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Thundersky vs Hi-Power Lithiums

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Johny
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Thundersky vs Hi-Power Lithiums

Post by Johny »

This came in from the yahoo AC-EV group (posting is rare).
I hope they won't me mind repeating it here.


Hey EV car builders,

I have been keeping an eye on the Ford Ranger EV Truck Group and they do not recommend using the Thunder Sky Batteries but recommend ones called or made by a company called High Power.

Lanny, who has installed at least 4 lithium packs in the Ranger EV truck using the factory BMS system with great luck, like 7K miles so far with a range nearly 100 miles.

The exact details are hard to recall exactly, but Lanny's site is a good reference point for lithium packs and how they have been working in the stock Ranger EV truck, using an AC three phase motor and controller system.

His website is:

http://southtownelanes.com/ranger_lifepo4_two.html

Lanny said: I have 100 of the 100AH Hi-Power cells in my Ranger EV , I installed them right around 1 year ago and I am right now coming up on 7500 miles on the pack with no problems and no failures , I have no BMS system on it yet , I have just been charging the pack up to 90% SOC and unplugging it so it does not get over charged ...

Other BMS information as posted on the ranger site:

This table shows the difference between the various BMS
> types:
> http://liionbms.com/php/bms_options.php# BMS_types
>
> A Li-Ion pack for the Sparrow requires a Balancer, or at
> least Monitor (a Monitor does not balance the pack, so the
> pack will lose capacity over time), either analog or digital
> (analog doesn't report individual cell voltages, which is OK
> for most users). In theory, protectors would work too, but
> there are none that will work with a pack for the Sparrow.
> Anything else will simply not protect the pack (or require
> constant human intervention) , so it would be a waste of
> money.
>
> So that leaves, ideally:
>
Digital balancers:
> http://liionbms.com/php/bms_options.php ... _Balancers
>
Analog balancers:
> http://liionbms.com/php/bms_options.php#Anlg._Balancers
>
> And, as a last resort:
> Digital monitors:
> http://liionbms.com/php/bms_options.php#Digit._Monitors
> Analog monitors:
> http://liionbms.com/php/bms_options.php#Anlg._Monitors
>
> For a digital BMS, prices for a Sparrow pack range from $
> 400 to $ 4500:
> http://liionbms. davideandrea. com/php/bms_ options.php# Digital_BMSs
> The cheapest is the Peter Perkins Do-It-Yourself, open
> source project.
> http://batteryvehic lesociety. org.uk/forums/ viewtopic. php?t=1245
>
> For an analog BMS, prices for a Sparrow pack range from $
> 800 to $ 1200:
> http://liionbms. com/php/bms_ options.php# Analog_BMSs
> The cheapest is Clean Power's MiniBMS:
> http://www.cleanpow erauto.com/ MiniBMS.html

http://www.cleanpow erauto.com/ MiniBMS.html

So, some useful information in the above...

Please keep posted with your build information what batteries you all decide to use and how they work out, we all need Lithium some day!!

Mark

Edit: Changed subject title
Last edited by Johny on Thu, 21 Jan 2010, 05:40, edited 1 time in total.

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acmotor
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Thundersky vs Hi-Power Lithiums

Post by acmotor »

" I have no BMS system on it yet , I have just been charging the pack up to 90% SOC and unplugging it so it does not get over charged ..."

That's fine. The logic falls down when you are guessing where 90% SOC is ! 90% of which cell ? The assumption is that the cells behave as 'ideal cells'.
Credit to the HiPowers for behaving (so far).
With less than 100 of 2000? charges done, one would hope than a BMS is fitted before the honeymoon period is over.

Hey Jack (of bottom balancing fame), here is a top balanced pack with track record ! Re-Balancing is a major spanner job though !

Image
iMiEV MY12     110,230km in pure Electric and loving it !

Squiggles
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Thundersky vs Hi-Power Lithiums

Post by Squiggles »

Johny wrote:

we all need Lithium some day!!

Mark

At least until Sodium comes along :)

antiscab
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Thundersky vs Hi-Power Lithiums

Post by antiscab »

i dont see the part where they recommend avoiding thundersky?

