[FireMedic_2009]

The backup batteries from Dynon and TCW are in the $250-$400 range depending on 3ah to 6Ah. There are LiFePo4 batteries with the protection circuits for way less about the same size n wt with a 6-8Ah. Any reason not to use these less expensive batteries?
Thanks

 

[Dad's RV-10]

The TCW batteries have an "Integral high-performance fast charger."

Not sure about other LiFePo4 batteries. Might be a risk of overcharging?

 

[dmattmul]

Earth X makes the ETX12A ($ 169.00 retail) that I was tempted to look at but since I already have 2 ETX1200's (And 2 independent busses) felt I had enough protection. Has the same BMS as in their certified batteries. I've been more than impressed the 6 years I have been using Earth X and 4 years of good service under less-than-ideal conditions. (2 batteries FWF one stock 14 location the other one lower FWF) Good luck and do your homework, worth it.

 

[Walt]

ETX12A:
Recommended Charger/
Maintainer Amps:
.8 - 5A
Max Charge Amps 20A (from vehicle charging)

 

[esco]

To the OP, no reason not to... if they fit your charging system.
One example, for an alternator that charges at 60a or less, is the ETX680: 4.1 lb, 12.4aH LiFePO4 for $379.

From this discussion:
"First off, what's the amperage output from your alternator? If you're using a 60 amp alternator, you'll be OK with the ETX680 (but the ETX900 is fine). If you're using a stronger alternator like a 70 amp, you need the ETX900.

A basic rule of thumb for the ETX series: The first two digits on the battery model should be larger than the alternator's amperage.

Examples:
For a 60 amp alternator, use the ETX68(0).
For a 70 amp alternator, use the ETX90(0)."

 

[Raiz]

A basic rule of thumb for the ETX series: The first two digits on the battery model should be larger than the alternator's amperage.

Examples:
For a 60 amp alternator, use the ETX68(0).
For a 70 amp alternator, use the ETX90(0)."

There is one exception to this rule of thumb in the EarthX range - the ETX104 at $179. This is a 4Ah battery designed specifically as a backup. It has internal charge rate regulation, so it doesn't care what size alternator you've got.

If you use this, you'd need to arrange to charge it via a diode, so it doesn't try to power the entire bus if it goes down. The TCW products (I'm not familiar with the Dynon) do this for you and also have some extra convenience features like a low bus voltage light. Depends whether you want to roll your own or pay extra for the convenience of a more complete package.

 

[FireMedic_2009]

To the OP, no reason not to... if they fit your charging system.
One example, for an alternator that charges at 60a or less, is the ETX680: 4.1 lb, 12.4aH LiFePO4 for $379.

From this discussion:
"First off, what's the amperage output from your alternator? If you're using a 60 amp alternator, you'll be OK with the ETX680 (but the ETX900 is fine). If you're using a stronger alternator like a 70 amp, you need the ETX900.

A basic rule of thumb for the ETX series: The first two digits on the battery model should be larger than the alternator's amperage.

Examples:
For a 60 amp alternator, use the ETX68(0).
For a 70 amp alternator, use the ETX90(0).

 

[FireMedic_2009]

I think I may have thrown everyone off. The backup battery I’m talking about is for the display. I assumed when I mentioned the Dynon battery and TCW everyone would know it’s not a back up battery used to crank your engine.

 

[MacCool]

I have two PC680s in parallel, one on each ignition switch. That extra PC680 is what I use for panel backups.

 

[esco]

Daren, Ray: thanks for the question, and answer, respectively: I'll be buying an ETX104 my own self...

 

[Walt]

Daren, Ray: thanks for the question, and answer, respectively: I'll be buying an ETX104 my own self...

Other than a little cheaper than the 6ah TCW, I don't see any advantage, in fact the TCW offers quite a bit more flexibility as a BU battery plus your choice of 3ah or 6ah sizes, all housed in a steel case.

 

[12vaitor]

The Dynon backup battery uses six 18650 battery cells with a BMS board. You can easily replace it with battery packs available on Amazon. Search for the thread "Reconditioning Dynon Backup Battery" in the Glass Cockpit forum, lots of recommendations. I have shared a SV-BAT replica case that is 3D printable if you want to make your own (same mounting holes).

https://www.printables.com/model/172802-dynon-avionics-sv-batt-case


John Salak
RV-12 N896HS

 

[FireMedic_2009]

It’s not worth the time to make your own when there are batteries available like these for pretty cheap that have a BMS. I assume the HDX trickle charges the backup battery, correct?

LiTime 12V 6Ah LiFePO4 Lithium Battery

LiTime 12V 6Ah LiFePO4 lithium battery is perfect for fish finders, kid's scooters, LED lights, alarm systems, security cameras, game machines, outdoor camping, hair curlers, etc.

www.litime.com

 

[Walt]

It’s not worth the time to make your own when there are batteries available like these for pretty cheap that have a BMS. I assume the HDX trickle charges the backup battery, correct?

LiTime 12V 6Ah LiFePO4 Lithium Battery

LiTime 12V 6Ah LiFePO4 lithium battery is perfect for fish finders, kid's scooters, LED lights, alarm systems, security cameras, game machines, outdoor camping, hair curlers, etc.

www.litime.com

Ain’t putting a $29 lithium battery anywhere near my bird !

 

[Tall_Order]

Ain’t putting a $29 lithium battery anywhere near my bird !

Just curious if anyone has ever heard of an issue with a lithium iron phosphate battery? I understand these are supposed to be stable, no? I found one that has roughly the same dimensions as the EXT12A that I'm cycling during my panel building so it would be an easy swap once it's flying and I'm not timing out a premium battery for years in the shop. FWIW I plan EarthX for the FWF battery.

 

[RV6_flyer]

It’s not worth the time to make your own when there are batteries available like these for pretty cheap that have a BMS. I assume the HDX trickle charges the backup battery, correct?

LiTime 12V 6Ah LiFePO4 Lithium Battery

LiTime 12V 6Ah LiFePO4 lithium battery is perfect for fish finders, kid's scooters, LED lights, alarm systems, security cameras, game machines, outdoor camping, hair curlers, etc.

www.litime.com

Ain’t putting a $29 lithium battery anywhere near my bird !

At that price, I may buy one but would be doing some extensive testing before it went anywhere near my airplane.

Does the BMS do what it says it does in the ad?
Would be testing to make sure that it does everything it says it does in the ad before it went near my airplane.

EarthX has done the testing that I would want done before putting a LiFePO4 near my airplane. I would pay them what they are asking because of the tests they have done with their proven product.