Dual battery with an inverter?

Sean Slavin

Sean Slavin

Adventurist
I'm doing some noodling on how I want to setup dual batteries. Leaning heavily towards the IBS system. Right now, I'm thinking of building a box in the bed to hold the second battery, compressor and inverter. I'm basing the wiring plan around this diagram from IBS.

db3e6e2da2.jpg


I'm going to attach the SwitchPros unit to the main battery. It will handle lights, lockers and compressor. I'm considering attaching the inverter to the aux battery. I'll want to use it for running photography gear and charging laptops/batteries.

How would I go about calculating the draw on the aux battery? I'd like to not drain the battery after having a bunch of strobes and a laptop plugged into the inverter.

I have a background in engineering, just not electrical, so this is a bit new to me.
 
Your aux battery will handle almost all you throw at it...the real question is for how long it handle it. The only to figure this out is add up all the for the stuff you wanna run and divide that into the battery amps. HOWEVER, firstly you have to pick a battery...volumes have been written on this topic. There are pros and cons for all the various types of batteries...discharge rates, recharge rates, discharge and recharge max percent, mounting location, etc. It is kinda dizzying and it is the point I am at now. Based on the battery you pick, the amount of solar you are gonna throw at it and the load draw on the system you can then see if all those components will get you through the evening or a meteor striking the earth.
 
Sean Slavin said:
I'm considering attaching the inverter to the aux battery. I'll want to use it for running photography gear and charging laptops/batteries.
Click to expand...
This is getting more and more popular, and I wish it wasn't.

Inverters are no simple device. Except for a good alternator, a decent sized inverter will OUTPACE any other charging method. In other words, an Inverter will drain the battery faster than 400 watts of solar can replenish it. There is a reason that Toyota (and other manufacturers) make it so that you can't enable the factory inverter unless the engine is running. Because you will kill your battery if it isn't getting sufficient charging.

An inverter is a "No other available solution" kind of device. I will bet you there are 12 volt chargers for ALL of your devices available on Amazon Prime. And if that's the case, why install the most inefficient device known to the automotive electrical world?

Please don't take this the wrong way. I'm not criticizing. I am attempting to motivate you to make sure that you've exhausted all other options before just jumping into installing an inverter and regretting it later. There are VALID reasons to have them, but most of the time I see them installed in situations where it could have been avoided, and that person ends up wondering why his batteries never charge all the way and need to be changed every year.
 
Great post Mitch! As much as I love gadgets and power, I've always shied away from even the best inverters due to their power hungry nature. Juice is not worth the squeeze IMHO.
 
Mitch said:
This is getting more and more popular, and I wish it wasn't.

Inverters are no simple device. Except for a good alternator, a decent sized inverter will OUTPACE any other charging method. In other words, an Inverter will drain the battery faster than 400 watts of solar can replenish it. There is a reason that Toyota (and other manufacturers) make it so that you can't enable the factory inverter unless the engine is running. Because you will kill your battery if it isn't getting sufficient charging.

An inverter is a "No other available solution" kind of device. I will bet you there are 12 volt chargers for ALL of your devices available on Amazon Prime. And if that's the case, why install the most inefficient device known to the automotive electrical world?

Please don't take this the wrong way. I'm not criticizing. I am attempting to motivate you to make sure that you've exhausted all other options before just jumping into installing an inverter and regretting it later. There are VALID reasons to have them, but most of the time I see them installed in situations where it could have been avoided, and that person ends up wondering why his batteries never charge all the way and need to be changed every year.
Click to expand...

This is great input. Thank you.

I have no doubt that I could charge laptop/camera batteries and run the fridge through 12V. My thought for the inverter came more for having a power source for studio strobes. That is all I wanted to power with it.

Yes, I have power packs for the strobes. I can get between 300 and 500 flashes (depending on power) out of each of the power packs. I don't know if I can charge the power packs with 12V. I'll have to check the power supplies and requirements for the packs.

If I can get by without the inverter, I would be more than willing to do so.
 
If you do get an inverter consider one with the ability to charge your batteries when plugged into shore power. This is a nice feature that allows your fridge to run and batteries be topped off before your trip or whenever on shore power. Most also have three stage charging which is better than your alternator can do. An inverter with this option may be too big for your application but works well in my van.

