Battery draining

800 mA/hr is not normal and may get your battery drained

You are right in stating that mA/hr should not have been used: I started
typing something else and forgot to delete the /hr.

Actually - not to have the last word - but there is a measure called
Ampere-Hour or Amp/Hr in relation to batteries - it is in relation to the
useable capacity of a battery (commonly referred to as C rating. ie C/10,
C/20 state the discharge rate over time).

If you draw more current than specified per hour, your battery capacity is
diminished.
But batteries are rated at some Amp-Hr. A 80 Amp/Hr battery would put out 20
Amps for 4 Hour or 1 Amp for 80 hours before it is totally empty.

Anyway, 800mA is not a normal current draw for a car parked - that's what I
meant to say.

 

Super! Mike F is the top guru on Volvos.

Mike

 

Sounds like a bad fuel pump relay, the in tank impeller pump side welded
closed, main pump contact working normally.

Have Fun,
John

 

We don't know what the capacity is, since cranking batteries are
rated in cranking amps.

But, I have a Group 27 fishing battery here, 12" x 6 1/2" x 8" = 624
cu. in., 115 AH capacity.

My mid-80's Civics use a Group 51, 9" x 5" x 8" = 360 cu. in.

Capacity might be proportional to volume. 360 / 624 = .577 x 115 =
66 AH for Civic battery.

If the battery were fully charged (it wasn't), .8 A would discharge
it in 82 hrs.

Based on the terminal voltage reading you gave, I'd guess it was
about 1/3 charged. So you're probably in the ball park.

Crappy batteries usually come with their plates only partially
formed, and need a stiff initial charge. Start at around 10 hr. rate
(capacity / 10), monitor voltage, limit it to 16 V. When current
falls to, probably, 2 A, you're done. Leave the cell caps on, so you
don't get acid sprayed around. (removing caps for charging is an old
mechanic's tale!<G>; so is putting it on a board.)

Don't do this to a sealed battery.


Tom Willmon
near Mountainair, (mid) New Mexico, USA

Judging from the taste, I'd say the other one is shinola.

Net-Tamer V 1.12.0 - Registered

 

Yeah. But let's drop the Amp/Hr idea. Here's why:

1 Ampere = 1 Coulomb [unit of charge] / second.

Amp / sec. would be Coulomb / sec (squared). That would be something like
acceleration, seldom useful in ordinary electricity. I've never seen it in
engineering work.

I agree.

Tom

An oyster is a fish built like a nut.

Net-Tamer V 1.12.0 - Registered

 

1 Ampere = 1 Coulomb [unit of charge] / second.

While it isn't used very much in most electrical engineering applications,
the Amp/Hr measure is one way they spec batteries. I agree with you that in
the strictest terms it doesn't make much sense.

You must also have EE or related training -- seems like many of us just come
out of the woodwork when electical stuff comes up, doesn't it?

I like that saying -- have to remember that one! Thanks!

 

It is a rate of current change, which is meaningful in inductive loads.
Steady amp/sec change across an inductor produces constant voltage, and
vice-versa. In automotive work it would only be used for ignition coils, but
it is the big factor in analyzing whether communication sites get whacked
when lightning strikes. The typical standard for lightning is 10K amp/sec,
simulating a 1000 amp strike with rise time of 0.1 seconds. At those rates
of current rise, a sharp bend in conductors usually causes lightning to
break back out into the air. The inductance of a straight piece of 4/0
welding wire is enough that lightning won't always stay inside, but often
flashes along the surface.

Mike

 

remco wrote:
|| 1 Ampere = 1 Coulomb [unit of charge] / second.
||
|| Amp / sec. would be Coulomb / sec (squared). That would be
|| something like acceleration, seldom useful in ordinary electricity.
|| I've never seen it in engineering work.
|
| While it isn't used very much in most electrical engineering
| applications, the Amp/Hr measure is one way they spec batteries.

I take it you mean Ah (ampere-hours, aka A*h)?

That's a useful measure for capacity. 10Ah means 10A for 1 hour, or 1A for
10 hours.

|| An oyster is a fish built like a nut.
| I like that saying -- have to remember that one! Thanks!

I get ampere-hours, but I don't get that saying. :/