Batteries

[HC-1 phil]

I have two house batteries that are a lot smaller than the group 27 I installed for the engine. They have no info on them that I can find.

[Skip426]

Quote:

Originally Posted by HC-1 phil I have two house batteries that are a lot smaller than the group 27 I installed for the engine. They have no info on them that I can find.

Sounds like someone put group 24's in, if they have 6 cell caps , possible not deep cycle. If your having any power problems , take them to Autozone/Napa for a free load test, also measure your available space, Including height, and consider installing,a pair of 6volt golf cart style batteries, for longer use time when boon-docking .

[wa8yxm]

IF they are wired in parallel, and have six caps or two triple caps (or look like they do if maintenance free) they are likely G-24 around 75 amp hour each.

If they need replacement like my G-31's do, and you can accept a slightly higher battery, Check out the GC-2 Golf car battery, If it will fit in the tray (It is taller) you will get quite a bit more capacity.

[DAN L]

Quote:

Originally Posted by HC-1 phil I have two house batteries that are a lot smaller than the group 27 I installed for the engine. They have no info on them that I can find.

where is your battery compartment located?
maybe it is in the stairwell as mine is. i installed 2 lifeline gpl-6ct 6v agm batteries from bd batteries online. these batteries are 13 1/4'' tall and weigh 90# each. they fit nicely on their sides in my battery tray. i went from about 190 ah capacity to 300 ah capacity.
there are pictures of my installation on this forum.
5 years ago these 2 batteries cost me $700 including shipping. kinda pricey but they are working very well.

[BryanL]

don't fall for the 'deep cycle' and '6v golf cart battery' myths!

A good retailer will be able to find batteries to replace your current set and will stand behind what he sells. Use cost, warranty, and specifications in purchase decisions and be very very careful about claims that do not have good measures behind them.

re: "i went from about 190 ah capacity to 300 ah capacity." -- what that means is that you increased the weight of your battery bank by nearly 60%. The energy density by weight of all lead acid batteries is very close to 45wH/kg (re batteryuniversity.com). That means that an RVer can expect to get about 12 usable watt hours per pound of battery (using the 50% DoD discharge target - see smartgauge.com). Check the spec sheets for batteries and you can see this.

[DAN L]

Quote:

Originally Posted by BryanL don't fall for the 'deep cycle' and '6v golf cart battery' myths! A good retailer will be able to find batteries to replace your current set and will stand behind what he sells. Use cost, warranty, and specifications in purchase decisions and be very very careful about claims that do not have good measures behind them. re: "i went from about 190 ah capacity to 300 ah capacity." -- what that means is that you increased the weight of your battery bank by nearly 60%. The energy density by weight of all lead acid batteries is very close to 45wH/kg (re batteryuniversity.com). That means that an RVer can expect to get about 12 usable watt hours per pound of battery (using the 50% DoD discharge target - see smartgauge.com). Check the spec sheets for batteries and you can see this.

what happens when you lay a flooded cell battery on its side? it makes a mess, doesn't it.
not so with agm batteries. my 5 year old lifeline agm batteries are working very well laid on their sides.
my point is that i was able to increase my battery bank capacity by nearly 60% (Bryan's calculations) by buying premium batteries that fit in the original location with no modifications.
a bonus is that there is absolutely no corrosion and i never need to add water.(can't even if i wanted to)
i do not discharge my batteries over 50% often and i expect to get at least another 5 years of service from them.

[BryanL]

re: "what happens when you lay a flooded cell battery on its side?"

oh, geeze ..

Very few RV's operate on their side or even very far off level (more than, say a 20% grade for the logical fallacy seeking crew) and wet cell batteries do just fine for RV service.

now, an aircraft used for aerobatics might present a different situation ...

It is super wonderful that you have enough room in your battery bank compartment (compliance with code assumed, of course) and sufficient available cargo capacity to be able to increase battery capacity significantly without any adverse effects on mileage, handling, or other things.

But I wonder just how much utility going from 2.2 to 3.6 (1.1 to 1.8 nominally usable) kWh is actually gained in light of the fact that a rule of thumb for RV battery reserves is typically 3 days; factors such as temperature, age, use profile, and cycle to cycle variation can each have more than a ten percent influence on available battery capacity' and typical non-restraints daily consumption runs at 30 kWh or more.

As for corrosion and needing to add water - I take care of that by using proper equipment to charge and maintain my battery bank.

AGM's are nice batteries. They generally cost about twice as much as wet cells and can be expected to have a lifespan 50% longer if properly used and maintained (re NAWS FAQ). When it comes to energy density by weight, AGM batteries tend to be a bit below the mean - calculate it yourself!

A suggestion: let's keep the context that of the RV community covering say, out to maybe 4 standard deviations or so from the mean. Let's avoid rationalizing fantasies by pretending what isn't.

[wa8yxm]

Quote:

Originally Posted by DAN L what happens when you lay a flooded cell battery on its side? it makes a mess, doesn't it. not so with agm batteries.

That is the one special case where I actually suggest AGM's, and the reason for it.

Just so you know.

My 5 year old AGM's have been bottoms down for all five years.. and they are now paper weights.. Good for nothing but keeping things from blowing away in the wind.

My six year old GC-2's still going strong

My even older G-29 flooded wet cell (And to think i thought it was a maintenance free) is not going strong, but it's in better shape than the AGM's it was partnered with.

But you are right.. If you got to mount them any way other than "This side up" AGM is the way to go.

[Dave78Chief]

HC-1 Phil,
To determine the size you currently have, you should be able to derive that from the physical dimensions and look it up on the chart here: BCI Battery Group Size Chart

From the wiring diagrams for your rig, it looks like yours was originally supplied with two 12VDC Deep Cycle batteries. Not sure what the original size was though. Measure the space you have available and then you can use that table to narrow in on a battery size that will fit in your space. 6 Volt batteries are listed at the bottom of the Table.

There is some good deep cycle guideline information contained here: DEEP CYCLE BATTERY FREQUENTLY ASKED QUESTIONS

There are a lot of brand names so look to see whats available in the size you need.
Marine Batteries | RV Battery
Trojan Battery Company
Johnson Controls Inc. | Battery Basics

Dave