IIRC, the ford ranger factory BMS does measure voltages at the sub pack level, which with lithium is IIRC every 8 cells (since originally it had 8v batteries and measured every second battery).

so full and empty can be detected by the stock BMS.
but yes, balancing is a PITA when you have to do it manually.

Matt
Matt
2017 Renault zoe - 25'000km
2007 vectrix - 156'000km
1998 prius - needs Batt
1999 Prius - needs batt
2000 prius - has 200 x headway 38120 cells

cadance
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Thundersky vs Hi-Power Lithiums

Post by cadance »

Yes,Hipower company was the one or two producer has began to research and develop LiFePO4 BATTERY as early as 5 years ago,and has exported 388v200ah battery pack for around 3years.So,as for Lifepo4 battery manufactures we have much more experiences.

In 0.5C continues discharge, Hipower battery keeping on 3.0 volt after released 90% capacity.
In 3C continues discharge, Hipower battery keeping on 3.0 volt lasting for 17mins.

Our BMS can monitoring and controlling the key parameters such as voltage, current, temperature, etc.,has applied for patent and charger details, you could search “energy balancing” in forum.
Also proved by our customer (in England) who using our battery accompany with BMS for 3 years with little volt down (checked in 2009.11).

if you would like to learn more datails (charge and diacharge curve or specification sheet,etc., )please contact me by Email,yxx1013@yahoo.com.cn.
cadance
Last edited by cadance on Thu, 25 Feb 2010, 07:19, edited 1 time in total.

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Alex_Brooy
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Thundersky vs Hi-Power Lithiums

Post by Alex_Brooy »

Hello, EV owners.
I use ThunderSky's LFP90aha on my little vehicle. I do not use BMS, but do use balancers. I have already passed 10 000 km from march 2009 till now. I don't understand how Ford Ranger's owner has run 7000 miles without balancers. I tried to run about 10 cycles on my LFP90Ah without balancing plates. As a result I got 0.1-0.2 V difference between cells. So I decided to make balancers to avoid any diference at the end of charge cycle.
You may see it on my page http://electricmobile.ru/balancers-for-lithium-cells/
Unfortunately for you, my site is almost all russian-speaking.

Alex

antiscab
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Thundersky vs Hi-Power Lithiums

Post by antiscab »

Hi Alex,

welcome to the forum :)

you can run a lithium pack without any BMS for a while.
many have done this.

If you start out with a balanced pack, generally it will stay balanced.
the role of a BMS is much more cell level LV and HV detection rather than cell balancing. the convenient balancing is just a bonus.

so without a BMS, most failures occur when a cell gets reversed.
i have observed coulomb efficiency to drop once a cell is discharged past 2.5v (at nominal 0.3C load).
so on recharge, some cells get overcharged, which is the other most common failure.

if the user avoids deep discharges, and manually balances the pack once in a while, they can run without a BMS.

the one thing you have to be aware of is that if you try to charge a reversed cell (these read 0v), it will burst and burn.
Its the only way i have found to make these cells burn.

Matt
Matt
2017 Renault zoe - 25'000km
2007 vectrix - 156'000km
1998 prius - needs Batt
1999 Prius - needs batt
2000 prius - has 200 x headway 38120 cells

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Alex_Brooy
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Thundersky vs Hi-Power Lithiums

Post by Alex_Brooy »

"if the user avoids deep discharges, and manually balances the pack once in a while, they can run without a BMS. "

- How can you balance the pack manually?
I charge my ev during night. It's unreal to check every cell manually during 4-6 hours. Even during 1 hour. Or did I misunderstand something?
You are right, I do avoid deep discharge. It is too much expensive for me to get battery failed :)

antiscab
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Thundersky vs Hi-Power Lithiums

Post by antiscab »

to manually balance a pack that is in service, you will need a 4v current limited power supply.

basically you fully charge the pack as per normal (so 3.65v * number of cells, till current falls below C/100), then go around with a volt meter and use your 4v power supply to bring the cells that are low up to voltage.

you don't have to do the manual balancing right away, but it does have to be while the pack is at full charge.

