Dedicated Alternator charging

OrangeSpear

new here
I have a Ford 7.3 powerstoke E450 RV with dual alternators. One alternator is for the engine/start. The second alternator is isolated. (not actually installed yet, because I keep reading that it can burn up if not connected to anything)

Currently using AGM batteries that currently only get charged when connected to shore. Possibly in the years to come i would upgrade to lithium batteries, but can justify the cost currently.

Ill need an invertor because the current setup in the RV only powers lights while driving. (goal is to power TV, small electronics, and Refrigerator while driving)
I figured that charging my battery bank with the extra alternator was a quicker solution to start with. Next phase i will add solar into this mix. Alternator for charging while driving, Solar to charge while not driving and not connected to shore, Shore power to charge while plugged into electricity.

The questions are:
- If i have a DC to DC charger like this Renogy 40A or a Victron Energy (not sure if this is the correct model i would need) do I still need a Alternator Protection Device like this?
- what is an intelligent battery combiner?
- where does this coming into play? Blue Sea Automatic Charging Relays
 

DiploStrat

Expedition Leader
Since no else has taken a swing at this, here goes.

I have a Ford 7.3 powerstoke E450 RV with dual alternators. One alternator is for the engine/start. The second alternator is isolated. (not actually installed yet, because I keep reading that it can burn up if not connected to anything)

Currently using AGM batteries that currently only get charged when connected to shore. Possibly in the years to come I would upgrade to lithium batteries, but can justify the cost currently.

Ill need an invertor because the current setup in the RV only powers lights while driving. (goal is to power TV, small electronics, and Refrigerator while driving)
This is not very clear. You won't need a inverter for small electronics or a refrigerator, unless you are planning to use an A/C refrigerator. (Probably a bad idea in a van.) Out of curiosity, why would you want to power a TV while driving? Children? Or am I simply being obtuse?

I figured that charging my battery bank with the extra alternator was a quicker solution to start with. Next phase i will add solar into this mix. Alternator for charging while driving, Solar to charge while not driving and not connected to shore, Shore power to charge while plugged into electricity.
-- An alternator dedicated to charging your camper/house battery is an excellent approach, assuming proper brackets, and proper size (for other than a specialized marine/hi-amp) alternator, you probably want to oversize it by 50-100%.
-- You will also want a dedicated, adjustable regulator that you can set to the proper voltages for your AGM. (Hint: Buy one that can also do lithium, should you decide to go that way, and in a van, you should.)


The questions are:
- If I have a DC to DC charger like this Renogy 40A or a Victron Energy (not sure if this is the correct model i would need) do I still need a Alternator Protection Device like this?
-- With a dedicated alternator/regulator, you do not need a battery to battery charger - it is basically either/or. Only need a alternator protector if your battery will ever disconnect abruptly. This typically only a problem with a lithium battery which has a battery management system (BMS) that can disconnect when there is a fault.

- what is an intelligent battery combiner?
- where does this coming into play? Blue Sea Automatic Charging Relays
-- These are simply different names for voltage sensing relays. Again, not needed with a dedicated alternator.

You may find three articles on this page useful:

-- Watts Up! - How to size system.
-- Charging Up! - Focused on saving lead acid batteries.
-- Doubling Up! - Building isolated battery systems.

Documents | DiploStrat

I would urge you to check out these references before spending any money.
 

OrangeSpear

new here
Thank you for taking the time to respond.
I will read those articles that you posted.
I also looked at the pinned post in the section but several are dead links or rather outdated. I do try to do a ton of research before starting to ask questions.
As to your question about the TV, yes kids. TV is not for me but rather for the wife and kid.
I currently do have a 2way fridge. It either runs on AC or Propane. However I would like to eventually be able to power it with DC power while running down the road and no propane.



