My original message:
'I've been extending my research and discovered that the Volt modules at a
purported 48v are really 45.6 nominal. My mower's low voltage cut-out kills the
blades at about 40-42, rather close to the Volt's nominal level. At least I
have juice to roll back to the barn, so to speak, but I'd prefer something
farther away from lvc for the module's nominal level, unless someone has a
suggestion to work around this (add a segment or two?)
Am I incorrect in expecting that operating voltage will drop to nominal? One of
my electric transportation devices is a 36 volt nominal, but it only drops
below that level under heavy load. The mower pulls only 20-30 amperes, hardly a
heavy load for a 350 amp capable Volt module, yes?
Same concept on the cooling side, it's not likely to get particularly warm at
1/10 design current. The charger I linked on Amazon is a 6 amp charger. Even if
it takes overnight to charge, that's not going to warm up the module to the
point of needing cooling, is it?
The ones I've seen on eBay show as 2kw, 47 ah ratings and about 45 pounds,
which is not a factor. The current pack of VRSLA batteries are about 150
pounds. Can a 4kw module be easily halved to get to the 2kw level if the
voltages would work out for my purposes?'
Jerry's reply:
Fred, Volt modules charge to 49.2vdc fully charged and driving my EV trike
pickup at about 60 amps it drops about 2 volts and very stiff after that.At
40vdc it is near/at 100% discharge so it won't have much problem and if stops,
just come back in at low power after it recovers if not far.They act more like
NiCad B660s than lead.And the volt modules in series put out 1k amps tested if
asked or 2k amps with 2 48vdc ones in parallel for the smallest module at
4kwh.For a charger use a power supply that can be adjusts to 49.2vdc exactly.
I'm looking for a 1-4kw one as my main charger if I can find one cheap.Though
might just go with a bulk charger and finish with a small PS one.Or use the
JDL404 wthr meter to turn them off with relays, contactors.Again splitting them
is not smart as can damage them as can not having them compressed makes them
swell and lose capacity. Now if you get both end plates, hose connections and
hopefully get it back together compressed without leaks, etc, it could work but
I wouldn't. I'll at least fill it with coolant as th cells at really buried in
the plastic case. Though I'm running the trike without cooling but being very
gentle with it. As I find out how much more I need for 100 mile range then i'll
plumb the whole thing up.I wouldn't pay more for split ones when you can get
whole ones for less at $150/kwh. If you can take 100lb of 2 48vdc sections,
the Volt is good. The size of 2 12v lead batteries.If you can't, use the Leaf
modules.Jerry
More questions from fred:
It seems like the Volt modules will have sufficient voltage to keep the mower
happy. My experience with my Gizmo EV trike and LiFePO4 matches your
description regarding "stiffness" as I had hoped. I don't have experience with
NiCad, so that one goes over my head.
Current capability at a thousand amps is way out there. The maximum current
draw I've ever seen on my mower is in the low to mid thirties, barely a trickle
in comparison. Even the Gizmo will pull about 250 amps if I'm heavy on the
throttle trigger, well under your referenced figures.
I'd like to avoid paying $600 for a pack when I need only half that though.
It's funny to think that I could charge once a season with such a monster
(relatively speaking) sized pack on the back end of the mower.
You've mentioned Leaf modules a few times, but the prices I've seen for those
on eBay seem astronomical compared to the Volt. Am I reading the specifications
incorrectly? They are listing at 7.6v, I'd need 6 modules and the totals are
approaching a thousand dollars with shipping. The amp-hour capacities are also
far more than I really need. A pack that gives me 40 ah in lithium would be
fairly close to the 75 ah lead pack that once worked fine at my preferred 50%
DoD with energy to spare. The Volt packs wouldn't even be pulled down to 30%
DoD in normal use.
I also can keep an eye on discharge with the CycleAnalyst (watt-hour/amp-hour
meter) installed on the mower.
As you've referenced your prices and I've looked up your listing on EV Tradin
Post, I had hoped to buy from you, especially as I can save on shipping by
arranging a pickup, but twice as many modules would be a waste of money. I
don't think I have to worry about compression too much with a 30 amp draw, nor
about overheating from such a low current flow. I suppose I'll find a cheap
eBay auction and take the plunge.
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