Quote:
Originally Posted by brucepick
I've also wondered about using a spare battery (marine or automotive) to run the engine heater via an inverter... If your heater is 2x my wattage, the battery will run about 1.5 hours (less in cold weather).
... In any case, use a SPARE battery, not the one that needs to start your car! Charge up the spare(s) at home, of course.
Calculations:
So with 90-minute "reserve" you could run a 25A load for 90 minutes. My load is about 11A so I could run it for a bit more than 180 minutes, three hours. But if you need an engine preheater, it's likely not 80 degrees outside. So your capacity in winter would be less than that.
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Suggestions on buying a battery that will be kept inside the passenger cabin (hatchback trunk)- AGM Group 27-4D=?
Lifespans:
- Starting: 3-12 months
- Marine: 1-6 years
- Golf cart: 2-7 years
- AGM deep cycle: 4-7 years
- Gelled deep cycle: 2-5 years
- Deep cycle (L-16 type etc): 4-8 years
- Rolls-Surrette premium deep cycle: 7-15 years
- Industrial deep cycle (Crown and Rolls 4KS series): 10-20+ years
- Telephone (float): 2-20 years. These are usually special purpose "float service", but often appear on the surplus market as "deep cycle". They can vary considerably, depending on age, usage, care, and type.
- NiFe (alkaline): 5-35 years
- NiCad: 1-20 years
Some common battery size codes used are: (ratings are approximate)
U1 34 to 40 Amp hours 12 volts
Group 24 70-85 Amp hours 12 volts
Group 27 85-105 Amp hours 12 volts
Group 31 95-125 Amp hours 12 volts
4-D 180-215 Amp hours 12 volts
8-D 225-255 Amp hours 12 volts
http://www.windsun.com/Batteries/Bat... Battery Types
This one is around $75 from Autozone but it's not AGM
Duralast/685 CA marine deep cycle battery
Part Number: 24MD-DL
Alternate Part Number: 24MDP-DL
Part Number: 24MD-DL
Weight: 44.65 lbs
Warranty: 3 YR
Type: Marine
Category: Deep Cycle
Application: Marine
BCI Cold Cranking Amps Value: Tested to BCI Standard
Battery Height: 225 mm - 8 7/8 in
Battery Length: 260 mm - 10 1/4 in
Battery Width: 173 mm - 6 13/16 in
Cold Cranking Amps (CCA): 550
Core Charge Applicable: Yes
DIN Designation: BCI or EN Only
EN Designation: DIN or BCI Only
Right Or Left Hand Positive: Left
Post Location: Top Post
Reserve Capacity (Min): 140
Voltage: 12