SLA batteries opinions?

On Tuesday, April 3, 2018 at 1:47:02 AM UTC-4, krasw wrote:
tiistai 3. huhtikuuta 2018 2.16.45 UTC+3 kirjoitti:
The theoretical number of times the batteries of each type can be cycled is irrelevant if they will die of old age in a number of years, even if that's 10+ years for LiFePO4 and only 3-4 years for SLA in my use.


In my experience lifetime of LFP is not better than SLA. My first battery died completely in 6 months, second had much reduced capacity after 2 seasons. Idea that chinese LFPs last thousand cycles or decade is just false.

5 full seasons on a bioenno 12 AH LFP battery. 30 or 40 cycles a year to around half charge. It tested last week at 11.5 AH. Just my experience. Quite happy with it.

T8

On Monday, April 2, 2018 at 10:47:02 PM UTC-7, krasw wrote:
tiistai 3. huhtikuuta 2018 2.16.45 UTC+3 kirjoitti:
The theoretical number of times the batteries of each type can be cycled is irrelevant if they will die of old age in a number of years, even if that's 10+ years for LiFePO4 and only 3-4 years for SLA in my use.


In my experience lifetime of LFP is not better than SLA. My first battery died completely in 6 months, second had much reduced capacity after 2 seasons. Idea that chinese LFPs last thousand cycles or decade is just false.

I going on my 5th season on the instrument LFP, it currently tests the same capacity as the label says. I generally replaced the SLA at 2 - 3 years as they had lost significant capacity by then. It cost 4x as much, or about the cost of two tows. To me the benefit of holding the voltage higher throughout the discharge cycle is worth that alone.

All batteries have a self destruct clock built in, ticking from the moment they leave the factory. SLA batteries have a shorter clock, but the thing that kills them is the use: deep discharge, followed by late recharge, followed by 6 months of idle storage. LFP batteries deal with this sort of thing MUCH better than SLA.

It's too early to tell if "chinese LFPs last thousands of cycles", but I know for a fact that Chinese LiPo batteries do, as I have a large number of devices that have. Chances are near 100% that if you are buying any lithium battery it was made in China. Chances are pretty good that if you buy an SLA it was made in China, too.

On Tuesday, April 3, 2018 at 11:44:49 AM UTC-5, jfitch wrote:
On Monday, April 2, 2018 at 10:47:02 PM UTC-7, krasw wrote:
tiistai 3. huhtikuuta 2018 2.16.45 UTC+3 kirjoitti:
The theoretical number of times the batteries of each type can be cycled is irrelevant if they will die of old age in a number of years, even if that's 10+ years for LiFePO4 and only 3-4 years for SLA in my use.


In my experience lifetime of LFP is not better than SLA. My first battery died completely in 6 months, second had much reduced capacity after 2 seasons. Idea that chinese LFPs last thousand cycles or decade is just false.

I going on my 5th season on the instrument LFP, it currently tests the same capacity as the label says. I generally replaced the SLA at 2 - 3 years as they had lost significant capacity by then. It cost 4x as much, or about the cost of two tows. To me the benefit of holding the voltage higher throughout the discharge cycle is worth that alone.

All batteries have a self destruct clock built in, ticking from the moment they leave the factory. SLA batteries have a shorter clock, but the thing that kills them is the use: deep discharge, followed by late recharge, followed by 6 months of idle storage. LFP batteries deal with this sort of thing MUCH better than SLA.

It's too early to tell if "chinese LFPs last thousands of cycles", but I know for a fact that Chinese LiPo batteries do, as I have a large number of devices that have. Chances are near 100% that if you are buying any lithium battery it was made in China. Chances are pretty good that if you buy an SLA it was made in China, too.

Here is my admittedly radical view-point: Just like the Imperial System of distance and temp measurements and downwind dashes in gliders, the SLA battery belongs on the scrap heap of history. Get over it, boys and girls.

