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Discussion Starter · #1 · (Edited)
We have just ordered lithiums for our MR2 Conversion, and we are currently looking at ways to mount the Thunder-Sky Batteries, is there any reason we could not mount them upside down?
You can view our Conversions at: THSEV.blogspot.com, [email protected], or EVHub.webs.com
 
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Why would you need to hang them upside down? I would not. Flat, on edge or up is fine. Odd you'd think you need to do them upside down!

Pete
 

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Discussion Starter · #3 ·
Well we would like to install them in a pan underneath the car, if we were to have them upside down we could still access the terminals without removing the pan.
 

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China HiPower recommends vents upwards for their lithium batteries.

I tested some before I knew that. They seemed to run fine on their sides until I vented them due to running ruinous amounts of current through them, beyond spec and on purpose to see what they'd take. 2 cells were immediately ruined, but a 3rd cell that spit out only a little bit seems to still be working fine.

Anyway, based on this experience I'm planning to do vents-up on my car now. While I'm hoping to run shy of ruinous amounts of current, I do plan to race and will be leaning on the cells harder than a commuter would.
I believe upside down is 'not recommended' from the OEM. It SHOULD only be a problem in cases of overcharge/overheat venting, which would hopefully 'never happen'. ;)
 

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Well we would like to install them in a pan underneath the car, if we were to have them upside down we could still access the terminals without removing the pan.
I would think that you would still need them not exposed to weather or road grime...so possibly laying them flat for easier access??:confused:
 

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Discussion Starter · #8 ·
Well, the plan was to have a cover over the terminals to prevent road grime/ whatnot from getting in their, but would still be easier than removing the pan. Our car wouldn't be pushed much harder than a commuter's so I don't foresee "ruinous amounts of current" moving through them. However, we didn't take into account the venting.
 

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Depending on where under the car you are mounting the batteries, and that you would need a cradle to hold them, could you not just hinge the cradle at one end or one side and lower the other side it to check the terminals?
 

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Why are you looking to access the terminals?

If it is just to test voltages instead of having BMS then how about running a wire from each battery to a multipin plug inside the vehicle?

If it is to check tighness of terminals then that may just mean after the first few times they should be sound. If not then there may be other issues to resolve.
 

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I would only use right side up. I have 4 cells laying on their side for about a week and 3 have a drop or two of an acid coming out the vent hole.
 

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... I don't foresee "ruinous amounts of current" moving through them. However, we didn't take into account the venting.
if your controller is limiting max amps to 3x the battery C (ah value) you *should* be pretty safe from overheat during driving. I f you are really concerned, one thermocouple on any one of the terminals to get an aprox read on the battery internal temp would be the best warning.

Overtemp during charging just depends on NO cell going over 4.0v for very long.... accomplished by top balancing and checking balance occasionally either manually or with a BMS.

If neither condition occurs to overheat internals.... no venting, no problem!
 

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Dan,
3C for a 100ah pack would be 300 amps continuous or all day long correct? Ok, so if you have a 156 volt pack and a 1000 amp controller and you do not limit current, is there a chart or rule of thumb for how long the Thunder Sky batteries can deliver higher currents?
For example, our car with lead acid will pull 600+ amps under full acceleration for a very short period and the current decreases as it accelerates. Will this be safe for the Thunder Sky pack, or should we limit the current to 300 amps like you say. My problem with that is the lack of acceleration ability when using short bursts, especially when we autocross. Won't the Thunder Sky pack be able to deliver higher current for short periods without worrying about damage. Guess I just need specs on how long at what current.
When we install our lithium pack we will be 600 pounds lighter, so this should reduce the time we draw higher current under acceleration due to the lighter weight....right?
Thanks,
Steve
 

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Dan,
3C for a 100ah pack would be 300 amps continuous or all day long correct?
not exactly. the 3C limit is 'suggested' by the OEM, and is not exact, but intended to provide a suggested limit to avoid internal overheating. The more current you draw, the more internal heat you get from (small) internal resistance. This is why the lower internal resistnce batteries are more expensive, but can take higher C. At 300 amps, a 100ah system would only go 20 minutes, not 'all day'. ;)


Ok, so if you have a 156 volt pack and a 1000 amp controller and you do not limit current, is there a chart or rule of thumb for how long the Thunder Sky batteries can deliver higher currents?
until the internal temp exceeds spec, the case heats, the electrolyte vaporizes and vents..... you might extend the period of high-C draw with cooling, but it will probably kill their life. If you want high-C dragster performance, you need to spend LOTS more money for batteries that are rated for it....

For example, our car with lead acid will pull 600+ amps under full acceleration for a very short period and the current decreases as it accelerates. Will this be safe for the Thunder Sky pack, or should we limit the current to 300 amps like you say. My problem with that is the lack of acceleration ability when using short bursts, especially when we autocross. Won't the Thunder Sky pack be able to deliver higher current for short periods without worrying about damage. Guess I just need specs on how long at what current.
I don't have hard and fast specs for you.... but you probably CAN pull more for 'short' periods, but you will affect cycle life and need to watch temp. best way to do that (from video) is a thermocouple on a post to get a handle on the internal temp. Simple fact is, if you race, its hard n the equipment. ;)

When we install our lithium pack we will be 600 pounds lighter, so this should reduce the time we draw higher current under acceleration due to the lighter weight....right?
yes, plus you will have basically no voltage sag.
 

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Dan,
Thank you. That is great information for me and my students(yes, Zandarr). This is our first foray into Lithiums. We would rather have gone with 200ah TS cells, but our minimal budget would not allow.
I am the primary(adult with 10 year EV experience) driver, so monitoring the amperage draw is not a problem. My students can drive while I am in the car/truck, but a few times a year they get to drive while at competition. When those adrenaline filled guys get behind the wheel in an autocross or drag event, I am afraid the damage may occur then. When/if we get our Synkromotive controller, we can limit the current from 0-750 amps. Currently, we have a Raptor 1200 that was converted to potentiometer input and the current limit adjust pot was removed by Peter Senkowsky at that time for some reason, thus we can not control the limits.
Steve
 

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I don't know how fast internal temps rise at 1000amp draw, and then how long it might take to dissipate that heat.... perhaps some of the drag guys can tell ya. You also want to consider amp limits to protect your motor. I think you might get more practical info starting a thread in the 'more watts to pavement' category...
 
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I think the current limits your referring to are for the controller limits. The Synkro will limit both the controller amps and battery amps. Battery amp limits are what you want to limit. Kept the limits on my Synkro to 200 peak battery amps. Anemic but functional. I am upping those limits today to see how much better it performs. Might want to check the limits on your Beta unit for the peak battery amps. I am still limiting my peak controller amps to 650 at this time.

Pete :)
 

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Pete,
The Synkromotive is actually in our 96 volt lead acid truck and doing fine. We are hoping to put the new controller in the MR2 when we get it. The 156 TS Lithium pack will be in this car. Since we can not adjust the Raptor, I am really hoping to get the Synkromotive for obvious reasons.
Thanks guys for the info. I did look in the "pavement to the road" section and there was a post that answers a bunch of my questions. Steep learning curve going from lead to lithium.
 
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