You might also look into the Blue Sea ACR for a dual battery system option. Having had issues with one of the popular dual charging systems in my last van I decided on the Blue Sea ACRs for this van.
Eric
 
Yeah, I'm not a fan of the National Luna packs. They are NOT intelligent, I don't care what ANYONE says. They ARE expensive though!

Knowing when the vehicle is running (charge voltage detected from the alternator) and when it isn't does not make a solenoid intelligent. Keeping them separated for 5 minutes to supposedly allow the starting battery to recover from starting is all marketing BS.

Knowing when the Auxiliary Battery is fully charged and cease throwing voltage at is is an intelligent system. Like a good DC to DC charger (CTEK for example) would do. AGM charging profiles instead of a pure flow of voltage and amps from the alternator. THESE are the signs of an intelligent dual battery system.
 
Mitch said:
I'm curious which dual charger you had issues with.
Click to expand...
National Luna but the original installer decided not to follow directions and ended up bypassing the voltage regulator frying all the circuit boards. Ended up buying new boards and re-wiring myself and added a higher amp solenoid. I decided to skip all those potential issues when re-wiring this van. Went with a few Blue Sea ACRs which are proven and simple with manual control option.

I had the National Luna Power Pack in my Montero and liked it. When I bring my fridge in other vehicles I use a Goal Zero Yeti with the 12volt socket plug to charge while driving. This is a nice setup because it is portable and has an inverter and power ports built in. Not meaning to sidetrack thread...sorry...carry on.
Eric
 
Blue Sea ACR's are great, they're voltage-aware, so they work the same as the National Luna without all the glitz, price, and headaches.
 
A couple of theoretical downsides to using the Blue Sea ACRs.

1: It will combine the two batteries if EITHER side is receiving a charge. Which means if you have solar panels charging the house battery, it will combine the two batteries. Which you may not want.

2: It will separate the two batteries if either side goes below 12.75 volts. Hypothetically, if you tried to cross a stream, and your engine died, and you were trying to winch out, you would most likely be getting power from only one battery and not both.

Both of these things lead me to think I am better off with a simple continuous-duty solenoid.

Info source on ACRs: http://assets.bluesea.com/files/resources/reference/ChooseACR.pdf
 
Optimistic Paranoid said:
A couple of theoretical downsides to using the Blue Sea ACRs.

1: It will combine the two batteries if EITHER side is receiving a charge. Which means if you have solar panels charging the house battery, it will combine the two batteries. Which you may not want.

2: It will separate the two batteries if either side goes below 12.75 volts. Hypothetically, if you tried to cross a stream, and your engine died, and you were trying to winch out, you would most likely be getting power from only one battery and not both.

Both of these things lead me to think I am better off with a simple continuous-duty solenoid.
Click to expand...

Well aware of those features.

I also have the in cab switch can helps me join or separate the batteries when needed. I run it on auto as the ACRs are smart. I also have an in cab monitor to help with ensuring both batteries have power and are maintained. I've never had an issue when my Overland Solar panels are plugged in and the ACR helps maintain the Oddesey batteries very well.

IMG_0832.JPG


IMG_0833.JPG
 
While either side of the Blue Sea ACR is voltage sensitive, with regards to the solar situation mentioned above, this will only happen once the auxiliary battery's voltage is high enough to trigger the ACR, 13.2 volts if I remember correctly?

The 7622 ACR has a manual control feature on it that would allow you to either operate via the switch or on the face of the unit, for those times when you need to combine for the extra power (Jump start, winch, etc), or lockout combining entirely.
 
Tim R. said:
Well aware of those features.

I also have the in cab switch can helps me join or separate the batteries when needed. I run it on auto as the ACRs are smart. I also have an in cab monitor to help with ensuring both batteries have power and are maintained. I've never had an issue when my Overland Solar panels are plugged in and the ACR helps maintain the Oddesey batteries very well.

View attachment 32617

View attachment 32618
Click to expand...
this is incredibly cool.
 
You must log in or register to reply here.
Back
Top Bottom