Coach Battery Life (Death)

[camaraderie]

Originally Posted by 360true

Follow-up.... Had the coach batteries tested. No load 12.6 with load 11.9 for each individually +/- .1 NAPA says they are fine.

Research: my xantrex inverter draws 1.3 amps. My fridge draws 1.5 running with 8 amp starting with ice maker off. There is other phantom draw like smoke detectors etc.

Test: unplugged shore power. All lights, fans etc off. Just the inverter and the fridge. Start battery bank 12.6 volts which dropped to 12.4 in a couple of minutes.

Then steady regular drop of available voltage testing every 15 minutes. Hit 11.9 in only two hours, when inverter beeped to warn of low power. Restored shore power charging voltage 13.4.

This help anyone figure out why only two hours with four 12 volt batteries only one year old?

Thanks. Signed Confused....

Are you perhaps mixing up AC amps with DC amps in your calculations?
Example...a fridge drawing 1.5 amps running is roughly 15 amps DC. 8 amp starting would be 96 amps briefly.
I still think you need a clamp meter to understand your amp (DC) draw in use. You can also then pull fuses or plugs to see where the big current draws are coming from. I recently found a short in my leveling system harness caused a huge draw down on my batteries. You'd never guess that looking at voltage panels.
I do agree that your batteries seem to be in good shape.

[formerFR]

Originally Posted by ppine

Wet cell batteries do not last when used often. They should never go below around 12.3-12.4 volts. Consider stepping up to AGM batteries.

again, someone who is espousing supposed information about something that is totally NOT true....
I have four 6v deep cycle RV FLA(Flooded Acid) 'wet cell' batteries in my coach, and they are the 'factory' installed ones from almost 5 years ago, and still going strong - I regularly use them when off-grid and they normally discharge down to 11.8 or 11.9 before I charge them for 30minutes with the generator. They also sometimes automatically cutoff the Inverter when they drop to 11.5 when I don't want the generator to start during overnights.

92,000 miles and many, many overnights off-grid, whether walmart, or Alaska, or a no-hookups campground...

I check the water levels infrequently, and add water as needed.



I'll have to disagree with your 'assessment' of wet cell batteries ...
they are actually the 'best' for RVs, for the money...

[360true]

Originally Posted by camaraderie

Are you perhaps mixing up AC amps with DC amps in your calculations?
Example...a fridge drawing 1.5 amps running is roughly 15 amps DC. 8 amp starting would be 96 amps briefly.
I still think you need a clamp meter to understand your amp (DC) draw in use. You can also then pull fuses or plugs to see where the big current draws are coming from. I recently found a short in my leveling system harness caused a huge draw down on my batteries. You'd never guess that looking at voltage panels.
I do agree that your batteries seem to be in good shape.

Cam
Good info. didn't know that doc amps were not the same as ac amps. Will begin now to story to trace down a short. Will keep y'all posted!

[tomkatb]

A real outside possibility in wiring.

If you have a big inverter tied into the ac panel, not a couple of plugs.

The inverter could be trying to power the converter. Real outside but, does happen.

A clamp on meter would be handy to check inverter out put.

That would wipe out a battery set overnight.

[360true]

Cam
You suggested that: Example...a fridge drawing 1.5 amps running is roughly 15 amps DC. 8 amp starting would be 96 amps briefly.

But the fridge is not drawing DC amps, it is drawing ac coming from the inverter. Wouldn't I just need to measure the DC amp draw of the inverter with the fridge running?

[camaraderie]

Originally Posted by 360true

Cam
You suggested that: Example...a fridge drawing 1.5 amps running is roughly 15 amps DC. 8 amp starting would be 96 amps briefly.

But the fridge is not drawing DC amps, it is drawing ac coming from the inverter. Wouldn't I just need to measure the DC amp draw of the inverter with the fridge running?

I was really making the point that if you don't distinguish between what type of amps (AC or DC) you are looking at...you could be grossly underestimating the drain on your batteries.
Batteries are the source of your inverter and they ONLY supply DC amps. On the other hand, a domestic refrigerator draws AC amps from the socket. If the spec on the fridge is 1.5 amps AT 120 Volts... that is the equivilent of 15 amps at 12 Volts...both numbers multiplied equal the same 180 WATT draw (ampsxvolts), Of course that is in a perfect world and you inverter will also suck some battery power (usually around 10% of total). And yes... IF the fridge is the ONLY thing plugged into your inverter...then CLAMPING the RED inverter wire to the battery while the fridge is running will give you the DC amp draw of the fridge. Likewise...clamping the main red battery wire will give you total DC amps being drawn by everything in the camper...or being put back into the batteries by your shore power & converter.
Hope this clarifies.

[360true]

It does, thanks.