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?

[SCClockDr]

ib516 wrote:
So is my math correct?

Two 208 AH 6V batteries (416 AH at 6V) would = 208 AH(?) at 12V for ~$300

Why is this an advantage over two 105 AH 12V deep cycle batteries which would be 210 AH for $220?

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

Generally the GC 6 volt jars are preferred as the plates are stouter and there is more space between the bottom of the plates and battery floor for debris thus protecting the plates from shorting.

[ib516]

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

Can you elaborate? 🙂

[red31]

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

[ib516]

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)?

[ib516]

corvettekent wrote:
Get the two golf cart batteries. When you had the 11.7 voltage reading was that after or during the inverter use? You should take the reading after the battery has rested for awhile.

11.7 was resting. 10.9 - 11.1 when drawing power for coffee. With the low voltage alarm screaming away...

[ib516]

Converter is a 45 amp ITOA. Based on the sound the generator makes (Eco-Throttle on), it seems to bulk charge for 30 min, charge at a lower level for the following 60 min, then go to a slow charge. The volt meter I have wired in reads 13.1 or 13.2 immediately upon the gen being fired up, then it slowly goes up to 13.3 or 13.4. When plugged into shore power for a while, it will read 13.5 or 13.6.

[red31]

make coffee when the gen is running, heat it up on the stove in the morning. or cold brew and heat up.
Keep using single Costco G27 and replace regularly.

add 200 watts of solar with controller that matches proper charging for use/storage as to replace batt less often.

[korbe]

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

[MEXICOWANDERER]

Love that handle 🙂

• You ran out of power with the one battery?
• You need more amp hours capacity regardless
• The CCA of your bank is not sufficient to run your inverter for making coffee
• You promise to not be a battery water miser
• A pair of GC220 batteries do not offer enough CCA to operate at great discharge levels - not in their job description
• The AGM batteries would fit the upcoming job description perfectly if you were Trump's brother-in-law
• A pair of Johnson Controls batteries would double your ampere hours
• And the Costco batteries would double your CCA rating for the coffeemaker

Double the amp hours, and double the CCA rating with a pair of "Costco" batteries is tempting isn't it? How would they stack up against a pair of "ideal" AGM batteries like the Concord Lifeline?

Selecting extremely high CCA AGM batteries would be silly because even a pair of flooded 6 cell Costco batteries would work for the coffee maker. What would extreme deep cycle batteries like the Lifeline to to convince a crying wallet the met the job requirements?

They would lost longer than other AGM batteries. I would not be afraid to take the Concorde's down down 40% state of charge repeatedly. The voltage slump when making coffee would be far less than if using the flooded Costco batteries. It means significantly faster brewed coffee.

The AGM battery accepts more amperage. So when running a generator to reharge more amps will flow for a longer period of time. Less Canadian priced gasoline - and generator runtime versus the flooded Costco batteries would be significantly less.

How long to amortise (For BFL13's sake) AGM increased initial cost with saved gasoline? Several hundred generator hours.

Price adjustment of 300% cost of AGM cost versus lifespan? Will the AGM last 3-times as long as the Costco flooded? Yes.

Now take a huge eraser. If your method of recharging batteries is not up to par then srub off everything above. Your converter must agree with what the (any type) of battery requires or the above is a pipe dream.

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.

[SCClockDr]

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)

[time2roll]

I recommend 4x GC2 for that usage.

[corvettekent]

Get the two golf cart batteries. When you had the 11.7 voltage reading was that after or during the inverter use? You should take the reading after the battery has rested for awhile.