Dual Battery System Management Recommendations?

[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]

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! :Wow1: 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]

- 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.........

 

[cruiseroutfit]

Another satisfied National Luna customer, zero complaints. I had the chance to meet with the engineer when he was in town last fall and get a one on one demonstration of how they are built, how they work, repairing faulty units, etc. Great product.

I run an older Wrangler NW system on my FJ40, it manually switchable (as is the overideable Luna) and it has served me flawlessly for 9 years now.

 

[Michael]

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

I didn't really do a cost comparison as the wiring rigs provided with the commercial products would not have fit my system. My sense is that I saved money doing it myself in view of the complexity of the system. Much of what I installed would have needed to be added to a Hellroaring or National Luna system. That said, the cables (#4 awg etc) weren't cheap and having the critical connectors sweated on at a battery shop (didn't want to do the high-current ones with just a compression fitting) cost a few bucks too. More info in another post here. I also went back and forth about the types of isolators but decided on the Blue Seas ACR because it had some nice features. Sometimes you just gotta pick one. I'm completely satisfied with the performance of the system for my needs and I guess that's what counts.

In the end, it all comes down to what works for you and what you can afford when you need to install it. I intentionally over-designed my system as I didn't want any problems whatsoever regarding safety or capacity. For instance, my choice of battery was in part determined by finding an AGM battery that had a vent port so I could run a vent tube outside the shell (old submariner habits die hard). I'll add a few more photos and a wiring diagram to show what else is handled by the aux power system.

There is some great info in this thread that should help people decide what they need. One bit of advice by wikid was right on -- you have to maintain the health of your batteries by a periodic deep cycle "smart" charge as well as monitoring how deep you discharge them. If you don't, your batteries will have a shorter life.

 

[ExpoMike]

So why would this not be a good system to go with? It looks to be fully automatic but had both a remote override and manual override. Seems like the best of both worlds. Plus it is rated for 500A continous and 1200A max with a 300A load switching.

http://bluesea.com/application/41/products/7622

Edited: Also, this is a magntic latching relay, so once latched, it claims a >10ma current draw

 

[MoGas]

K.I.S.S.

This is the setup that I have.

Dave

 

[theksmith]

K.I.S.S.

This is the setup that I have.

Dave

i can appreciate simplicity, you have to just choose between ultimate simplicity versus in-cab convenience and fancy monitoring... different stuff appeals to different people.

i guess in order of complexity, it goes: manual boat switch, remote boat switch like the last post, manual/remote boat switch with isolator, hellroaring style full system, national luna or ibs style full system.

the only thing i don't understand about your setup... do you run around most of the time with it switched to "both" so they can both charge, and have to remember to switch back to just "primary" every time you turn off the truck so that you don't accidentally discharge "backup" somehow by leaving something on?

or do you just run in the "primary" position nearly all the time and not maintain constant charging on the "backup" battery, just relying on it's ability to hold a charge for a few months?

 

[MoGas]

...the only thing i don't understand about your setup... do you run around most of the time with it switched to "both" so they can both charge, and have to remember to switch back to just "primary" every time you turn off the truck so that you don't accidentally discharge "backup" somehow by leaving something on?

or do you just run in the "primary" position nearly all the time and not maintain constant charging on the "backup" battery, just relying on it's ability to hold a charge for a few months?

I run starting batteries in both positions right now and just switch between battery 1 and 2 every time I check the engine oil. (every fuel fill up). If I am running the winch, I will put them both together. If I am running the fridge while stopped to camp for the night, I just run the rig on #1 and let #2 run the fridge, then when I start up, I go over to 2 so it can get a good charge if I'm not going very far. If I will be running all day after an evening fridge draw, I'll just leave it on 1+2 until I am camped for the night so they will both be charged up, then

When one of the starting batteries go, I'll put a deep cycle on the 2 position and just charge it every once in a while when not in use for the fridge or some other constantly running device. Or, more likely, I'll put Die Hard Platinums in both slots and only separate the 2 when I am camping for the night and want to be sure that I have one fully charged for the morning start-up.

On the other hand, I know guys that live in Phoenix, who have been running one battery for years, with a fridge going 24/7, with no issues. They drive their rigs daily, though.


Dave

 

[ntsqd]

Avoiding that exact issue is why I've gone to using the VSR/ACR in parallel with the boat switch. I can leave the switch set to "One" and the ACR/VSR will keep the aux battery charged without my having to open the hood every time that I drive the truck.

The flip side is that if the truck won't start off the primary battery, maybe I should open the hood to have a look at what's going on before self-jumping? Even if I know what's up and don't need to look under the hood, the compactness and self redundancy really appeal to me.

The only downside that I see to the large current ACR is the price of entry. I'd still combine it with a paralleled battery switch for redundancy.

 

[keezer36]

There's another issue:

If I am running the fridge while stopped to camp for the night, I just run the rig on #1 and let #2 run the fridge, then when I start up, I go over to 2 so it can get a good charge if I'm not going very far.

How long is this going to take? Of course there is no one answer for all vehicles and all batteries in all situations. Bit it is reason to consider some type of monitoring. There is also Xantrex monitors. I looked at them some time ago, what you might save in other areas would be spent here.
The only comment I have ever heard on charging time from any credible source was on Car Talk (NPR radio). It was said that on average it takes about 40 minutes at highway speed to charge your battery. Take that with a grain of salt. I call them credible because they both went to MIT which officially puts them in the forty pound head category in my book.

 

[craig333]

K.I.S.S.

This is the setup that I have.

Dave

Same system I use in the Jeep and the camper. Nothing to fail. Does require a bit more manual effort.

Camper stay on both unless I'm worried about having enough power to start the engine. Jeep gets switched back and forth regularly. But its easy to do since its in the dash. I don't expect anyone else to cut a hole in their dash. Works for a 1960 CJ5 though

 

[THATSALEXUS?]

One thing that I notice about alot of dual battery setups is the tendency to "what if" yourself to death. My personal favorite method merely involves a solenoid or a Sure-Power 1315-200. It will do what 95% of people doing dual battery setups are trying to accomplish and is relatively simple and it's a no brainer configuration.

Best of all it's relatively inexpensive (probably a little over $100 in parts) and you can make changes or upgrade things pretty easily. Sure solid state relays are nice but they haven't proven themselves to be any more reliable than a high quality solenoid. Want a gauge, add one. No problem. I think this will give most people what they are looking for, for the least expense and with minor variations, can be personalized to specific needs.

Here are the main attributes of this system:


Batteries are islolated when key is off

Batteries parallel when key is turned to accesssory position (this eliminates a dead aux battery from dragging down the good battery during start

If front battery is fully drained, jump start switch will manually parallel batteries