Li-poly replacement for lead-acid SLA in car

[Nehmo]

What's the most reasonable way, with current off-the-shelf materials, to make a battery unit using Li-poly to replace a regular lead-acid auto battery?
I mean not just the cells but the whole package, the electronics, the Battery Management Unit (BMU) and the cells. If we need a size to start from, say a 3L modern ICE engine car with typical lights, in other words, a starting, lighting, ignition (SLI) battery.
I'm not concerned with making a competitively priced device, nor something that competes on safety, just a plug-in Li-poly alternative to the common lead-acid SLI battery.

 

[Scott]

I am serious about doing this. My truck, a small 2.6L Mazda pickups’ 6 year old battery pretty much died today (would not start this morning). Yesterday it barely started to the point that if it had to turn the motor over one more time it would not have started. I also left the lights on while I got a subway sandwich on my way home from school and the battery died from just 10 minutes of the lights being on. It had no problem starting when when I turned it on to leave school prior to it dying at subway.

I wanted to get this 3s 8.4 Ah 40-80c Turnigy nanotechTurnigy nanotech LiPO battery pack but they are not in the US warehouse so I am going to go with this 3s 5Ah 65-130c Turnigy nanotech LiPO battery pack. Both batteries put out about the same amperage 325 amps constant and 650 amps burst (about 20 amps difference) the first battery just has 3.4 more Ah in it.

To charge the battery I am thinking of using this DC to DC converter
It takes voltage from 5-36 volts and puts out 0.06 to 32.4 volts at 40 amps. It only cost $6.
I will probably not use the converter at the full 40 amps as this is the max charge current for this battery. I might try 20 amps and see how much power I need to run lights and every thing else.

The only thing I don’t know about is if I need something between the alternator and the DC to DC converter and if the alternator will have problems regulating the voltage if there is not a battery or capacitor before the converter.

Also I bought 8x 8s battery cell monitors/alarms but I don’t use them on my bike because they draw all their power from the first 2 cells. I would probably run balance wires to the cab and have the cell monitor right there to plug in to check on it every now and then.

Here is a video of a Luke cranking a battery than has less than ½ the power than the one I am thinking of getting and it is amazingly powerful!
[youtube]http://www.youtube.com/watch?v=WkKRqaNPIBE[/youtube]

 

[Hillhater]

What's the most reasonable way, ...
.... to replace a regular lead-acid auto battery?
I mean not just the cells but the whole package, the electronics, the Battery Management Unit (BMU) and the cells.
I'm not concerned with making a competitively priced device, nor something that competes on safety, just a plug-in Li-poly alternative to the common lead-acid SLI battery.

most reasonable way, ...
whole package,....
.. not concerned with making a competitively priced device,....

Then why not just buy a ready made one ?..
http://www.superstart.com.au/Products/ProductList/tabid/108/mode/details/bid/15/Default.aspx

 

[TheBeastie]

What's the most reasonable way, ...
.... to replace a regular lead-acid auto battery?
I mean not just the cells but the whole package, the electronics, the Battery Management Unit (BMU) and the cells.
I'm not concerned with making a competitively priced device, nor something that competes on safety, just a plug-in Li-poly alternative to the common lead-acid SLI battery.

most reasonable way, ...
whole package,....
.. not concerned with making a competitively priced device,....

Then why not just buy a ready made one ?..
http://www.superstart.com.au/Products/ProductList/tabid/108/mode/details/bid/15/Default.aspx

I bought a ballistic evo 12v battery for my quad bike, it was a rip off price and doesn't actually work that well in performance.
I recently replaced the dead SLA battery in a portable jump starter unit I have with 2 x 3S Turnigy batteries in parallel (internally incased in steal) and that has been working well. The jump starter unit is now significantly lighter and also works significantly better then the ballistic evo battery at a fraction of the price.
I figured just buy more 3S and parallel them if I find something bigger I cant start but so far I have started a car and quad bike and ride on lawn mower with it no problem.