On Monday, April 2, 2018 at 10:47:02 PM UTC-7, krasw wrote:
tiistai 3. huhtikuuta 2018 2.16.45 UTC+3 kirjoitti:
The theoretical number of times the batteries of each type can be cycled is irrelevant if they will die of old age in a number of years, even if that's 10+ years for LiFePO4 and only 3-4 years for SLA in my use.


In my experience lifetime of LFP is not better than SLA. My first battery died completely in 6 months, second had much reduced capacity after 2 seasons. Idea that chinese LFPs last thousand cycles or decade is just false.

In my experience LFP batteries are much better than SLA and deliver close to the label AH for many cycles. And if you drop them on your foot is does not hurt as bad.

Richard

Richard

I have flown with both an LFP and SLA battery in my ship for 5 years. I alternate which one is primary and which one is secondary on each flight. A PowerSonic 12V14Ah SLA vs Powerizer 12V15Ah LFP. With all my instruments running the SLA voltage drops below the minimum requirements of my radio by 5 hours. My LFP has never failed to power everything up to a 7 hour flight.. The SLA gets replaced after 3 years. My LFP is six years old and still working perfectly.

When I fly in very cold conditions (0C) the SLA is usually not driving my radio by three hours. Again, the LFP has run up to six hours without any significant voltage drop.

On Tuesday, April 3, 2018 at 10:12:41 PM UTC-4, Richard Pfiffner wrote:
On Monday, April 2, 2018 at 10:47:02 PM UTC-7, krasw wrote:
tiistai 3. huhtikuuta 2018 2.16.45 UTC+3 kirjoitti:
The theoretical number of times the batteries of each type can be cycled is irrelevant if they will die of old age in a number of years, even if that's 10+ years for LiFePO4 and only 3-4 years for SLA in my use.


In my experience lifetime of LFP is not better than SLA. My first battery died completely in 6 months, second had much reduced capacity after 2 seasons. Idea that chinese LFPs last thousand cycles or decade is just false.

In my experience LFP batteries are much better than SLA and deliver close to the label AH for many cycles. And if you drop them on your foot is does not hurt as bad.

Richard

Richard

What if we want to drop it on Herb's foot?
Chris

On Monday, April 2, 2018 at 7:16:45 PM UTC-4, wrote:
On Monday, April 2, 2018 at 4:29:49 PM UTC-4, Darryl Ramm wrote:
You may be better off using LiFePO4 batteries.

Well I've been wondering about that each time I buy a new SLA and still find that I cannot justify the much higher cost of the LiFePO4 batteries (5x to 10x, depending on size, brand, etc). The theoretical number of times the batteries of each type can be cycled is irrelevant if they will die of old age in a number of years, even if that's 10+ years for LiFePO4 and only 3-4 years for SLA in my use.

This depends also on how much capacity you need vs. the weight and volume needed to hold the battery(ies) in the glider. In my case my modest needs, in warm weather, are usually met by one 4AH SLA, and I can also use a 12AH when I want spare capacity (or a bit of ballast :-). If I had a fancier computer, plus transponder and FLARM, then the picture might be different, since the LiFePO4 can be discharged more deeply without damage while the SLA should only be taken to about half-full (and even when I test them I stop at about 11.5V).

I just switched to lifepo4, got tired of killing SLA's. 5 to 10 times more expensive? Do you include the predicted lifetimes in that estimate? I paid $65 for my last 14 ah SLA and replaced it with lifepo4 for $130. So next year, or the year after, when I don't have to buy another SLA I'll be even? And I don't really have to worry about storage, running out of battery on a long flight, and the charge time is much less. With the new prices lifepo4 seems a no brainer to me. But I just bought it so we'll see.

On Tuesday, April 3, 2018 at 10:54:21 AM UTC-4, wrote:
I just switched to lifepo4, got tired of killing SLA's. 5 to 10 times more expensive? Do you include the predicted lifetimes in that estimate? I paid $65 for my last 14 ah SLA and replaced it with lifepo4 for $130. So next year, or the year after, when I don't have to buy another SLA I'll be even? ...

