However some batteries last much longer than others. We've been selling
so called pure lead RG batteries for around six years. My original
customer is still using his 13 amphr model on his C90 engine. However
some people seem only to get around 18 months out of their batteries and
they don't appear to fly more hours and claim they don't do anything to
damage the batteries.
We have found two things which upset these modern lightweight batteries.
1 Leaving on the master switch. We recently had a battery returned to
us at under 5 volts with no mechanical damage. The owner claimed it was
working fine and he took it off to re-charge. Batteries in general don't
just drop to 5 volts and don't recover easily from this condition. If
you do leave the master switch on then get the battery onto a charger
(or get your engine running) as soon as possible. Leaving them
discharged kills them.
If it wont re-charge give your supplier a call. The distributor we use
can often recover their batteries if over discharged but the sooner they
get them the more likely they are to succeed. The charge (no pun
intended) for this service is 20 + VAT and shipping.
2 Undercharging leads to poor starting and short battery life. If
your charging voltage is too low then the battery is never going to
perform at its best and will die young. The manufacturer we use
recommends 14.4 volts.
Well maintained batteries should last five years even the small ones we
sell for use on Rotax engines. We are currently preparing to test a 4
amphr battery weighing less than 2 kgs on a 912S engine. You can't
expect the same life out of a small battery because it is being worked
harder, that is the percentage amount of discharge and re-charge is
higher. Providing the weight is OK we normally recommend our 14 amphr
battery as a good compromise on 912 / 912S and Jabiru 2.2 engines.
We have just done a new care sheet on our batteries. If anybody wants a
copy just send me an Email and I'll send a .pdf file.
regards
Jerry
Ahr
kg
L W H
Amp
Price
Inc VAT
51
17.5
220 121 255
1400
210.00
246.75
35
12.5
250 97 204
1100
138.00
162.15
26
9.0
250 97 152
850
130.00
152.75
16
6.1
182 77 168
480
80.00
94.00
13
4.9
176 84 130
400
80.00
94.00
14
5.0
200 77 137
550
79.00
92.83
8
2.8
138 86 101
300
70.00
82.25
LTS@avnet.co.uk
www.avnet.co.uk/touchdown
----- Original Message -----
From: "Shaun Simpkins" <shauns@hevanet.com>
Subject: Re: Looking down the road at batteries
> Good points.
>
> Bob did make the point that the smaller the battery, the more frequent
the
> load checking to avoid dead battery in air syndrome. B&C do not quote
CCA
> on their website, and I've asked them to provide such information for
> comparison.
>
> Shaun Simpkins
> A207
>
> ----- Original Message -----
> From: "Fred Fillinger" <fillinger@ameritech.net>
> >
> > It's odd they use that ampere-hour stuff (mere capacity), whereas
for
> > cranking engines, internal resistance is as important per Nuckolls,
so
> > stuff like CCA - cold cranking amps - is the spec on batteries for
> > engine applications. Cranking amps reflect both capacity and
internal
> > resistance, and the Odyssey PC625 I have is 265 CCA (440 HCA - "hot"
> > at 80F). Cranking amps is the amps it delivers for 30 sec. while
> > maintaining 10-point-something volts. "AH" is based on something
like
> > a 20-hour discharge rate, but other specs suggest the PC625 is about
> > 13AH. That's also why Nuckolls says even an 8AH batt, if RG and
hence
> > low internal resistance, will work, but I would add not for too much
> > cranking nor allow for in-service degradation.
> >
> > Also, the 50W starter draw would be average. If you've ever seen
the
> > wild needle dance on those little induction ammeters placed on a
> > battery cable, it's the compression stroke that hurts, and quick
> > starting is oomph into that stroke rather than average cranking RPM,
> > else no one could hand-prop an airplane. And Bob H. notes the
effect
> > of 50% more oomphs per revolution on his six-banger. That's what a
> > higher CCA provides.
> >
> > Regards,
> > Fred F.
> >
> > The Europa List is supported by Aviators Network UK -
info@avnet.co.uk
> >
>
>
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