Lipo power to weight ratio. - Page 1
Forum section: electronics / general

author: SMdude
author_rank: Frequent Contributor
timestamp: July 08, 2017, 01:10:06 am
content: Hi Guys,Just wondering if anyone has some general power to weight ratio for lipo packs?For my 7.4v packs I get about 28ma/gram.Reason I am asking is I have just taken delivery of some packs and they are smaller than my last packs and lighter.And on a third note, does anyone have a battery manufacturer for custom lipo packs they have used and trust that they would like to share via pm?I'm feeling like I might have been a little done over here...Cheers

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: July 10, 2017, 12:37:08 pm
content: SpecificationThat sounds about right if this battery is anything to go by.I assume you are talking about Energy/Mass or Wh/gram. Apparently it is called specific density, whereas Energy Density is measured as Wh/LBecause u say power/weight but measure in Current/Mass. So careful with your units.Quote(random internet battery.)Energy/Mass = V * Ah/kg = 3.7 * 1/ 0.022 = 168 Wh/kg(your battery.)Energy/Mass = V * Ah/kg = 7.4 * 28 = 207 Wh/kgMaybe the series cell arrangement is confusing you. This will give the same Wh/kg, a higher voltage but less Ah/kg

author: SMdude
author_rank: Frequent Contributor
timestamp: July 10, 2017, 01:23:38 pm
content: Thanks!Yeah, my power to weight is really just a quick check of mAh/weight.It seems there has been a booboo! I have run these new packs through several cycles and they are consistently 1Ah less capacity than my 40g heavier 3 years old(in storage) packsSo far no response from the seller/manufacturer, though only emailed a few hours ago as I had to do a lot of testing to make sure my battle was a worthy one!Lol, and it was the one pack I could not compromise onThankfully, I can make use of them.

author: Nusa
author_rank: Super Contributor
timestamp: July 10, 2017, 02:32:31 pm
content: In the end it's not whether they're better or worse than your previous packs.It's whether they meet the specification the manufacturer promised to deliver.

author: SMdude
author_rank: Frequent Contributor
timestamp: July 10, 2017, 10:23:53 pm
content: And the answer to that is a big fat NO.But being on an entirely different continent, I am not holding my breath that it will get sorted out.All I can do is work out a way to use/unload them and get more from a different supplier that are built to spec.

author: Audioguru
author_rank: Super Contributor
timestamp: July 18, 2017, 05:53:50 pm
content: I order excellent North American batteries from the manufacturer when they have free shipping or from my local hobby store. I don't buy cheap fake Chinese stuff from ebay.

author: SMdude
author_rank: Frequent Contributor
timestamp: July 19, 2017, 09:41:22 am
content: I don't buy cheap lipos off ebay either!No, this is just a stuff up that I am most likely just stuck with now. The quality of what they are is good, just not quite what I wanted.I have a new product 2/3rd designed to utilise them, I see this as a quicker way out as I am sure I could argue for months and probably get nowhere anywayAnyway, they sure as hell know now what I wanted and want in the future.