Re: (ET) Specific Gavity

["David Roden (Akron OH USA)" <ellencwn ald net>]

On 17 Jun 2001, at 6:36, Dick Both wrote:

> After charging my 3 deep cycle marine batteries (180amp/hr) I get a SG of
> over 1.300 after the voltage settles to 12.96-13.04 terminal voltage. 
> This is on all cells. Water is up. Use only distilled water. A few months
> ago they topped out at ~1.280. 

That's a bit higher than usual, but the weather is also warmer than it 
was a few months ago.  I suggest you obtain a temperature correcting 
hydrometer.

> When I turn on the PTO switch(3 mower
> motors) the voltage drops to 12.45V. The electrolyte is a bit murky. I
> know I should get 6 golf cart batteries but $600 CDN is a major 
> investment
> - as much as I paid for the whole rig. 

Unless you don't have enough capacity to do the work you need to do, you 
should be in good shape; 12.45v under a modest load sounds fine.  

In my experience, it's not unusual for the electrolyte to gradually get 
grey over the months.  It indicates advancing sulfation.  Make sure 
you're not undercharging; other than that, again don't worry until your 
capacity is too low.


>You'd think after using commercial
> lead acid batteries over 100 years that this would be down to a science.

Chargers have improved a lot in the last 15 years.  Thanks to 
microprocessor control, they have the science part down fairly well, but 
maintaining batteries is still almost as much art as science. 


David Roden - Akron, Ohio, USA
1991 Solectria Force 144vac
1991 Ford Escort Green/EV 128vdc
1979 General Engines ElectroPed 24vdc
1974 Honda Civic EV 96vdc
1970 GE Elec-trak E15 36vdc
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