Hi Cor and All, Thanks for that. Apparently my
DVM is bad at that voltage range, only showing 45vdc vs the 58vdc they are.
If these are 45 amp modules wouldn't at 60vdc nom be 3kwhr
packs instead of the 2 rated? Or are they 30amphr? I've looked for an hr and
can't find out online though I remember seeing it. They are
sitting at 3.8vdc/cell and within .01vdc so far. It was too cold to check them
all.Though doesn't change much as I'll still use 4 packs in parallel.
While I could split the 1kw out of the 5kwhr pack, for now I think
I'll just be happy with 60vdc nom.
My controller is a 72vdc nom Curtis 1209 and building
the charger from scratch so the 17cell works best for me for now.
Jerry Dycus
From: Cor van de Water via EV <[email protected]>
To: Electric Vehicle Discussion List <[email protected]>
Sent: Monday, February 2, 2015 9:42 PM
Subject: Re: [EVDL] Volt pack arrives
Jerry,
The 4 parallel packs that you quote as nominal 48V are in fact 60V at 3.5V per
cell and 17 in series.
The extra module of 8 could be split in 4 parallel 2-series pairs to increase
the voltage of your
Total pack from 60 to 67V, but at 19 cells in series the top charging voltage
then goes to
19 x 4.1V = 78V, I don't know if your charger and controller will be happy with
that, or better to
Stay at the max 70V with the 17 series cells - depending on your existing
component specs.
Success,
Cor van de Water
Chief Scientist
Proxim Wireless
office +1 408 383 7626 Skype: cor_van_de_water
XoIP +31 87 784 1130 private: cvandewater.info
www.proxim.com
-----Original Message-----
From: EV [mailto:[email protected]] On Behalf Of jerry freedomev via EV
Sent: Monday, February 02, 2015 5:48 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Volt pack arrives
Hi Adam and All, Thanks for your part helping me get these as
time I got into lithium light batteries to go with my lightweight EV's.
Yes I understand the current limits and a major reason for the e
controller. Though the first set up with have 4 in parallel at 48vdc nom
likely too much amps available!! I'll run lighter cables to limit max amps
too. With just another 24vdc group I can go 2 strings of 120vdc
nom. Or another 5kwhr and do 156vdc nom pack might give me 150 mile range.
Looking at the bus bars, etc 120amp cont looks right. It's good we
didn't break up the pack. I'll fuse each 48cell set though I
make my own fuses. Not hard if you understand them. On voltage
I have your earlier post on it and seeing what others might have experienced.
So anyone else have experience with Volt batteries?
I was thinking using the BMS cables getting a couple model airplane 7
cell BMS' IC's with meters that have a balancing function plugging them in say
1/month to equalize. Mostly just relying on monitoring. It
has motivated me to get the Ewoody and FreedomEV going now I have batteries
that will give it good range. The fact the weather is getting warmer helps as
in Fla mid Feb to June is building season . Looks like my
front suspension design, double A frame, is good so mostly a matter of getting
stuff mounted, skin on and electrical. By then my wthr
meters, etc for battery charging will be in and I'll have a chance to put some
cycles on them. It's going to be strange having so much data
to work with as until now it's just been volts, amps and AC charging wattmeter.
I just happy good wthr meters have dropped so much in price, Lightobject 404,
with so many great features like charger turn off when 95% charged, fuel gauge,
volts, amps, high/low alarms, etc. Thanks,
Jerry Dycus From:
Adam Chasen <[email protected]>
To: jerry freedomev <[email protected]>; Electric Vehicle Discussion List
<[email protected]>
Sent: Monday, February 2, 2015 12:28 AM
Subject: Re: [EVDL] Volt pack arrives
Glad you are enjoying your cells! I have been using 4.1 as my top and 3.5 as my
bottom voltage. The Volt battery module was not designed to provide more than
120A current continuous based on the components found in the battery
(specifically the relays in the head unit are rated for 120A continuous, but
much higher surge). Or course hooking yours up in parallel multiplies that
current by the number of packs you have.
I strongly encourage you to invest in some "semiconductor fuses" to protect the
packs from one another when hooking up in a parallel scenario. Note: These
fuses are likely to be incompatible with using a contactor style controller.
The fuses are available in various amperages on ebay (new old stock). In the
case of a cell failure (cells usually fail short), one pack will have lower
voltage. This will result in the other parallel packs dumping current into the
failed pack's remaining good cells. This can cause a dangerous situation due to
overvoltage and thermal runaway on the failed pack. I believe these fuses will
provide some protection from this situation in addition to providing some
protection to an electronic motor controller (they are actually designed to
protect high power diodes and transistors from catastrophic failure).
Keep those tops on and any liquids away from them! You are correct in that they
are very dangerous to work around. I strongly encourage using rubberized tools
(not that it should be treated as the only safety measure).
Adam
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