-- An alternator dedicated to charging your camper/house battery is an excellent approach, assuming proper brackets, and proper size (for other than a specialized marine/hi-amp) alternator, you probably want to oversize it by 50-100%.
-- You will also want a dedicated, adjustable regulator that you can set to the proper voltages for your AGM. (Hint: Buy one that can also do lithium, should you decide to go that way, and in a van, you should.)
Proper brackets -- My 7.3 powerstroke E450 has the ambulance package and that means a second Alt waiting to be used.
Proper size Alt -- 220 amp Alt (not installed)
Dedicated adjustable regulator -- something like this? Balmar MC-614H - High Performance External Alternator Regulator with one of these Sterling Power 12V or 24V - Alternator Protection Device
OR a DC to DC charger. Does the DC to DC charger have the alternator protector and regulator built in?

Again thank you, im heading over to those articles now.
 

DiploStrat

Expedition Leader
...
I currently do have a 2way fridge. It either runs on AC or Propane. However I would like to eventually be able to power it with DC power while running down the road and no propane.
You will probably be happier selling it and buying a pure DC refrigerator.

Proper brackets -- My 7.3 powerstroke E450 has the ambulance package and that means a second Alt waiting to be used.
Proper size Alt -- 220 amp Alt (not installed)
Think of it as a 100A alternator and you should be perfect.

Dedicated adjustable regulator -- something like this? Balmar MC-614H - High Performance External Alternator Regulator with one of these Sterling Power 12V or 24V - Alternator Protection Device
OR a DC to DC charger. Does the DC to DC charger have the alternator protector and regulator built in?
...
The Balmar is one of the best regarded of its breed. It is what I would look at. With lead acid (e.g. AGM) you should not need the alternator protection device. With lithium, absolutely.

A battery to battery charger (B2B) is a different way of doing things. At 90 MPH and at a REALLY high level. B2B's got their start back when alternators typically ran at 13.9v and were killing deep cycle lead acid banks that needed 14.4v or more. So a B2B takes in 13.x volts and boosts it to the desired level. To do this it throws away amps to get volts and, in the process, generates heat. (See ventilation requirements.) But, 14.4v at 20A will charge a LOT faster than 13.9v, even at 100A. (See "Charging Up!" to understand why. Then factory alternators all went to 14.x volts and B2B's went into decline. Now they are coming back for lithium with the addition of circuitry to actually drop the voltage as needed. So, a well designed B2B will:

-- Provide battery isolation/protection. Basically, it won't switch on until the source battery (typically your starter) is at better than "full" charge, (e.g. 13.2v) and it will switch off if the source battery drops back to "full" charge. (e.g. 12.7v) Some may also have the option to monitor the alternator temperature. Because these devices typically use diodes, most will prevent any spikes from the camper battery from reaching the alternator. (And, in any case, as there is usually a lead acid starter battery in the mix, the alternator is further protected from any sudden loss of load.

-- Pad the starter battery to assure that the alternator switches on and provides current. Typically by drawing the voltage down to about 13v. Then boost or buck the voltage provided to the house/camper battery, according to the selected profile. This is the selling point and Sterling Power makes models that can be tweaked to your exact needs.

I would double check with Sterling, but there is probably no reason that you could not connect a 100A Sterling B2B directly to your second alternator if you didn't want to use the Balmar regulator. If you use the regulator with lithium, then you DO, absolutely, want the Sterling alternator protector or similar device.

I hope this is useful and I believe to be correct, but you probably need to find someone close to you will real experience to help you design your system. I have seen lots of bad ones!

Accordingly, all of my comments come with the Oklahoma 50/50 guarantee - if you follow my advice and it breaks in two, you own both pieces.
 

broncobowsher

Adventurer
A trick you can do is install a starter solenoid/relay to connect the 2 systems temporarily (momentary push button). This gives the option of jump starting yourself.

With a correct voltage regulator on the secondary alternator you don't need anything extra added on. Solar is a simple parallel installation. If the alternator fills up the battery, the charge controller will see that and stop as well. Same thing also works the other way around.

Don't plan on a 12V to 120V inverter (powering the fridge) as a long term solution. There are too many losses when bumping power around like that. Get a fridge that will run on 12V. Save the inverter for short duration loads (like watching TV). Few hours, not all day.
 
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