Aux Battery Set-up with Ram EcoDiesel

[adventurevrogger]

I'm looking to set-up an aux battery system with my Ram EcoDiesel using an isolator such as this PowerStream. However the product page for the PowerStream states, "150 amps is the maximum current that the relay can reliably break", and the alternator on the EcoDiesel is spec'd at 230 amps. I don't understand the "big picture" of the aux battery systems well enough to understand if this is an issue or not, but the PowerStream page seems to indicate that it is.

Additional info about the batteries: The main truck battery controlled by the 230 amp alternator is a 12 volt, 800 cca, AGM battery, and the aux batteries I've purchased are also 12 volt AGM batteries. I would assume that if the alternator can safely recharge the main battery then it can safely charge my new aux batteries since their specs are basically the same.

Anyone have any thoughts on this and how I should proceed? Is it just a matter of looking for bigger solenoid to work as the isolator?

Thanks!

 

[DiploStrat]

Were I Thee

​I would go with the Blue Sea ACR, rated at 500A: https://www.bluesea.com/products/7620/ML-ACR_Automatic_Charging_Relay_-_12V_DC_500A

That said it is very unlikely that you will ever see an amp flow over 200A. The amp flow depends on:

-- Size of your wiring; bigger is better, start looking at 1/0 AWG. (I use twice that.)

-- Difference in state of charge between the two batteries you are connecting; that is the more your camper battery is discharged, the greater the amp flow. As the camper battery charges, the amp flow will drop.

Sadly, once your camper batteries start to develop a surface charge, the amp flow will drop all too soon.

My alternators are rated at 250A and my relay, a Blue Sea unit, is rated at 200A.

N.B. Hopefully your camper batteries are deep cycle batteries.

 

[adventurevrogger]

Thanks, DiploStrat. I appreciate the detailed response to let me understand better whats actually happening with the electrical.

I hear great thins about all things BlueSea, but the price point is a bit out of my range. Looks though like the current I need to be concerned with is across the solenoid and that is a product of the difference between the two batteries?

Yes, the aux batteries are deep cycle AGMs.

 

[DiploStrat]

Look Here

Chris Gibson's site, Smartgauge, holds a wealth of information. He and Charles Sterling, Sr. are the two best gurus that I know of when it comes to charging batteries. They differ, greatly, on how best to do this for secondary (camper, house, domestic) batteries. Most of the time, assuming that all batteries are lead acid, I go with Gibson.

Directly to your question, this is why you might want to consider the Blue Sea relay: http://www.smartgauge.co.uk/more_relay.html (N.B. Smartguage do not sell their relays in the U.S., but the concept is the same, avoid low quality, undersized relays.)

Basically, two batteries connected together will come to the same voltage. The speed that this happens depends on the resistance between them. So, bigger wire, clean contacts, etc., results in a higher amp flow. Most of the RV industry uses 6 or 8 AWG wires and correspondingly small relays. Will this work? Yes, but it will make a slow process much slower. So much slower that you will find lots of Internet chatter to the effect that: "You can't charge your camper (trailer) battery from your alternator." A better answer would be: "Small wires cannot flow high amperage."

You can play with this calculator to see the impact of wire size on voltage drop as you change amperage and distance: http://www.calculator.net/voltage-d...ce=20&distanceunit=feet&amperes=150&x=53&y=17

This converter will let you translate AWG into mm2. http://www.rapidtables.com/calc/wire/awg-to-mm.htm

Compare:

Classic 8 AWG = 8.3 mm2.

1/0 AWG = 53.4 mm2

That is a lot more copper. I use 2x1/0 AWG and routinely see charge rates exceeding 150A.

It is the old "Speed is money, how fast do you want to go?"

N.B. You can download lots of mind numbingly pedantic information on this from my website, under "Documents."

Hope you find this helpful. (And I hope I don't have a fatal typo in here.)

