Battery question

[Mike Lewis]

General battery question -- On average, how long will a pair of 6V batteries last? Yes, I know there's a big standard deviation in that average, but assuming reasonable care and not draining the batteries below 50% too many times, how long?

[thoer]

Originally Posted by Mike Lewis

General battery question -- On average, how long will a pair of 6V batteries last? Yes, I know there's a big standard deviation in that average, but assuming reasonable care and not draining the batteries below 50% too many times, how long?

Mike - probably too many variables. My experience, the ones on our 17B were 6 years old and still performing like new when we sold it.

[KarenB]

According to the article cited previously, the 12 volt side of life, 2-8 years.....

[KarenH]

I actually got ten years out of my six-battery bank at my cabin and I took them down below 50% many, many times. The second set, I got seven years, and I am now in the fifth year of my third set. But, as above...way too many variables for comparison.

[alanmalk]

Originally Posted by KarenB

..
Question is, could we use the 2 12's, hooking up parallel, instead of the 6's in serial?? If Yes, would there be anything we would need to do other than hook up & go? How does trailer know which battery to use?
...

I've been using a pair of 12v AGM batteries in parallel for a couple of seasons now. They are hooked up directly - meaning no switch between them - so they appear as one single, rather large, 12v battery to the trailer systems. I did not change the solar charger settings - except to turn off the occasional equalizer charge cycle, as recommended by the manufacturer.

Since they were new on installation and the same make and model and size there was very little self-discharge loss. (I measured 5 milliamps after they had been installed for a week. FYI -this is the loss where one battery tries to charge the other. A pair of mis-matched batteries in parallel could have significant losses.)

I do not take them out of the trailer for storage as the solar panel keeps them at full charge. Full charge is necessary to prevent winter damage. For insurance I keep the master switch in the "off" position. To reduce my stupidity quota I also keep a bunch of the trailer lights in the "on" position, just to remind me to turn off the master switch.

As far as weight goes: Total amp-hours is almost directly related to weight. 200 AH from a pair of 6v batteries will weigh roughly the same as 200 AH of 12v batteries. In other words, weight = power. No big weight advantage from using a pair of 6v batteries vs a pair of 12 batteries. The 6v batteries have twice the AH for 50 pounds of weight but half the voltage.

6v batteries are thought to have sturdier interior construction so may have an advantage in vibration resistance. AGM batteries may not have this disadvantage but I don't have any data to back this up. I do know that I have been abusing my smallish 12v trolling motor AGM battery for 6 years and it still seems to be going strong.

--
Alan

[alanmalk]

7 Ways To Kill Your Batteries.

Much easier to kill batteries than than the opposite - keeping batteries healthy, so this is easier to write - I think.

1. Drain your batteries and don't recharge for as long as possible. This lets the used-up lead/acid slowly turn into inactive materials that can not be reused.

2. Dischange your batteries below 20% frequently. Easy do do by keep using them without charging until the lights go dim and the pumps and fans run slowly. Again, this creates materials that can't be reused. A few times per year probably won't have this effect, especially if your batteries are one of the well respected brands. Those batteries are just too darn tough to be killed by a few deep discharges.

3. Don't check the water/acid level - let the plates dry out. This changes the water/acid ratio and helps convert the pure lead into oxides that won't generate electricity and can't recover.

4. Don't follow the manufactures recommendations on "equalization" cycles. Since equalization changes some of the hard-to-process solids back into lead, and prevents sludge from settling in the bottom of the battery, skipping equalization or going overboard is a good tool for killing batteries. This one may be difficult to implement since the Escape chargers are set by default to equalize.

5. Don't remove corrosion at the battery connections. Corrosion will trick the charger(s) into thinking your batteries are full when they are not, keeping them undercharged and closer to steps 1 & 2 above. Plus - you won't get all the electricity you paid for - the power goes up as wasted heat. A double bonus...

6. Store under-charged batteries in a sub-freezing environment. A 100% discharged battery freezes at about the same temperature as water. Instant and permanent death without hardly any effort.

7. Store your batteries on concrete. Whoops! Wait - that won't work unless your batteries are more than 100 years old when they were built with tar-soaked wood cases. Forget this trick - it won't kill a modern battery.

If for some reason you want to keep your batteries working for a long time then you will have to avoid all the above. Too much work...

