Lazy Daze Owners' Group

Mine are 2 years old. They are on stage 2 of the 3 stage charge and showing only 75%.
I should have treated them better I guess. I thought I was pretty good.
I now realize the value of having a real battery monitor.
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Yes, a battery capacity monitor can pay for itself over the long haul.

Larry

"I thought I was pretty good...I now realize the value of having a real battery monitor."

You're not the only one!

I started out RVing in 2001, in a 1985 Lazy Daze. Thanks to the previous owners (hi, Judie!), I had an advanced electrical system for the time: 160 watts of solar panels and four AGM batteries. Over the next five years I became increasingly frustrated by the fact that despite having a background in electronics, I just could not seem to get a grip on my power situation. Time after time I would get up in the morning to find that my batteries were close to 12 volts. Over time I added more and more solar panels--I ended up with nine, in all shapes and sizes!--until it was almost impossible to walk on the roof. It didn't seem to help much. I had the batteries replaced. That didn't help as much as I thought it should have either.

Finally I got a Xantrex Battery Monitor--an amp counter more or less equivalent to Victron's BMV-7xx series. It was as if a blindfold had been removed from my eyes! At last I had a feeling for the state of charge of my expensive batteries.

That confident knowledge only lasted until the batteries began to age; then the monitor's readings grew increasingly overoptimistic--but I didn't know that. In that rig and my next rig, I beat the batteries to death by trusting a battery monitor that that had been programmed for the rated capacity, and not derated 8%-10% per year as Larry has recommended. As I recall, I went through three or maybe four sets of very expensive AGM batteries in my last rig before I got it all figured out. (One or two of those sets were burned out by an aging solar controller that, it turned out, was feeding them 16-17 volts. Months went by before I caught that. My fault.)

There were a lot of things about RV battery/solar systems that I didn't know in my first fifteen years of RVing, and it took me far too long to learn them. Off the top of my head, here are a few of the things I didn't know.

• As we’ve discussed here, voltage alone wasn’t a reliable way to judge my batteries’ state of charge. I was incredibly frustrated for years until I understood this.

• Amp counting battery monitors are great as long as you remember to lower their "bank capacity" setting every year.

• Adding all those solar panels was pretty much a waste, since my wiring was inadequate. My first LD ended up with 589 watts of panels (on a 22-footer!)… but the wiring had been sized for 160 W, and I didn't have the brains to realize that the voltage drops were throwing away gobs of power. That's probably why I didn't burn out my 400 W (max) solar controller. It's also why my batteries weren't getting recharged. I should have spent money on heavier wiring instead of more panels. And I should have learned to use a voltage drop calculator.

• Idling the engine doesn't do a good job of charging batteries. It doesn't put out that much juice at idle speed (it's optimized for driving, not sitting still), and its output voltages aren't regulated for best charging. I did a lot of this in my first couple of winters, when my solar panels weren't doing the job and I was desperate to get power into the batteries. Not only was it annoying and a waste of gas, but I ended up paying for new exhaust manifolds and other repairs that were probably needed, or needed sooner, because of all that idling.

• Pulling 70 to 150 amps from my batteries (via inverter) in order to run a microwave oven or Shop-Vac—even briefly—drained them a lot more than I thought, due to the Peukert effect.

• Not bringing AGM batteries back up to 100% every day shortens their lifespan considerably. So does overcharging them, but for the first five or six years I didn’t have either my charger or my solar charge controller set to the optimum voltages for AGMs.

I could go on, but you get the idea. I made a lot of mistakes, and paid thousands of dollars dealing with the consequences. Now I have lithium batteries, so I have a chance to make a whole new set of mistakes! ;-) I guess the moral is: read up and educate yourself as much as you can, or you'll end up paying for what you didn't know.

Andy

Now I have lithium batteries, so I have a chance to make a whole new set of mistakes! ;-) I guess the moral is: read up and educate yourself as much as you can, or you'll end up paying for what you didn't know.

With this monitor I am seeing just how slow my PD4600 converter charges these batteries on shore power.
It seems generator charging is quicker...no?

I just reset my baseline capacity from 225 amp hrs to 171 amp hrs.
These batteries have degraded 24% in 2 years.

We're leaving soon for a 5-6 month trip.
Should I replace them? We will be at sites with no electricity a lot.