No start/hard start: it's getting maddening. (2024)

Regardless of Jelf's current battery starting the car Today, Tomorrow or maybe next week. A "starter" battery isn't the best choice for a Model T. While they work for some, they may not work for others (meaning short lived). Today's batteries are designed for Today's vehicles (car, motorcycle or lawn car) and technology (alternator with a voltage regulator). Batteries have several specifications that often mislead buyers to a selection.
Voltage choice, 6 or 12, is simply decided upon the device requirements being 6 or 12 volts. Amperage has to do with the the load on the system and how those amps need to be delivered to the load.

Starter Batteries - Starting, Lighting, Ignition (SLI)
These batteries deliver a large burst of power for a short time as needed for normal engine starting. The battery is then recharged by the alternator. Unlike a deep-cycle battery, starting batteries are not designed to withstand multiple discharge/recharge cycles, and draining it can significantly shorten its life. Today's cars have starters requiring more amps (400-600amps) while a good working Model T starter is in the range 0f 150-160 amps
Starter batteries have a very low internal resistance, and the manufacturer achieves this by adding extra plates for maximum surface area. The plates are thin and the lead is applied in a sponge-like form that has the appearance of fine foam. This method extends the surface area of the plates to achieve low resistance and maximum power. Plate thickness is less important here because the discharge is short and the battery is recharged while driving; the emphasis is on power rather than capacity.

By Ron Patterson-Nicholasville, May 14, 2012"
"Assuming the starting motor is operating properly on 6 volts it should draw 70 amps free running, 150-160 Amps cranking engine and 450 Amps stalled pushing 12 pounds of torque. Model T battery cables should be 1/0 with soldered (not crimped) wire terminals. "
-
CCA, cold crank amps, is the specification for starting and nothing else. It's the number of amps a battery can support for 30 seconds at a temperature of 0°F until the battery voltage drops to unusable levels.
RC Reserve Capacity (RC) is a very important rating. This is the number of minutes a fully charged battery at 80 ° F will discharge 25 amps until the battery drops below x volts (10.5 volts for a 12 volt batter).

Deep-Cycle Batteries
These batteries are designed to provide a steady amount of current over a long period of time. Deep-cycle batteries can be repeatedly discharged and recharged without causing damage or shortening their life. They are well suited to powering numerous electronics and plug-in accessories, or other applications that place high demands on them such as marine or RV.
Deep-cycle lead acid batteries for solar battery systems, fork trucks, golf cars, scooters and wheelchairs are built for maximum capacity and high cycle count. The manufacturer achieves this by making the lead plates thick. Although the battery is designed for cycling, full discharges still induce stress, and the cycle count depends on the depth-of-discharge (DoD). Deep-cycle batteries are marked in Ah or minute of runtime.
-
The important specification for these is Ah - its simply the time that the battery will deliver x amps. So a 100Ah battery can roughly deliver 10amps for 10 hours (100Ah/10hours).

Some deep-cycle batteries can be used for engine starting as well (these are sometimes referred to as dual-purpose), but be sure to check the CCA rating to ensure the battery has sufficient starting power.

A starter battery cannot be swapped with a deep-cycle battery and vice versa. While an inventive senior may be tempted to install a starter battery instead of the more expensive deep-cycle on his wheelchair to save money, the starter battery won't last because the thin sponge-like plates would quickly dissolve with repeated deep cycling. There are combination starter/deep-cycle batteries available for trucks, buses, public safety and military vehicles, but these units are big and heavy. As a simple guideline, the heavier the battery is, the more lead it contains, and the longer it will last. Below we compares the typical life of starter and deep-cycle batteries when deep-cycled.

---
Two battery solution 6v and 12v simply remove the jumper and hook your light battery to light circuit and your coil battery to the other post