Starting batteries instead of deep cycle

We easily power a 1100 watt (line input, not cooking power) microwave with our two Costco 6-volt GC2 batteries (110 amps DC). Briefly powered a 1250 watt coffeemaker with no issue, but generally we use a smaller k-cup coffeemaker that only draws 750 watts.

If I was having similar problems as the OP I'd be checking voltage at the battery and inverter terminals under maximum load. With the batteries fully charged, the voltage at the battery terminals shouldn't drop much below 11.8 volts or so with a 100-120 amp load (with two GC2 batteries). Ideally, I’d strive for no more than a 2% (.24v) voltage drop between the battery and inverter terminals with a maximum load. Any irregular voltage readings might be indicative of a bad battery, too small battery/inverter cables, or bad connection/ground.

ajriding wrote:

burningman wrote:

ajriding wrote:
No, just no to the OP.

Starting a motor is WAY more draw than any inverter you would be using. Your inverter is still only requiring a slow discharge from the battery. I'll stop here

I got the much-touted two-six-volt Trojans. Now my inverter won’t run my coffeemaker.
I had two 12-volt Costco marine/RV batteries. I always just used regular starting batteries before that. The screwy thing is, they would run it.
These real deep cycle Trojans just can’t put out enough current at once.
.

I'd have to do more research. My first thought is not that the batteries were not up to snuff, but maybe the wiring or something else is happening on this one incident. If you are pulling so many amps that a marine battery cannot keep up then I suspect that you are demanding more than 1000-1500 watts of a coffee maker or that there are other issues preventing a free flow of amps to the always inefficient inverter.
I have started cars with one marine battery and I do not suspect that a coffee maker on an inverter requires more amps than a starter motor.

This rigidness of resisting the camping lifestyle when camping seems to be costing RVers a lot of money (in this case for batteries they really do not need). Getting in an RV mindset means using RV-friendly coffee makers, which probably will run on propane, not electricity. Many things RV are designed to be efficient on what the RV offers. Those that want the exactness of house living usually buy brand new class-A motorhomes with huge generators they plan to run all the time.

I would ditch the idea of creating enough power to run a house and get on board with the camper life.

I have 2-0 “double-ought” cables that are about two feet long. That sure isn’t the problem.

I’m talking about electricity and making some gear I own work the way I want it to.
Not whether you think I “should” have my electric coffeemaker.
I can throw a few batteries in and still be WAY below what lots of guys are spending on new F450s and new Rams to carry their camper on.
This setup worked on regular old batteries. That’s probably what I should go back to.

burningman wrote:
I got the much-touted two-six-volt Trojans. Now my inverter won’t run my coffeemaker.
I had two 12-volt Costco marine/RV batteries. I always just used regular starting batteries before that. The screwy thing is, they would run it.
These real deep cycle Trojans just can’t put out enough current at once.

I understand what starting batteries are for and how they’re made.
I also see what the 6-volt deep cycles can’t do that my old conventional batteries couid do. So what’s a guy to do?

If it ain't broke,don't fix it..

The internet is ruining RVing,making it way more expensive than it has to be...So many things work and have worked for years but there all but black listed on the net and anyone that does it that way is a neanderthal..Laffin

Kayteg1 wrote:

zcookiemonstar wrote:
... This system was designed with AGM deep cycles not starting batteries. If starting batteries were a better option I think they would have use them here.

AGM batteries are another sample how customer can be fooled by sales pitch overwhelming common sense.
The only advantage of AGM batteries in any application is that they can work upside down, or lay on its side + they have higher charge ratings.
Sadly they don't last long.
In older Mercedes cars we had flooded battery lasting 13 years, when in newer models AGM batteries seldom last longer than 4 years.
You can still buy flooded starting batteries with 96 months warranty, when the best warranty on AGM is about 1/2 of that.

No the reason for the AGM in this case is because they are in a house and do not off gas like a flooded battery so less need for venting to the outdoors.

Point was not for the AGM but the deep cycle battery.

burningman,

The answer is in the cell count. A pair of marine 12 volts have 24 cells. A pair of six volts only have 12 cells. So the demand per cell is twice as high.

Many batteries are rated at 25 amps per cell.

burningman wrote:

ajriding wrote:
No, just no to the OP.

Starting a motor is WAY more draw than any inverter you would be using. Your inverter is still only requiring a slow discharge from the battery. I'll stop here

I got the much-touted two-six-volt Trojans. Now my inverter won’t run my coffeemaker.
I had two 12-volt Costco marine/RV batteries. I always just used regular starting batteries before that. The screwy thing is, they would run it.
These real deep cycle Trojans just can’t put out enough current at once.
.

I'd have to do more research. My first thought is not that the batteries were not up to snuff, but maybe the wiring or something else is happening on this one incident. If you are pulling so many amps that a marine battery cannot keep up then I suspect that you are demanding more than 1000-1500 watts of a coffee maker or that there are other issues preventing a free flow of amps to the always inefficient inverter.
I have started cars with one marine battery and I do not suspect that a coffee maker on an inverter requires more amps than a starter motor.

This rigidness of resisting the camping lifestyle when camping seems to be costing RVers a lot of money (in this case for batteries they really do not need). Getting in an RV mindset means using RV-friendly coffee makers, which probably will run on propane, not electricity. Many things RV are designed to be efficient on what the RV offers. Those that want the exactness of house living usually buy brand new class-A motorhomes with huge generators they plan to run all the time.

I would ditch the idea of creating enough power to run a house and get on board with the camper life.

ajriding wrote:
No, just no to the OP.

Starting a motor is WAY more draw than any inverter you would be using. Your inverter is still only requiring a slow discharge from the battery. I'll stop here

I got the much-touted two-six-volt Trojans. Now my inverter won’t run my coffeemaker.
I had two 12-volt Costco marine/RV batteries. I always just used regular starting batteries before that. The screwy thing is, they would run it.
These real deep cycle Trojans just can’t put out enough current at once.

I understand what starting batteries are for and how they’re made.
I also see what the 6-volt deep cycles can’t do that my old conventional batteries couid do. So what’s a guy to do?

Two thousand dollars for a pair of lithium’s isn’t happening. I don’t use this camper enough to justify what it already cost, much less adding that. That’s 142% out of the question.

No, just no to the OP.

Starting a motor is WAY more draw than any inverter you would be using. Your inverter is still only requiring a slow discharge from the battery. I'll stop here

zcookiemonstar wrote:
... This system was designed with AGM deep cycles not starting batteries. If starting batteries were a better option I think they would have use them here.

AGM batteries are another sample how customer can be fooled by sales pitch overwhelming common sense.
The only advantage of AGM batteries in any application is that they can work upside down, or lay on its side + they have higher charge ratings.
Sadly they don't last long.
In older Mercedes cars we had flooded battery lasting 13 years, when in newer models AGM batteries seldom last longer than 4 years.
You can still buy flooded starting batteries with 96 months warranty, when the best warranty on AGM is about 1/2 of that.

Not sure how much it relates but I have a battery back up sump pump system. My system uses a 1/2hp A/C pump. The system uses two 12 volt 100 ah agm deep cycles and a 24 volt dc to 120 volt A/C inverter. The system is designed to run several hours during power outages. Sump pumps are high inrush shorts runs over and over. This system was designed with AGM deep cycles not starting batteries. If starting batteries were a better option I think they would have use them here.