lipo4 lithium battery

On Thursday, January 1, 2015 12:49:40 AM UTC-8, wrote:
A very good point made my the poster above, perhaps I should have elaborated:

Stark
- Internal battery management comes as standard. Voltage & charge control, cell balancing, etc.
- These batteries were given to an electronics nut (said with love Frank!) to deliberately abuse. He did all he could to them and they just kept bouncing back. Nil faults found and this the decision was taken by K&G to stock them
- A skeptical friend frtested them himself for capacity and found they supplied the advertised current to within 2%

General
- You'll need a new battery charger. It's a different cell chemistry that requires a different charging method (no trickle/float)
- This is not the battery chemistry for engine starting. It's too high a current draw; avionics only (though JS runs their jet on them)
- You'll get best storage retention when not in use at 50% capacity in a cold environment (fridge is good, freezer is not)
- Personally, I've flown 4hrs with LX9000/V9, Trig VHF, Trig XPDR, PowerFLARM & FlarmView and am yet to drain 1.
- Equally, I'm yet to learn of a bad experience with K2

"- This is not the battery chemistry for engine starting."

Not really true, LiFePO4 batteries will work fine for engine starting. You must pick one designed for the high current that that requires, Stark (and others) make them.

I used a Stark power instrument battery all last season and also haven't a single complaint.

For now, I hesitate installing a very large amp hour LiFePO4 battery required in starting a self launch glider engine. It is a lot of energy in case of a short circuit.

Just for clarity, I am not an expert on this matter, however, it is the advice I have received from people I respect.

Tom

On Thursday, January 1, 2015 8:56:58 AM UTC-8, wrote:
For now, I hesitate installing a very large amp hour LiFePO4 battery required in starting a self launch glider engine. It is a lot of energy in case of a short circuit.

Just for clarity, I am not an expert on this matter, however, it is the advice I have received from people I respect.

Tom

A starting battery need not have a very large amp hour capacity, just the ability to supply a large current for a short time. Due to the cost of the materials, engine start LiFePO4 batteries generally have 1/2 or 1/3 of the amp hour capacity compared to the LA batteries they replace while providing more starting current longer due to lower internal resistance.

A lead acid engine start battery has plenty of energy itself to start a fire - it can produce at least 1500 watts for several minutes if shorted. I don't think there is much difference in safety in this application between LA and LiFePO4. In fact the Lithium is probably safer, since the better ones have a BMS that shuts the battery down in an over current situation.

Regarding using LiFep04 batteries for engine starting. I have sucessfully been using a Shorai 36ah equivalent battery as an automotive starting battery for over 1 year with zero problems. The battery doesn't have a BMS and charges with no modifications to the charging system. Lithium starting batteries we're primarily introduced for motorcycles and race cars but as others have mentiond there are many advantages over lead acid and the costs have come down quite a bit.

EarthX motorsports makes several LiFep04 batteries that have a BMS and cell balancer. These batteries are designed for high amp current draw (unlike the K2) and are designed for engine starting.

Based on the OLC flights of some of the posters, I think I know the answer, but have you had any issues with poorer cold weather performance from the Li than the Pb?

On Saturday, January 3, 2015 12:30:16 PM UTC-8, Auxvache wrote:
Based on the OLC flights of some of the posters, I think I know the answer, but have you had any issues with poorer cold weather performance from the Li than the Pb?

How cold is cold? A good flight where I fly is generally 20 deg F ambient for several hours. I don't know what that translates to where the battery lives on the luggage shelf, but I have had no issues.