New 12 volt Battery , weighs just 3 pounds .

Kpeters · April 3, 2013

Looks great weight savings is great specially for track cars. As long as they are not the same manufacturer that does the ones on the 787 we should be fine haha. Had to say it...

TobyB · April 3, 2013

li ion or li poly require special charging devices

yeah, they do, emphatically. Like, burning 787, they do.

So if there's an equalizing circuit in there with protection, then they're safe

for cars... mostly.

If there's not, they'll do the amazing Sony laptop flambe.

There must be.

The model flying community uses unregulated cells, and there's quite a bit

of attention paid to keeping them safe.

Because they can be quite dangerous if not taken care of properly

(as in, better than an alternator does for a lead- acid)

t

ndog · April 3, 2013

^that is very,very true.I watched a truck almost burn to the ground after a guy hooked a li-poly model airplane battery up to the charger connected to his truck battery. If the cells get just slightly damaged/overdischarged/overcharged, they are very unstable.

LimeySteve · April 3, 2013

Well I am going to be the guinea pig & fit one to my car tomorrow , hopefully it won't go like a bomb Under the hood , I did get the plastic covers & they fit perfectly.Time will tell , I have a single wire alternator .

jimk · April 4, 2013

What are the manufacturer's published instructions? If none, I'd stay 30 feet away and certainly not risk having it burn my non-replaceable car. If the mfr's inctructions are not followed, the user is on his own.

ndog · April 4, 2013

Well I am going to be the guinea pig & fit one to my car tomorrow , hopefully it won't go like a bomb Under the hood , I did get the plastic covers & they fit perfectly.Time will tell , I have a single wire alternator .[/quote
steve if they work on bikes iam sure all is okay,I only have limited experience with li-ion,li-poly 30c discharge rates for toy airplanes.If they push these on 2 wheels, then sign me up after your beta test.

Rocan · April 4, 2013

Well I am going to be the guinea pig & fit one to my car tomorrow , hopefully it won't go like a bomb Under the hood , I did get the plastic covers & they fit perfectly.Time will tell , I have a single wire alternator .[/quote
steve if they work on bikes iam sure all is okay,I only have limited experience with li-ion,li-poly 30c discharge rates for toy airplanes.If they push these on 2 wheels, then sign me up after your beta test.

I've seen lithium ion batteries overcharge with terrible results on motorcycles. Granted, this was when the technology was fairly new years ago, but as with any new product, I'd like to see proof of the reliability as well as proper instructions from the manufacturer (or at least a guide stating "what not to do" )

robsanab · April 4, 2013

Some manufacturers have electronics built in to prevent the under and over charging idiosyncrasies of these… does this battery have that? I don’t see it mentioned on the website. Maybe that’s why this is a comparatively cheap Li for it's fairly high capacity.

AGM’s seem to have this similar intolerance to under/over charging only without such violent results. Most of the problems I’ve seen in the forums about these look like misapplications to me… too small capacity for the car.

Yes please, post updates periodically. I’ll be looking at this for my EFI conversion to avoid running battery to trunk/seat. Right now I have my eyes set on the Braille B2618 AGM battery (8.1”x3.5”x6.3”, 18lbs, 475CCA, 27AH, RC=35min, $210) which looks like it may allow me to fit the EFI air filter above the battery, as you can see it too is only 3.5” wide. Maybe this Mirai would give me another option minus several more pounds to boot.

OT - I have also been researching a battery replacement for my mustang that is getting some mods this month. Since I’m in the market for a battery NOW I have decided on the Braille B3121 (6.6”x5.2”x6.8”, 21lbs, 550CCA, 31AH, RC=75min, $180).

LimeySteve · April 5, 2013

Here is the answer I received from them today .

Make of it what you will I'm fitting one tomorrow.

Hi Steve,

Regarding overcharge protection, most of the products out there do not

have a true overcharge protection system, it's a gimmick more than

anything else.

There are two types of "BMS" systems out there used in practice where

companies claim they have overcharge protection, 1. is simply a cell

balancer which shouldn't be called a BMS at all, the other 2. is an

actual BMS that has all the protection circuitry for over/under voltage,

over/under current, etc.

