Help understanding battery Group # sizes

[abosely]

I could use a bit of assistance in understanding the differences in Group battery sizes, such as 34/78, 34, 34R & 78. Going to be using a duel battery set up, with one isolated for starting and anything needed to run engine only. It's a Land Rover 300Tdi so don't need huge battery, but want it on the larger size so won't be pulling it down a lot. Space isn't really an issue, so would prefer to be on the larger size.

The second battery will be for vehicle lights, fridge, basically anything else that uses power on the vehicle, but no winch. I would like to use a large deep cycle battery for this but in the range of 'normal' size batteries, not some odd over size battery. I understand that size doesn't necessarily equate to amp hours, but looking for the Group size options. Probably will be using NorthStar batteries.

The vehicle is a 69' Series IIA SWB, that I've built custom HD chassis, FJ60 diffs & modified axle housings, 4 wheel discs, rear FF conversion, 300Tdi, Stubby R380, LT230, 2' military style lift, Rocky Mountain parabolic springs, rear springs in front flipped (so front chassis horns only need to be extended 3-1/4") new bulkhead, rebuilt tub among other things. I have a build thread on FB, 69' Series IIA Build. I started a build thread here on the Land Rover forum when I was getting started on the build, I'm going to update it now that I have a bit more done.

Cheers, Allen

 

[john61ct]

http://www.batteryweb.com/bci.cfm

 

[john61ct]

The best battery value by far is Duracell (actually Deka/East Penn) FLA deep cycle golf cart batteries, 2x6V, around $200 per 200+AH pair from BatteriesPlus or Sam's Club.

99.9% of 12V automotive form factor are labeled fraudulently, not true deep cycling.

 

[john61ct]

If you need AGM then Northstar is good.

Also Lifeline and Odyssey.

But more expensive, harder to charge to spec, and won't last as long as FLA.

 

[abosely]

I don't know if I really need AGM batteries or not, most likely will be able to mount them up right, so that is a help. Forgive me for asking such a basic question, I know I could research it myself, but what are the salient differences between AGM and FLA batteries in this kind of application. I would want to have maintenance free ones as it isn't going to be as easy to get to the batteries as when under the hood.

It seems that AGM batteries are touted as the latest and greatest thing. lol

If you need AGM then Northstar is good.

Also Lifeline and Odyssey.

But more expensive, harder to charge to spec, and won't last as long as FLA.[/QUOTE]

 

[abosely]

John, you make an interesting point, I remember now reading about using two 6V deep cycle batteries instead of a single 12V if there was room to mount them. I don't remember all the points that were made as to the advantages, but remember thinking that would be the way to go, at the time.

Do they need to have the 'water' level checked and topped off or are the maintenance free, or nearly so?

What about them being mounted under the tub floor, if wading through water, would this harm them, or would they need to be mounted in waterproof boxes?

The best battery value by far is Duracell (actually Deka/East Penn) FLA deep cycle golf cart batteries, 2x6V, around $200 per 200+AH pair from BatteriesPlus or Sam's Club.

99.9% of 12V automotive form factor are labeled fraudulently, not true deep cycling.[/QUOTE]

 

[john61ct]

No all differences already at least implied above.

Nice having access to cell electrolytes for hydrometer SG diagnostics.

Also no harm done overcharging long as you keep up with water. Should be checking connections regularly anyway.

Overgassing AGM can't put it back.

Little extra work is IMO well worth the greater value $ / AH / year.

But many are willing to pay lots more for a little convenience.

Watch your weights per unit for hand-hoisting too!

 

[john61ct]

Standing in water doesn't hurt one more than the other, don't allow top or wiring to short of course

but you do want acid resistant tray at least under FLA.

Don't seal the box completely unless you also vent from the top to outside.

 

[abosely]

John thanks for the info and input! That answers my questions and concerns, It won't be a problem making them accessible from a hatch in the tub floor. As you say, should be checking on the connections and general condition regularly anyway. So two GC2 6V batteries and one FLA starting battery and I'm golden. I want to keep the two systems separate.

Cheers, allen

 

[john61ct]

A VSR / ACR / combiner is the best way if you need charging both directions.

Being able to handle high amps across the connection makes them pricey, e.g. self-jumping off House if Starter fails.

https://www.bluesea.com/products/7620/ML-ACR_Automatic_Charging_Relay_-_12V_DC_500A

Most cost-effective is to wire all charge sources direct to House, then a little Echo Charger keeps Starter topped up.

https://shop.marinehowto.com/products/xantrex-digital-echo-charger

PS checkout the electrickery HowTo's at this site, golden learning. . .

 

[abosely]

A VSR / ACR / combiner is the best way if you need charging both directions.

Being able to handle high amps across the connection makes them pricey, e.g. self-jumping off House if Starter fails.

https://www.bluesea.com/products/7620/ML-ACR_Automatic_Charging_Relay_-_12V_DC_500A

Most cost-effective is to wire all charge sources direct to House, then a little Echo Charger keeps Starter topped up.

https://shop.marinehowto.com/products/xantrex-digital-echo-charger

PS checkout the electrickery HowTo's at this site, golden learning. . .

