Battery questions

[ib516]

I know there are some very knowledgeable folks on this topic, hoping you'll chime in.

Current set up is a small 17' hybrid that HAD a new (Costco), single group 27 12v (105 AH) battery. I use a 2000w inverter generator to charge it using the on board converter. I also have a 2500w modified sine wave inverter attached for running a 760w coffee maker in the morning before generators are allowed to run (9am to 1030am and 5pm to 7pm ONLY). Well, I completely fried that G27 battery (Costco brand). I neglected to check the water level and had to add about 500-750mL of distilled by the time I thought to check it. Also, the 5 min it took to brew a pot of coffee would basically kill the battery. It would go from 12.3-12.4V down to 11.7-11.6V to brew one pot.

So, I got rid of the G27 12V battery, and need an upgrade.

Here are my options:

• 2 of the same Costco (but new) G27 12V 105AH batteries that I will be more diligent at checking electrolyte levels
• 2 12V AGM batteries ($$)
• 2 Costco 6V golf cart batteries listed as 208AH @ 6V

Which of these would be best?

[sportsman_500]

Been lurking here following this thread. I have a similar question but different hardware. I have a Kuerig coffee maker that brews one cup at a time. The initial warm-up lasts around or under 3 minutes drawing 1500 watts. The water tank re-heat cycle after brewing is 200-400 watts and lasts around 60 seconds. At idle the Kuerig draws 60 watts.
I would be running this with a 3000 watt inverter solely for the coffee maker. Trying to keep weight down I would like to keep it to 1 group 27 or 31 deep cycle. How long do you guys think the one battery would go if starting from fully charged?

[SoundGuy]

To the OP ...

One thing that seems to be missing in this conversation is how much, how frequently, you rely on battery reserve alone. :h Unless I've missed it the only thing you've mentioned is being able to run your coffee maker ... if that's the case a single G27 can handle the task. The trick is to load support the trailer's battery with your truck idling, just as I do. Without it, the inverter under heavy load from a toaster or coffee maker is likely to alarm but with load support it won't come anywhere near close. Obviously this isn't a solution for those who regularly dry camp without shore power but for those of us who only intermittently do so and have limited requirements load support works just fine and certainly simplifies battery reserve requirements. Considering this, perhaps you can better outline just what you expect these batteries and inverter to actually power, and how often. :@

[dave17352]

I agree with the Mexican. Two AGM"S would work just fine. They are cut out for delivering a lot more power a lot quicker. They also charge a lot quicker. Less generator run time. They are sealed so you won't forget to maintain them. The perfect choice. Unless of course you want to spend the big bucks for lithium but they have some other rather extensive requirements, you probably don't want to deal with.
Also lets keep the batteries right next to each other and the inverter right next to them.

🙂

[OldSmokey]

SCClockDr wrote:
Golf Cart batteries X2.
A 2K inverter can draw 200 DC amps, your coffee maker will draw 75 DC amps. A 100 AH battery can deliver 50 AH's of service. It is unlikely the 2 GC batteries will reliably completely brew your morning coffee given the RV has been drawing current all night & evening.

The above #'s are simplistic rule of thumb for easy in your head calculation.

I would recommend a stove related brewing solution. (That's camping)

760W @120V from a typical 90% efficient inverter is (760*1.1)/12 = 69.6 Amps

need more coffee ? :B

[OldSmokey]

ib516 wrote:

red31 wrote:
do your store the trailer in shade?

battery care is all year long.

No, but when I'm not using it, I disconnect the battery. Parasitic loads will kill it in about a week to 10 days otherwise.

Also, being from Canada, the trailer sits in storage for winter. I then remove the battery and bring it inside and put a 2 Amp charger/maintainer on it for a few days a month.

to be honest, battery and inverter for coffee is just wrong..
get a stove top percolator, use the battery for lighting and you'll be happy.

[ib516]

red31 wrote:
do your store the trailer in shade?

battery care is all year long.

No, but when I'm not using it, I disconnect the battery. Parasitic loads will kill it in about a week to 10 days otherwise.

Also, being from Canada, the trailer sits in storage for winter. I then remove the battery and bring it inside and put a 2 Amp charger/maintainer on it for a few days a month.

[red31]

do your store the trailer in shade?

battery care is all year long.

