Charging battery

Submitted: Monday, Apr 25, 2005 at 23:47
ThreadID: 22371 Views:1743 Replies:9 FollowUps:2
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Tonight I tried to jump start a Mazda 323 using a dual battery system connected in parallel in a 80 cruiser and when i connected the earth to the mazda chassis massive sparks and when my son started to crank the starter the battery in the 323 started bubbling and spewing acid. Whats wrong, is the amperage too heavy from 70zzl batteries in parrelel.
I'm using 400 amp leads with a Matson unit in line??
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Reply By: Member - Jerry C (WA) - Tuesday, Apr 26, 2005 at 00:03

Tuesday, Apr 26, 2005 at 00:03
Welcome,
AnswerID: 108166

Reply By: Member - Jerry C (WA) - Tuesday, Apr 26, 2005 at 00:09

Tuesday, Apr 26, 2005 at 00:09
Welcome5,
Watch the finger trouble, may I suggest that you connected the batteries in series, that is positive to negative and negative to positive.

Jerry
AnswerID: 108167

Reply By: techie - Tuesday, Apr 26, 2005 at 00:10

Tuesday, Apr 26, 2005 at 00:10
2 possible causes.
1/ battery reversed polarity. either 323 is positive earth or leads connected wrong.
2/ you have 24v system connected to 323 12v system.

Amperage is dictated by the voltage and the resistance.
A device on a set voltage will draw the same current (amperage) determined by its resistance.

The excess current can be caused by connecting 24v across a 12v system.
The 323 battery will see a massive current flow causing the acid to boil trying to dissipate the extra energy absorbed.
The headlights of the 323 would be brighter but the 12v batterty will limit the overvoltage of the jumper.
This is more likely than reverse polarity.

Regards
Donk
AnswerID: 108168

Reply By: Welcome5 - Tuesday, Apr 26, 2005 at 00:18

Tuesday, Apr 26, 2005 at 00:18
its running a liemack fridge in the back and its reccomended that they are wired in parralel to make it a 12v system
AnswerID: 108169

Reply By: techie - Tuesday, Apr 26, 2005 at 00:20

Tuesday, Apr 26, 2005 at 00:20
I'd guess a reverse polarity then.
The jumper lead would have gotton very hot very quickly.
Donk
AnswerID: 108171

Reply By: Welcome5 - Tuesday, Apr 26, 2005 at 00:24

Tuesday, Apr 26, 2005 at 00:24
oh and the polarity was correct
AnswerID: 108172

Follow Up By: Member - Ed. C.- Tuesday, Apr 26, 2005 at 00:54

Tuesday, Apr 26, 2005 at 00:54
Then I'd guess that the mazda has a massive short to earth ... hence the flat battery in the first instance, & all the "fireworks" in the second instance....
Methinks that said mazda is in urgent need of attention to find (and correct) that short... prob'ly needs a new battery too:(

Regards, Ed. C.
Confucius say.....
"He who lie underneath automobile with tool in hand,
....Not necessarily mechanic!!"

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FollowupID: 364992

Reply By: Mainey (WA) - Tuesday, Apr 26, 2005 at 00:48

Tuesday, Apr 26, 2005 at 00:48
Welcome5,
do I understand you have connected the pos (+) lead from one of your 12v batteries, to the pos (+) terminal in the Mazda .....
AND ....
connected the neg (-) lead from your same battery as you have your pos (+) lead connected to, connected to the neg (-) terminal in the Mazda ???
AnswerID: 108176

Reply By: Tim HJ61 (WA) - Tuesday, Apr 26, 2005 at 00:50

Tuesday, Apr 26, 2005 at 00:50
Another option is that the Mazda battery was dead flat and old and the internal resistance was so high that the heaps of good juice flooding through the cables was all too much for it.

Bit surprised it happened so quickly. About how long after the leads were connected did the eruption start?

Umm, if it happened when the starter was engaged, that would be creating another big draw through the dead battery adding to the resistance, adding to the heat, adding to the eruption.

Not sure the best way to start a car with a dead flat battery - like one that the lights have been left on and every little bit drained out. Maybe a low current charge to start off with. Difficult to do with a pair of N70's!!

Tim
AnswerID: 108177

Follow Up By: Tim HJ61 (WA) - Tuesday, Apr 26, 2005 at 00:54

Tuesday, Apr 26, 2005 at 00:54
A bit more.
Massive sparks connecting leads can be the voltage difference between the helper battery and the dead battery. To be expected with a real flat battery and that's the reason why we connect the last earth lead away from the battery to minimise risk of sparking triggering a gas explosion in the battery.
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Reply By: Welcome5 - Tuesday, Apr 26, 2005 at 08:40

Tuesday, Apr 26, 2005 at 08:40
put in on battery charge and now starts ok
AnswerID: 108190

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