 

[adventurevrogger]

Thanks again. This info about specifically about how AWG effects charging is new to me, but obviously makes perfect sense. Thanks for that.

Just so I'm clear, does the relay also work to isolate the vehicle battery from the aux battery bank, so I won't tap the starting battery while chilling beers and running other toys off the aux?

Edit: Starting to look at the documents on your website. Looks terrific. Thanks!

 

[DiploStrat]

… does the relay also work to isolate the vehicle battery from the aux battery bank, so I won't tap the starting battery while chilling beers and running other toys off the aux?
Thanks!

There are two reasons to separate the starter battery from the camper battery, one bad and one good:

-- The "bad" reason is so that you won't run down the starter battery while chilling your beer. This is "bad" only because it misses the point; you need to size BOTH batteries so that they are large enough to do the job required. I.e., start your vehicle or chill enough beers for enough days.

-- The "good" reason is that the starter and camper batteries are of different types for different jobs. The starter battery gives you a big jolt to start the truck while the camper battery gives you less power but longer and is better able to withstand a deeper discharge without damage.

You want to tie the batteries together when there is a charge present and disconnect them when they are discharging.

If you have only one charge source, your truck alternator, then a manual switch (which you can forget to turn) or a key controlled relay (which is automatic) is all you need. Add a solar charger or shore power and then an intelligent relay (smart battery combiner, voltage controlled relay, etc.) is a better bet.

Intelligent relays differ in capacity and in the details of their algorithms, but basically they all sense voltage at one, or more commonly, both batteries.

-- Charge present, determined by voltage rising, typically above 13v for a given period of time, relay closes to share the charge.

-- Discharge present, determined by voltage dropping, typically below 12.7v ("full" charge for a 12v battery), relay opens.

Thus an intelligent relay will do exactly what you want. A remote override, typically a switch on the dash or in the camper, is nice for special circumstances, e.g., self jumping or winching.

N.B. With a properly sized system and reasonable solar, a self jump won't ever be necessary until the starter battery actually reaches the end of its life.

None of this is hard, but it is a bit complex when you first look at it.

Most dual battery systems fail because:

-- The wiring is too small to move enough current during the time that the engine is running, or,

-- They use a diode isolator which introduces a 1v drop at high current.

You can also spend extra money on devices that are probably not required. See note below.

N.B. 2 If your vehicle's system does not reach at least 14v, or if you use lithium batteries, or if you have a new Euro V vehicle, then all bets are off.

 

[adventurevrogger]

Thanks again-and-again, DS.

So I'm sold on the Blue Sea ACR. Is there a wiring diagram for setting it up on truck/camper on your site or someplace already posted on these forums?

Second question: I'm also installing a solar system (i know, it's a tight fit. I might have to ditch Pluto.) Are you aware of a wiring diagram for joining these two systems, and what device do I use to switch between them?

 

[fisher205]

This is a good thread for you. http://www.expeditionportal.com/for...ke-a-cheap-isolated-dual-battery-setup-for-50. It should be a sticky and/or cross referenced with the solar FAQ.
This link https://handybobsolar.wordpress.com/ as mentioned numerous times in this forum is an excellent explanation on solar systems and maybe the moderators could permanently link it in solar FAQ also. These two links probably helped me the most as far as anything else posted. Good luck figuring your dual batteries out. Would like to see what your putting together with your Eco diesel.

 

[DiploStrat]

One Easy, One Harder

Blue Sea has owners manuals and diagrams at their site. Boat, truck, camper; it's all the same.

N.B. The "Start Isolation" and "Engine Isolation" wirings are not needed.

Truck camper is the same as my Tiger, unless you want a quick disconnect so you can remove the camper. Friend of mine has one of these, let me ask. In the meantime, ping "dwh" and see what he recommends. Methinks you want something like the connectors used to charge a forklift or a golf cart.

