6volt

Submitted: Saturday, Oct 23, 2004 at 17:28

ThreadID: 17246 Views:2029 Replies:3 FollowUps:3

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Member - Brian (WA)

Dont laugh at question. A 12volt deep-cycle batt is fully charged at 12.80 and
flat around 12.20. what are the figures for a 6volt deep-cycle ( 6.40 and 6? )
cheers brian

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Reply By: Mike Harding - Saturday, Oct 23, 2004 at 17:57

Saturday, Oct 23, 2004 at 17:57

Terminal voltage is not a very good indicator of the state of charge of a lead acid battery but if you're sure the battery is in good condition it will give you a fighting chance of estimating the charge level.

12V5+ is around the right number for a fully charged battery but it will discharge to much lower than 12V2 - I'm not sure what the bottom figure for a deep discharge battery is (if you find out please let me know) but a normal cranking type battery can go down to 10V5 before it's in danger of suffering damage.

6 volt batteries will be half the above figures at they comprise 3 cells whereas 12V batteries comprise 6 cells.

Mike Harding

mike_harding@fastmail.fm

AnswerID: 81347

Follow Up By: V8troopie - Sunday, Oct 24, 2004 at 01:15

Sunday, Oct 24, 2004 at 01:15

Mike, let me qualify your statement about a cranking battery suffering no damage if discharged down to 10.5V.
This only holds true IF the battery is IMMEDIATELY re-charged.
If you were to leave a discharged battery for some days you would find that the plates have sulphated and this did indeed damage it.
Klaus

FollowupID: 340621

Follow Up By: Mike Harding - Sunday, Oct 24, 2004 at 06:47

Sunday, Oct 24, 2004 at 06:47

>Mike, let me qualify your statement about a cranking battery
>suffering no damage if discharged down to 10.5V.
>This only holds true IF the battery is IMMEDIATELY re-charged.
>If you were to leave a discharged battery for some days you would
>find that the plates have sulphated and this did indeed damage it.

Sulfation is a slow chemical process so don't worry too much about IMMEDIATELY recharging the battery. I wouldn't try and put a precise time limit on it but you could certainly leave the battery in a discharged state for a day or two without significant sulfates building up. However the thrust of what you say is quite correct and even a fully charged battery should be "topped up" every month or so if it's in storage - makes you wonder about batteries sitting on the shelf in a dealers for months on end?

Also high temperature is bad for batteries so maybe store them in a cool spot in the house rather than in a garage if your garage gets hot in summer.

A good site for all things battery:
http://www.uuhome.de/william.darden/

Mike Harding

mike_harding@fastmail.fm

FollowupID: 340625