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Re: (ET) Elec-trak Digest, Vol 15, Issue 39
David,
I disagree. I'm about to build AGM chargers for my batteries and there's not
much to it. I'll publish the circuits when my electronics is done for the
motor drive and the chargers but it's simply a matter of reading the
manufacturers data sheets and contouring the algorithm to their battery.
I've done it many times before and with todays power transistors it's
relatively easy. Manufacturers want you think it's a big deal because they
sell these things - at a huge markup!
Rob
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From: elec-trak-request cosmos phy tufts edu
Sent: Saturday, May 20, 2017 12:00 PM
To: elec-trak cosmos phy tufts edu
Subject: Elec-trak Digest, Vol 15, Issue 39
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Today's Topics:
1. Re: Multi-bank 12V chargers (David Roden)
2. Re: E-15, need a smart battery charger guidance &
recommendations (Darryl McMahon)
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Message: 1
Date: Fri, 19 May 2017 19:07:05 -0400
From: "David Roden" <etpost drmm net>
To: elec-trak cosmos phy tufts edu
Subject: Re: (ET) Multi-bank 12V chargers
Message-ID: <591F4259 6461 5B2489A8 etpost drmm net>
Content-Type: text/plain; charset=US-ASCII
On 19 May 2017 at 14:10, Ken Olum wrote:
It may be that Minn-Kota has some more complex algorithm, such as
waiting for the rate of decrease of the current to fall below some
level.
If I'm not mistaken, Lester Electrical patented their DV/DT algorithm. I
don't know about its twin brother, DI/DT (what you're describing). And the
patent may have expired by now.
For an ET with golf car batteries, you could do a lot worse than a used
Lestronic or Lestronic II golf car charger. They're just about
bulletproof.
They do tend to overcharge a bit, however.
One nice thing about DV/DT and DI/DT is that they automatically deal with
the lower peak on-charge voltage as batteries age.
Setting the voltage threshold for an IU algorithm is a balancing act. Too
low, and it undercharges new batteries. Too high, and it overcharges old
ones and may never get out of bulk phase. (Maybe GE had the right idea
with
their age-calibrated timer after all, eh?)
Some more sophisticated IU chargers have watchdog timers that end the bulk
phase (or the charge) if it runs too long, or delivers too many amp-hours.
Using a charger that's too small or too large for the battery can muzzle
the
watchdog, though.
Another method of preventing overcharging is to monitor battery temperature
rise. That requires at least one temperature sensor in the battery pack.
Ideally, any watchdog should set an error flag and warn the user.
Charging batteries isn't as easy as it looks, and the more sophisticated
the
battery, the harder it is. That's why commodity rechargeable consumer
appliances have such crummy battery life. Chargers are one of the first
places the bean-counters look to cut costs, since the effects on battery
cycle life don't show up right away (ideally, about a month past warranty
expiration).
Also, exaggerating a bit, proprietary replacement batteries are to
rechargeable appliances as ink carts are to inkjet printers.
(Canon MG2522 scanner/printer with "starter" ink carts: $29.98)
(Canon 245 & 246 ink cart set for MG2522 scanner/printer: $39.99)
David Roden - Akron, Ohio, USA
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Message: 2
Date: Sat, 20 May 2017 10:59:51 -0400
From: Darryl McMahon <darryl econogics com>
To: elec-trak cosmos phy tufts edu
Subject: Re: (ET) E-15, need a smart battery charger guidance &
recommendations
Message-ID: <244038a9-5d4f-fb1f-3b01-d2cbf491f2e4 econogics com>
Content-Type: text/plain; charset=windows-1252; format=flowed
Sorry, I'm a little behind on e-mail (busy days).
Regarding questions on Soneil. My company (Econogics) is a full-line
distributor for Soneil lead-acid battery chargers. (This isn't how I
make a living, so I'm just as happy to not sell a charger into an
inappropriate situation as sell one into an appropriate situation. I
don't make enough on selling these to justify spending the time fixing a
bad sale. [I think that's a bit beyond typical disclosure.])
Soneil also has a line of lithium batteries and chargers, and is just
now starting to sell a line of 'crystal' lead-acid batteries; a
valve-regulated technology (which should not be used with brute-force
ferro-resonant chargers). Soneil claims extended life due to the
battery internal technology (beware the claims of battery salespeople,
especially anything which they claim happens beyond the warranty
period). I'm not a distributor for Soneil's lithium charger line, or
any of their batteries.
