Dual Battery System Management Recommendations?

[Trail Monkey]

National Luna all the way...

[Michael]

Originally Posted by theksmith

I know this has been discussed before, but I'm looking for recommendations for the most current products and also if anyone that owns a specific system can tell me for sure if it meets my requirements.

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After looking at the commercially available power management systems, I decided to go the DIY route with my aux power system in my '06 Tacoma. I wanted to keep my stock battery for stock items only and put all the extra 'gadgets' (nav system, radios, Engel 35, GPS, inverters, etc) on an aux battery. I've learned to never trust my memory, so I wanted the system to charge automatically when I drove. To meet that wish-list, I started by adding an aux battery in the shell with a multiple fuse box, fuse, and isolation switch. I ran a #2 ga cable from the back to the eng comp and a fused #8 ga cable from the back to the cab to power accessories. I put a 1-2-both switch, a Blueseas 7610-SI-Series ACR, and an 80 amp fuse under the hood. I removed the ganged cables on my OEM battery's positive terminal (alternator, ECR, etc) and installed them on a fabricated 'power tower' near the OEM fusebox that gets its power from the 1-2-both switch. The end result is that the batteries charge automatically (photo of green light is LED charging indicator in cab), separate/isolate when under load, and either battery (or both) can be used to start the truck as needed. Lots of details left out for brevity here. A few photos follow. This set-up should work with almost any vehicle that has room for an extra battery.

Wiring diagrams, parts lists, more photos, etc available if this looks like it might work for you.

[ersatzknarf]

Very nicely done !
Thanks for posting that.
How do you think that going the DIY route compared in cost to say the NL set-up ?



Frank

[keezer36]

Originally Posted by theksmith

i'm still on the fence... but i understand more about the products now... i get that the products brake down into basicly either a big solenoid with some microprocessor controlling it (national luna and IBS kits), or a solid state switch (hellroaring).... what are the pros/cons to each type (sure the solenoid kits come with fancy monitoring controllers, but what else are the differences that might really matter)?

it seems a solid state switch can handle more continuous current but draws more power when running? is the solid state device like hellroaring better at charging 2 batteries when one is full and the other is nearly dead (i know with a regular solenoid connecting the batteries in parallel with that condition results in a very slow re-charge of the nearly dead one)?

Not sure your question about charging can be answered with any great degree of accuracy in that it will be dependent on your charging system as a whole. All you need is one poor connection or one cheap item to degrade the entire system.
I will say I went with the Hellroaring not because I found anything negative about the National Luna but that the kit did not suit my needs. That being, I had no use for the cabling provided and preferred to purchase everything separately.
Regardless of which unit you go with, do read through the FAQ's at Hellroaring's site if you haven't already done so. Particularly the diagnostics available. He gives a lot of good basic info about setups in general like having your better battery as the backup. News to me.
Speaking of my setup, I always have a surface charge indication at my remote switch and can take my main battery out and crank my engine through the unit and a total of 20' of 2 AWG in winter. I did this for about two weeks last winter while I was shopping a new main battery. Check in the box.

The more you dig into this, the more questions you'll have, until you bump into the engineering side of things and either cry uncle or learn math.

[theksmith]

so i spent lots of time reading today about this and even called hellroaring (very nice and helpful on the phone).... here's what i come away with for those that may want lots of info before making a decision:

there are 5 types of battery management systems that i count...

1. a manual high-current switch with A/B/BOTH selectors (a "boat switch")

- there are no "smarts" to the system, it only does exactly what you tell it, this can be good and bad (good that you have full control, but bad as you could leave it set to "both" and leave something on thereby depleting both batteries and having no backup)

- when in "both" mode, the batteries are not isolated in any way, i.e. if one is a different physical type that rests at a lower voltage, it will always be trying to discharge the higher resting voltage one

- good in the fact that you wouldn't have to remove a completely shorted battery physically from the system. i.e. you could just set the switch to "B" if "A" had completely shorted out.