--
Alan

[rbryan4]

Alan, I would perhaps add one more. Use a cheap charger without a desulfation cycle and smart charge technology. That way you won't be supplying the recommended charging voltage, will increase sulfation, and are well on your way to shorter battery life.

Sent from my SM-G930V using Tapatalk

[alanmalk]

Originally Posted by SFDavis50

...
I wouldn't have known the difference between a 12v and 6 v battery
...

Reminds me of a funny story - true I believe.

Final exam in a physics class.
Professor says "for extra credit, what is the voltage of this battery?"

Puts the battery and a voltmeter on the table in front of the class.
The battery in question is a traditional automotive style with 3 water caps.
Everyone writes down "6v".

Had they bothered to visit the table and use the voltmeter they would have
discovered that there was a small 12v battery inside the 6v case, and would
have actually received the extra credit.

--
Alan

[Rossue]

Geez Alan- hated you trickster Profs! So question to you: will charging dual 6V Interstates using ETI solar panel with Samlex contoller exclusively properly take care of the batteries?

[rubicon327]

Originally Posted by KarenB

The other thing to ponder, we took them to our local chevron (all we have without driving to Reno or Carson), and had them charge and check them, they told us batteries toast and replaced them with the 12v. We discovered immediately and returned them. We wonder if they charged the old batteries as 12v and killed them by doing that, as clearly they didn't even know they were 6v.

It sounds like the batteries were removed and you didn't take them the trailer. Good thing because if they picked smaller 12V's (group 24) they would likely fit very similar to the 6V's and if they wired them up in series you would have had a 24V system and some very unhappy appliances.

[alanmalk]

Originally Posted by Rossue

So question to you: will charging dual 6V Interstates using ETI solar panel with Samlex contoller exclusively properly take care of the batteries?

The above, in fact, is a trick question. Lots of unknowns prevent a sure-fire answer.

Assuming - and that is a big IF - your typical daily battery drain is about equal to, or less than, the 150 watts provided by the standard ETI solar panel, then you are in good shape. Only you know the real answer to that.

Check your battery voltage first thing in the morning before using power and before the sun hits the panel. Do this for a number of days and give us the daily voltage readings. If mostly above 11.5 early each morning then you are probably not stressing the battery(ies).

Do the same voltage check around 3 or 4 PM each sunny day and confirm that the voltage has risen above 13 v - again without using power if possible for an hour or two before hand. If the charger gets the battery above 13 v then you are close to fully charged. (13.8 might be ideal once in a while.)

Finally, don't stress about it, unless your batteries fail in under 2 years. Enjoy camping - not battery theory.

--
Alan

[alanmalk]

Originally Posted by rubicon327

It sounds like the batteries were removed and you didn't take them the trailer. Good thing because if they picked smaller 12V's (group 24) they would likely fit very similar to the 6V's and if they wired them up in series you would have had a 24V system and some very unhappy appliances.

As insane as that sounds - I have personally seen this done. I rented an expensive boat and as soon as I walked into the cabin I could smell boiling battery acid.

How anyone with two functional eyeballs and an equal number of brain cells could do that and not notice the damage... !!!



--
Alan

[Rossue]

Originally Posted by alanmalk

The above, in fact, is a trick question. Lots of unknowns prevent a sure-fire answer.

Assuming - and that is a big IF - your typical daily battery drain is about equal to, or less than, the 150 watts provided by the standard ETI solar panel, then you are in good shape. Only you know the real answer to that.

Check your battery voltage first thing in the morning before using power and before the sun hits the panel. Do this for a number of days and give us the daily voltage readings. If mostly above 11.5 early each morning then you are probably not stressing the battery(ies).

Do the same voltage check around 3 or 4 PM each sunny day and confirm that the voltage has risen above 13 v - again without using power if possible for an hour or two before hand. If the charger gets the battery above 13 v then you are close to fully charged. (13.8 might be ideal once in a while.)

Finally, don't stress about it, unless your batteries fail in under 2 years. Enjoy camping - not battery theory.

--
Alan

Alan- I really appreciate your insight and especially the last paragraph which distills the essence for me. We've had one episode of forgetting to switch from 12V fridge back to propane: oops! 4 AM alarm makes you never forget. Then last 4 week outing saw some 11.7 (or lower ) readings on controller after making coffee (one four cup Cuisinart) - then toast (recent addition, probably ditching) Batteries are 18 months old; thinking of Lifeline AGM next.

