critterhunter

No, I don't work for Dymond. Just want to share my experience thus far with their batteries as I think the lipo (and brushless motor) companies out there are taking us all for a ride with the high prices. I don't want to pay for anybody's new boat because he's a lipo salesman. That being said, the lowest price I could find (and it was VERY low) was Dymond Motorsports Lipos. I picked up to 10C 3 cell 2000ma lipos for $35 a piece! Other "quality" brand names wanted $60 to $90 for a similar rated lipo. These packs look to be built of good quality with no skipping on the wires or wrapping. I've had great luck with them thus far and they only get slightly warm running a BP21 brushless motor at full throttle until it dies. It's hard to say, but I'm guessing I'm getting a good 15 to 20 minutes of full throttle flights on my Stryker with the BP21. The other day the plane lost full throttle and thus the battery was drained but I ended up landing it high in a tree. It spent over two days up there and when I got home the lipo was at less than 3.5 volts. The lipo charger wouldn't accept it so I took a risk and charged it on a Nihm charger for less than 5 minutes to get the voltage up to where the lipo charger would take it. The battery is fine with no problems! WARNING: This is VERY unsafe so don't try it unless you know what you are doing and have safety gear on to protect eyes and such. Anyway, I'm very happy with Dymond lipos and want to spread the word so others can stop paying through the nose to other companies. I think Dymond is now selling 12 or 15C packs as well.

jfcgnv

My Feedback: (1)

I read with interest you report on your lipos that had exceeded the minumun voltage where we are told that they are trash if this happens. I don't know if you and I are just lucky or what but I have had a similar experience. I left a Thunder Power 3S 2100 lipo pluged into my receiver overnight and the next morning it was "dead". I would just move the indicator on my analog volt meter. Well at 79.00 bucks I was really upset with myself for being so careless. I said what the "HEY" and tried to charge it with my lipo charger and it would not take a charge or show any indication of life. I then hooked it up to my NiCad charger and it showed life. As soon as it reached 9 volts I hooked it up to the LiPO charger and it started taking the charge from the charger. My charger is a Microlader. The battery took 1850 Ma and the charger cut off . I was really intreged now as this could not be happening. I then connected my battery to my Alfa F-86 Saber with a Hi Max 2025-5300 and it pulled 17 amps and 10.5 volts for a power of 180 watts. it held this for several minutes with the battery getting slightly hotter than warm. It was not too hot to hold though.

Either we have been extreemly lucky or there is more to LiPo's than we are lead to believe. If anyone has had a similar experience let the forum know. My thunder power battery is still charging and discharging normaly even after the above experience. Like I said "How can this be".

John C

twinturbostang

I was getting ready to buy two TP 1320's. I've seen the stuff on dymond's website, but was skeptical because it was so cheap. Should I take another look then?? Something that's confusing though... the 12C 3S 1500 for $39 says "no connector". Some of the other ones say "with leads". What does this mean?

jfcgnv

My Feedback: (1)

No connector usually means that the wire leads are coming out of the battery pack and you can solder your own connector to match the system or connectors that you are alreaddy using. No leads means that the battery are without wires coming from them. You will have to solder your own wires and connectors to the battery(S). If you purchase a battery without leads please be careful when you solder the wires to the battery because some of the battery terminals where you solder the wires are not solder friendly and you can ruin your battery very easily. I suggest you always purchase batteries with leads attached, you can solder your own connectors very easily with just basic soldering skills. When you solder the leads to your connector make sure that you insulate the solder joints with heat shrink to prevent shorting out and to strengthen the wire connector attach point.

twinturbostang

Ok, thanks. So I should get one with the leads, and then I can just solder on a connector.

Speaking of which... do you know how many amps the micro deans is good for? I have a couple of the standard deans and they are nice, but it bit heavy. Was hoping to go with something smaller to save weight, as long as it's ok with the the amp draw.

jfcgnv

My Feedback: (1)

The Micro deans should be good up to about 10 Amps. A good rule of thum is if you use the standard 280 350 brushed motors the micro or standard deans is fine. If you use a brushless motor and two or three cells use the larger ULTRA deans. You can never go wrong by using the larger Deans if weight is not an issue.

