If you're going with the timer then you can go even lower tech on the charger. Just find any old 12V to 15V rated wall wart that's not regulated and puts out around 15VDC. You can likely find one for free (you might even have one in your house already) and it'll work as good as a cheap charger for maintaining your battery.

I consider most electronic components, such as microcontrollers, to be very reliable. That is, until some designer screws up the application of said component.


Peter

 

Thank you for clarifying that Peter, of course you are correct about that. I understand there are 5 levels of computer engineering for aircraft depending upon whether it involves systems where failure is life threatening down to just controling the cabin lights. Maybe BT microprocessor is on the cabin lights level.

 

I'm pretty happy with my $19.95 sale priced Sears Die Hard Float Charger. It may be crap, but it works well.

 

I'm hesitant to enter into this discussion but am currently researching battery maintainer options right now so am motivated to learn everything I can. I have never owned a Battery Tender Junior or any other Deltran product.

Reading the reviews on Amazon and other internet retail sites, the reviews are decidedly outstanding for the product. Yes, they do fail but it seems to be a rare occurrence.

I'm sure Plasticman knows what he's doing using timers and has developed a reliable system that works for him. But realize that it's not as easy as it sounds. Assuming the typical C5 electrical system drains 20mAh/day to maintain memory then a 30 minute charge at between .75A and 1.0A for thirty minutes a day would exceed the drain by 355mAh to 480mAh each day! If the charger used is not able to detect an overcharge there's a 100% chance the battery will become overcharged.

So we know doing nothing will kill the battery over time (been there). We know overcharging will kill the battery (been there too). What we're left with is a battery maintainer that will malfunction occasionally and kill the battery. How often will a Battery Tender malfunction? 1%, 3%, even 4% of the normal service life? I don't know but the two alternatives will kill your battery 100% of the time.

(It would be nice if someone broke one of these devices apart and reverse engineered the circuit. It's unlikely Deltran is using custom processors or IC's. We would then be able to see how these things fail and how to prevent it. An ammeter readout could be cobbled together with a $6 display from allelectronics.com but it's only going to tell you how much the unit is charging. It will still have to be watched constantly to detect a malfunction before the battery is harmed.