Duralite capacity issue

[Havoc]

I tried to call but the tech guys are at Florida Jets. I had a problem where my Duralite 4000mah pack lost capacity to the point of only getting 2 or three flights before the Duralite tester showed the no fly voltage. I sent it off and it was quickly replaced. Now my other pack on another heli is showing the same signs. Or at least I think it is. It seemed strange that two packs would do this within a fairly short time of each other and I suspected the Duralite charger had gone bad. After only one flight the pack went from a fresh charge to showing 7.2 volts under 1 amp load. After waiting 10 minutes it was up to 7.3. But a load test with the Futaba tester shows 7.6. This duralite tester has been my measuring stick since I first got the batteries and when I was having trouble with one battery the other battery seemed good with the same test. So I don't know if maybe the tester went bad or what the deal is.

[DavidH]

Showing 7.2 volts with a 1 amp load from a freshly charged battery is not unusual after 1 flight. Mine with they come off charge show 8.1 to 8.2 with no load. Apply 1 amp load and they show 7.5 or 7.6. Make a 13 min flight with all digitals and the battery will show 7.2 to 7.4 with 1 amp load. Then over the next several flights it will stay in the 7.0 to 7.2 volt range. At least that has been my experience for the last 2 years.

The difference in the Duralite volt test and the Futaba tester could be the load that is being applied. The Futaba is adjustable up to 3 amps. The Duralite will apply a .5 or 1 or 1.5 amp load depending on the buttons pushed. If the Futaba tester is set for a lesser load than they Duralite it should show a higher voltage.

What is the battery voltage when the battery comes fresh off a full 5 or 6 hr charge? NO Load and then 1 AMP load

David

[Clintstone]

I had one of my packs which I thought I had a problem with which ended up being a bad connector on the test lead. I found it by bypassing the sw/reg to the Battery. It should good voltage but would drop under a load. I replace the bad conector and all was fixed.

[Havoc]

Thanks guys. Thats good to know. I might just be paranoid after my other battery problem but I was thinking I was getting 7.4 or greater after the first flight. The futaba test was a 1 amp load but it is not my tester and I don't know much about it. I usually check before each flight but since the battery problem I've also been eager to check right after each flight. It does seem like the voltage creeps up a little after the battery sits? I have not charged my batteries since the flight last sunday. I only got to fly mine once since I was working on another guys helicoper. So I tested it just now and it is up to 7.36 under load on the duralite tester. I then checked straight from the battery and did gain another .06 giving me 7.42 so i will go ahead and replace the lead. It was also 40 degrees outside but I don't think that should cause much of a problem?

[DavidH]

Yes the batteries are temp sensitive. I would say that in 40 deg weather that the capacity of the battery will be down some compared to 70 deg weather. I have use the batteries when the temps were down close to freezing. I noticed the batteries do not last as long as they do when the weather is warmer. That is normal with any type of battery.

David

[Havoc]

Seems like I get half the flights at 40 degrees as I do above 70. Duralite seems to say this is normal. I got a new switch also.