Dual batteries: Fancy kit or regular kit?

[CanuckMariner/Nomad]

I'm sorry but I'm bewildered by the info above. All the better battery companies write technical papers. I like to think that companies that make batteries for commercial aircraft and ocean going vessels know their products. Marine electrical design is a huge and serious business. You don't see Optima Red or someones expensive hobby battery separator on a real boat.

There's no reason to believe Optima Red Top is a deep cycle battery. They infer a lot of features but provide no comparable specs. Actual AGM deep cycle batteries take a high charge through the absorption phase. Battery life is rated by the number of deep discharge. Intentional deep discharge will shorten life.

The NL thing seems to be made in some guy named Ed's basement. A marine automatic charge relay is much higher quality and spec. The NL blinky lights can be replaced with a $25 digital voltmeter/alarm. That's two purchases instead of one but it saves $150+ and is much nicer equipment. Put $100 towards a battery not marketed by color and pocket $50.

All the products in this thread are directly comparable on technical merit alone. This isn't a "Land Rover or Range Rover" type discussion.

Blue Sea
VoltMinder
Lifeline

Edit: I'm sure the BEP products are fine too. Any of the mainstream marine switching product sold to ocean going vessels will be very high quality. Cheaper automotive electrical products are suppose to cost less.



.

I don't believe I said the red top was a deep cycle battery which it is not, I simply used it as an example as a previous post mentioned it was used as a starting battery, what Optima recommends. Also it has the side connections which are not recommended for winch use.

Nothing mentioned about Land Rovers/Range Rovers. Don't know where that came from.

Otherwise I do not see what you are getting at. Sorry?

 

[Hedge]

OK, here's my question: when, if ever, would it be advantageous to power devices (fridge, lights, inverters, stock vehicle electrical loads, etc.) from separate busses? It seems to me that a second battery should serve only two functions:
- a temporary parallel power source when winching for extended periods and the main battery/alternator combined output is not sufficient to power the winch
- a starting backup if the main battery has been drained from the aforementioned loads while the alternator is off (engine not running).

If the loads are split between two separate busses then there would be a risk of having two dead batteries, thereby negating the self-jump-starting feature of the second battery. Thus it seems to me that the ideal setup would be a main battery that is responsible for starting and all accessory loads, while the secondary battery would be a backup starting battery that is isolated from loads when the alternator is off so as to avoid having two dead batteries.

 

[evldave]

OK, here's my question: when, if ever, would it be advantageous to power devices (fridge, lights, inverters, stock vehicle electrical loads, etc.) from separate busses? It seems to me that a second battery should serve only two functions:
- a temporary parallel power source when winching for extended periods and the main battery/alternator combined output is not sufficient to power the winch
- a starting backup if the main battery has been drained from the aforementioned loads while the alternator is off (engine not running).

If the loads are split between two separate busses then there would be a risk of having two dead batteries, thereby negating the self-jump-starting feature of the second battery. Thus it seems to me that the ideal setup would be a main battery that is responsible for starting and all accessory loads, while the secondary battery would be a backup starting battery that is isolated from loads when the alternator is off so as to avoid having two dead batteries.

The ideal battery technology that starts your truck is different than the ideal battery technology to run electronics for extended periods of time w/o charging (starting battery vs deep cycle).

In a perfect world, you would have your starting battery run ONLY the starter, and your deep cycle battery run everything else in the truck. This is kinda hard to do in modern vehicles, but not impossible.

In the real world, you generally end up splitting the 'factory electronics' to the starting battery and the 'house' or aftermarket electronics to your deep cycle. This means if you plug in your fridge to the factory 12v plug in the truck (starter) and have your 12v heated blankets for your RTT (deep cycle) running at the same time, you run the risk of hosing both batteries at the same time.

Most people run the 2 (deep cycle) line throughout their truck so they can pretty much run as much as possible from the backup battery.

 

[Viggen]

I went with a Power Gate from Perfect Switch. I didnt go with a Luna kit because it was more than I needed and skipped the Hell Roaring kit because I actually wanted to use my second battery. The HR kit does little more than act as a trickle charger for the aux battery to allow for self jump starts. The Power Gate is easy to set up and allows for pure second battery isolation so I can run the accessories constantly and not worry about the starting of the truck later. It works with what I want out of a system. Its perfect, efficient and doesnt lose anything through heat (most of the Hell Roaring kit is a heat sink), handles 150+amps without a problem, very easy to set up and is completely hands off in its operation. Ill have it installed on Saturday, hopefully, so a review will be coming soon...

 

[OptimaJim]

Another thing that is good for all batteries (AGMs, etc) that are rechargeable from the bottom up (read NOT the factory starting battery), it is a good idea to discharge (leave head lamps on over night) them routinely. Then recharge with a normal charger to about 6 volts and then use a smart charger (trickle) to get them back to the 12.5-13.5 volts (as per Optima/Interstate instructions). Like all rechargeable batteries, they will forget (hysteresis) the portion of the battery that is not used over and over again. Optima either does it at the factory or recommends complete discharging of a new AGM batteries before use. Extends life for up to +50%. Additionally, when an item is not used continuously, like a camera or net book PC, which is used with a rechargeable battery, it is better to remove the battery, fully discharge it and store it like that until just before use.

Hello, I noticed our batteries being mentioned in this conversation and I wanted to clarify our position about battery maintenance. I can't speak for all AGM manufacturers, but I'm going to respectfully disagree with Jan's suggestions about totally discharging our batteries. Fully-charged, our RedTops will measure approximately 12.6-12.8 volts and our YellowTops will measure approximately 13.0-13.2 volts. We do not recommend completely discharging our batteries. In fact, the key to long battery life for lead-acid batteries (including AGM batteries) is to make sure voltage never drops below 12.4 volts. When lead-acid batteries are discharged below this level and allowed to sit, sulfation will diminish both capacity and performance. This is especially important when these batteries are stored for extended periods of time.

I understand that the Internet is full of misinformation, so if Jan or anyone else has come across information that contradicts what I just posted, please send me a link, so I can correct that as well. Thank you!

Jim McIlvaine
eCare Manager, OPTIMA Batteries, Inc.
www.facebook.com/optimabatteries