John C

twinturbostang

Thanks. Maybe I'll stick with the Ultra Deans then.

RC Extreme power

My Feedback: (24)

There are a few good low cost lipo's out there but Dymond is on the bottom of the list as far as putting out the C rate that they advertise. You have a 2000 mAh battery that is rated at 10C which should be able to do a 20 amp continous discharge. You are running a bp 21 that should be pulling no more than 14 amps. That is about 7C rate static and about 5C when unloaded in the air. When you try and use them at 10C you will hit LVC in about 15-20 sec.
Milton

RC Extreme power

My Feedback: (24)

just read your post a little closer and seen where you said that you were getting 15-20 min. flights
At 15 min. your C Rate would be 4C or 8 amp draw
At 20 min. your C rate would be 3C or 6 amp draw
A long way from 10C that they are rated.
If you do not run them any higher than you are they will perform for you but at a higher rate they will not.
Milton

twinturbostang

Milton: Based on the fact that you are a competing battery vendor (judging by the website in your sig), is this information you are providing from your own personal experience with Dymond batteries, or something other?

RC Extreme power

My Feedback: (24)

I need to change my sig. Have not dealt in batteries for a while. I to got excited when I seen the add about a 10C battery for about 1/2 half the price of other 10C batteries and orderd a 1300-1800 and 2000 mAh battery to check them out.
Below are the discharge graph for the 1800 and 2200 mAh batteries.
Milton

twinturbostang

Wow. That looks pitifull! Have you done testing on any other batteries from them? I wonder if you got a bad batch or something. That's definitely grounds for a return. I just ordered a 12C 2100 3S. I'm hoping it performs a whole lot better than what your graphs show.

critterhunter

How long ago did you order those packs? Lipo chemistry is getting tweaked as we speak. Newer packs are able to handle higher amp draws and too far of voltage draw downs than older packs. Then again, even if they are advertising C ratings that are a bit above what they can handle just buy a higher C rated pack from them (I think they have 12 and 15C packs as well now) than you need. You'll still be saving money over the "quality" brand names out there. I'm not real sure if my flight times are 15 to 20 minutes. Haven't timed it but they feel that long. I'm guessing 10 to 15 minutes at full throttle would be more realistic. I know it feels twice as long as a stock stryker using an 1100ma Nimh pack. I'm using a 7x6 prop and think I've read the BP21 with this prop on a 3 cell lipo draws somewhere around 15 to 18 amps. I believe a 10C rating for my packs means they can handle 20 amps, so I'm well near the limits of them and have not had a problem yet. In fact, the packs are just a tad warm after a full throttle flight...much less warm than one of my Nimh packs gets in various planes I run them in. I would think that if the pack was being stressed by the amp draw it would be getting pretty toasty.

RC Extreme power

My Feedback: (24)

If you are drawing 15 amps from a 2000 mAh pack that is 7.5 C rate discharge at that rate you would get about 8 min. flying time at WOT. If you have a watt meter see what you static amp draw is. If it is 15 amps you will see a big drop in voltage.
Milton

twinturbostang

Well, my 2100 3S Dymond seemed really strong for 5 minutes. Didn't get a chance to test it any longer than that though. Here's why: http://www.rcuniverse.com/forum/m_3372244/tm.htm

critterhunter

Timed a flight or two the other day with the Dymond lipos and I'm getting right at about 10 minutes of flights. The BP21 draws about 15 to 18 amps with a 7x6 prop. In other words, I'm very close to the 10C rating of these packs and they are only slightly warm (much less so than a typical nimh pack after a flight). Still performing great and I'm very happy. These are 3 cell 2000ma 10C packs which would be the ability to supply 20 amps.

