RE: Best Way to charge gel 7a 12v on way to field?

RE: Best Way to charge gel 7a 12v on way to field?
View related threads: (in this forum | in all forums)

Logged in as Guest

Users viewing this topic: none

Printable Version

All Forums >> Radios, Batteries, Clubhouse and more >> Batteries & Chargers >> RE: Best Way to charge gel 7a 12v on way to field?

Page: << < prev 1 [2] 3 4 next > >>

Login

Message

<< Older Topic Newer Topic >>

RE: Best Way to charge gel 7a 12v on way to field? - 10/10/2005 9:12:02 PM

JNorton

Posts: 3134
Joined: 1/29/2002
From: Montague, MI, USA
Status: offline

TopRudder,

quote:

What the best solution would be is to use an intelligent multi-stage charger, but you would probably only find one that operates from 120v AC, and you are back to using an inverter.

Actually Multiplex makes a LN-5014 DC charger for $80.00 that chargers Lp just fine.
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXKSY1&P=ML

I'm still using my original 7aH lead acid gell. It is now 4 years old. My trips to the field are approximately 1/2 hour in length. My vehicle charging system puts out 14.0 volts after starting the car. It would be easy enough to put a 3 amp diode in series to limit the voltage to 13.3. I haven't an 1141 bulb or I would try it - I still might for curiosities sake. Basically all I am doing is to keep the gell cell topped off.

KISS

John

_____________________________

Have desk ... Will Fly....
Saito Member #467

(in reply to toprudder)

Post #: 26

RE: Best Way to charge gel 7a 12v on way to field? - 10/10/2005 9:47:14 PM

toprudder

Posts: 167
Joined: 10/4/2005
From: Raleigh, NC, USA
Status: offline

quote:

ORIGINAL: JNorton

TopRudder,

quote:

What the best solution would be is to use an intelligent multi-stage charger, but you would probably only find one that operates from 120v AC, and you are back to using an inverter.

Actually Multiplex makes a LN-5014 DC charger for $80.00 that chargers Lp just fine.
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXKSY1&P=ML

I'm still using my original 7aH lead acid gell. It is now 4 years old. My trips to the field are approximately 1/2 hour in length. My vehicle charging system puts out 14.0 volts after starting the car. It would be easy enough to put a 3 amp diode in series to limit the voltage to 13.3. I haven't an 1141 bulb or I would try it - I still might for curiosities sake. Basically all I am doing is to keep the gell cell topped off.

KISS

John

Thanks for the link, I am looking for a decent field charger. However, the technical information in that link regarding charging does not mention anything about the charge method for lead-acid batteries. It almost reads like it is constant-current, which is a no-no for LA batteries. It should at minimum have a constant-voltage mode for LA.

(in reply to JNorton)

Post #: 27

RE: Best Way to charge gel 7a 12v on way to field? - 10/11/2005 1:09:18 AM

JNorton

Posts: 3134
Joined: 1/29/2002
From: Montague, MI, USA
Status: offline

quote:

Thanks for the link, I am looking for a decent field charger. However, the technical information in that link regarding charging does not mention anything about the charge method for lead-acid batteries.

http://www.multiplexusa.com/RC-comp/Chargers/LN-5014.htm Top right of the page is a link to the instruction manual.

_____________________________

Have desk ... Will Fly....
Saito Member #467

(in reply to toprudder)

Post #: 28

RE: Best Way to charge gel 7a 12v on way to field? - 10/11/2005 1:25:09 AM

JNorton

Posts: 3134
Joined: 1/29/2002
From: Montague, MI, USA
Status: offline

TopRudder,
I've been looking for more information on the LN-5014 and came up short. The algorithum for LiPo is similar to that of charging Lb. I cannot conceive of a large corporation like Hitec / Multiplex failing to make a suitable charger. I do know that Red feels this is a good charger for the money but since I do not own one I cannot give any further information on it.

Perhaps this would give you more information.
http://www.rcuniverse.com/forum/m_3188884/tm.htm

John

_____________________________

Have desk ... Will Fly....
Saito Member #467

(in reply to JNorton)

Post #: 29

RE: Best Way to charge gel 7a 12v on way to field? - 10/11/2005 3:31:23 AM

iflynething

Posts: 1910
Joined: 8/23/2003
From: Charlotte, NC, USA
Status: offline

1.) Take off cap

2.) Put battery acid into mouth

3.) Swish until at field. The longer you live from the field the better.

4.) Once at field, put acid from mouth (you have been swishing, right) back into battery, and you're good to go...

5.) Wash mouth out with mouthwash (I'm going to say some Listerine or Scope)

6.) Repeat as necessary to get more charge throughout the day.

I hope this helps

~Michael~

_____________________________

Michael Carr
Funtana, S100, Fut. 3050 / Rap 30, OS 32, JR 537, Fut. 401

(in reply to JimTrainor)

Post #: 30

RE: Best Way to charge gel 7a 12v on way to field? - 10/11/2005 3:57:38 AM

toprudder

Posts: 167
Joined: 10/4/2005
From: Raleigh, NC, USA
Status: offline

quote:

ORIGINAL: JNorton

quote:

Thanks for the link, I am looking for a decent field charger. However, the technical information in that link regarding charging does not mention anything about the charge method for lead-acid batteries.

http://www.multiplexusa.com/RC-comp/Chargers/LN-5014.htm Top right of the page is a link to the instruction manual.

Thanks!

The manual is a little lacking in information. It still does not mention at all what the charging algorithm is for Pb batteries. It did mention that that nominal voltage must be entered, so that implies that it somehow limits the charge voltage. I still would like to know, but after reading the other message thread you pointed me too, I guess I will still keep looking, however I won't rule this one out.

