which? two 6 volt or one 12volt battery?

[Bbasso]

This is for a house battery question.
Will not be connected to the engine starting batteries.

I've got plenty of room for either.
So which would last longer, better results and a smarter decision?

Two Trojan T-105 6 Volt, 225 Ah Deep Cycle Battery
Or
A single 12v 8D-AGM
?

I have no clue on my power consumption but I'm frugal and sooner than later will do a simple 100wt. Solar setup. But for now this will be getting charged through an isolater from the vehicle's alternator. ( if that makes a difference in choosing the battery)

I would like to be able to add more 12volt storage later...

Thanks!

If I left out any info, ask so I can get the best advice possible.

 

[wrcsixeight]

GC batteries are usually the most durable batteries, and most bang for the buck.

But they offgass. If they are to be installed in a passenger compartment, then AGM is better as they only offgass if severely overcharged.

A single 8d battery weighs 125-150 lbs. Can you move this by yourself into intended location?

In general it is not good to parallel new batteries and old batteries. The new batteries will quickly "age" to the level of the older batteries, meaning reduced capacity and less than expected.

Plan on getting alternator power to additional batteries sooner rather than later, and wire it with fat wire (2awg or fatter) and do not use the old finned heat sink diode based isolators, but use a solenoid, smart dumb or latching to ensure proper charging voltages can reach the distant house battery bank.

Prompt and regular recharges extend battery life. Leaving them to discharge slowly and leaving them there is batterycide.
Complete dependence on alternator recharging leads to a chronically undercharged battery and less than expected lifespan and performance during it.
A good grid powered charger applied every so often and directly after an outing ensures maximum performance and lifespan.

 

[zelatore]

I hate dealing with 8D batteries just for the sheer difficulty of moving them. Keep in mind it's one thing to heft that 130+lbs standing in the warehouse, but it's quite another to actually put that battery into some awkward position. I work on yachts for a living, and regularly curse designers who put big heavy 8Ds into places even two men working together have difficulty getting them into.
I prefer the 6v battery pair for house loads, and in general I prefer AGM to any other style as well. Safer and most importantly (at least on a boat) lower maintenance. Few people these days comprehend the idea of checking the water in their batteries. AGMs eliminate that.
Any reason you wouldn't want to go with 6v AGMs? That would give you the best of both worlds. The only downsides are cost and weight as the AGMs are more of each.

Another options would be to look at Rolls batteries. They make a line of 2v 'cells' that you link together into a single 12v battery. Available in a variety of capacities, but you can build massive battery banks out of them. And each 'cell' is small and light when it comes time to change them.

http://www.rollsbattery.com/

 

[Bbasso]

I don't have any preference in which I choose other then staying reasonable affordable and least worries about problems. I don't mind maintenance, or how big, heavy or awkward. Once it's in place it's very unlikely to be moved again. Venting if needed shouldn't be an issue, I'll do what's needed (making holes for breather tubes/stuff ĺ

As for what's in the van atm, I'm not sure but tomorrow I'm buying it and taking it home. Then I'll know for sure, but the current owner said it's one 100ah battery getting power through an isolater.

I plan on building it up and using it a lot. Having steady electric on board is important to me.

 

[wrcsixeight]

Are you going to be doing a lot of the work yourself?

Venting flooded batteries to the exterior of the van is not so cut and dried, and if you are going to be stationary charging, you will smell flooded batteries charging.

In general, "isolators" are the Diode based lossy devices which guarantee undercharging when the alternator is the primary method of recharging. When the house battery is low, you should check and write down the voltages at the alternator, the engine battery, and the house battery at both idle speeds and at higher rpms.

A clamp on AC/DC ammeter will be an awesome tool and great investment as you gear up toward " steady electric on board"

It will allow you to see the current flowing through any single wire. Most people would be shocked to see just 8 amps flowing into their thirsty house battery from their 130 amp alternator. The majority prefer to remain ignorant and believe in the power of the magical all powerful alternator, at least until the batteries can "no longer take a charge".

Then they blame the battery.

 

[Bbasso]

I just picked up the van about an hour ago and it has dual alternators. Yippee!
I'm going to take a picture of the current setup. Tell me what you think, please.

 

[Bbasso]

 

[wrcsixeight]

That marine battery box is good, in a boat, but will be venting fumes into the van, and right onto the surepower isolator. Sparks? Better than not having a battery box but venting it to the exterior is still a challenge.

Looks like fat cabling was used from alternator (+) which is good.

Not sure of the voltage drop across that isolator. Minimum 0.3, max 0.7v

If I had 2 alternators, the second one would be dedicated to the house battery, and no separator/isolator would be necessary.

 

[Bbasso]

It came with the van, hard to complain lol

 

[wrcsixeight]

It came with the van, hard to complain lol

I'd be interested in seeing how much voltage was making it to a depleted battery in that battery box.

Since it is likely that it is clipped and will never raise into the 14's, the actual amount of offgassing caused by alternator charging is very little, the result from this being undercharging, and shortened battery lifespan.

If you really want a simple improvement, google 'Blue Seas ACR', and if you want to not worry about offgassing, get an AGM, or build a battery box below the floor with a sealing access hatch for watering, and perhaps installation and removal from above.

Or You can leave it as is and just resign yourself to replacing the battery more often and possibly smelling charging fumes.

Even if one spends hundreds and tries to get the perfect recharging system, the batteries will still wear out, albeit it, slower.

One must factor in the stress of worrying about getting the best recharging system, vs just replacing the batteries more often, and hoping it is not too inconvenient to replace when they can no longer meet one's needs.

 

[4RunAmok]

The use of a charge isolator while having two alternators seems curious.

I would do anything in my power to get rid of that surepower isolator. This is a diode type isolator that will cause a lot of voltage drop because of the diodes, and connected batteries will NEVER get a full charge as a result of the loss.

If the battery inside the box is not an AGM, I would change it to one ASAP, and hook the main battery to the stock alternator, and hook the new AGM battery to the AUX alternator. Having two alternators also allows you to mix the battery types within your system. You would not want a Flooded Cell and an AGM charging from the same alternator, since the AGM recovers and charges faster than a Flooded Cell, you run the risk of overcharging the AGM, thus killing it. Putting each battery on its own alternator solves this problem, and now you can throw that isolator in the trash where it belongs.

 

[Bbasso]

My van has two starting batteries, what of them?
(Only a few months old)

 

[wrcsixeight]

Are you saying that there are 2 starting batteries in the engine compartment and another battery in the back, in the box, or that you have two batteries total and then one in back is a starting battery as well.

If two in the engine compartment, congrats on having a diesel

 

[zelatore]

I would assume the two starting batteries are in parallel; effectively one big battery.

 

[jbob]

I would assume the two starting batteries are in parallel; effectively one big battery.

Yeah, he probably has one under the hood and another on the passenger-side frame rail wired in parallel. Seems like he'd want to run one alternator to that battery bank, and the other to the house battery or batteries (and ditch the isolator).