it isn't cheaper than 12 volt (just the opposite), it just helps get around some technical challenges in higher power systems. That is why you see it implemented in golf carts.
 

Jackies Dog Grooming

2016 NCV3 144" 4 banger
Thanks, Harry. I've told my wife that when she starts generating more income from her mobile grooming business, we'll spend more on upgrades. She's been a groomer for over 25 years, but starting a new mobile business has been expensive.
 

Nightpanda

2016 4x4 144 premie
The key is to think in KW and KW-Hr rather than amp-hours.



Example (from what I use)

- 130 amp - hour battery, 12 volt ,LiFe, size 27



- 4 each x 12 volt x 130 amp - hours = 6.2 KW-Hrs



It doesn't matter if they are in series or parallel, they will supply the same amount of KW-Hrs.



LiFe battery life depends somewhat on depth of discharge. The ones I use are rated at 3 000 cycles at 100% charge / discharge, which if you think about it is 10 years at 1 cycle per day.



In order to be completely sure that my customers are happy, I de rate this to 4 KW-Hrs usable, but it is more for how I choose to market them rather than a technical reason



LiFe batteries like that weigh about 50 Lbs each. (Li ion are lighter but less stable) For ultimate performance, people use Li Ion or Li Co. For substantial improvements in safety, people use the slightly lower performing LiFe.



When you add in a heavy duty protective case, mounting, BMS, wiring, auto protections, battery to battery charging, etc, the package is more like 300 Lbs.


I'm wondering how KW-hours equate to amp hours? Are you saying the same bank in 12V-400Ah will provide the same duration as a 48V-100Ah? Will this change depending on circuit characteristics (i.e. Inverter vs D.C.)? In a mobile operation, 12VDC is a necessary need (heater, fan, etc), outside of A/C needs. How do you maintain duration?




Sent from my iPhone using Tapatalk
 

HarryN

Well-known member
Power systems are all about being practical.

In a home, most of the power being used is 120 or 240 VAC, so that is what is in the socket. The power consumed by computers and cell phones isn't zero, but it is very small compared to running the furnace fan, clothes dryer, or cooking.

In an RV or van conversion it already has 12 VDC, so when possible, it makes sense to use it.

Add up what type of loads will be run (5 VDC USB, 12VDC, and 120 VAC). If most of your loads are 12 VDC and none of them pull more than than 30 or 40 amps at 12 VDC, it probably makes sense to just run 12 volts around and not spend the extra money.

Example, espar, exhaust fan, lights - just stay with a 12 volt system and spend the money on other enjoyable things.

On the other hand, suppose you decided to buy nearly all appliance as 120 VAC instead of 12 (refrigerator, exhaust fan, cook top / electric skillet, lights, sound system, TV, blow dryer, air conditioning, etc) With nearly all of the load on the inverter, and very few 12 VDC loads, it potentially changes the plan.

If you are going to heavily use an inverter or for routine 120 VAC cooking, and they are routinely pulling 1000 - 4000 watts, then it is worth giving serious thought to either a 24 or 48 volt system.

If you do decide that you want to run a 48 volt system and have a few 12 VDC loads, then you buy a 48 VDC to 12 VDC converter.

Example, suppose you have a load that needs 10 amps x 12 volts. (12 x 10 = 120 watts)
- buy a 300 watt converter
- There are some inefficiencies, so it will actually consume around 150 watts (rest becomes heat)
- 150 watts / 48 volts = about 4 amps being drawn into the converter at 48 volts, 10 amps coming out at 12 volts
- Rough numbers - about $100 - 150 / each for one of these converters.

Each time you add a piece of hardware like this, it cost money, so it only makes sense to use something other than 12 volts when you have specific large loads.
 

DieselFumes

2015 4x4 2500 170 Crew
Harry, you've said a lot about 48v systems. I think that it would really help to remove folks' skepticism if you could show us your Sprinter van built out with the 120v AC appliances you mention and running your 48v system. Preferably with numbers for how much of the potential power in the battery bank is lost to conversion inefficiencies from having to constantly run a 48v inverter and 48v to 12v converter in the real world.
 

HarryN

Well-known member
Good point.

To be honest, if I were to take what I know now and apply it to a typical small DIY RV / van conversion, probably I would instead use 24 volts rather than 48.

There are a ton of 24 volt components around due to its use in heavy (semi) trucks and boats and rather easily available.

It is a pain in the neck to get parts really rated for mobile, 48 volt use, since the fully charged battery voltage nearly 60 volts.

Example, most blue sea stuff is designed for 24 volt systems, but relatively little of it is rated for 48 volt systems.

The main reason I went to 48 volt systems is that my son needed 2 each, 4 KW inverters for a project and that was nearly impossible with 12 volts, but viable in 48 volts. If you keep everything under 60 volts DC, it stays below additional regulations.

Higher voltage bus, mixed use (5, 12, 48 VDC + 120 VAC) setups are not more efficient, perhaps more likely somewhat less. The main advantage in my mind is that the higher voltage inverters have a wider voltage input range, so if you loose a volt to system loss and a few volts to sag it all still works. In a 12 volt system, if you loose 3 volts to (sag + losses), the inverters turn off.
 

HarryN

Well-known member
Many of the people on this forum doing DIY conversions live in areas where an exhaust fan is sufficient to be comfortable - that doesn't take much power.

In my area, summer camping is nearly impossible without air conditioning. Vehicle interiors get seriously hot and you have to run the engine / air conditioner for a while before your kids can get in or they will literally get burns from touching the seats belt buckles.

Mother's stand in parking lots in 110 F, full sun heat with their kids cooling down the car before they can get inside.

Nearly every year, a young family suffers from the horrific experience of a sleep deprived parent accidentally leaving their child in the back seat.

That is what drives me toward higher power, 48 volt systems and engine - off air conditioning.

I view efficiency as a means to longer run time, not the primary goal. That is why I suggest the association of the need for moving away from 12 volts only makes sense if you have specific, high draw appliances, like a multi - KW inverter.

Edit - sorry, I get carried away on this topic area.
 
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Boxster1971

2023 Sprinter 2500 144wb AWD
Good point.

To be honest, if I were to take what I know now and apply it to a typical small DIY RV / van conversion, probably I would instead use 24 volts rather than 48.

There are a ton of 24 volt components around due to its use in heavy (semi) trucks and boats and rather easily available.

It is a pain in the neck to get parts really rated for mobile, 48 volt use, since the fully charged battery voltage nearly 60 volts.

Example, most blue sea stuff is designed for 24 volt systems, but relatively little of it is rated for 48 volt systems.

The main reason I went to 48 volt systems is that my son needed 2 each, 4 KW inverters for a project and that was nearly impossible with 12 volts, but viable in 48 volts. If you keep everything under 60 volts DC, it stays below additional regulations.

Higher voltage bus, mixed use (5, 12, 48 VDC + 120 VAC) setups are not more efficient, perhaps more likely somewhat less. The main advantage in my mind is that the higher voltage inverters have a wider voltage input range, so if you loose a volt to system loss and a few volts to sag it all still works. In a 12 volt system, if you loose 3 volts to (sag + losses), the inverters turn off.
You don't need 48V components, other than the inverter and main battery pack. Then just add a 48-12V DC-DC converter to provide 12V DC for all the normal 12V stuff. That's what the auto industry did for hybrid and electric vehicles. High voltage pack for main propulsion and a DC-DC converter for all the normal 12VDC electrical stuff.
 

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