As for the solar, that's easy. It goes on the roof of the camper, connect it to the camper batteries. You do not need any special switching. Indeed, that is the whole point of the intelligent relay - when there is a charge, on either side, all of the batteries share the charge. When either battery drops to 12.7v (e.g., no charge present) then the relay opens so that each discharges separately.

As long as your wiring is within the ball park, ALL of your batteries will be charged any and all of the charge sources that are active. It really is that simple.

N.B. Do make sure that you in include a decent meter in the mess, either a stand alone, like the TriMetric, or, better yet, one that has temperature sensing and is integrated with your solar controller. For smaller systems, Bogart has a new controller that integrates with their TriMetric meter. Looks really nice: http://www.bogartengineering.com/content/solar-charger

 

[DiploStrat]

My friend used one of these: http://www.andersonpower.com/products/multipole-sb.html

 

[adventurevrogger]

Thanks fisher205. i've been using the "50$ dual-battery set-up" post as a guide while wrapping my head around the basic set-up. It's been great at simplifying things for me, and giving me a basic understanding of what to shoot for. Because of the relatively high output of the Ram EcoDiesel alternator it seems I'm better off going with something rated for more amperage. Based on DiploStrat's advice I've gone with the Blue Sea Automatic Charging Relay-- but obviously the same basic principles apply as made so clear over in evldave's post.

I'm just building a basic camper shell rig in the bed of the Ram, using an ARE mid-rise shell. I've built a nice little deck in there to build on top of, securing it with turn-buckles so I haven't had to drill into the truck bed at all. I'm setting-up the aux power so I can run a Dometic fridge, lights, laptops, and some sort of venting system I haven't figured out yet. The whole set-up is super compact, but one of my main goals is to stay stealthy. I want to keep the truck just looking like a normal contractor's rig rather than on overland rig-- flying under the radar, nothing to see here folks

 

[adventurevrogger]

Blue Sea has owners manuals and diagrams at their site. Boat, truck, camper; it's all the same.

Awesome! On it.

Truck camper is the same as my Tiger, unless you want a quick disconnect so you can remove the camper.

I'm just building a shell camper in the bed of the Ram. Don't think I can disconnect it from the cab

Do make sure that you in include a decent meter in the mess, either a stand alone, like the TriMetric, or, better yet, one that has temperature sensing and is integrated with your solar controller. For smaller systems, Bogart has a new controller that integrates with their TriMetric meter. Looks really nice: http://www.bogartengineering.com/content/solar-charger

Hmmm, that does look interesting. I already ordered a Tracer (Chinese) MPPT controller off of Amazon. It seemed to have a lot of positive reviews, but the super cheap-o remote monitor they sell for if had terrible reviews, but is the only device programmed to work with the Tracer. Should I cancel/return the whole cheap-o package and go with the Bogart PWM and monitor set-up?

 

[228B]

.

Should I cancel/return the whole cheap-o package and go with the Bogart PWM and monitor set-up?

.
It's the best there is! in small solar electric componentry. The Trimetric battery meter alone! is invaluable, but it's installation, although straightforward, involves using a Negative battery shunt among other, much smaller system wiring.
.
I'm saving for the meter, and if I were to build another camp trailer solar setup*, I'd use the Bogart charge controller -and- the meter. Why? 'Cause HandyBob said so. :sombrero:
.
*I had already purchased my Morningstar charge controller by the time I was introduced to HandyBob, and was too gung-ho to get my system up and running to sell the charge controller and get the Bogart Trimetric. Now, although my MPPT is delivering excellent performance for what it is... I secretly wish I had the Bogart Engineering complete setup. In time, I will. Meanwhile...
.

