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Old 02-23-2012, 07:26 PM
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Default Re: [EVDL] "Breaking in" a new lithium pack?

Thank you, David for this information; it lets me know that I need to
reprogram the EV Display. I can now say this definitely, because it showed
me 13200 Wh before I left my shop to drive home; 2.65 miles, with some
decent acceleration and one nice long hill along the way. When I first
arrived, the meter showed 12900, but when I went back to check 45 minutes
later, it showed the same reading as before I drove home=3D13200. I did see=
a
little lower numbers on the volts climbing the hill today compared to
yesterday, 118 vs 121 (which would equal 2.95 vpc), but the 'fuel gauge'
on the Display still shows "Full" and "100% SOC", none of which could be
true without violating several laws of physics....
Reprogramming tonight!
MIchael B

[quote] David Nelson <xxx@xxx.xxx> wrote:

> The short answer, don't charge until after your 20 mile drive and then
> only just before you need the pack to be full.
>
> First of all, I would change the number of Wh you have programmed into
> your EV Display. Using 3.2vpc as your nominal voltage is much closer
> to what you really will get than using 3.475vpc. A much closer value
> is 12,800Wh or 12.8kWh. I have 40 TS-LFP100AHA cells in my pack and
> 3.2vpc or just under it is what I get as an average voltage when I
> calculate it from the Wh consumed and the Ah consumed. Typically when
> most of my drive is at a little over 0.6C and the batteries are below
> 20=B0C the average is closer to 3.15vpc.
>
> I find it hard to believe that you only used 600Wh to go 8 miles. That
> comes out to only 75Wh/mi which is just over half of what I use with
> my Gizmo when I drive it gently. I know another Gizmo owner who lives
> in FL and is an expert hypermiler gets around 100Wh/mi with his Gizmo
> so I question the 75Wh/mi figure you have. I would think that for an
> Escort wagon you would be closer to 200Wh/mi. Suppose it is actually
> 200Wh/mi and you drive 20 miles that will be a total of 4000Wh,
> assuming that the 8 miles actually consumed 1600Wh you would only be
> at a total of 5600Wh or a little less than half your pack's total
> capacity. I personally don't charge my rig unless my distance needs
> will dip much into the bottom 50% of my packs capacity. I also don't
> charge until just before I need the energy because the pack life will
> be longer if it is left in a partial SOC rather than at 100%SOC. Since
> I don't have a timer on my charger this usually means that I plug in
> just before going to bed. I also use my slow charger most of the time
> unless I need a quick fill up.
>
> Isn't going to LiFePO4 cells nice? It makes for a completely different
> rig and well worth the expense. Once you go to lithium you don't ever
> want to have to go back to lead.
>
> On Tue, Feb 21, 2012 at 7:19 PM, Mike Beem <xxx@xxx.xxx> wrote:
> > I have just had my first day driving my Escort EV wagon which has been
> off
> > the road for 5 weeks while I changed from 18 USB Golf Cart batteries to
> 40
> > CALB 100Ah cells=3D BIG EV grin! What a difference in handling, much lo=
wer
> > amp draws on acceleration and hills, like a different EV.
> > My question to those who have done this is this: I spent a great deal of
> > time with the new pack assembled on the bench (with mini BMS installed)
> > testing the charger and BMS together, and top balancing the pack until
> > all cells hit 3.55 volts at the same time. I only drove 8 miles today, =
to
> > work and back, and the EV Display shows a drop from 13900 W-h to 13300
> W-h.
> > I have a longer drive tomorrow, but still under 20 miles, so I wonder,
> with
> > a new pack that I am just beginning to work with, should I go ahead and
> > charge back to full capacity tonight, then see what the usage is with t=
he
> > longer drive, freeway driving, etc, or not charge, and just drive
> tomorrow
> > like I have "7/8 of a tank"?
> > Thank you!
> > Michael B
>
>
> --
> David D. Nelson
> http://evalbum.com/1328
> http://2003gizmo.blogspot.com
>
> _______________________________________________
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_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
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| Multiple-address or CCed messages may be rejected.
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