I have a 3S parallel balance cable (2xJST-XH) connecting the two turnigys together sticking out the back of the jump start unit to charge it. http://www.hobbyking.com/hobbyking/store/__27077__jst_xh_parallel_balance_lead_3s_250mm_2xjst_xh_.html

Using this cheap wall plugin charger from HK.
http://www.hobbyking.com/hobbyking/store/__8247__turnigy_2s_3s_balance_charger_direct_110_240v_input.html

 

[Hillhater]

replace a regular lead-acid auto battery...
I mean not just the cells but the whole package, the electronics, the Battery Management Unit (BMU) and the cells......

You need a little more than a bunch of 3s lipo packs, to be able to "plug and play" in a car. !

 

[Nehmo]

You need a little more than a bunch of 3s lipo packs, to be able to "plug and play" in a car. !

What exactly do you need? I assume you'd need the battery protection board, and in the vehicle environment,
this would take into account the variable charge V from the alternator. Is there any suggestions how to accomplish this?
And I recognize this isn't a Li-poly replacement, on youtube, there's a guy who uses a supercap just wired in. [youtube]z3x_kYq3mHM[/youtube]

 

[bobc]

Normal car alternators are designed to charge lead acid batteries.
This means nominal 14.4V voltage source reducing a tad at high temperatures.
I don't want to be alarmist, but shoving 14.4V into 3s Lipo is sort of asking for trouble in my view.
I would keep a small SLA in there & connect the 3s Lipo on the side, so the Lipo aids cranking via a damn big diode & gets charged using a standard Lipo charging circuit.
That way the alternator & car electrics see what they want (a lead acid battery) and the Lipo only gets used when it's needed (cranking).
A lot of cranking will still destroy the Lipo - you'll have to be careful.....

 

[TheBeastie]

On one of the other videos where that guy shows off his ultra capcitors he adds a *LiFePo4* pack from hobbyking.com
http://www.hobbyking.com/hobbyking/store/__14067__ZIPPY_Flightmax_4200mAh_4S2P_30C_LiFePo4_Pack.html
I noticed some retards in the youtube comments who obviously cant listen to him say LiFePo4 or visually attain he is using a lifepo4 pack and give him negative comments amount marrying the ultracaps and hk pack together.
They do look exactly the same though, except for the LiFePo4 writing on it.
http://www.hobbyking.com/hobbyking/store/__14067__ZIPPY_Flightmax_4200mAh_4S2P_30C_LiFePo4_Pack.html

I use an old lipo pack to start my ICE quad bike, that said I wouldn't use a lipo pack in my car.
I think a quality investment in a booster cap is the way to go, it could be supplemented with a small lifepo4 setup, maybe consider 18650 cells which are deliberately designed to be safe (considering there in everyone laptops etc).

I don't think its possible to ever use a ebike BMS circuit build because they are designed to give a controlled amount of amps out, the old SLA battery has no circuits, its just designed to dump as much power as it possibly can.
If you bought 18650s that have built in protection circuits (along side boostcaps) it could save a lot of work in terms of protection, even Lifepo4 HK packs are comparatively soft and vulnerable while 18650 cylindrical cells are fully encased in steal.

There are a bunch of sellers on ebay selling carbooster kits, most recommend the maxwell caps, I would say because of the tiny internal resistance they have.