I recently acquired 2 E-15s, which means there are now 3 E-15s (one
functional) and an E-12 (original workhorse which hooked me on ETs) in
my city lot yard. Between basketball net & stand, garden, dandelions
and tractors, more yellow than green on the landscape. (There is also a
Nissan Leaf and Ford Focus Electric in the driveway (I may have an EV
problem. <smile>) Anyway, my E-12 needs a battery replacement (10
year-old Exides - originally bought as seconds, old stock and from
different batches in fall of 2007 - are now growing 'tumours' around
most of the battery posts). I'll probably buy a set of the Soneil
'miracle' batteries to try them out. I don't plan to be a distributor
for the batteries, but will report on my experience with them if anyone
expresses interest.
I will be using a Soneil 3624SR16 with those. I had been using a
3610SRF for about 15 years before it failed last year (permanently
tucked in under the hood to keep it out of rain and snow, but exposed to
outdoor temperatures). It was plugged in pretty much continuously for
the 15 years, other than when the tractor was in action. I will be
wiring the new charger to connect via the 'appliance' plug, so I can
move it across tractors easily as I hope to be working on 2 or 3 over
the next year or so, as the 'work' tractor may be changing a couple of
times through that period.
I see the Soneil line as a solid value-for-money proposition for our
tractors. It's no Brusa, and it's not a bottom-end battery cooker. It
comes with a solid 3-stage charging algorithm, and floats the batteries
once it reaches the fully-charged threshold. It then monitors the
batteries, and if the charge level drops, it automatically restarts the
charging cycle. The Soneil charger can be left plugged in indefinitely
and will not harm the batteries. I have long wished for a 6-volt
version, or a 6x6 multi-bank version, but I don't see that being
available anywhere. The 3 x 12-volt approach is an option, but it does
not address the 18-volt taps for the front and rear lifts (per GE OEM
configuration).
The Soneil chargers are mostly made in China, Malaysia and the
Philippines. Build quality is generally good (I see a fail rate around
1% in my pre-ship testing). There is pretty much nothing
user-serviceable or configurable in these chargers. Most come with a
120/240 volt input switch and some with a battery selector switch
(AGM/gel). There is no setting for flooded, because the Soneil is never
going to boil/equalize your batteries. Other than that, Soneil thinks
the charger smarts will do the rest. They are reverse polarity
protected, and sense for the battery before supplying any output
current/voltage (which does lead to some user confusion when they want
to test the charger with no battery connected). The Soneil chargers
will dissipate some heat all the time they are plugged in, as the
'smarts' are always on. I have measured this at 3-5 watts. They
dissipate more when actively charging. Power factor correction is not a
strength for these chargers (about 80-85% PF per monitors I have used -
slight variances by monitor and charger model).
A Soneil is not going to 'equalize' a battery pack via overcharging -
ever. It brings a different mindset to the issue. It does 'equalize'
to an extent via the long, slow charging period at end of charge every
cycle (assumes sizing to have at least a couple of hours for this each
charge cycle). Some people call this saturation charging; the fully
charged cells will dissipate the additional energy as heat while the
lesser charged cells will use most of that available energy to complete
charging. However, if you are discharging some batteries to dead and
others only lightly each cycle, a single pack-level Soneil charger is
not going to miraculously solve that issue on a long-term basis, any
more than the stock GE battery boiler will. For that you want
module-level charging. My tractors are not in daily commercial service,
so I have that time. If I was operating in the daily 'run until dead'
commercial scenario, I would invest in higher capacity chargers and get
rid of all the partial pack loads. (I also probably would not be using
a collection of 40+ year old tractors.)
The Soneil approach brings several advantages. Greatly reduced need for
battery watering (I eventually ended up checking once a year and adding
water about once every 2-3 years). 2) Reduced watering means reduced
acid misting, so less need to wipe off battery tops and battery box
corrosion is reduced. (Does not fix the accumulation of pine needles
and maple seed 'helicopters' which somehow still find their way into my
battery boxes - my tractors live outside winter and summer). 3) The
battery pack monitoring function means the tractor is always charged and
ready to go, even if it sits idle for a week or a month or more.