- doesn't work well remotely... i.e. you need to mount the switch near the batteries or else you are going to have to run 3 cables of some very large gauge wire all the way to wherever the switch is (i've seen it done, but not practical for most people)

2. a "boat switch" and a battery isolator (such as from sure power or perfect switch)

- all the same characteristics as just a "boat switch" but without the worry of one battery "bleeding" the other, the batteries are isolated in that only charge current goes to both of them, but no current transfers between them

- i my opinion this would always be the way to go in a completely manual system, you wouldn't want to just go with the boat switch when you can pickup and isolator to use with it for pretty cheap

3. an intelligently controlled solenoid system (national luna or IBS for example)

- in this case a solenoid (high current relay) acts as the "boat switch", except in all systems i know of, you only have "A" and "BOTH" settings. the big plus is that you run a small cable to a remote controller to set the state of the solenoid instead of having to run giant cable in order to relocate the "boat" switch (and the solenoid stays near the batteries).

- the intelligence is in the form of a small microcontroller that can monitor either ignition state and/or time and/or each battery's voltage, and based on that information set the solenoid switch to "A" or "BOTH"

- - when i say monitor ignition-state/time/voltage, it depends on the system. some merely tie the batteries in parallel (i.e. the "BOTH" setting) when the car is running and for a few moments after the car has been shut off, then it sets everything back to the main battery (i.e. the "A" setting). other systems may be smarter and actually look at each batteries voltage and the incoming voltage and sense that it's ok to tie them together when there's a supply voltage (i.e. the car is on) and then sense that if for any reason one of them starts to loose voltage (bad battery, whatever), it shuts off feed to that battery.

- ussually these systems have an override so that when you want to, you can manually set the batteries in parallel (the "BOTH" setting) for winching power or for starting from the backup ("B") battery.

- the only downside compared to the "boat switch" + isolator method is that in most systems you only have the "A" and "BOTH" setting, you have no pure "B" setting... i.e. if your "A" battery actually shorts out, then you will have to physically remove it from the system... you wouldn't want to switch to "BOTH" in that scenario. now if your "A" battery is just low (more typical situation), then you can safely switch to "BOTH" in order to start the car still.

- these manufactures will tell you a solenoid (high current relay) is tried and true simple switch that is less prone to failure than fancy digital switches

- national luna and IBS both offer fancy remote controllers with voltage monitors for both batteries, audible alarms, etc.

- IBS's "BOTH" setting is timer based so you can't easily leave them connected for too long. national luna's "BOTH" setting has a warning light to show you it is engaged.

- IBS's system handles 500 amps (200 continuous) whereas national luna is rated at 400 amps (85 continuous). note the continous rating is very different, might matter for when you want to tie both batteries together for a large winch.

- IBS and National Luna are about the same price, and i hear that Etreme Outback is carrying the IBS system even though their site doesn't show it yet (according to winter overland journal).

4. in intelligently controlled digital switch (hellroaring for example)

- pretty much the same as the intelligently controlled solenoid except that the solenoid is replaced my a modern digital switch

- these manufactures will tell you a digital switch is supposedly better technology than a solenoid which can get contacts stuck, worn, corroded, or filmed (opposite of what the solenoid people say, i tend to believe that modern solid state electronics are better than traditional high current relays, but this is personal opinion).

- hellroaring uses the voltage monitoring method of intelligent control instead of just a timer and ignition switch check.. i.e. if you alternator fails then it will sense the non input voltage and isolate your backup battery so that you aren't draining them both. a lesser system might just know that the car was runnign and therefore assume it was safe to tie the batteries together for charge when in reality it would be letting them both run dead.

- hellroaring has a remote switch module that lets you put the system in "A", Automatic, or "BOTH" but doesn not have fancy voltage monitors (you could add these yourself for cheap). it also does not have a timer circuit (so you are more likely to accidentally leave it set to "BOTH" and then potentially run both batteries down).