i should stress this:
even though it is possible to run a lithium pack without BMS, i don't recommend it.

to prevent fire, you must at a minimum be able to determine if a cell has been reversed (comparing the voltage of two pack halves can do this).

although the pack will go out of balance fairly slowly, if any cells fall behind (for instance by deep cycling) the higher cells will get slightly overcharged.

overcharging doesn't result in fire (at least not if charging to 3.65v average), but it will cause capacity loss, increased self discharge and a cell can leak.

once any cell in the pack has been overcharged, the pack will lose balance more rapidly.
cells that have been overcharged are easy to spot, as they will not hold their surface charge.

a cell charged to 3.6v, and disconnected from everything should stay at 3.6v for months (mine have).
if its been overcharged, it will fall back to 3.3v in hours.

Matt
Matt
2017 Renault zoe - 25'000km
2007 vectrix - 156'000km
1998 prius - needs Batt
1999 Prius - needs batt
2000 prius - has 200 x headway 38120 cells

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Alex_Brooy
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Thundersky vs Hi-Power Lithiums

Post by Alex_Brooy »

I think it's time to make a topic something like "BMS: to be or not to be" :)
I agree that it is very nice to have bms onboard. Someday I will have it, no doubt. I don't have it not because of a good life. Factory made BMS is rather expensive for me (don't forget, I am from Ukraine with its average wages of $200-400!). I have ideas how to make nice BMS, but it takes for me a great deal of time to build reliable pcb and debug a program.
Any way, I want to tell that I successfuly ride on my LFP without BMS avoiding deep discharge. I do not reach overcharging because of balancers. They have 2x5W shunt resistors. Resistors are switched on when the cell voltage exceeds 3.9V. That helps not to overcharge the cell. That's it.

antiscab
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Post by antiscab »

how much current do you charge at alex?
at what voltage does your charge cross from CC to CV?

also, what resistance are those 2 x 5W resistors?

generally if your CV voltage is around the 3.65v average, and you can detect if a cell gets reversed, and don't go past 90%dod, you should be fine.

the cells probably won't last as long, but nothing should burn.

Matt
Matt
2017 Renault zoe - 25'000km
2007 vectrix - 156'000km
1998 prius - needs Batt
1999 Prius - needs batt
2000 prius - has 200 x headway 38120 cells

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Post by Alex_Brooy »

I charge with 7-10A depending on DOD.
Charging is going with the help of transformer with rectifier - it means CV all the time. The resistance is 2 x 5,6 Ohm in paralel, or => 1,4A when balancer is "on".
Practice has shown that nothing extraordinary had happened during 10'000km.
Ones again, I'm not saying that using LFP without BMS is good. But it may be used so under certain conditions (regularly no deep discharges, periodical tests of every cell after 50-70% depth of discharge every 2-3 weeks).

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Post by antiscab »

alex, how do you terminate charge?

do you do it manually?
or perhaps with a timer?

or does the current just fall to 1.4A when the pack has reached full?

Matt
Matt
2017 Renault zoe - 25'000km
2007 vectrix - 156'000km
1998 prius - needs Batt
1999 Prius - needs batt
2000 prius - has 200 x headway 38120 cells

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Post by Alex_Brooy »

I detect the end of charge cycle when all balancers are switched on. Charging current falls down to aprx. 1,5 A. The voltage of every cell is 4 - 4,1 V.
There is no timer.

antiscab
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Post by antiscab »

is the transformer the auto type (so it maintains constant voltage output regardless of movements in AC voltage)?

your approach does work when the pack is balanced, and the charger (in your case transformer and rectifier) limits voltage.

did you balance the cells manually for the first charge?
or just monitor the pack for the whole first charge, and turn off power to let the high cells get pulled down?

i don't recommend people take your approach, for redundancy and failure mode reasons, however, it will work acceptably quite some time.

do you use an Ah counter to determine SOC?
if not, what do you use?

Matt
Matt
2017 Renault zoe - 25'000km
2007 vectrix - 156'000km
1998 prius - needs Batt
1999 Prius - needs batt
2000 prius - has 200 x headway 38120 cells

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