If you really believe the 'kick' at start up has great value, Soneil can
accommodate with the model 3660SR60. 27 amps constant current in the
bulk charge state for as many hours as required (probably about 4 for a
heavily discharged ET). If that's not enough power for you, you can
stack 2 or more in parallel, so if you really want 190 amps output,
Soneils can accommodate (though your wallet will be considerably
lighter, and you will need a 240-volt, 50 amp AC supply). Never mind
that wimpy 25 amps for a couple of minutes you get from the GE stock
unit. (Personally, I'm not a fan of the 'kick-start' or overcharging,
but it's the customer who gets to decide.)
I'm providing a price list of 36-volt Soneil options below in US$ (my
web site only lists in CDN$). This is for information purposes only,
exchange rates vary over time, shipping extra, no taxes on sales to U.S.
addresses). If you want additional information about a specific unit,
please contact me off-list (darryl econogics com) Happy to answer
general queries here on the list.
There are several 36-volt Soneil models with less than 4 amps output;
I'm ignoring them for the purpose of this e-mail. (fixed width font
recommended for the block below)
Soneil Max Out Price
Model Current US$
3610SRF 4.5 A $177
3616SRF 8 A $201
3624SR16 12 A $216
3632SR32 16 A $469
3640SR40 18 A $491
3648SR48 24 A $723
3660SR60 27 A $759
By my math, the best deal in amps/dollar is the 3624SR16. If you don't
think 12 amps is enough, stack 2 of them in parallel for 24 amps (or
more for higher output).
Enjoying the charger discussion so far,
Darryl
On 5/18/2017 1:49 AM, David Roden wrote:
Warning, this message is pretty long.
On 17 May 2017 at 22:20, Hank Ralston wrote:
I have always disliked the random "age of the battery" charging
settings.
There's nothing elegant about the GE charger, but there's actually some
rationale to the timer settings. Older batteries have less capacity, so
with a dumb charger like this one, charging them the same length of time
as
new ones overcharges them.
What should we look for in either specifications &/or brands of external
golf
cart battery chargers should we consider?
A few things to think about:
1. Bulk current capability. You want a charger with a bulk phase current
capacity of around 10% of the batteries' C20 capacity. To get good life,
batteries seem to need a good sock in the gut at the start of the charge.
Thus low current chargers aren't just slow, they're not a great investment
in the long run.
Most golf car batteries are 220 to 250AH, so a 25 amp charger would be
about
right for a large frame ET. You could probably get by with a 15+ amp
charger, but 20+ is better. A small frame machine would be fine with a
10
or 12 amp charger.
2. Brains: Flooded golf car batteries are pretty forgiving (compared to
gel
or AGM batteries and - goodness knows - lithium). But a little
intelligence
in the charger will extend their cycle life.
I'd want to see an IU or IUI algorithm. That would be constant current to
a
voltage limit of 43.2 to 44.4 volts, then constant voltage at that voltage
until the current falls to 0.02 * C20 (2% of the battery's C20 amp hours
expressed in amperes).
What should happen next would depend on what kind of ET you have.
The large frame tractors are a particular charging challenge because they
have battery taps for the lift and lights. Unless you never use the lift
or
lights, they unbalance the battery pack with each cycle. This means that
some batteries in the pack are discharged more than others.
The "right" way to deal with this would be to quit tapping the pack.
Either
convert the lift and lights to 36v, or add one or two DC:DC converter(s)
to
provide the 12v and 18v (or 24v) from the 36v battery.
I've been sorely tempted by some of the obscenely cheap Chinese-made DC:DC
converters I see on Ebay, but I'm leery of reliability issues. I'd hate
to
have one fail and put the full 36v onto its load.
Barring that, the large frame ET battery needs aggressive equalization on
every charging cycle. In bringing up the more-discharged batteries,
equalization overcharges the batteries that are less discharged. This
inevitably shortens battery life. So it goes. :-(
Small frame ETs discharge their batteries evenly, so they need
equalization
only once in a while. I'd say maybe every 10 or 15 cycles, so for many of
use just a couple of times a year. You want to monitor the specific
gravity
of the cells, though, and equalize if they're getting too far apart.