[skyfree]

Originally Posted by alanmalk

7 Ways To Kill Your Batteries.

Much easier to kill batteries than than the opposite - keeping batteries healthy, so this is easier to write - I think.

1. Drain your batteries and don't recharge for as long as possible. This lets the used-up lead/acid slowly turn into inactive materials that can not be reused.

2. Dischange your batteries below 20% frequently. Easy do do by keep using them without charging until the lights go dim and the pumps and fans run slowly. Again, this creates materials that can't be reused. A few times per year probably won't have this effect, especially if your batteries are one of the well respected brands. Those batteries are just too darn tough to be killed by a few deep discharges.

3. Don't check the water/acid level - let the plates dry out. This changes the water/acid ratio and helps convert the pure lead into oxides that won't generate electricity and can't recover.

4. Don't follow the manufactures recommendations on "equalization" cycles. Since equalization changes some of the hard-to-process solids back into lead, and prevents sludge from settling in the bottom of the battery, skipping equalization or going overboard is a good tool for killing batteries. This one may be difficult to implement since the Escape chargers are set by default to equalize.

5. Don't remove corrosion at the battery connections. Corrosion will trick the charger(s) into thinking your batteries are full when they are not, keeping them undercharged and closer to steps 1 & 2 above. Plus - you won't get all the electricity you paid for - the power goes up as wasted heat. A double bonus...

6. Store under-charged batteries in a sub-freezing environment. A 100% discharged battery freezes at about the same temperature as water. Instant and permanent death without hardly any effort.

7. Store your batteries on concrete. Whoops! Wait - that won't work unless your batteries are more than 100 years old when they were built with tar-soaked wood cases. Forget this trick - it won't kill a modern battery.

If for some reason you want to keep your batteries working for a long time then you will have to avoid all the above. Too much work...

--
Alan

I strongly suspect #6 as Carson City gets well below freezing many winter nights, and this year got down to 6F in December. We live part-time in South Lake Tahoe but store the trailer in Fremont where it barely gets below freezing a couple times a year. Once we move to Tahoe permanently I will also have to store the trailer in Carson City during the winter so we will be in the same boat.

[alanmalk]

Originally Posted by Rossue

...
Then last 4 week outing saw some 11.7 (or lower ) readings on controller after making coffee (one four cup Cuisinart) - then toast (recent addition, probably ditching)...

Something to consider...
If you are addicted to a hearty breakfast (coffee, toast, etc) and use the inverter regulary on those 4 week boondock trips, then you might want to consider an additional portable panel to help with the recharge.

Your low voltage may be the result of insufficient solar charging during the day. That is why it is also important to confirm a mostly full charge (13+ v) at the end of the charging day ( say around 3PM as the sun angle begins to drop). Also, you may want to consider how shady your campsites are, and the amount of cloudy weather - all of which have a significant impact in recharging. One leaf or a heavy layer of dust on your panel can waste a lot of recharge.

For example, I camp frequently in heavy Colorado pine forests, and also during the shoulder seasons when the sun is low most of the day. For that reason I plan on taking my 150 watt portable panel on those specific trips lasting more than a few days. I have found that aiming the portable panel right at the sun on a late October morning can triple my charging amps over the roof mounted ETI panel.

One possible conclusion: If you are convinced that you get plenty of charge during the day but still see low batteries after breakfast (allowing the batteries time to rest before checking), then yes, you may have lost battery capacity due to one or more of the "7 ways to kill your battery". And you may be ready for some nice AGM batteries. Remember, you don't get more power from AGM batteries that are the same size as the originals, but you do make it harder to accidentally kill or injure, your batteries.

--
Alan

[Rossue]

Originally Posted by alanmalk

....One possible conclusion: If you are convinced that you get plenty of charge during the day but still see low batteries after breakfast (allowing the batteries time to rest before checking), then yes, you may have lost battery capacity due to one or more of the "7 ways to kill your battery".

--
Alan

Forgot to mention that they jump right back up to 13.5+ within an hour, maybe less. So for now I will be more cautious and hope I get at least another 6 months to a year out of these Interstates.