Best Power-Weight For 4 AH System?

My dual DC9360's seem tb on the way out: they're down from a total of 4.4 measured AH per charge to about 3.7.

If the decline curve flattens out, maybe I'm good for a few more seasons... but if it steepens....

If/when I replace them, I'll be looking for something in the neighborhood of 4 AH... or even 3.... because my use is only to help me get up hills without mouth-breathing in cold air.

I'm guessing there's not yet anything better yet than the DC9360's A-123 cells.

But is there something comparable power-weight-wise at a lower price?

Other chemistries?

Maybe Bosch?

As far as power to weight in small packages, the turnigy nano-tech packs are hard to beat. And 4ah packs are available pre-assembled. What voltage do you need?

Farfle said:

As far as power to weight in small packages, the turnigy nano-tech packs are hard to beat. And 4ah packs are available pre-assembled. What voltage do you need?

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The DeWalts claim 36 but measure more like 32 off the charger.

I wouldn't want to go lower than that. A true 36 would be great. The controller can handle 48, but I don't need to go very fast.

Take a look at a 10s lipo pack. Here are a few. 10s will give you 37v nominal, and 41v when full.

http://www.hobbyking.com/hobbyking/store/__21368__ZIPPY_Compact_4000mAh_10S_25C_Long_Lipo_Pack.html

http://www.hobbyking.com/hobbyking/store/__21377__ZIPPY_Compact_5000mAh_10S_25C_Lipo_Pack.html

http://www.hobbyking.com/hobbyking/store/uh_listCategoriesAndProducts.asp?idCategory=86&LiPoConfig=10&sortlist=&CatSortOrder=desc

Farfle said:

http://www.hobbyking.com/hobbyking/store/__21368__ZIPPY_Compact_4000mAh_10S_25C_Long_Lipo_Pack.html

Click to expand...

Any idea what the tradeoffs are between that one and the Turnigy product at roughly twice the price?
viz: http://tinyurl.com/b5aluff

I see higher discharge/charge rates. Is that about it?

Or might there be chemistry-specific safety considerations? One of the attractions that my old-version DeWalts have for me is their relative foolproof-ness.

I'm guessing they do not include a BMS and not over-draining would be on me.

Also guessing that foolproof plug-and-play chargers are readily available.

Older Dewalt batteries uses A123 26650 LiFePO4 cells. They have very high discharge rate, higher than 99% of ebike users will ever need. They are also the safest chemistry of all lithium.

Newer Dewalt batteries uses Samsung LiFePO4 cells. Not as high discharge rate as A123, but sufficient for most ebikes.

RC LiCo (LiPo) is Lithium Cobalt in pouch format, the most volatile chemistry of all. If safe and "fool proofness" are what you are after, RC LiCo is the last thing you want to consider.

Farfle,
Thank you so much for those links! I just srarted poking around the forum foe any sources of ebike battery in the 4-8ah range.
i enjoy running 80+ volts at 20amp. I've experimented with many battery since I made my bike many years ago. Thats a good price for the voltage I need. Then all I need is chargers. And then some sort of lvc. my lyen controller is set for 63lvc Ive been told. I'm thinking I need some lv alarms on some cells just to be safe. Cause if there is a way to destroy my battery, I will definately experience it.

SamTexas said:

Older Dewalt batteries uses A123 26650 LiFePO4 cells. They have very high discharge rate, higher than 99% of ebike users will ever need. They are also the safest chemistry of all lithium.

Newer Dewalt batteries uses Samsung LiFePO4 cells. Not as high discharge rate as A123, but sufficient for most ebikes.

RC LiCo (LiPo) is Lithium Cobalt in pouch format, the most volatile chemistry of all. If safe and "fool proofness" are what you are after, RC LiCo is the last thing you want to consider.

Click to expand...

Rc lipos are dangerous, they have a near-zero tolerance for neglect, and the results of neglecting to treat a pack right can vary from trashing the pack, to trashing your house, workplace, garage etc...


That being said. If you invest in a good balancing charger (Icharger, Hyperion etc... ) and an easy to use cell voltage checker like a cell log or battery medic, you can be just like the tens if not hundreds of people on this forum that run lipo everyday without issue.

Now that your sufficiently scared . lipos are great for small packs!

electricridefl said:

Farfle,
Thank you so much for those links! I just srarted poking around the forum foe any sources of ebike battery in the 4-8ah range.
i enjoy running 80+ volts at 20amp. I've experimented with many battery since I made my bike many years ago. Thats a good price for the voltage I need. Then all I need is chargers. And then some sort of lvc. my lyen controller is set for 63lvc Ive been told. I'm thinking I need some lv alarms on some cells just to be safe. Cause if there is a way to destroy my battery, I will definately experience it.

Click to expand...

I wouldn't go with those 10s packs for a high voltage setup. Doing things in groups of 6s packs is much easier, as chargers and monitors (battery medic etc...) are typically built for increments of 6 cells. The only reason I reccomended a 10s pack for Pete is that it was pre-assembled for his voltage, technically the 6s packs are more cost effective.

yeah, but, the size is perfect, and the less cells I have to mess with the better. My last battery was 12 7.4v rc packs connected together. but that was nimh...never gonna do that again. I just need some sort of low discharge protection with these lipo. What is the best solution for this? I should be very wary of this?

Farfle said:

Rc lipos are dangerous, they have a near-zero tolerance for neglect, and the results of neglecting to treat a pack right can vary from trashing the pack, to trashing your house, workplace, garage etc...

Click to expand...

Somewhere on Endless-Sphere, there was a minimalist build by somebody in the UK that included a standalone charging station - located away from the house/garage.

At the time, I wondered.... Now I think I understand.

I found EuJangles' build (http://endless-sphere.com/forums/viewtopic.php?f=6&t=43256) quite appealing in the first place.

But now it looks even better to me in that the battery looks amenable to a swift kick to separate it from the frame in the event of fire.

PeteCress said:

Farfle said:

SamTexas said:

Rc lipos are dangerous, they have a near-zero tolerance for neglect, and the results of neglecting to treat a pack right can vary from trashing the pack, to trashing your house, workplace, garage etc...

Click to expand...

Click to expand...

Click to expand...

You had the quotes mixed up. I didn't say that.

SamTexas said:

You had the quotes mixed up. I didn't say that.

Click to expand...

My bad. It's fixed now.