Edited by brett_32i, 05 April 2006 - 08:25 PM.

Low Maintenance Car Batteries
#51
_brett_32i_
Posted 05 April 2006 - 08:25 PM
#52
_Hotrodder_
Posted 05 April 2006 - 10:50 PM
If the cells are in good nick and one has been installed in a reverse polarity situation by mistake yes it will, just 4 volts lower overall than expected.Curious with the battery reversal though - can the battery bank still pass a reasonable current with one if its series cells being reversed?
However if the cell has gone bad - ie reverse polarity by itself - it will still show say 12 volts for 6 cells in series whilst under a charge situation. Try putting a load tester on it and it will very quickly show a 4 volt drop with bugger-all load.
An example, just 2 weeks ago I had a fault report where an existing battery bank of 48 volts was playing up, disconnecting power at night when the solar panels stopped charging. I went out to the site with the load tester and checked 12 volt sets at a time until I found one that dropped to 8 volts with only 50Amps load - it should be able to deliver 500-800Amps with no probs - so I knew I had a bad battery. Switch over to a 6volt test and put the multimeter on each 2volt cell and watch what happens, you'll soon find one that goes from +2.2volts to -2.2 volts. I just pulled it out completely and the system worked better for a couple of days with only 46volts in operation, until I went back with another cell.
extreme sulphation from undercharging is usually the cause of that.
BTW, heard back from the techo from my supplier/manufacturer this arvo regarding the battery on concrete thing, his view is simply temperature differences cause problems as follows.
The concrete acts as a huge heatsink sucking temperature out of the battery, causing stratification, and incresing the likelyhood of sulphation which is increased with temperature decrease. A battery will self-discharge over a period of time, higher temps will increase self-discharge so putting a battery on a cold surface will actually decrease self-discharge, but the temp difference top/bottom will have other effects too. Charging a bettery in this situation will cause buckling of the plates because heat is generated within the battery under charge conditions however not likely in modern car batteries like it will in standby batteries, certainly in older technology but not so critical today. Automotive batteries are not as succeptible to this as large storage batteries of course, but still effects tham a little bit.
Imagine this scenario: Youve just put the battery from your car on the ground as its the most convenient place after you have just yanked it out of the car after you have flattened it trying to start the engine, and put another one in. The half-flat battery will sulphate much quicker with the temperature being sucked out of it from the concrete, and often its left discharged for a few weeks before you realise that you probably should whack it on the charger - too late, sulphation has stuffed it and capacity has decreased to the point where its no longer able to deliver the current required to start an engine peoperly.
So basically dont try and charge a battery whilst its sitting on concrete, and if you do put it on the floor make sure you put it on the bench or something and let the battery get to an even temp before connecting the charger to it, as soon as possible.
So it looks like Im also a bit behind the times too when it comes to automotive stuff, but Im still right when it comes to the standby batteies that I was applying my experience to.
Does that clear things up a bit?
Edited by Hotrodder, 05 April 2006 - 10:56 PM.
#53
Posted 06 April 2006 - 12:13 PM
I have 11.7 to 1 comp and a 650 thou roller cam. The only thing I can think of is a tilton starter, but then again I have electric fuel pumps thermo fans central locking and all the usual accessories. The guys in The Canberra Torana Club can vouch for the no problems starting.
#54
Posted 06 April 2006 - 01:25 PM
Wow - that setup's an issue for any battery to crank and start - on paper, anyway. Maybe your bonus is the extremely low internal resistance of the Odyssey battery, and probably an equally low resistance of the starter as well. You'd be able to use the whole capacity of the battery to crank and start. I presume you have an electronic ignition too, which is usually better able to cope with lower cranking voltages while still supplying a good spark to start.Re Dangerous
I have 11.7 to 1 comp and a 650 thou roller cam. The only thing I can think of is a tilton starter, but then again I have electric fuel pumps thermo fans central locking and all the usual accessories. The guys in The Canberra Torana Club can vouch for the no problems starting.
Once started, as long as the alternator can keep ahead of the electrical devices, then it wouldn't need too much extra capacity to recharge the relatively small battery.
PS - your car sounds like a bit of an animal - way to go

#55
Posted 06 April 2006 - 01:35 PM
All sounds clear to me!Does that clear things up a bit?
Hmm, a solar/battery setup that can deliver 800 amps at 48 volts - that ain't no domestic system

Re the batteries and concrete - my small 'battery bay' is in a shady corner of the garage, with battery boxes sitting on small carpet squares. For the cost of a battery box and an old bit of carpet, it makes for a cheap and safe area to store and charge batteries.
Your point about ripping out a flat battery that you've just cranked the guts out of is a good one. Not only is the battery in need of some immediate TLC, but a hot flat battery which may be bubbling away internally and not being too chemically stable needs precautions to handle. Just 'cos it's flat doesn't mean that it isn't dangerous.
#56
Posted 06 April 2006 - 03:20 PM
#57
_devilsadvocate_
Posted 06 April 2006 - 04:08 PM
(Hotrodder @ Apr 5 2006, 11:50 PM)A modern automotive battery has plates of pure lead and lead oxide immersed in sulphuric acid, and yes they will expand at different rates.
Does that clear things up a bit?
Well no, are you sticking by this claim?
#58
_Hotrodder_
Posted 06 April 2006 - 11:06 PM
Actually it is a domestic system, has 5kW of solar panels, a 1kW wind turbine and a 30kVA backup diesel genset running a small 3 residence community.Hmm, a solar/battery setup that can deliver 800 amps at 48 volts - that ain't no domestic system
What's it running/backing up?
Im working on putting one together at the moment with 10,000watt wind turbine, 1660Ah batteries at 120 volts, 50,000W 3phase inverter, 110kVA diesel generator and 10,000watts solar panels, and no its not a domestic system, its running a small mine. Small by grid standards but large for a stand-alone system. Worth around $300k, cheaper than getting the power connected which was around $800k.
#59
_Hotrodder_
Posted 06 April 2006 - 11:09 PM
yes I am, and I think you'd better read it all again.Well no, are you sticking by this claim?
Obviously some just dont get it.

#60
Posted 07 April 2006 - 11:02 AM
Truce?

#61
_CHOPPER_
Posted 07 April 2006 - 07:35 PM
1 user(s) are reading this topic
0 members, 1 guests, 0 anonymous users