Todd Dore's LiFePO4 batteries

[todd.dore]

More updates -

Yesterday the temp was hot outside - 90 F per my car's temp gauge.  I was stuck in Friday traffic for about 1-1/2 hours.  With much stop and go.  Even though my blower fan runs constantly, the motor temp was pretty hot as well - you could not keep your hand on it for too long after the trip.  I let it run for about 45 min after I got home to cool it down.

I showed up at the Riverside Cruise Night on Thursday 6/10.  There was a lot of interest in EVs and the Lithium batteries!  I also ran the blower motor while the car was stationary for about 1 hour for demo purposes.  Note to the club - where is the FVEAA signage?  I would like to get some next time!

Over 3 days I drove 51.9 miles.  Many of those were battling a strong wind from the south yesterday.  So, the heat, wind, traffic, and 'idling' the car for a couple hours took its toll on the efficiency - I had about 20kWh for 51.9 miles - 385Wh/mile.  Ouch!  I think that stop and go traffic and the heat take their toll on efficiency!

The battery temps never got above 90 F so we're ok there.  I have about 1,000 miles on the new pack.  Hopefully it will last another 99,000!  So far so good.


Go Lithium!!!

[tim.moore]

Does this mean your fan for the motor is not good enough to cool the motor?  Does the fan have to be mounted some place else to get more cooling fan air? 

[todd.dore]

Tim -

I think the fan is good enough to cool the motor - it's just that on 90+ F days, it is still going to get hot.  If anything, my fan may be overkill.

Yesterday I drove to Ted's house and back, with a side trip for dinner (burritos).  Total miles = 45.9, energy = 14kWh.  Efficiency = 305wH/mi.  That's more like it!

[tim.moore]

Okay, great.  I wish I could run the fan off of a separate (not attached to the auxilliary battery) rechargeable system that could be switch off in the car.

[todd.dore]

So far, I have almost 1,200 miles on the Lithium pack.  So far so good!  I've saved about $115 in fuel costs over the last 2 months, based on my retail electricity rate ($0.13/kWh which includes all admin. charges) and today's gas prices.  Over time, I'll save more as gas goes up and electricity costs stay the same.

As Steve G. mentioned in his post, we set the RPM and current limit in my Zilla to be more gentle on the batteries.  That works fine so I'm happy with the results.  It should result in longer lasting Lithiums.

Go Lithium!!!

[miodrag.zubic]

What kind/brand of speed sensor do you have on your motor and what RPM limit did you set?

[todd.dore]

I think I got the speed sensor kit from EV Source in UT.  If not there, then EV American in NH sold it to me.  Check online - the websites will have this.  The entire kit was made for the WarP! 9" motor.

RPM limit is 4800.

[todd.dore]

On Monday 6/21 I went about 65 miles on a charge, almost all highway.   I even drove through one of those major rain storms we've been having - a microburst in the South suburbs.  Anyway, towards the end of my trip I was drawing high current (accidentally started off in 3rd gear) for a little too long and the alarm went off - for just a few seconds.  I backed off and took it easy the rest of the way home (a few miles).  Back in the garage I measured all the batts, and they were all within 0.011V of each other.  No red lights - so I'm still not sure if I have a bad cell monitor or what.

Without knowing my true SOC (I don't have a meter yet), and without the ability to see the batt voltage as I'm driving, I really cannot tell if I'm pushing these batts or not.  The lowest voltage was 3.269 (resting - with a very small load) when I got home, so no signs of any stressed batts.

On Thurs. 6/24 I went on my longest single run to date - 70.6 mi. on a charge!  About 1/3 highway and 2/3 local, with lots of stop and go with heavy traffic.  I've learned that even though you do a lot of acceleration, at speeds < 40 mph I can draw well under 40 a.  At highway speeds, I draw 50 - 75 a, with some bursts at 100-200 a (acceleration, up a slight incline, etc.).  So, the highway truly does use more power.  I'm concluding that I may have about a 65 mi. range on the highway (in the summer) and probably  75+ mi. with local driving.  But, I still don't know my ultimate range!

To date - I have about 1,400+ miles on the pack, used up 439kWh, for a cumulative efficiency of 305 Wh/mi - pretty good!  I'm coming up on 9,000 mi. electric in the Bug.  I'll let everyone know when I hit 10k.

[tim.moore]

I know you are focusing on your batteries at this time, but do not forget the motor maintenance as well.  I have been driving my car with the new rebuild, and have been amazed at the range I am getting. I am getting three times the range I got before the motor rebuild.  I even sent an apology to the EXIDE battery sales manager because I had earlier said it was the batteries.  I know I missed the meeting AGAIN because of the storm, but I really want to be educated as to how to drive and maintain the motor of these EV's.  If the fan blower to the motor is the answer, I hope a kit comes out very soon.

[nathan.stowe]

Tim, 

If you have some interesting info on motors, perhaps you could write it up in the forums....  As you pointed out, not everyone can make it to the meetings.

Nathan.

