I was recently browsing around in an electronics store and saw one of those portable battery packs for charging iPhones/iPads that had a 10,000 mAh capacity for $20. If I'm doing my math correctly that's 10 Ah ($2 per Ah of capacity). A pair of T-105s might run you about $250 and get you 225 Ah of capacity, but not going below 50% SOC means just 112 usable Ah. That's $2.23 per Ah of capacity.Of course I'm sure there's more to it than that. The iPhone charger was a sale item and may not actually reflect current Li-ion prices. Also, who knows what the overall longevity/durability of the Li-ion batteries will be compared to the FLA and if 100% of the stated capacity of the Li-ion pack is usable. However it is obvious that Li-ion prices have been steadily dropping while FLA prices are stable. Also, since AGM is about double the cost of FLA, it seems reasonable to think that Li-ion may already be competitive with AGM, if not cheaper. So, this gets me wondering how far we are from seeing widespread use of Li-ion batteries in the RV industry.

One other thing that occurred to me, watt hours would be a better comparison. Ah as capacity is only valid as a comparator if the volts are the same, and I don't think these portable chargers are 12v. Still, the overall argument is the same, Li-ion prices are dropping and FLA is not. Im just wondering when will the crossover occur.

787 uses Lithium Ion batteries.

They will probably drop in price when WalMart starts importing them from China by the boat load.

I've been flying electric RC planes for 10? years now and have seen Lithiumbattery prices plummet (?) in that time period. I now purchase twice the Ah for 1/2 the price. The advantage of Lithium is that they can deliver enormous amounts of current (full throttle on my plane equates to 80amps @ ~18Volts) and the weight is small in comparison.I see FLA batteries going away within the next 5 years - cars will no longer have FLA batteries and be equipped with small/light-weight Li; The RV industry will surely follow.

that lithium phone pack is what voltage 5v ? 3.7v ?you need (3) times much to equal the same 10ahr as 12vso you would need to spend $60 for (3) packs in series to get 15v~14.1v so that becomes $6 per amp hr, your 225ampHrs would cost $1350 to buildyes i think you can buy One cheaper than that, but way more than FLA12v ? lithium cost more than 12v AGM, so NO its not cost competitive with FLA NOT Yet

Li-ion soon to be price competitive with FLA? | Good Sam Community

wa8yxm
Explorer III
Sep 21, 2015
Well. first observation is you need a math lesson or an observation less or both.

Story of a doctor telling how they used to diagnose Diabetes by tasting the urine (If it's sweet then Diabetis Mellitus (means sweet or honey like) is indicated, if it's not then Diabetes Incipidus (means weak) (Diabetes means water flows freely, in short you pee a lot).

Doctor dips a finger in, tasts a finger and says "Yup, that horse has Diabetes" and asks for a student volunteer to try it. One does and disagrees with doctor as to diagnosis.

Doctor then goes on "And this shows the importance of proper observation.. I tasted THIS finger.(Holds up one finger) but I dipped this one (the finger next to it) .

So.. What did you not observe? The voltage.. I-phone pack is five volts or more likely around 4.5 volts... T-105 pair is 12.

That said.. One could indeed make up a fairly good battery pack out of these things for less than the T-105's cost. So good that you brought it to our attention.. perhaps soon we will have 12 volt LiOn packs in the 200 amp hour/100 dollar range.
MEXICOWANDERER
Explorer
Sep 21, 2015
LED LIGHT 30 WATTS! $3.00 US very good very good. (Power consumption 2.5 watts.)

TOOL Extra heavy duty Chrome Morrlybedeneum. (sheet metal)

Slow Learners will jump right on the Chinese LiPo band wagon. Wise shoppers will wait until the flies clear to find out what's real and what isn't. I've got a DRAWER FULL of bad Bridgelux and CREE chips. Sorry Charlie I do not have enough resources to play pin the tail on the LiPo.
MrWizard
Moderator
Sep 21, 2015
Ok not AA, but that Chinese adv was pure fabrication, regarding the capacity
brulaz
Explorer
Sep 21, 2015
If those 18650 cells are LiCoO2 batteries, as used in most portable electronics, I wouldn't want to put a bunch of them together (say 100Ah at 12V worth) and accidentally over-charge them.