1. Most companies that claim to use a BMS simply use a cell balancer,

which just puts the charge from the cell with the highest voltage to the

one with the lowest voltage until they reach equilibrium. It doesn't do

anything to protect the batteries and usually they constantly place a

load on the battery, so they do affect the shelf life of the battery

pack. If there is one bad cell in the pack to begin with, the cell

balancer will constantly be trying to charge that bad cell so ultimately

it will wear out the life of the pack sooner as well. The amount of

current that it moves from one cell to the other is also very small so

in practice, it just provides a false sense of safety since it doesn't

protect the battery at all.

This is like the system on EarthX, they claim overcharge protection, but

if you look at their manual, it can't protect an input voltage over 15v.

If you have a bad alternator, it can not only exceed 15v, but it can do

so at a very high current, that will destroy BMS PCB immediately. The

LiFePO4 cells are able to absorb higher voltages for short periods of

time without any circuitry, they have to be able to withstand 5.5v per

cell for over an hour without causing a fire or exploding to pass safety

standards, they will vent and smoke, but again, this type of circuitry

will not do anything to prevent that.

2. The second type is very rarely used in the industry as the costs are

prohibitive in this type of application. A true BMS should have

protection from over/under voltage and over/under current, but the

amount of current drawn during start-up could be several hundred amps,

no consumer grade PCB can withstand that. You can get an idea of how

much this would cost by heading to the following link. A 100amp BMS for

a 4 cell system is priced at $138.95, a 500amp system which would be

necessary on our model with 450CCA would cost 5 times as much and

require a substantially larger footprint. Keep in mind what gauge wire

you would need for 500amps, clearly PCBs will have a hard time dealing

with just the heat generated from a 500amp load.

http://www.batteryspace.com/pcmforlifepo4packs.aspx

Again, we've tried both methods during the course of development of our

batteries, and neither provided a good system. The better solution was

to use better cells in the first place and have them impedence matched.

LiFePO4 cells do not require as strict cell balancing as standard LiCoO2

and LiMnCoO2 cells do, it isn't easy to get an LiFePO4 cell to combust.

Granted, it can if you short it long enough or put it under a load

greater than it is designed for, but in such circumstances, any battery,

lead acid included, will cause a safety hazard just due to the sheer

amount of energy involved.

Hope you find this helpful. Please let me know if you have further

questions. Thank you and have a great weekend!

==============================

ndog · April 6, 2013

very very light battery........

and this 2.46lb plane will launch vert out of my hand. Its about time li-po go's mainstream....

ndog · April 6, 2013

and b4 someone mentions burnt hand/fingers I did it with a plasma "smoke wrench" not a li-po

TobyB · April 6, 2013

The better solution was
to use better cells in the first place and have them impedence matched.

LiFePO4 cells do not require as strict cell balancing as standard LiCoO2

and LiMnCoO2 cells do, it isn't easy to get an LiFePO4 cell to combust.

This convinces me thoroughly that a lead- acid battery is still the

best answer for all of my cars. LiFe for the laptop, LiPo for the planes.

I'll save those 15 lbs somewhere else, thanks very much.

t

Rocan · April 6, 2013

The better solution was
to use better cells in the first place and have them impedence matched.

LiFePO4 cells do not require as strict cell balancing as standard LiCoO2

and LiMnCoO2 cells do, it isn't easy to get an LiFePO4 cell to combust.

This convinces me thoroughly that a lead- acid battery is still the

best answer for all of my cars. LiFe for the laptop, LiPo for the planes.

I'll save those 15 lbs somewhere else, thanks very much.

t

This exactly. Yes, using "better cells" (whatever that means) and having them impedence matched is a good idea, but it does not mean that it is safe. Them stating that the other manufacturers overcharge circuitry "doesn't really work" is just a defense for them not having one. I have seen friends lose 10,000 dollar bikes thanks to overcharged batteries igniting and the fire spreading to the gas tank which isn't far away. Whatever BMS certain guys like AGM use, it works. Once the batteries were a bit more developed and the bugs sorted, the number of fires decreased significantly.

Now this is all on a motorcycle with a relatively small charge output compared to our cars. The bit where they said

"A true BMS should have