I don't know any of these sellers below or have any affiliation with them, but their booster packs look nice.
http://www.ebay.com/itm/Ultracapacitor-Module-KIT-Battery-Eliminator-Car-Audio-Starting-Remote-Solar-/301412233890?pt=LH_DefaultDomain_0&hash=item462d91b2a2
http://www.ebay.com/itm/6pcs-3000F2-7V-Maxwell-ultracapacitor-super-farad-capacitor-booster-cap-BCAP3000-/281506741294?pt=LH_DefaultDomain_0&hash=item418b1bfc2e
http://www.ebay.com/itm/16V-83F-Ultracapacitor-Engine-Battery-Starter-Booster-Car-Ultra-Super-Capacitor-/171380193143?pt=LH_DefaultDomain_0&hash=item27e70e3777
http://www.ebay.com/itm/181391254764?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT


There is a guy who put one of these and went for a bike ride on this forum many years ago.
http://www.ebay.com/itm/Maxwell-48V-165F-Ultracapacitor-Module-Energy-Storage-Electric-Vehicle-Solar-/181590783365?pt=US_Motherboard_CPU_Combos&hash=item2a47a77585
https://www.youtube.com/watch?v=KW8PF5RiRnI
He traveled 0.75 or 1.2km of distance out of his pure no battery 48v ultracapacitor ebike (only 24volts usable due to LVC)
i = C dV/dt, so dt = C dV/i = (160 F)(24 V)/(20 A) = 192 s = 0.05 h
0.05 h * 24 kph = 1.2 km = 0.75 miles
I don't know why but there are some people on here that believe ultracapacitors are not capable of any kind of usage in these types of circumstances.

 

[Hillhater]

For < $100 you get a new Pb auto battery with a 5 yr replacement warranty.
Until someone comes out with a proven "swap in". Li package, I don't see any point in risking fire or failure just to prove a point.
But yes, LiPo in a portable jump starter, makes a lot of sense.

 

[Nehmo]

For < $100 you get a new Pb auto battery with a 5 yr replacement warranty.
Until someone comes out with a proven "swap in". Li package, I don't see any point in risking fire or failure just to prove a point.
But yes, LiPo in a portable jump starter, makes a lot of sense.

The auto lead-acid warranties I've seen are pro-rated. That is, the longer the battery lasts, the less you get back as a discount on a new one. In reality, people get 3-4 years of service.
In any case, I made the price irrelevant in the way I posed the question.
A plug&play replacement is what I want to make. It seems all I would need is a Battery Protection Module (AKA Battery Management System) to interface between the car and battery.
I would imagine a properly designed Li-Poly 3s system would be superior to a lead-acid one. It would be lighter for one thing, and the other advantages of Li-Poly would also come into play. I would expect the danger would be lower.
A Lead-acid battery is a pain.

 

[spinningmagnets]

You can easily do it with Headway LiFePO4 4S cells. Four of these would be about $100. I would house them in an insulated box with a warming pad for cold mornings. I don't know what to use as a BMS.

10C discharge, 8-Ah, so roughly 80 amps peak. Max charge voltage of 3.6V/cell = 14.4V for the pack.

http://www.headway-headquarters.com/38120hp-8ah-headway-cell/

edit: a while back, LFP started a car with a single LiPo nanotech brick, just to show it was possible. However, I haven't seen a charging board to balance and protect the pack from overcharging from the 14V alternator on the car. I'm certain there must be several ways to do that, but I am not electronically inclined enough to figure that out.

Also, Ive never done this before, so...if you spend $100 on 4S Headways and they die immediately, or set the car on fire...you've been warned.

 

[Hillhater]

You do realise the cranking current for a simple 2ltr gas motor can be hundreds of amps ?
.. Let alone a big V8 or a modern diesel .!
And think of how stiff those motors are on a northern winter morning .

 

[MrDude_1]

Ive actually done this a couple times... twice with sportbikes and once temporarily for a car.

You just take a hobby king 4cell LiFePo4 pack, and connect it. Thats it. Yes it can pull massive amps cranking, but somehow it works. The alternator can use the battery to stablilize its voltage regulator just fine.. and it all bulk charges ok. the downside is it slowly slides out of balance...

All you would need for a permanent solution is a LiFePo4 pack that had a balance circuit... that circuit needs to only turn on when the the car is running(that is, either when the voltage reaches a specific level, like 13.8v... or maybe whenever the input voltage exceeds the pack voltage, if you can tell that.).. and then it just needs to keep the cells balanced.