RC Extreme power

My Feedback: (24)

If you are getting 10 min flight that is equal to a 6C discharge rate or 12 amps in a 2000 mAh pack
Milton

goplug

Anyone know what type of temp sensor is used on the Dymond charger?? Diode, thermistor, etc.
Thanks.
Jim

TManiaci

My Feedback: (6)

Just throwing in my 2 cents... thanks turbo for pointing me to this debate.

I have one Dymond 10C 3S 2000 mAH, one 3S 12C 1500 mAH, one 12C 3S 1350 mAH, two 12C 3S 2100 mAH, one 10C 2S 1100 mAH and one 10C 5S2P 8000 mAH. All of these batteries are perfoming with regularity every bit as well as the Thunder Power batteries we have. I use a wattmeter, and load test with attention to details like overload performance, long run overheating at C rating, flight times and general quality.

I have to say, Kudos to Dymond. Great stuff, Helmut should be proud. I don't care what those charts say, all these batteries we have are performing to thier specifications consistently. If they don't, Dymond will replace them, no questions asked. Great customer service! I have been in the store in San Diego and met the people... they care and will do anything to make the customer happy.

My recommendation... buy them like a cheap stock ready to go thru the roof! Great value!

Looks to me like Milton has a bone to pick here... he doesn't complain about flight performance or make examples of troubles he's had... he provides sophistocated discharge graphs that no common modeler would invest $$ in to produce. Smells like a covert competitor to me...

twinturbostang

Wow. Did you buy stock in the company too?!?!

TManiaci

My Feedback: (6)

LOL, no, but if I could, I would. I'm ordering two more 3S 12C 1500 mAH soon. You can't beat the low price and high quality... I hope I'm not dissapointed as time goes on, but so far - so good.

critterhunter

Well, he might have got a bad batch of lipos from them as it sounds like he knows what he is doing. I can only say that I'm very happy with the price and performance of my 3 cell 2000ma 10C lipos with my BP21 brushless Stryker. They don't even get warm when charging at 2 amps. They only get slightly warm after a 10 minute flight at full throttle the entire time. And, as I think I said, I even brought one back from the dead when it spent two days in a tree and had dropped to less than 3.5 volts. It performs just as well as the other lipo. The wiring and wrap that came with the packs is top notch. I've even ejected the batteries in some bad crashes with no dents or dings on grass. I feel brushless motors and lipos are way overpriced and I'm glad to see that Dymond is bucking this trend. I'd also recommend the Balsa Products BP21 brushless motor for it's price and performance at less than $20. You can even package it with a 30 amp BP speed control for about $48 total and THAT is a great price. Using a 7x6 prop the speed and power of this little motor is amazing.

twinturbostang

Just don't eject it at 200 ft up. I posted a link above (post # 15) to what happened to mine. []

gt_jumper

i have my trustee old kokam 1050 rated at 15c, this battery cost me like $40 au. they owned the market for a few good months here. but has any one thought of getting some 12c -16c packs from ebay?

http://cgi.ebay.com.au/Li-Poly-11-1v...QQcmdZViewItem

that pack is going for $55 au and candischarge at 33 amps, although id never touch that with my little motor, i could keep my funfly up for like half an hour with that pack ( getting 17 mins just stoogin around ). i have never seen any thing about these packs, any one have one and whats there opinion of there value? i have a ebay speedy for 18 amps, cost $19 and has never let me down, is programable (sounds like an air horn lol ).

TManiaci

My Feedback: (6)

I have spoken to some "battery" guys. I would be very shy of 15C and 20C batteries for a while. They said... and I quote...

"... The 15C and 20C have a relatively short cycle life. The technology is pushing the limits now. You can only expect 30-100 charge-discharge cycles from these ultra-high-discharge batteries, depending on how hard you work them..."

and...

"... think of them as Fuel Cost, like a nitro plane. You buy some, use them up, and replace them..."

Now I have no idea what 10C and 12C battery cycle life is today, but I'm betting it's many times those numbers. For the high cost of these newer high-dischage batteries, I'm not too excited about them becoming pretty paper weights in a couple months [].

my two cents... I could be wrong . Someone have better information?