I really like the BlueSea Auto Charging Relay, online they're not too bad, $165 for the one with switch and remote switch. This would be worth it for the ease of setting up the system and gives option of self jump starting.

Thanks for this information, things just got a lot simpler for me now. I'll check out the HowTo's also.

Cheers, Allen

 

[restorationrides]

I could use a bit of assistance in understanding the differences in Group battery sizes, such as 34/78, 34, 34R & 78. Going to be using a duel battery set up, with one isolated for starting and anything needed to run engine only. It's a Land Rover 300Tdi so don't need huge battery, but want it on the larger size so won't be pulling it down a lot. Space isn't really an issue, so would prefer to be on the larger size.

The second battery will be for vehicle lights, fridge, basically anything else that uses power on the vehicle, but no winch. I would like to use a large deep cycle battery for this but in the range of 'normal' size batteries, not some odd over size battery. I understand that size doesn't necessarily equate to amp hours, but looking for the Group size options. Probably will be using NorthStar batteries.

The vehicle is a 69' Series IIA SWB, that I've built custom HD chassis, FJ60 diffs & modified axle housings, 4 wheel discs, rear FF conversion, 300Tdi, Stubby R380, LT230, 2' military style lift, Rocky Mountain parabolic springs, rear springs in front flipped (so front chassis horns only need to be extended 3-1/4") new bulkhead, rebuilt tub among other things. I have a build thread on FB, 69' Series IIA Build. I started a build thread here on the Land Rover forum when I was getting started on the build, I'm going to update it now that I have a bit more done.

Cheers, Allen

I agree that the overall form factor does not necessarily dictate the greatest capacity rating. But, in my experience, I'm usually limited in the overall space that I can insert the battery or batteries into.

With this in mind, I can usually find one or two or three groups that are the best fit for the space. (BTW, the "R" typically means reversed +/- poles compared to the standard version.)

Once I find those groups, then I look at their CCA ratings to determine which one has the most storage capability.

But, in all cases, I only use AGM style batteries at this point in time. Both theoretically and experientially, I find them to be vastly superior to traditional FLA technologies...

Regards,
RestorationRides

Sent from my REVVLPLUS C3701A using Tapatalk

 

[abosely]

What do you find superior about the AGM style batteries over the FLA types? Does this apply to starting type or also to deep cycle batteries? I don't need really high capacity for this application, as it's going in, well under the rear tub, of a 69' Series IIA SWB, granted it's pretty well custom built, but it's not a vehicle that I'll live out of for weeks at a time. Plus I'll be building a M416 style type trailer that will have a small house battery bank 2 batteries at most.

I have a FB page about the build, 69' Series IIA Build, check it out, let me know what you think.

Cheers, Allen

 

[john61ct]

A battery even having a CCA rating usually indicates not suitable for deep cycling use.

AH quoted at 10- and 20- hour discharge rates, cycle-lifetime graphed against average DoD% is what you should be looking for.

AGM's advantages over FLA are: ability to install lying sideways, no need to check water levels, and less fumes. That is all.

But the disadvantages are: they cost more, don't last as long, require higher-amp and finer charge regulation, are easily damaged by overcharging, require getting to true 100% Full more often, and unable to measure SG.

 

[DaveInDenver]

A battery even having a CCA rating usually indicates not suitable for deep cycling use.

AH quoted at 10- and 20- hour discharge rates, cycle-lifetime graphed against average DoD% is what you should be looking for.

AGM's advantages over FLA are: ability to install lying sideways, no need to check water levels, and less fumes. That is all.

But the disadvantages are: they cost more, don't last as long, require higher-amp and finer charge regulation, are easily damaged by overcharging, require getting to true 100% Full more often, and unable to measure SG.

All totally valid points. One thing you might have mentioned is AGM tends to handle shock and vibration better than flooded. That's one of the major reasons Optimas caught on in the first place. Their construction can make them more immune to failure being bounced around. It wasn't really rare for a battery to give up suddenly from the plates getting jarred and shorting, which is almost unheard of anymore now that AGM are more widely used in 4WD circles.

I'd like to suggest though that we (as in OHV and 4x4 crowd) tend to lump all lead-acid batteries as fungible and the marketing of AGM doesn't exactly discourage this. But technology of VRLA has evolved quite a bit over the past decade or so to the point that industries are starting to use them in traditional FLA applications. They can last longer exhibiting less aging and requiring less maintenance and venting, which are not small advantages when you consider UPSes are necessary in more and more out of the way places for telecom and remote sensing.

When you approach the application with realistic goals and accept that FLA and VRLA must be treated as distinct technologies you start to see potential benefits. If you just substitute a VRLA/AGM for a FLA and expect benefit doing nothing else it's usually going to be a failure, which is often what you hear ("I dropped in an Optima and it only lasted 2 years!") and it's totally predictable.