MaxAmps 8000mAh LiPo for T600

[crewchief]

I've been trying to figure out the best compromise between size, weight and capacity for my T-Rex 600. I wanted to have the largest capacity within reason, in order to make numerous short AP hops, and then baby it at night with a 1/2C charge. I've been very pleased with my MaxAmps 5000mAh pack, and very unhappy with the ThunderPower 5000mAh which started to fail after about 60 cycles. The MaxAmps 5000mAh still discharges to 4970 mAh after 70 cycles, and is a much better bang for the buck cost-wise.

I exchanged some emails with Austin at MaxAmps and we came up with the idea of this 8000mAh 6s2P. It's 137mm tall, so it sits flat against the tilt bracket without bumping into the vertical side frames, and is not too wide to prevent the canopy from being installed. It weighs 1060 grams, which is not a lot of added weight for the longer flight times (I think the 5000mAh is 730 grams). I also figure he will be able to save me a couple hundred bucks on the Maxi Joker 10s3P's when I need them, too.

[cbdane]

Are these available?

[crewchief]

Are these available?

Yes, now that they've done the first one it should be easy for them to duplicate it, but you'll need to contact austin@maxamps.com to order one.

[lowandslow]

What's the C rating?

[bullaculla]

The MaxAmps 5000mAh still discharges to 4970 mAh after 70 cycles, and is a much better bang for the buck cost-wise.


You are putting back 4970mAh back into a 5000mAh pack?
isn't that bad for the lipo? :confused:

[crewchief]

You are putting back 4970mAh back into a 5000mAh pack?
isn't that bad for the lipo? :confused:
My Astro Flight 109 charger can do a slow discharge of the battery to test the true capacity of a LiPo. When I first got the 5000mAh battery I tested it after a full charge and it had a capacity of 5300mAh - a lot more than I'd paid for. In contrast the Thunder Power 5000mAh tested at 4300mAh new - a lot less than I'd paid for.

The discharge test takes many hours as the battery is discharged at less than 1 amp load. The 6S is discharged from 25.2v or 4.2 v/cell down to 19.5v, or 3.25v/cell. At that point it freezes the display which shows how much time has elapsed and how many mAh have been discharged. Figure about 1 hour per 1000mAh.

After the capacity test you can reverse the operation and charge the battery back up for usage at 1C or 1/2C, whatever. This is what the system is designed to do, so I don't see how it could hurt the battery. It's also about the only way you can truly determine the condition of your batteries. They'll continue to charge to full voltage, but your flight times will become shorter as their capacity diminishes and this can lead to unfortunate circumstances if your timer hasn't been adjusted!

lowandslow,
All MaxAmps batteries are rated at:

20C constant
30C sustained
50C burst

[bullaculla]

Cool :cool:

[Efliernz]

This does look good for us running 6S camera ships.

I'm running the TP 6S 5000 packs and I've a good run so far, although they are below 25 cycles. I fly conservatively using the lipo alarm. I rarely find I'm going below 75% as once I have done 2-3 sorties for the same photo site, I might as well swap packs before flying at a new venue. As well get busier, a longer flight for 250g extra is well worth it.

[crewchief]

Yep, it's working out pretty much as I'd hoped. Right now I'm starting out with the timer on the DX7 set to 10 minutes with the fairly lightweight camera & mount. I shot 4 houses down one street with juice to spare. I pop up and shoot and when I land I check the time on the timer. I immediately reset the Tx countdown timer to that time, so next time I power up, the Tx the timer is set with the correct remaining time. Have to remind myself to do this before turning off the Tx!!! Today I flew a little over 10 minutes and had almost 23 volts left on the battery. Tomorrow I'll try 11 minutes, and keep upping it. I usually like to avoid running a 6S down below 22.5v if possible. I think it starts doing the tail wag at about 21v(?). The first time it did that I almost had a heart attack! Probably one of the reasons I frapped the Thunder Power.

[crewchief]

I ran an endurance test today (T600), with the light camera rig mounted, and about 5 or 6 takeoffs, climbs, hovers, descents and landings. It showed signs of sagging at 16 minutes and I landed and checked the battery voltage, which indicated 21.8V.