- I paid under $30 for my 12AH SLA, shipped. And when I bought 3 smaller SLAs (about 4 or 5 AH each) it was about $27 total for the 3, shipped (from apexbattery.com). Money wise I'm way ahead relative to LiFePO4. Would be nice to have the other advantages of LiFePO4 (no damage from deep discharge, better low temperature operation), but the price would have to drop by another factor of 2 to make sense for me.

On Monday, April 2, 2018 at 11:14:19 AM UTC-6, john firth wrote:
Recently I tested two 12v SLA s which had been in use
sequentially for some years usually recharged before going
going flat, or at least within one day.
Both were run down to 10.5 v with a 10 ohm load and then recharged to 14v,

The Yuasa 7 AH bought 2005 was good for about 2.5 AH
the UB 1280 8AH 6 years old good for 2AH.
On this showing the Yuasa look like the better battery.
Both were used as panel supplies running at .5 A load.

Any opinions on competing SLA batteries?

John F

Just for reference, 4.5 hrs on Duracell 9AH to drop to 10.5V. This is running everything including PF and TX. No more than 2 seasons use. I buy one every season from local high volume outlet (Around 25 bucks). Will occasionally use a smaller tail battery as well.
The biggest determinant of longevity is the charger. I have been using SLA for decades for soaring and other applications and for some reason I have been having a hard time finding good chargers lately. Used the PowerSonic chargers for years (No longer made) but sold these with my last ship. Have fried more than one battery when the charger did not detect peak and shut of (Or float) before the battery got hot. I have never measured it but this always results in a noticeable reduction in capacity.
3 years max (With the right charger) sounds about right. We are only talking 20 some odd bucks.

On Monday, April 2, 2018 at 10:51:03 PM UTC-7, wrote:
On Monday, April 2, 2018 at 11:14:19 AM UTC-6, john firth wrote:
Recently I tested two 12v SLA s which had been in use
sequentially for some years usually recharged before going
going flat, or at least within one day.
Both were run down to 10.5 v with a 10 ohm load and then recharged to 14v,

The Yuasa 7 AH bought 2005 was good for about 2.5 AH
the UB 1280 8AH 6 years old good for 2AH.
On this showing the Yuasa look like the better battery.
Both were used as panel supplies running at .5 A load.

Any opinions on competing SLA batteries?

John F

Just for reference, 4.5 hrs on Duracell 9AH to drop to 10.5V. This is running everything including PF and TX. No more than 2 seasons use. I buy one every season from local high volume outlet (Around 25 bucks). Will occasionally use a smaller tail battery as well.
The biggest determinant of longevity is the charger. I have been using SLA for decades for soaring and other applications and for some reason I have been having a hard time finding good chargers lately. Used the PowerSonic chargers for years (No longer made) but sold these with my last ship. Have fried more than one battery when the charger did not detect peak and shut of (Or float) before the battery got hot. I have never measured it but this always results in a noticeable reduction in capacity.
3 years max (With the right charger) sounds about right. We are only talking 20 some odd bucks.

BTW if an SLA battery charger does not switch to float, the first thing to suspect is the battery is faulty, a cell shorted or partially shorted... and then the charger being in bulk charge mode across the other cells for a long time will tend to evaporate out the small amount of electrolyte in the battery and kill it pretty fast. If it's happening in multiple batteries then obviously suspect the charger.

---

To everybody/more generally: using missized SLA/VRLA chargers can cause problem, the charger needs to be an SLA/VRLA charger, and should say the battery capacity they are designed for, ...or use around C/5 to C/10 bulk charge charge current (where C is the battery capacity in A.h). Too large a charger can damage the battery, too low a charger may never get to float mode and might fry the charger. Some chargers have temp sensors... you want them and the battery near each other and well ventilated. Solar chargers might put a surface charge on the battery but not actually much charge capacity. it's important to hammer the nail in with the right screwdriver :-)