Re: [EVDL] * Discover agms ?
Nice report. That's what I was looking for.
Nice report. That's what I was looking for.
--- Roger Stockton <[email protected]> wrote:
> Seth Myers wrote:
> > Yesterday I went to the local batery distributor
> to pick up a
> > Trojan T105 or T125 [...] preached to me the
> virtues of
> > the Discover dry cell (agm).
> > The chief virtues are the following:
> > - no acid (esp since 10 will sitting in the
> > compartment (we'll have adequate
> > - no hydrogen gasing
> > - no acid spray
> > - costs about 2x ($325 ish vs $170 ish) as much,
> but last 2 -
> > 2.5x as long
> I think you'll find that this is just the usual
> price differential between floodies and AGMs.
> Compare the cost of the Discovers to other AGMs of
> similar size and you'll likely find them to be quite
> > and they seem to have pretty decent performance
> > characteristics (124 minutes rc at 75 vs 115 for
> Trojans, I
> > think) so it just seems to be a matter of buying
> 4-6 yrs.
> > worth of batteries up front vs. 2-3. (??)
> I've cycled Discover's L16 and T105-size 6V AGMs and
> they will deliver their rated capacity at 75A.
> > I had initially shied away from Discover when
> I heard
> > they were essentially agm, meaning in my mind
> 200-300 cycles
> > before going kaput, but it looks like they are
> more like
> > 1000-1100 cycles at 50% dod (compare vs Trojan's
> specs of 438
> > cycles T105, 492 cycles for T125).
> They aren't essentially AGMs, they are exactly AGM.
> The Trojan numbers you refer to sound like their
> "lifetime eneregy unit" (LEU) ratings, not cycles.
> A 6V flooded battery is typically rated to about 700
> cycles @ 80%DOD, and this will increase dramatically
> at shallower DOD, just as it does for the AGMs.
> Without digging up the Discover specs to fins a
> cycle vs DOD plot, I would expect them to deliver
> about 300-400 cycles @ 80%DOD, or about 1/2 the
> cycles of the floodeds. Despite this, they *do*
> apparently last longer in certain applications than
> floodies simply because floodies often die well
> before their rated cycle life due to lack of
> maintenance and other operationsla abuses. If your
> floodies die in 12-18months and the Discovers (which
> require no maintenance) last 24-36months, then one
> can honestly state that the Discovers last 2x as
> > I recall Firefly said their lead acid battery
> > would end up being something like 5x in price a
> regualr lead
> > acid, so since this is just 2x, these seem like a
> midway step
> > in the firefly direction ...
> Not quite. To their credit, the Firefly folks
> compared their projected prices to those of present
> AGMs (not floodeds). That is, the Firefly is
> predicted to cost about 1.5-2x the cost of your
> Discover (or any other) AGMs, not 1.5-2x the cost of
> There is also nothing revolutionary about the
> Discovers; they are just a decent quality AGM.
> As to actual EV use, I'm not aware of anyone using
> the 6V modules. Randy at CEV has built a few Neons
> running packs of the Discover EV31A-As and has been
> quite pleased with the performance. I've got a 120V
> set of the Discover EV34A-As in my EV at the moment.
> It is too early for me to say anything about their
> cycle life, but my first impression is that the
> EV34A-As are not as stiff as the elderly Optima YTs
> they replaced. I would not recommend them to
> someone as a less costly power battery than Optimas,
> Orbitals, or Hawker/Odesseys.
> However, the EV34A-A is pretty much a drop-in
> replacement physically for the Optima Group 34 YT.
> The main difference is that the EV34 is a more
> conventional flat-plate construction, and has the
> threaded insert style terminals rather than the
> automotive SAE posts. The EV34s are 70Ah and 50lb
> vs the 50 (55Ah?), 43lb YT.
> If you are the sort who looks after your batteries,
> then it would be difficult to recommend any sealed
> battery over floodies in terms of cost. You will
> need a decent charger to hope to approach the rated
> cycle life for any type of battery. If you need to
> locate batteries in the passenger compartment or
> someplace where access for routine maintenance will
> be difficult, then sealed batteries may be
> appropriate. If you want a stiffer pack, then AGMs
> may be appropriate.
> Note that Discover makes sealed batteries in both
> gel and AGM types, and the gels tend to have longer
> rated cycle life than the AGMs. If your application
> will use discharge rates compatible with the gel
> ratings, you might be better off using them than the
> AGMs. This is especially true if you are
> considering large sealed 6Vers since even a very
> modest 2-3C rate is 450-700A for a 225Ah-ish module.
> If you decide to consider gels, you might want to
> comparison shop against the DEKA/East Penn and
> Sonnenschein 6V gels since these brands are
> typically associated with high-quality gels.
> Discover's site is at
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