Here are some further notes concerning these batteries. Do take note I did not read the subsequent posts when I composed this, they are simply based on my personal experience.
Some important facts about these Marine Start and Troll Batteries:
- They are actually automotive batteries with coarser lead crystals on their plates. Hence, they still have good starting power but are more robust that standard cranking batteries. In other words, they have slightly reduced starting amps but can carry the load slightly longer. What better combo for a diesel?
- The 'Deep Cycle' means depletion to 50% (instead of about 20% IIRC for starting batteries) before they go flat. True deep cycle of the type used by power companies are way better than that (but have no high current starting ability).
Why am I a Marine Start and Troll Battery Convert:
- Starting Amps: they are not much lower than starting batteries (25% maybe). However, that has no real effect because when the truck came out, the starting amps specs of the batteries of the time were much lower than what they are now. Also, running a 24V starter does not require as high amps than a 12V. Hence these batteries are perfect for use in a 24V starting setup.
- Construction: they are supposedly built more robustly for the vibrations and shocks seen in boats, so presumably they will survive better on what passes for roads around here.
- Cost: they are usually less expensive than similar sized car batteries. Go figure. Probably because car batteries are 'boosted' (or should I say 'hyped') so much. HOWEVER, they have much shorter warranties (presumably because folks forget them for months in their boats without using them and they tend to sulphate).
- Reserve Capacity: Better than automotive start, granted (leaving parking lights on all night or headlights a couple of hours is OK, been there, done that), but they do not like large loads for long, such as that required by a hair dryer (tried that with my inverter, which quickly drops the voltage below the inverter cut-off (10.5V). Testing on a standard 100A load tester it will drop more than an automotive starting battery of the same size, but remain at that voltage for much longer while the starting battery will drop noticeably in the same time period (say, after 30 second of applying 100A).
- Battery Connections: allow for much better, positive connections, as they come standard with stud terminals which, I find, are much tougher and probably allow for a better connection. No intermediary connection between a cable and a clamp. The battery cables I simply insert in a copper sheath (piece of 5/16 or 3/8 copper tube) then flatten the end once soldered and drill to the size of the stud. Much tighter fit that won't come off. Allows me to use SS hardware (washers, spring washers and Nylocks), whcihch, as you know, won't corrode in presence of sulphuric acid (316 SS type at least).
- Size: the 31 size barely fits in the HDJ81 battery compartments (with no battery warmer). The 29 size allows for a battery warmer. I would recommend the 29 size if you have an HDJ81 in Canada and wish to use battery warmers, not that the batteries lacked power at -30°C.
- About Walmart Marine Batteries: in Canada they cost $99 (Energizer brand) and are made by Johnson Controls, which has an excellent reputation. The ones from the US that I acquired a couple of years later are slightly different (Everstart brand), cost $59 and may be made by Exide (there is no marking on the battery to help identification). Understand though that they tend to change manufacturers.
So here you go, that's my experience, hope this helps.