I'm just a little leary about how it charges Pb batteries. I've had a real education on that during the last year with my camper. I just installed a new converter and battery in it, due to the inadequacies of the old converter.

(in reply to JNorton)

Post #: 31

RE: Best Way to charge gel 7a 12v on way to field? - 10/11/2005 6:31:06 AM

AS-EE

Posts: 191
Joined: 8/25/2005
From: Greenville, SC, USA
Status: offline

JimTrainor, that 6 ohm of resistance for the battery internal is wrong. You more than likely just measured the current limiting resistance of the whole system. What you did was take 15.2 volts - 13.4 volts = 1.8 volts/ 300mA= 6 Ohms. That is the current limiting resistance AND NOT the battery's internal resistance.

(in reply to JimTrainor)

Post #: 32

RE: Best Way to charge gel 7a 12v on way to field? - 10/11/2005 7:37:13 AM

JimTrainor

Posts: 1308
Joined: 10/25/2002
From: Ontario, ON, CANADA
Status: offline

By gosh AS-EE, I think you've got it! You've mastered Ohm's law!
The "whole system" here is two wires, a fuse, the battery, the power panel's bananna jacks, and the meter.
I don't think the panel jacks, a wire, and fuse have 6 ohms of resistance. But then, I didn't think a lead acid battery could have a impedance of 6 ohms either (but there I could be wrong due to lack of detailed understanding of lead acid batteries... certainly 6 ohms would be astronomic for nicad - the only one I'm really familar with). Leading me to question my own measurement, or understanding of the battery (as I stated!).
Anyways, AS-EE has it all figured out, so I'll chime out. But I'll watch for AS-EE's own concrete numbers on the subject since I am interested in this.

< Message edited by JimTrainor -- 10/11/2005 1:32:03 PM >

(in reply to AS-EE)

Post #: 33

RE: Best Way to charge gel 7a 12v on way to field? - 10/11/2005 6:57:03 PM

AS-EE

Posts: 191
Joined: 8/25/2005
From: Greenville, SC, USA
Status: offline

I am way beyond the basic Ohm's law stuff. I am at the point where there are circuit networks where the resistors are not in parallel OR series and not even a combination of the two. Ohm's law alone will not help you in these networks. These types of networks must have special theorems applied such as Thevinin and Nortons, and my favorite being the Superpostion theorem. Also I am in AC networks which is many times more complex than DC networks. Finally, I am in Digital and semiconductor studies as well.

Anyways, I have a pictorial to show you how the current limiting resistor works:

You can see here that applying Kirchoff's voltage law around the loop will reveal that any voltage difference between the two batteries will ALWAYS be across the resistor. This voltage difference across the resistor will determine how much current will flow to the lower voltage potential E2.

(in reply to JimTrainor)

Post #: 34

RE: Best Way to charge gel 7a 12v on way to field? - 10/11/2005 8:00:42 PM

JNorton

Posts: 3134
Joined: 1/29/2002
From: Montague, MI, USA
Status: offline

AS-EE

quote:

ORIGINAL Jim Trainor -> battery voltage no load: 13.4 V (it is fully charged)
charge voltage when the Hanger 9 charger is attached: 15.2 V
charge current: 300 mA

Actually the impedance of the battery is changing while it is charging. The voltage across the battery no load without the charger connected is 13.4 volts. The voltage across the battery connected to the charger is 15.2 volt and the current is 300 mA. Battery current in Lp batteries decreases as it becomes charged. This is a dynamic variable and cannot be explained as you are attempting to. Sorry.

See the graph - note the resting voltage.

John

EDIT-> http://www.homepower.com/files/battvoltandsoc.pdf

Attachments

Click to see fullsize image.

Click for fullsize

< Message edited by JNorton -- 10/11/2005 8:04:45 PM >

_____________________________

Have desk ... Will Fly....
Saito Member #467

(in reply to AS-EE)

Post #: 35

RE: Best Way to charge gel 7a 12v on way to field? - 10/11/2005 8:39:52 PM

JimTrainor

Posts: 1308
Joined: 10/25/2002
From: Ontario, ON, CANADA
Status: offline

Yeah, I get that.
I found a link yesterday with a paper that had charts of charge and discharge impedance for a 12 Ah lead acid battery.
AS_EE - keep up the good work at school. Seriously... models are good place to put some basic theory and practice to work.

(in reply to JNorton)

Post #: 36

RE: Best Way to charge gel 7a 12v on way to field? - 10/11/2005 9:33:45 PM

toprudder

Posts: 167
Joined: 10/4/2005
From: Raleigh, NC, USA
Status: offline

quote:

Actually the impedance of the battery is changing while it is charging. The voltage across the battery no load without the charger connected is 13.4 volts. The voltage across the battery connected to the charger is 15.2 volt and the current is 300 mA. Battery current in Lp batteries decreases as it becomes charged. This is a dynamic variable and cannot be explained as you are attempting to. Sorry.

See the graph - note the resting voltage.

John

According to those numbers, and the graph, the battery was way past being fully charged.

(in reply to JNorton)

Post #: 37

RE: Best Way to charge gel 7a 12v on way to field? - 10/11/2005 11:26:30 PM

JNorton

Posts: 3134
Joined: 1/29/2002
From: Montague, MI, USA
Status: offline

TopRudder,

Generic graph as I have no way of knowing what the actual battery used was. It is close enough to illustrate the point I was trying to make. Tough audience.
John

_____________________________

Have desk ... Will Fly....
Saito Member #467

(in reply to toprudder)