My TCH is a 2007 and still has the original battery in the trunk. Should this be replaced based on testing at a local supply store? What readings should this battery be good at? Can i replace the oringinal with a DieHard regular 12 v battery? Any thoughts, observations, concerns?

 

no.
no.
no. reason being, local parts stores do not have battery testers designed for deep cycle batteries and that's what you have. readings are not correct, they simply do not tell you this.
no, as you have vented deep cycle battery with temperature sensor. diehard does not make those.
no, as you must replace it with deep cycle battery only. conventional batteries simply are not designed for what it is used for. you can go to dealer and buy OEM one for around $300. or, you can go to Sam's and buy yellow top Optima. Used to be $160, but they jagged price to $179. it still does not have provisions for venting hose attachment, but at least has simple vents. temp sensor it t-fered from old battery, simply unglue it with flat head screwdriver and stick onto new battery.
USE BACK UP 12V BATTERY HOOKED UP PARALLEL TO THE OLD ONE, WHILE REPLACING IT. this car does not like to stay without auxiliary 12V power supply. even a small battery will do, process takes what, 5 minutes maybe?
mine is 2007 either, and I am not worried. I charged it about 6 mths ago. works fine.

 

Those batteries last for a long time, they are not the conventional types. I just cut and pasted the service manual for storing TCH for a long time (specifically charging the batteries)


CAUTION:
The Camry HV auxiliary battery is a special Valve Regulated Absorbed Glass Mat
(AGM) design and should NEVER be replaced with a conventional battery design.

MAINTENANCE FOR HV BATTERY & AUXILIARY BATTERY – PD020-06 March 31, 2006
Page 3 of 7
2. Charge the auxiliary battery.
HINT:
If the auxiliary battery was stored at
32°F (0°C) or below, charge the auxiliary
battery in a room above 32°F (0°C)
using the following procedure.
A. Using a digital voltmeter, measure
the auxiliary battery voltage
between the terminals to
determine the charging time.
AUXILIARY BATTERY
VOLTAGE
CHARGING TIME
Above 12.4 V 2 – 3 hours
12.0 – 12.4 V 5 – 6 hours
11.9 V or below 8 – 10 hours*
* Do NOT charge for over 10 hours.
NOTE:
�� If measuring the voltage with the
negative (–) terminal connected, push
the power switch to select the “OFF”
mode, turn OFF all electrical systems,
and wait 60 seconds or more. This
removes the surface charge.
�� Prior to measuring the voltage, wait
20 minutes or more after the hybrid
system stops. This removes the
surface charge.

 

I just bought a 4 way charger, mostly because of this battery. It charges glass mat batteries, car batteries, solid state batteries, and something else. automatically selects charging mode and goes into float charge mode after battery is fully charged.
I have this battery here and another, larger one, for my gate opener. wasn't even much of expense, only around $50.
personally, I can connect/resin hydrogen vent tubes to a yellow top optima. their rep told me it will void the warranty, but I do not give much. yellow tops have built in provisions for hydrogen escape, tubes can be easily attached to them and, later, to the factory hydrogen vent.