Charging Amps engine alternator vs Generator

The drop in voltage will explain the amps. Compare the source voltage to the battery voltage.

Going to check the alternator this morning with the ammeter. The volts at the battery this morning are 12.41 or 70%. They must not have been fully charged as the amounts used since we stopped to camp show 24 amps drawn. That's about right.
Going to check engine battery volts at battery and scan gauge. Then start engine, will check volts at battery, scan gauge snd house battery monitor. Then have DW rev engine to 2K and recheck all again. Should tell me what's going on?????

The procedure with the VEC1093DBD is to charge till it says FUL,(actually about 97%) then turn it off and back on, set to WET, set to the 4 amp setting, and push the Equalize hidden button so the green light flashes.

Let it run till it says FUL again. Now check the SG with an hydrometer. If not up to your baseline SG (spec SG with batts new--eg 1.285 for new Interstate 6s) run another Equalize till it says FUL again. That should do it for getting back to baseline SG.

That closely replicates the three stage charging profile recommended here (but with a higher voltage Finish stage), and it has worked very well with my 6s now almost four years old and still at baseline SG. Love my 6s, love my VEC :)

http://pdf.wholesalesolar.com/battery-folder/charging_instruction_2011_2.pdf

From the OP - could it be my alternator isn't putting out what it should. My DW moticed a squeal under the hoohd. I thought it was my belt and sprayed it with belt dressing. I changed the belt 3 1/2 years ago. Maybe 25k in miles. So maybe it's the alternator squealing.

Sagecoachdriver,
Your measurements all seem about normal. Your new house batteries, fully charged should be around 12.7. Your used chassis battery might measure a bit less. Don't trust those indicator lights, they're only good for a night light. If you want to see voltage at a glance, replace the indicators with an inexpensive meter.

If your rig is set up like most RV's, you'll always have some parasitic draws from radios, circuit boards on appliances, and alarms.

If you wish to have totally accurate battery SOC measurements, the hydrometer will be the best tool. It's better to establish a base line SOC using the hydrometer so that reference in the future can be made accurately. Different batteries will have a different baseline specific gravity but most are close.

Because your batteries aren't really full. You might have gotten them to the low 90% range. Voltage does not tell all. Different charging methods are required for dry campers.

from the OP-- Out here dry camping at the beach. New battteries were charged with a Vector Smart Charger 40 amp. Took about 5 hours to get to full. Then I installed the batteries. The sat for 2 days with the Inteli -power converter charger attached. I watch the amps slowly drop on the Xantrex battery monitor down to zer0 charging over those 2 days, It was fully charged this morning when I disconnected my shoreline power. After sitting for an hour or so before we took of on this trip, the voltage was 12.8 volts at the battery monitor. Now to confuse me. The engine battery was fully charged before leaving using the Vector charger again. However, when we arrived at the beach, the Xantrex battery monitor read 12.7 volts and the battery /tank monitor reads 2/3; not FULL????
Something is screwy with this system. I just checked the Xantrex battery monitor and it reads 12.7volt and down 8.3 amps after 9 hours on house batteries. I checked the battery connections at the Inteli-power converter/charger from the battery. It read 12.45volts. I went outside and checked the house new house batteries themselves with the ammeter and got 12.45volts. The battery/tank monitor reads 2/3. If I only used 8.3 amps which sound exactly right for my 9 hours on the batteries, how come everything is showing 75-80%. It should be down only 5-10%.
Could the alternator not be charging the house batteries whle driving and the engine is drawing off the house batteries?

MEX wrote:
Has anyone worked up a chart that reflects generator run watts versus charger potential limitations? Maybe that would be a help.

You bring up a subtle point that I have been trying poorly - and with minimum data other than personal experience - to make for quite some time in the forums.

In boondocking areas where generator use presents no problems to other campers any time of day or night, I'm not convinced that a small generator run for hours is a less efficient way to trade fuel for electrical storage than using a large generator run for way less hours to trade fuel for electrical storage.

In other words -

1) Are small gasoline four-stroke generators less efficient than larger gasoline four-stroke generators?

AND

2) Do lead acid (wet or AGM) batteries charge more "efficiently" (not talking charge speed here -> efficiency is not necessarily related to speed) when charged fast .... or when charged slow?

Of course if you have to run a rather largish generator for hours anyway for daily air conditioning, I guess is doesn't matter at what speed it's replenishing the batteries so long as it gets the job done during the air conditioning cycle. :h

As an example, we camp with friends who run a very quiet itty-bitty little four-stroke generator every evening for 4-5 hours to bring up their batteries while watching evening TV - so they're probably restoring 30 to 35 amp hours somewhat slowly and very quietly each day. We camp with them in places where they can get away with this procedure.

(By pure coincidence we have the same itty-bitty generator model as they and sometimes use it the same way.)

I've been reading these posts with interest. It seems that today's battery banks are ever growing in capacity and unfortunately the big banks are chosen by folks who remain off grid for weeks at a time. Couple that with a small size generator and potentially shaded panels and it spells "challenge" in all capital letters.

Has anyone worked up a chart that reflects generator run watts versus charger potential limitations? Maybe that would be a help.

Down here a rig parked in the sun means 108F temperatures in the afternoon.

Lots of amp readings. Not much on voltage. When the batteries are low and you start the generator make a voltage measurement at the converter and at the battery while the converter is in boost mode. You should easily get 40 amps into the battery or there are issues to solve or improve.