From what I read (on Wikipedia), LiCoO2 is much less stable than LiFePO4 (but has a higher energy density). Most Electric Vehicle conversions and marine yacht installations use LiFePO4, for the safety reasons I suppose.
landyacht318
Explorer
Sep 21, 2015
The highest capacity 18650 cells are Panasonics at 3600Mah, as far as I know, And you will be lucky to find a single cell for less than 15$

The claimed capacity of cells sold, go well into the ridiculous category. Many of the cells sold are rewrapped laptop cells.

I've harvested 18 laptop 18650 cells 2 of those were bad, the rest have usable capacity left. New they might have been 2100mAH. I'm lucky to get 875mAH from them when using a single cell to recharge my Phone, or Bluetooth speaker, but there are inefficiencies involved.

While my harvested laptop battery cells can take my phone from 15 to 85% or so before the battery cannot support 4.75+ converted volts, my Panasonic NCR18650b cells can take my phone from 5% to 100% nearly 1& 2/3 times.

A pair of Panny NCR18650Bs runs about 22$ minimum. I buy a 9 cell laptop replacement battery for about the same, but the cells are junk, in comparison.

I think the 18650 cells are the highest energy density cells currently available to the general public. I thought Tesla is using a few hundred 18650 cells in series parallel for their battery packs, but will not put money on this.
NinerBikes
Explorer
Sep 21, 2015
MrWizard wrote:
AWE AA's

sorry but i don't believe 9.8 amphr in an AA cell even lithium
at what discharge rate, 1ma ?
those aren't AA cells. an AA in lithium gets 4.2V to 3.7 volts claimed at 900 Mah.... an 18650 is 18mm by 65 mm in size, a laptop battery is made up of a bunch of them. And they each are probably 2400 to 2500 mah at that size, not 4000 or 4400 mah.
MrWizard
Moderator
Sep 21, 2015
AWE AA's

sorry but i don't believe 9.8 amphr in an AA cell even lithium
at what discharge rate, 1ma ?
Golden_HVAC
Explorer
Sep 21, 2015
I was looking up the 18650 battery at AliExpress.com and found this deal.

16 batteries, 9800 mA hour and 3.7 volts each. $22.80 or $1.43 each.

16 lot of batteries

So it will take 3 in series to make 12 volts (almost) and 15 of them will make about 48 AH! all for $23.

You can also find battery packs that hold the 18650 battery - three packs.

3 battery holder

Good luck,

Fred.
Golden_HVAC
Explorer
Sep 20, 2015
I have been buying 5 Ah 3.8 volt Li-Ion batteries for my flashlights for a couple of years now, $3.20 - $4 each and they are very reliable. But I somehow think the same battery is not 'good' for starting a car. I am using the 18650 battery, I guess it is 18 mm diameter and 65 mm long. They also sell a USB output 5.0 volt portable power supply using 4 of the Li-Ion batteries for about $10 without the battery. It would be easy to make a 10 AH battery supply for only $30 this way.

They also make a 26650 battery with a lot larger capacity.

I was looking at an electric scooter online today - GoPed.com and it has between 16 and 32 of the Li-ion batteries and cost above $3,000! The lead acid version is only $1600. I guess they have not found the lower priced chargers and batteries?

Yes there are manufactures out there making different size Li-Ion batteries, and some are square, and other shapes. I don't know how well they will work in 12 volt car batteries, because they tend to run to high of voltage while driving, and that will overheat a Li-Ion battery. Yet anything is possible.

Good luck,

Fred.
brulaz
Explorer
Sep 20, 2015
What wizard and landyacht are saying.

You will want four 3.2V LiFePO4 batts in series to get 12V.

LiFePO4 are safe (NOT like the Li ions in most cars and airplanes), and you can use 80% of their rated Ah. So a 130Ah 12V LiFePO4 pack would give 104 usable Ah, roughly equivalent to two 6V golf carts rated at 210 Ah.

Four 3.2V 130Ah cells currently cost about 4*170= 680US$

But then you need a BMS and a low-current contactor/PowerRelay to be sure you do not exceed the 10-90% Ah range. (~125$US for BMS, ~190$US for low-current contactor)

You will also want a Ah meter, as the V is very flat between 10 and 90% Ah making it difficult/impossible to estimate battery status from V (~175$US ?).

So the prices add up! Because of the fixed accessory equipment cost, larger battery banks make more sense to me. I've been tempted, primarily because of their very low weights, but the prices are still too high for me.

Oh, and you will want to ensure that you do not charge the batteries when their temperature drops below freezing. In my case that wouldn't be a problem, but I think PianoTuna rejected them for that, in part.