Li battery - deep discharge type

[RWebb]

I was at Batteries+ today, trying to find a deep discharge battery to run a device with about a 2 - 3 amp draw. The device needs to run overnight for at least 2-3 nights.

The salesman tried to sell me a lead acid AGM Werker with 35 amp-hr capacity. Unfortunately, it is pretty heavy ~~ 25 lb. or so and only has a 1 year warranty.

I asked the salesman about a Lithium battery and he said they could not function (for long) once they got deeply discharged, and would soon fail, which is why they did not sell them. I asked about laptops and he claimed that was "different."

Any thoughts? Can some sort of Li battery be sued in this application?

It would save a LOT of wt. and hence trouble, expense, etc.

[nota]

Shorai LFX36A3-BS12 Lithium-Iron Battery - Free Shipping: BatteryMart.com

but $330 36 amp/hour at 5lbs

and 3 amp draw x10 is 30 for one nite
so one nite ok but noway 3 nites you need 100 amp hour for that [with a margin]

we used deep cycle batterys on the boat for tv or radio
100 amp hour = about 100 hours at one amp too

[RWebb]

yeh - I may be able to substitute a lower power device...

the Werker is 35 Amp-hr but is 27. lb.

[Rusty Heap]

your quoted need at 2-3 amps............at watt (ha hah) voltage?


Simple math really. Amp/hrs to weight and duration per battery characteristic performance (wet/dry/ni-mh/li-ion/fluxcapacitor) > cost$$$


The rest is wattage and power density per battery type.

sound like you're more interested in weight.........watttt's your application?


I'm in the same boat for long term GoPro Time Lapse in remote areas.

[RWebb]

12 V DC

but there is actually more to the situation - some batteries can take a deep discharge better than others

[Flieger]

Everything I've heard about Lithium batteries is that once they are discharged past a certain critical amount they are dead as a doornail. Not rechargable anymore.

[Rusty Heap]

amps


hours.

watts

lifespan.

cost


weight





pick your top 3.

[bpu699]

Lithium batteries are extremely unforgiving. If you deep discharge it ONCE, its toast.

Laptops have a low voltage cutoff, you can't deep discharge them.

Bo

[Porsche-O-Phile]

I recommend proper use of a suitable rubber insulating sheathing material prior to engaging in any "deep discharge", but it's up to personal preferences...

[Flieger]

Bwahahahahahahaha! I liked the unedited version better.

[schamp]

Not sure how big a battery you may need but see if Lifeline Batteries has something you can use. Just flat out the best battery you can buy. American owned and American made. Expensive but worth it in my book. Just bought 6 6 volt for my motorcoach. hth

[beepbeep]

Lithium has power/density edge. It's roughly 3x times better than lead/acid but as other people said, it's precision device that doesn't tolerate discharge past certain point. Most Lithium-run devices monitor each cell, temperature and cell voltage.

Thus you might want a Lead/Acid or NiMh battery after all.

Edit:
They seem to sell LiFe chargers as well:
http://www.batterymart.com/p-sho-bms01-shorai-battery-charger.html
(Notice all additional wires used to charge the battery)
If you need power/density and can protect the batry from deep discharger, then it'll work.