If you mean it's reading 12.9V ( at open circuit with a test meter) then it's fully charged! It's NOT a Gell type battery, all Dekas (as far as I know) are AGM type.........When charging do NOT ever exceed 14.4V..........They are best charged using a multi stage electronically controlled charger that feeds a high ( say 40-50A - they can take a very high amperage quickly) bulk charge at 13.25 - 13.85V and then when 80-90% fully charged switches to 14.1-14.4V @ say 5-10A and then when fully charged leave on trickle charge of 12.8-12.9V indefinetly. Fully charged they can read 12.8V O.C.
Deka is a premium quality battery and will last 3-5 or 6 times longer than the best ordinary lead acid batteries and give outstanding slow and deep cycle use as well as good high CCA........But you need to re-charge them correctly (NEVER exceeding 14.4V).....
They work really well in a Jeep, with 1996 on OBD2 Jeeps that use the ECM to control charging......I don't know about Toyotas, but I think a lot of Jap cars charge at higher than 14.4V which will destroy them (they are a "sealed" VRLA AGM -Valve Regulated Lead Acid Absorbent Glass Mat Battery which can't be allowed to gas or bubble which will happen as the water component of the electrolyte solution breaks down into Hydrogen and Oxygen gases and can exlode and burn!!! - a la Hindenberg!!!
Hope that helps a bit......I have used Dekas before and currently have 2X AGM Deep River 75A/H and 100A/H in my Jeep and 2X Deka 120A/H in my Land Rover S2A 109" wagon, in the LR they're charged by an electronic 12V/12V 40A charger that works off the CaAg Sealed Lead Acid 800CCA engine battery charged by a Delco Remy 120A Alternator.
There exists reams of info on Dual battery set ups on here and other places......but remember my points about the special charge regimes for AGM type batteries.
Last edited by Doctor W; 09-11-2011 at 03:59 AM.
Jeep ZJ Grand Cherokee Limited 4.0L, 2 1/2" Coil Lift; Dana 30, ARB Air Locker, RCV Alloy CV's; Dana Super 35 with Trac-Loc and mechanical locker; Quadra Trac 1; 245/75x16LT.Also 1968 Land Rover S2a 109" Hard Top 2 door ex-military with a GM 202 cid, full Roof Basket and ladder, bonnet + rear door spare tyres, 7.50x16LT, twin fuel tanks, 3 x batteries, 240V inverter, 80W Solar, 220 Amp alternator, 40 gal. Water. Rough country expedition self sufficient camper.