Tuesday, November 12, 2013

After Seven Long Years of Heavy Use... the RV Solar Batteries Get Replaced Today

Made a long haul Monday morning, with NASCAR finished, all of 25 miles or so.

Before I leave Phoenix I figured it to be easier to squat at my sisters place and do some maintenance before I vanish into the far country of Arizona...

The Truck tires got replaced when we passed through Denver. That ate up $1400 bucks, or nearly so.... Here in Phoenix I'm replacing the solar power battery bank... Those six batteries will eat up another $750 or so...

Add in the federal extortion that caught up with us on the day we got our first beet check... and the rewards of piling beets are rapidly disappearing.  Yup... working for a living is like having a leaky bucket... pour income in the top and it runs right on out the bottom! ;)

Can't complain too much about the batteries. They were installed in October of 2006... the way I add up the months... that's a bit over 7 years for an RV Solar Battery Bank.

So... the folks that told me I'd better replace those Solar batteries when they turned 3... and 4... and 5... and... well... they were wrong. ;) one more time.

Fact is... the current batteries are working ok... sort of... but it's time. They drop voltage a lot faster than in the old days. The new batteries are ordered and should arrive today. If I'm ambitious enough I'll have 'em in and charging before dark.

How did they last so long? Well, the plan had been to install (4) to (5) 130 watt panels... but... the money to do that didn't happen so we've been living, full time on two Kyocera 130 watt panels. Powering the computers, the lights, the hair dryer, microwave and furnace... on this bank of Trojan T-105 batteries.

The trick has been to hold discharge to 20% or less the vast amount of the time. Finding the "routine" to do that takes a lot of stress off the batteries and greatly extends their ultimate life. The way it does that, I believe is; Staying at 12.4 volts or above pretty much eliminates sulfation in the plates, the death of batteries and the reason for "equalization" cycles. I have NEVER run an equalization cycle... just saying...

Discharge below that, approximately 12.4 volts has been rare. On the days the panels didn't bring the charge level back to 12.8 I topped the batteries off with a generator run. That actually was also a rare occurrence, mostly only in the winter. Between April and November, generator use has been rare.

Learning the routine is not much of a big a deal. It's never been an inconvenience. Only learning a new "choreography" for living. After a bit it becomes automatic without even thinking about it. You only use the lights you need. You turn 'em off when you aren't using them. You use more blankets at night rather than more furnace. You "think" a bit and slowly work into an easy, sustainable routine.

It's not, or shouldn't be a paranoia about the dang voltage. It's just a common sense, relaxed staying aware of what's going on.

In the winter I tip the panels up to maximize the Solar efficiency... that gains 30% or so in charge rate over leaving them flat...

One big key is to have a battery bank sized sufficiently to allow you to use the power you need and leave the batteries still at 12.4 or above. Too small a bank and you HAVE to pull 'em lower... your batteries will sulfate... and you WILL be replacing in three years... or four.

The consequence for me and my way is RV batteries that have lasted 7 years. Maybe I don't know what I'm talking about... but all those others have spent double on their batteries... and the guy who don't know... didn't ... so... you decide how ya'll are gonna run. ;)

That, holding back the income leaking out of the bottom of the bucket... is how you stretch your wandering dollars as well. When you have some trouble pouring the nickles in the top... you'd best make sure they ain't runnin' out the bottom too quick.

Waiting on the Arrival of Batteries

1 comment:

Mike OBrien said...

Howdy Mr Gore, NDR;

Most of the information available on the internet concerning batteries is filled with inaccuracies and half truths. As usual, the devil is in the details. For instance, sulfation is not the primary failure mechanism of lead-acid batteries. Sulfation occurs during every discharge and is reversed by recharging. Sulfation only persists when there is insufficient recharge. Under charging will reduce battery life.

You obtained long battery life due to the following:
1. You bought and installed new or properly activated batteries that had not been sitting on someones shelf for many months. This means that your batteries started off life in a fully charged condition.

2. You avoided spending much time in high temperature environments. The life of a lead-acid battery is reduced by 50% for each sustained 15 degree increase in temperature over the standard temperature, which is 80F for automotive batteries. Cooler temperatures will increase battery life, but not nearly as much as high temperatures reduce battery life. A 15 degree increase in temperature will cut life by 50%, but a 15 degree decrease will only extend life by approximately 10%. All this assumes that the battery is properly charged for the given battery temperature.

3. You limited your depth of discharge. You claim that you limited the discharge to about 20%, which may be correct, but given the life you have achieved I would guess that your depth of discharge was closer to 10-15%.
Limiting the depth of discharge is crucial to obtaining long battery life. Think of your battery as a log and every discharge cuts off some of the log. The larger the discharge the larger the piece cut off the log. A 10-20% discharge is like taking a pocket knife to the log where as a 50% discharge is like using a chainsaw. A battery's entire life can be consumed by a single long discharge.

4. You kept your batteries properly charged. Lead-Acid batteries need to be maintained at a full state-of-charge and recharged ASAP after a discharge to obtain long life. You did this.