LiFePo4 Batteries

[Dmb408]

I know BradP talked about his using one AntiGravity battery for lightweighting but I was wondering some things before pulling the trigger. Anyone out there know a lot about batteries?

I want to run two of these in parallel http://www.amazon.com/Battery-Tender...tender+battery I guess my questions are:
1) are our voltage regulators smart enough to not overcharge a lithium battery
2) is there anything dumb about me putting these in parallel to get about the same CCA as our stock battery
3) if i buy the tender for it, it will tender two just fine right, because the modern tenders have microprocessors and would know to send more

I figure I do two of these and some foam packaging and such, additional wiring and I'll drop about 50 pounds (OEM 59 minus 9 of total new weight) and if I treat them right they should cycle twice as long as the OE battery and thus have price parity.

Help appreciated, thanks!

[Other_Erik]

I know BradP talked about his using one AntiGravity battery for lightweighting but I was wondering some things before pulling the trigger. Anyone out there know a lot about batteries?

I want to run two of these in parallel http://www.amazon.com/Battery-Tender...tender+battery I guess my questions are:
1) are our voltage regulators smart enough to not overcharge a lithium battery
2) is there anything dumb about me putting these in parallel to get about the same CCA as our stock battery
3) if i buy the tender for it, it will tender two just fine right, because the modern tenders have microprocessors and would know to send more

I figure I do two of these and some foam packaging and such, additional wiring and I'll drop about 50 pounds (OEM 59 minus 9 of total new weight) and if I treat them right they should cycle twice as long as the OE battery and thus have price parity.

Help appreciated, thanks!

Linked battery is rated for 240CCA - If you want to start the beast, especially in the cold, you're going to need 3, stock battery is rated 760CCA, and I've been using an oversize/deep cycle rated for 920CCA that did the job okay-ish when temps were in the -20F territory here in the DC area this past winter.

Sorry I can't help you on the smarts of the Voltage Regulator question, but I assume if you're running parallel that the batteries should theoretically charge/discharge at the same rate, you may need to worry about cell quality between individual batteries though.

The question about a battery tender (assuming the type you plug to 110vA/C) would be better asked of the manufacturer - they do answer some questions on the amazon page regarding using their battery tender, not sure if they've touched on anything about use in parallel, but I'd think that it would work fine, just at 1/2 (or 1/3 if you go with 3 in parallel) speed of charging if they end up discharged for whatever reason. Not necessarily a bad thing, since trickle charge seems to be the best way for lead-acid batteries, though I can't speak specifically to Li-I or other battery technology.

O_E

[hahnmgh63]

http://www.amazon.com/Battery-Tender.../dp/B00F9LPL5E 480cca
I've been using the Odyssey 925T battery for 5+ yrs with only an occasional slow start. I do leave it on a battery tender if I'm not planning on driving it for a few days. All CCA ratings are not the same, there is usually fine print but the 925T is only rated at 330cca and it weights 27lbs. I might give the one I listed above a try.

[Dmb408]

I mean so here is my predicament in more detail, the 480 one would definitely work because I keep the RS6 stored 95% of the time (bad I know but that's how it is working out with this second one) and could keep it on the tender. I bought the car with 107XXX miles and it has 108XXX miles, I don't even think I have put on 1000 miles in about a year.

But, and here is the but, I have two sets of wheels now and will get the 4 OE's switched over to snow tires for winter and I will want the car for snowy cold days (i.e. not slushy days, want the awesomeness in snow but not the bad feeling about ruining the body). So those days will be pretty cold.

[Dmb408]

Parked at home in winter it would be on a tender in a non-heated garage although I could move it to the heated garage if I knew I'd be driving it a lot a certain week. At work it would be in an above ground parking structure that would only shelter it from wind and extreme cold, so it would generally sit at ambient temp.

[lswing]

Odyssey 925T, battery tender if sitting for a few weeks. Small and plenty of power.

[Dmb408]

Oh I agree Lswing, tried and true with the 925 at least with normal temps, but I am trying to go big or go home here and see if I can drop an additional 20lbs over the 925 and have more cranking.

[urs6ville]

off topic, but I hate that we are already talking about cold temp starts.... got a metric sh*t tonne of snow last year, summer has been too short. *sigh*

[atikovi]

I want to run two of these in parallel http://www.amazon.com/Battery-Tender...tender+battery

Don't remember the details but read somewhere that the alternator wont keep a LiIon fully charged. If you want to experiment, try these AGM batteries for just $28: http://www.ebay.com/itm/STX12-BS-Pow...198510?vxp=mtr Bought one for a Lotus to replace a 30 pound stock battery. Rated at 180 CCA but tests out at over 250.

[bmlee007]

Or try this...

http://www.streetunit.com/Braille_15...y_p/b2015c.htm

I'm planning to get one for my GTI, maybe a second for the beast.

[RSoverAll]

Here you go. Let it sit, will start during the cold and lightweight. Problem solved.

http://www.amazon.com/Braille-Batter...=braille+i49cs

[Dmb408]

RSoverall, i hear you on that one if money was no object (with the wife) i might say why the hell not. I still want to solve this parallel riddle or find someone who knows more because I think two of the 4 pounders together will strike the right balance, some ability to cold start and will be able to sit for about 2 weeks.

[atikovi]

http://www.amazon.com/Braille-Batter...=braille+i49cs

$3,500 for a car battery? Somebody on crack. Or designed by the people that brought you $500 toilet seats and $800 hammers for NASA.

[Dmb408]

Called one of those local battery places and they parallel up some lithium ATV batteries (as they call them) for golf carts from time to time. I'm gonna stop by on my way home and look at the cables. Over the phone it seemed like the person was saying 60v 6 gauge wiring, obviously voltage sounds cool and the gauge seems about right.

[RSoverAll]

Called one of those local battery places and they parallel up some lithium ATV batteries (as they call them) for golf carts from time to time. I'm gonna stop by on my way home and look at the cables. Over the phone it seemed like the person was saying 60v 6 gauge wiring, obviously voltage sounds cool and the gauge seems about right.

6 awg is tiny. May be suitable for starting smaller equipment but I doubt that's heavy enough for the amperage requirements for the RS6's starter. Even for the wiring to cross link the batteries I would want at least the gauge of the factory OEM positive cable otherwise the lesser gauge becomes a bottleneck and will not be able to carry as much amperage.

Also keep in mind the longer the run of cable your available amperage/voltage at the other end of that cable will be a bit less due to the natural resistance of the copper. Thats just Ohm's law.

[C300]

I've seen the damage caused by Lithium Ion Batteries. Not going to put me near one. (except at work)The good thing about them is that they can discharge ALL of their reserve amperage in seconds. thing is, not much can handle it. charging is a science. done wrong = melting to China. HOT ass Plasma. following manufactures instructions is paramount. run it down too far and it's scrap. check out the different kinds of Li-Ion batts, charging issues and spider charts at http://batteryuniversity.com

[Dmb408]

6 awg is tiny. May be suitable for starting smaller equipment but I doubt that's heavy enough for the amperage requirements for the RS6's starter. Even for the wiring to cross link the batteries I would want at least the gauge of the factory OEM positive cable otherwise the lesser gauge becomes a bottleneck and will not be able to carry as much amperage.

Also keep in mind the longer the run of cable your available amperage/voltage at the other end of that cable will be a bit less due to the natural resistance of the copper. Thats just Ohm's law.

Do you know stock gauge?

[Dmb408]

i think i am going to go with shorai, it has a lot of testing in the lotus world.