- hellroaring handles 500 amps (150 continuous)

- hellroaring is a fair bit less expensive than national luna or IBS, but doesn't offer nearly as fancy of controller interface

5. some "i did it this way" method that use pieces from the above types of systems

- i guess the ultimate system would be to use 2 digital switches (probably from perfect switch, as they supposedly have the best digital switch) and your own custom microcontroller that would allow you to have all the system sensing and control qualities of national luna/IBS/hellroaring products, but with a "B" setting too (instead of just "A" and "BOTH"). add to that your own digital voltage readouts of both batteries and custom control panel with override switches and timers and audible alarms.

the above would be $$$ and room for errors since it's a custom system instead of a tried and true system tested by thousands of users.

more reading:

http://www.nationalluna.com/DIY.htm
http://www.hellroaring.com
http://ibs-tech.ch/en/products/dual-...ith-uproc.html
http://www.surepower.com
http://www.bluesea.com
http://www.perfectswitch.com/power-g...ge-controllers

so what am i going to do?

well i'm about a month or so from actually finishing up my battery relocation project and therefore being ready to purchase a system. i'll have to look at my funds when the time comes. i won't do a "boat switch" based system because my batteries are going in my spare tire well in the trunk and i don't want some janky looking giant switch run into the cab, i want a clean remote control.

i'm completely satisfied with what hellroaring offers for the price. i think it's a great system and if funds are tight i'll get it.

if i feel like splurging, i'll get the IBS sytem just for the fancy controls and voltage monitors... it's about the same price as national luna and offers more current handling and timer based "BOTH" setting, and if indeed extreme outback is willing to carry it, then it must be a good product.

please add to this if any of my facts are incorrect, otherwise most things are just my opinion... your mileage my vary.

[wikid]

I have been running the National Luna for about 2 years with absolutely zero problems. I will qualify that by saying, you need to monitor your system and keep track of battery management. Don't let them run down too far, Plugging my frig into A/C when using it for extended periods at home. I have a CTEK Charger conditioner permanently mounted and wired in to maintain battery health . It's actually very little work. You just need to be aware of your conditions and workload.

[AKRover]

For what it's worth I had a sure power smart solenoid battery interconnect thing in my 95 Range Rover. It sounded like the perfect solution because I wanted to use my batteries together but I wanted to be sure that I always had at least one for starting.

I had it installed for about a year and during that whole time I had the weirdest electrical gremlins ever. Things like the entire electrical system shutting down for a second while driving down the highway and things like that. Being a Rover owner I took it in stride as kind of "normal" until I decided to pull that thing out and see what happened. After that everything has returned to normal. It's probably just a Rover thing.

It's for sale if your interested.

[TangoBlue]

Originally Posted by theksmith

so i spent lots of time reading today about this and even called hellroaring (very nice and helpful on the phone).... here's what i come away with for those that may want lots of info before making a decision:

there are 5 types of battery management systems that i count...

WOW! Great job - this is the best explanation I've had of all the systems together. Thanks for your initiative!

[ntsqd]

The combo that I prefer is a "smart" solid state relay combined with the 'boat' switch, which is a variation of one of your list items. Sized correctly the boat switch can handle full starting or winching current (up to 1000 amp surge is not an unreasonable switch capacity) and the "smart" SSR will handle the charging function independent of the boat switch's setting (excluding a "both" setting as then it is redundant).

There are single sensing and dual sensing "smart" SSR's available. The former only senses the Aux battery's state of charge while the latter senses both and discriminates.

AFAIC diode bridges ("battery isolators") have no place in a vehicle's battery charging system. They can be made to work, but that requires a customized alternator. Something that I see no point in as it makes field repairs or replacement a problem.

[01tundra]

Originally Posted by theksmith

- IBS's "BOTH" setting is timer based so you can't easily leave them connected for too long. national luna's "BOTH" setting has a warning light to show you it is engaged.

FYI - My National Luna's over-ride for "both" operation is timed automatically to terminate in 5 minutes if the user does not manually terminate before the 5 minutes is up.

Taken directly from NL's manual -

"When active, the “TIMER OVER-RIDE” light
will flash and will remain active for 5 minutes only.
Use the same procedure to de-activate the timer “over-ride”."


Oh yeah - and after actually "reading" the operating instructions for the first time.......a few minutes ago (oops ), I noticed that they say to not instantly try to start the the truck off the reserve battery in the event that the primary is dead, because it could result in blowing the systems in-line fuses. They say to wait a few minutes after hitting the over-ride button and allow the reserve battery to charge the primary. Well I can tell you from experience that the fuses will not necessarily blow because I've had to jump myself off twice.............due to accidentally leaving the ignition on all night after working on my truck (getting old and forgetful sucks !) and as soon as I hit the over-ride I cranked the truck right up both times.........