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NEVCO recently made a change in the standard battery pack for the gizmo. We have decided
to provide eight Trojan T105 6 volt "golf cart" batteries in series for a 48 volt system. Our experience
with sealed AGM type batteries is that they are capable of giving better performance that flooded deep cycle batteries,
but they are fragile. Because they are sealed, there is no way to add fluid to the cells. Unless a perfect charging
algorithm is used each time they are charged, and they are charged almost immediately after use, and the system
is kept in balance for its entire life, and they are not discharged past 50% very many times, they will loose battery
fluid. The charging process that this entails causes gassing of hydrogen, which depletes level of liquid. Once
the plates are exposed, the deterioration process proceeds more rapidly. We have some packs that have lasted over
three hundred 50%cycles with the owner paying very close attention. But on balance, people are not fastidious enough
to maintain this vigilance. We have had some packs that lasted only about 100 full cycles. In order to help extend
range, we have tried balancers, and the pulse generators, with only minimal success. |
There are many factors, often uncontrollable due to everyday occurrences,
that can negatively affect the sealed batteries. Continued deep discharges and intermittent charging are only the
most obvious. We have decided that the most reliable batteries are the ones designed for rugged treatment for the
golf cart industry. They are flooded, in that the battery fluid (water) can be added to keep the plates covered.
They have lots of plate area to handle deep discharges. They are relatively inexpensive. Unfortunately, they are
heavy by comparison. The smallest pack we can put in a Gizmo weighs 520 lbs. This compares to the smallest AGM
pack of 240 lbs., and the previous standard pack of 320 lbs. This has reduced acceleration slightly, and speed
on hill climbing somewhat, but has extended the range of the standard Gizmo to over 45 miles in tests under a variety
of circumstances. We expect this pack to last as much as 1000 full cycles, based on data from golf cart users,
assuming the fluid level is maintained. This requires periodic checking of the batteries, which may also be neglected
to the detriment of the system. To that end, we are offering as an option, Hydracaps made by Hydracap Corp. of
Miami. During charging, hydrogen gas escapes from the cells. Using a catalyst, the Hydracap causes this hydrogen
gas to combine with oxygen from the air to form water, which drips back into the battery. This technology has been
used in submarines for years. This is beneficial to the batteries, and eliminates the need for continual watering.
The cost of replacing a battery pack is about $500 installed. Replacing battery packs has been the bane of the
EV world for a long time. A new EV is great until the expense of replacing the battery comes up. You can often
find great deals on EVs, except that you have to replace the batteries, which in some cases can mean several thousand
dollars. This price, and the length of time the pack lasts, should be much more reasonable to swallow. This pack
may not work in cases where people's driving route includes along steep hill, which will slow the Gizmo to about
18 mph. It may also not meet some drivers need for especially fast acceleration. For those requirements, we are
still offering an AGM pack that weighs 320 lbs, We are adding to that the Power Cheq battery balancing/management
system. This pack has a range of about 35 miles, and costs an additional $800. The Gizmo comes with a Zivan multistage
charger specifically designed to charge deep cycle lead acid batteries. Typical chargers work at a constant voltage,
which means that the amperage declines as the battery charge increases, and pulls less power. This continues until
the battery is almost, but not quite, fully charged. Every time it charges, a small amount is left uncharged, which
over time builds up sulfate, reducing battery capacity. Testing has shown that a charger that keeps a higher amperage
going to the batteries causes the sulfate to be more completely dissolved. The Zivan charger maintains a constant
amperage until the battery is 80% charged. It then gradually reduces to 5 amps, where it stays until the battery
is 100% charged. 115 volt or 220 volt Zivan chargers are available. The 220 volt charger will charge four times
faster than the 115 volt charger, but costs an additional $400with charge cord.
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