Equalization is the last I in the IUI algorithm. To equalize, instead of
shutting off at the end of the constant voltage phase, you charge constant
current at the (0.02 * C20) rate until either the voltage stops rising, or
the on-charge voltage reaches 46.8 volts (flooded batteries). (Either
condition should terminate charge.)
As for specific charger brands, I don't know every brand out there by any
means. Here are a few that I've looked at and, in one case, used for my
ETs. I would love to hear from other people with experience.
DELTA-Q: I rather like Delta-Q chargers. They're smart. The problem is
that
Delta-Q won't sell to individuals. Maybe one of the ET parts dealers
could
work with Delta-Q to develop appropriate charging profiles for large-frame
and small-frame tractors. (Jim Coate, Harold Zimmerman, are you
listening?
Any thoughts?)
Delta-Qs have some other issues I'm not 100% comfortable with. They're a
Canadian company, but the chargers are manufactured in China. And I'm not
entirely sure about the availability of service should one develop a
fault.
Those would be matters for our friendly parts dealer to check into.
https://www.amazon.com/gp/product/B00C5NV2DY/ref=s9_acsd_hps_bw_c_x_4_w
QUICK CHARGE: I've looked briefly at these chargers too. They're somewhat
old-tech and heavy, but seem sturdy. They're US-made. They have some
smarts, but not as much as the Delta-Q chargers.
Looking at the QC literature, I can't tell how much their algorithm relies
on time and how much on voltage and current. It APPEARS that they're a IU
/
IUI charger, but the 12-hour scale on their charge profiles worries me.
They have a way to extend the absorption phase. That might handle the
equalization. All in all though I'm not sure QC's chargers are as smart
as
their price would suggest. They are probably an improvement on the GE.
https://www.quickcharge.com/select-a-charge-on-board-chargers.html
http://www.chargingchargers.com/quick-charge/obsc36-25.html
SONEIL: Darryl McMahon is on this list and is a dealer (distributor?) for
Soneil chargers. The inexpensive Soneils are too small (low-current) for
ET
use, but I remember him mentioning the 3624SR16 10-amp charger (adequate
for
a small-frame ET) at a pretty attractive price a few years back.
http://soneil.com/product/model-3624sr16/
This model would be more suitable for a large frame tractor, but I don't
know whether it could handle the equialization needed:
http://soneil.com/product/model-3640sr40/
Maybe Darryl is reading this, and can weigh in on whether the Soneil
chargers can be configured to equalize aggressively enough to deal with
large frame pack imbalance.
Some if not all Soneils are made overseas (mostly in China, I think). I
know nothing about their repair-ability. Darryl would probably know more
about those issues.
12V CHARGERS: This might be the cheapest route. It's what I use ATM.
I charge both my E15 and New Idea rider with 3 individual 12v "Exide"
brand
automatic automotive chargers (cycle-dropping algorithm) made by Cliplight
in Canada. They still make something similar to my chargers, which are
over
20 years old, but they claim the current version is smarter.
http://www.cliplight.com/battery-chargers/12v/10-amp-linear-charger/
https://www.amazon.com/Cliplight-Volt-Amp-Battery-Charger/dp/B003F1G8PM
I use East Penn G24 gel batteries in both tractors, 3 in series in the New
Idea and 6 in series-parallel in the E15. These are C20 rated 74ah with a
reserve capacity of 140 minutes at 25 amps.
The Cliplight chargers are rated 10a and peak at 12a into flat batteries.
This is fine for the New Idea, and a little on the light side for the E15.
On the E15, I use a 12v tap for the lights and a 24v tap for the lift. I
haven't had any problems with the lift at 24v, touch wood. YMMV.
These batteries are over 20 years old now. Just in the last year or two,
they've finally started to lose capacity significantly. They now test at
only 30-40ah at 22 amps, or around 50-70% of original capacity. But I
figure the charging routine I've used all this time hasn't done too badly.
Warning: one hazard of using multiple chargers is that you need to monitor
them, or have some kind of voltage monitor on each battery. If one
charger
fails and doesn't properly charge its battery, you can ruin that battery
the
next time you use the ET.
OTHER CHARGERS: If anyone has had positive experiences with other charger
brands, please post your comments.
David Roden - Akron, Ohio, USA
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me a private message, please use the address shown at the bottom
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End of Elec-trak Digest, Vol 15, Issue 39
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