[ted.lowe]

as well.  I have been driving my car with the new rebuild, and have been amazed at the range I am getting. I am getting three times the range I got before the motor rebuild.  I even sent an

WOW Tim!!!  This is great news!  i suspect i have a similar issue with my motor (range is poor and don't think it's all the batteries fault).  What did your motor rebuild include?  i'm a DIY type guy, so i'm interested in the details :-) Thanks!

[todd.dore]

Update on Elec Bug and the Lithiums -

The summer drums beat on...

Temp has been in the 80s and 90s - the motor gets very hot during these days!  Even with the blower motor cooling system, after driving for 45 mins. on the expressway the motor seems to really heat up.

During a trip to my company office in Lincolnshire (not my normal stomping grounds), the car died on Half-Day road, and again in the company parking lot.  Both times I turned off the ignition and restared, and all was fine.  It could be due to the heat, but I really cannot tell.  Nothing obvious - no wires loose, etc.  DC-DC seems to be ok, but there's no way for me to really test this part.

The other night I came back from about a 25 miles run (local roads), and notice some coolant leaking (the Zilla is liquid cooled).  I needed to flush it out anyway to replace with phosphate-free coolant, so I spent a total of 5 hours underneath the damn car (again!) to try to flush out and fix the leak.  I tightened all  the hoses that I could reach (the leak is at the bottom of the reservoir tank) and filled away with the new pink coolant (VW G-12 - no phosphate).  Most of it just drained right out to the garage floor - so I actually made the leak worse!! Oh well, I cannot fix it.  Fortunately there's enough coolant in the reservoir (it didn't all leak out) so I could drive to the green fest and back today.  I'll take the car into Jim Dawson's shop on Monday - he'll be able to fix the leak (the motor needs to come out in order to repair or replace the reservoir tank).

Total miles on Lithium - 1,839.5.  I'm getting close to 2,000 miles.  Total energy - 1,156 kWh.  Average mileage - 309.6 wh/mile.  Not bad at all!   Longest run on 1 charge - 71 miles, and I still had a fair amount left in the batts.  So, I don't know the range, but it's up there.

[todd.dore]

Update -

After 2,100 miles and 4-1/2 months of Lithium battery use, it's time to balance.  Note my BMS is really battery monitoring not battery balancing.  Anyway, after a full charge, I notice that about 8 of the 48 batteries don't show a red light at the top of the charge - meaning they don't reach about 3.65V.  So, I measure them, and they are all at the 3.4 - 3.5V level, and therefore starting to get out of balance.

I borrowed the battery monitoring system from Ted (thanks Ted for loaning it!).  It is set to do either 1 or 4 cells at a time, and so I set it to 'balance' on 4 cells in series - that is, set it up so that it holds the voltage on the 3 of 4 which are all topped off, and put a charge on the 1 that needs to be brought up.  Unfortunately, the system is not made to handle these large storage batteries, and after 2 hours and less than 1.0Ah, the thirsty battery didn't really have any more energy.

So, I bypassed and am charging the low batteries one at a time.  I've been putting about 4-5Ah into them to bring them up to 3.62-3.66V, so the charger is topping these batteries off as best it can.  With 1 battery at a time, I can pump up to 5A into them, so each one is taking about 1-1/2 hours or so (the charger automatically backs off when the batts reach about 3.5V and drops to about 2.5A).


This is quite a tedious process, and I've finished with 5 of them and am doing the remaining 3 batts tonight.  You have to watch the system, although the battery charger knows when to quit.

Ideally I would like an automatic system that can balance all by itself.

I've ordered 2 individual chargers that can do 1 battery at a time, and bring the batts up to 3.8V using 3.0A.  I'll let everyone know how that goes.

By the way - my average efficiency is 313.5Wh/mile.  Not bad!!

[todd.dore]

Another update - I apparently (slightly) over-charged some of the batts by 1-2 Ah - so I have to discharge a couple of them.  This takes longer, since the max discharge rate is 1.0A.

Anyway, Maribel & I went for a nice long suburban drive in Elec Bug tonight.  Mostly higway - from 55-60mph, and some local.  Total distance - 80.2 miles!  I noticed some minor sag in the battery performance towards the end, but otherwise no problems.  The resting voltage was 3.23 - 3.24V for every battery, so they weren't out of juice!  I could probably have gone another 10 miles if I wanted to, but I don't need to push it.

I still don't know the maximum range of this car but it is at least 80 miles!  Can anyone say 100? 

Lithiums are the best ever!

[todd.dore]

Another update today - 90,000 miles on the VW New Beetle - 10,000 EV miles!

The Lithium batteries have about 2,700 miles on them - going strong!

I bought a parking pass (monthly) downtown at the garage that lets me charge for free - sweet!

Overall efficiency is 313.1Wh/mile - not bad and much better than lead acid!

Finally, I brought the last 2 'out of balance' batteries up to speed with my 'dumb' Lithium chargers - you have to watch them manually, but they work just fine.  And very simple to use - they are user friendly!

GO LITHIUMS!!!!!