[ib516]

I could add a 100w solar panel and a cheap charge controller for ~$200....problem is where we camp in the mountains, the sites are either 100% shaded, or only have direct sunlight for a couple hours a day. Not sure it is worth the hassle.

From my limited knowledge, a 100w solar panel, in full sunlight will produce about 6 amps...and if I get full sun on it for a couple hours, I'm only recovering 12 AH, so not sure it would be worth it.

[Matt_Colie]

Let's just be honest with this guy.

You can't do what you want with what you have or even what you can add easily.

Even if you go to 2ea GC2s (which will handle the short term load in spite of what has been said here), your generator and converter charger will not be able to recover the bank past 90% in the 3.5 hours of generator time you are allowed even if you upgrade the converter to a 65 (about what GC2s can handle) be they either Progressive Dynamics or Iola. It just takes too long.

It may sound goofy since you are only asking for about 7.5 AH (including the Peukert function), but the fact is that recovering the top of the charge density where it is hardest because the chemistry cannot tolerate the plate voltage needed.

Go to the Progressive Dynamics site and read all about this.

You do have a single bar-cost option. Get a LiPo bank of over 100AH and use that. It can be recovered in as little time as you can provide power to do. Though the drag-down will not be good for it, it is not as bad as it is for a Pb/H2S jar.

One thing that seems to be missing here is how long you want to do this. If it is the two days of a weekend and then you will drag to PU home and hook it to shore power, the batteries (a pair of GC2) could stand that and with a good three stage (that is really 4 including the storage mode) converter, you could be ready to go the very next weekend.

I did a lot of this stuff for performance cruisers (read retired racing sloops) before the depression killed the business. This was not an uncommon issue.

Matt

[MEXICOWANDERER]

A pair of group 27 batteries has the potential of close to 80 amperes initial charge acceptance.

[MEXICOWANDERER]

The average G220 battery has a CA rating of 425 ampere hours at 20c. A single Johnson Controls group 27 battery has close to 550 CCA. And the 6-cell group 27 did not cut the mustard.

Defenders of a pair of golf car batteries, please defend your recommendation.

[MrWizard]

No your math is wrong
Your two sixs can be 416 @ 6v
Or 208 @ 12v
It can Not be 416 @ 12v

When batteries of the same voltage are paralleled you add the Amphrs and voltage stays the same

When batteries are put in series you add the volts, and the amp hrs stay the same

75 amps is high current for a 6v battery, remember they are in series to get 12v , like flashlight cells

Two 12v in parallel would only need to deliver 37.5 amps each

If you were not making inverter powered coffee with high amp load , i would recommend the two 6v, which are great for lighting etc..
As it stands, i recommend the two 12v agm in parallel
These can produce the needed amps to power the inverter without being severely damaged like your previous single 12v

Do run the generator for the full 4 hours each day,
When you can, adding some solar would be very good for the batteries

ib516 wrote:
So is my math correct?

Two 208 AH 6V batteries (416 AH at 6V) would = 208 AH(?)

The 6V batteries are $150 each, the 12V batteries are $110 each.

So I guess my question is....
Why would I be better off paying $300 for 208 AH (Two 6 V batteries) versus $220 for 210 AH (Two 12V batteries)?

[time2roll]

+1 for IQ controller. You should see the battery climb to 14.2+ volts for an extended period.
Some OEM IOTA don't have the port.... check first.

[SCClockDr]

korbe wrote:

SCClockDr wrote:
.......I would recommend a stove related brewing solution. (That's camping)

I would recommend a stove top percolator. But, since the OP wasn't asking about that, I think I'll hold off on that recommendation until later. :B

Agreed!
With the size of TT involved options are limited, hence I strayed.

[red31]

ib516 wrote:

red31 wrote:
6v are better DC batteries but don't have umph for your inverter!

Can you elaborate? 🙂

MEXICOWANDERER wrote:
A pair of GC220 batteries do not offer enough CCA to operate at great discharge levels - not in their job description
This leads directly to interrogation about your converter make and model. It has now rudely broken into your plans about which battery to buy. Remember, a mere pair of golf car batteries ain't gonna ut it.

you need to add the Iq4 and start taking better care AKA FULLY charge, solar!

http://www.iotaengineering.com/iqx.htm

gen charging in the 13.5v wastes fuel and does not charge fast enough for the limited charge windows, solar!