Test results LiFePO4 glider batteries after 6 years

So after all this, the question remains, are they worth it? I'm ready to replace my 14volt lead acids, the advantage is that the Lifepo4 will give me enough voltage with out building 14volt packs of lead acid. So again are they worth the extra hassle/money?

On Tuesday, March 7, 2017 at 6:26:07 PM UTC-6, wrote:
So after all this, the question remains, are they worth it? I'm ready to replace my 14volt lead acids, the advantage is that the Lifepo4 will give me enough voltage with out building 14volt packs of lead acid. So again are they worth the extra hassle/money?

The answer is clear as can be Cliff: No hassle and well worth the money. Take the plunge.. Lead-acid is so quaint.. keep up with the Jones'es.

Yes worth it. Higher voltage will be appreciated by the radio. More capacity.
Lighter weight, longer life.
Not really a hassle with the right charger, just a little different.

SF wrote on 3/9/2017 6:16 PM:
Yes worth it. Higher voltage will be appreciated by the radio.

The radio will show it's appreciation by using less current; otherwise, a "modern"
radio won't care. "Modern" radios use power regulators that provide the correct
wattage to the radio, within a wide range of input voltages.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/...anes-2014A.pdf

My Dittle FSG60M, (May it RIP after it's death three weeks ago) Was the first thing in the airplane that suffered from the effects of low voltage. It seemed to receive just fine, but it made me sound like a Wookie when trying to transmit. That is the source material for my radio comment.

I've hated sailplane batteries ever since one died on a gold distance badge flight, I was 10 miles out at 6,000 FT. My argument that the landing witness should suffice for the missing final 10 miles of the .igc file, wasn't persuasive enough, so I had to do it again, with a different battery.

SF wrote on 3/12/2017 5:15 PM:
My Dittle FSG60M, (May it RIP after it's death three weeks ago) Was the first thing in the airplane that suffered from the effects of low voltage.

Definitely not a "modern radio", as the design is over 37 years old, but it was a
very good radio back then.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/...anes-2014A.pdf

Mine is a Terra 720 and suffers badly during transmit when voltage drops below 12v so I have always made 14v packs which are over 3+ years old now and need replacing. Hence the quandary about new Lifepo4's I am in communication with "Dakota" batteries and they are putting a BMS system into there batteries the has cell balancing starting in April sometime. And are selling for about $90 ea for 10 amp hour.

I've had my K2's for about five years now. Last spring I bought a CTEK LiFePo4 charger, which has 8 stages and ran the batteries through several recharges. Each time the batteries seemed to absorb a bit more.

Last week I flew one battery for over 7 hours on two flights. The Air Glide S showed the voltage flipping between 11.9 & 12.1. Note that the Air Glide S seems to underread by about 0.6V compared to the Tasman. Poking around with probes showed no drop in voltage between the battery and the Air Glide.

Back on the charger it took over three hours to get the battery back up to float. The charger was quite warm for the 2.5 hours in stage 2.

The other battery flown for three hours charged back up in a little over an hour.

I suspect that the batteries need heavier usage than just 3-4 hours of flight before accepting a full recharge.

On Thursday, March 9, 2017 at 6:16:51 PM UTC-8, SF wrote:
Yes worth it. Higher voltage will be appreciated by the radio. More capacity.
Lighter weight, longer life.
Not really a hassle with the right charger, just a little different.

The thread has inspired me to test my LFPs.

3 year old Starkpower 12AH used for instruments, 11.86AH (tested to 11V @ 1.5A). This improved to 11.91 on the second cycle.

3 year old Starkpower 9AH used for self rig wing dolly, 8.60AH (to 11V @ 1A).

2 year old CTC 19.8AH used for engine start, 19.38AH (to 11V @ 2A). I may give this one a second cycle to see if it improves.

While I was at it, a 5 year old PowerSonic 14 AH SLA, 9.8AH (11V @ 1A). This battery had been sitting idle and uncharged for 3 years, till I charged it for the test.

The SLA had a nearly linear drop from 12.8V to 11V, dropping under 12V at about 60% discharge, while all of the LFPs stayed above 12.5 until about the 90% discharged point.

On 3/12/2017 10:54 PM, jfitch wrote:
While I was at it, a 5 year old PowerSonic 14 AH SLA, 9.8AH (11V @ 1A). This battery had been sitting idle and uncharged for 3 years, till I charged it for the test.

I would have expected 3 years of uncharged storage to turn that
Powersonic into a doorstop.