Car jump start

[lukin1977]

I`ve been always told that when you jump start a car with low battery by using another car (I belive it is called JUMP START) you must do it while the good car engine is ON and at mid range rpm

Is this really true? why?

 

[dgallup]

Cars parked outside where there is no AC power are not candidates for float chargers. If I had to do it again I would get a solar panel charger that could be left on the dashboard. Never the less, I would not depend on the alternator to recharge a dead battery. As a further note on the subject, completely discharging a lead acid battery one time will reduce it's capacity ~10% (assuming it's not a deep cycle battery). It only takes a couple of times before the battery is toast.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[itsmoked]

These days I'd have to say it will reduce the capacity no less than ~10%. I'd add the corollary of 25% per week left drained.

Of course for 'gel cells' call it 40% with a further 10% per hour.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[NormPeterson]

An alternator that is purposely cycled off must have a quite good ability to charge the battery when it is called to operate because it has to re-charge the battery that has been discharged while it wasn't working.

One would hope so. But what will the battery tolerate, long term, in higher than 'traditional' recharging rates? I have a 2A/12A charger that also has a 50A start-assist mode. I don't think the 50A mode is intended for recharging purposes, but what I don't know is whether the limitation is on the battery or the charger/starter.


Norm

 

[LionelHutz]

These days I'd have to say it will reduce the capacity no less than ~10%. I'd add the corollary of 25% per week left drained.

Of course for 'gel cells' call it 40% with a further 10% per hour.

Do you have any data or link to info on the damage rate of 'gel cells' Keith?

 

[itsmoked]

Hi Lionel.

I have looked high and low for something quantitative in that regard but never found anything. I sure the makers know about this and have no interest what-so-ever in it getting published and no one else is interesting in destroying expensive batteries to gather useful data or if they have, they have their own reasons for not wanting to publish it.

I'm stating that on my experience of using or working with probably ~300 gelcells in my career. Early on gelcells were fairly robust. Some like Exide state their gelcells are more robust than AGM batteries and they could be. Gelcells can be made very robust by having extra electrolyte and less antimony for plate strength owing to supporting gel etc.

However, about 10 years ago the cells I work with; Panasonic, BB Battery, Power-Sonic, GNB, and Yuasa all got extremely touchy about the same time. A battery that we'd get new, install in a test and run down overnight would be found to have lost significant capacity in the exercise. This got progressively worse until we actually got some that lost essentially all capacity when severely drained overnight and then attempted to be charged the next day. These were batteries purchased from reputable places like Digikey, received, fully charged by us, and used and completely useless 48 hours later.

Perhaps in a specsmanship war the makers all upped their Ahr ratings in the standard footprints by more plates and insufficient electrolyte or some other cost cutting measure. Now I treat gelcells with extreme care and attention. Any I have around I recharge every 30 days if they have been out of circuit or leave floating.



Keith Cress
kcress -

http://www.flaminsystems.com