From HandyBob's Nine Golden Rules...
.
1. You must have a real meter to live successfully on battery power. Buy a Trimetric. Period.
.
Neither a remote read out for the charge controller or an inverter remote is a real meter...
.
---
.
9. If you bought into the AGM marketing hype [as forum user 228B did], or if you bought them because you just you cannot get to your batteries to add water [as forum user 228B cannot], you cannot check your sealed batteries with a hydrometer and you are probably convinced that equalizing is never needed, even though Life Line has now changed their minds and, as well as raising their recommended charge voltage, they are now recommending equalizing. Heresy! Undercharging AGM's is death for them. A real meter gives you the ability to watch what those expensive sealed batteries are doing and to take good care of them so you might just get your money's worth out of them. Oh, for crying out loud, the echo here is getting annoying.
.
I guess when you get down to it this Bob guy really only has one golden rule:
.
You need a real meter and you need to know how to use it. Buy a Trimetric. It will improve your life.

.
.
Granted, we may not be "living" off our batteries full-time, but that doesn't make monitoring them any less important. I still can't believe I've not purchased the meter, yet. Probably because my system, with it's completed and tested installation, isn't "in service" just yet. Yeah, that's the ticket... "not in service yet". Yeah...

 

[DiploStrat]

Get it Right the First Time

Like many others, I tend to worship at the altar of HandyBob. Don't always agree with him, but then my requirements are different.

My solar kit came from AM Solar: http://amsolar.com There are probably many other good suppliers, but there are also lots of folk who sell junk.

I use this kit: http://www.amsolar.com/home/amr/page_234_68/sunrunner_signature_40mppt4pro_core.html (HandyBob is not a fan of Blue Sky, but mine has been working well for years.)

I also have a TriMetric meter in parallel and note that the two meters are within 0.1A most of the time. Doing it again, I would not bother with the TriMetric, but I did not know that at first.

For a smaller, less expensive kit, I would go with the new Bogart system that I linked previously. Why? Because Bogart is the gold standard and their charging algorithm is probably excellent. And, HanyBob said to get a TriMetric. But do add the temperature sensing option; essential for those of us who camp a lot below freezing.

While most solar installations fail because of bad installations, small wires, bad connection, rather than because of bad components, I would still pay more for better gear. Remember, your solar charge is zero when your stuff doesn't work

If you don't want to go with Blue Sea, the Cole Hersee is less expensive and 200A should be enough: http://www.amazon.com/Cole-Hersee-48530-Battery-Isolator/dp/B00LMGPHW2 But you will want to wire up some form of manual control.

 

[adventurevrogger]

Like many others, I tend to worship at the altar of HandyBob. Don't always agree with him, but then my requirements are different.

My solar kit came from AM Solar: http://amsolar.com There are probably many other good suppliers, but there are also lots of folk who sell junk.

I use this kit: http://www.amsolar.com/home/amr/page_234_68/sunrunner_signature_40mppt4pro_core.html (HandyBob is not a fan of Blue Sky, but mine has been working well for years.)

I also have a TriMetric meter in parallel and note that the two meters are within 0.1A most of the time. Doing it again, I would not bother with the TriMetric, but I did not know that at first.

For a smaller, less expensive kit, I would go with the new Bogart system that I linked previously. Why? Because Bogart is the gold standard and their charging algorithm is probably excellent. And, HanyBob said to get a TriMetric. But do add the temperature sensing option; essential for those of us who camp a lot below freezing.

While most solar installations fail because of bad installations, small wires, bad connection, rather than because of bad components, I would still pay more for better gear. Remember, your solar charge is zero when your stuff doesn't work

If you don't want to go with Blue Sea, the Cole Hersee is less expensive and 200A should be enough: http://www.amazon.com/Cole-Hersee-48530-Battery-Isolator/dp/B00LMGPHW2 But you will want to wire up some form of manual control.

Done, and done.

Returning the MPPT charge controller and remote monitor that arrived last night, and "Doing it right the first time". This still counts as the "first time", right?

I've double-checked, but just to double-double-check, these are the droids I'm looking for, yes? http://solar.altestore.com/search?p=Q&rs=1&rstotal=1&w=TM-2030%20TriMetric%20Battery%20System%20Monitor&rsdate=2015-07-22&rsloc=1... plus shunt.