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    • #2309
      MyPrevost
      Keymaster

      I’m managing someone else’s budget, and here’s the situation:

      The 94 Marathon XL has been owned for 10 years but hasn’t seen much use. It’s going to continue being used sparingly with no plans to sell. We’re focusing on three major areas:

      1. Chassis Suspension and Brakes: No need for help here; this is sorted.
      2. Tires: We’re settled on this. The bus currently has 12R22.5 tires and it’s a 40-foot, non-slide lightweight model.
      3. Inverters and Battery Bank: This is where I need advice. The chassis has OTR AC, so we’re looking at 24V inverters with 6 4D batteries. We’re not dealing with heavy inverter loads—just a fridge, microwave, TV, and a few outlets.

      For a couple with the budget to go high-end but an older, lighter bus that’s rarely boondocking, we could save a lot by exploring alternative options for tires, inverters, and batteries.

      With numerous choices and price ranges for batteries and inverters, I need some solid suggestions to ensure they get the best value for their money.

      #2352
      MyPrevost
      Keymaster

      I’ve been looking at tires for my 85 XL in the 12R22.5 size and am considering a set of 8 Yokohama 104ZR tires. The total cost is $4500 from Reliable Tire in Sacramento. They seem like a solid choice—Reliable Tire outfits 500 school buses here, so they must be good.

      As for batteries, I haven’t made a final decision yet. My coach currently has 4 brand-new Interstate FLA deep cycle batteries for the 12-volt house system, and they’re performing well. I’m not having any issues with FLA batteries.

      I’m in the market for a 24-volt battery pack for my Trace inverter. It originally had a 400Ah 24-volt pack, but I’m currently getting by with two group 27 no-name FLA batteries. I’m leaning towards Northstar telecom batteries for the new pack. You can check them out here: Northstar Blue Plus Battery. They seem like they could be a good fit for our needs, but I’m still weighing my options.

      #2353
      MyPrevost
      Keymaster

      Assuming your looking for a budget battery, consider Fullriver. My price is 475.00 each delivered to a commercial address.

      #2354
      MyPrevost
      Keymaster

      Tom what is the price on a 4d lifeline delivered?

      #2355
      MyPrevost
      Keymaster

      After giving it some more thought, I’m leaning towards recommending a Magnum inverter setup—either a 4000-watt, 24-volt inverter or a pair of inverters. For the battery bank, the options would be 2, 4, or 6 Lifeline batteries, depending on their needs.

      If they go with a single inverter and just 2 batteries, it would be the bare minimum but still fully adequate for trips between power sources. Plus, if they decide to get into boondocking or sell the bus in the future, it can easily be restored to its original specs.

      I also considered the Northstar batteries, but they seem too tall to fit without modifying the battery compartment. I couldn’t find the dimensions or cost on the spec sheets, which makes it harder to assess. Given that 4D Lifeline batteries at around $550 each are hard to beat, I’m leaning towards those but am always open to exploring new products.

      This isn’t my first time upgrading an old Marathon with an inverter system. In previous projects, I had the pleasure of working with Dick Wright at Wrico Electronics. His expertise with older coaches was invaluable—he even guided me over the phone with wire numbers and colors for the panel and relays of the antiquated auto-start system. With his help, integrating the new Magnums was seamless.

      I’ve also sourced “Marathon generator heads” from him, which came with exceptional customer service and support. His products never disappointed, and his post-purchase support is unmatched.

      When it comes to finding components, Wrico’s customer service and expertise are second to none.

      #2356
      MyPrevost
      Keymaster

      Stephen,

      Those telecom batteries are exactly the ones I was considering. My sole reluctance was that I’m not sure they were built to withstand vibrations.

      #2357
      MyPrevost
      Keymaster

      Numbers:

      2 Magnum 4000W 24V Inverters with remotes and leads: $2000 each, $4000 for the pair.
      6 Lifeline 4D Batteries: Shipped cost $3500.
      Total: $7500 for the current setup.

      Alternative if you boondock infrequently:

      1 Magnum 4024 Inverter: $2000.
      4 Lifeline 4D Batteries: $2500.
      Total: $4500.
      That’s a $3000 saving, which could be better spent elsewhere.

      Currently, with 2 inverters, you have 5000W. Switching to 1 4024 Magnum would reduce this by 1000W, but it would still provide almost twice the power needed for the fridge, microwave, outlets, and TV.

      Question for the math:

      How long will a fridge, pulling about 7-8 amps when the compressor runs, last on 4 fully charged 4D Lifeline batteries before they drop to around 12 volts?

      If it lasts about 8 hours, that’s acceptable. Plus, you’d save $3000 and maintain the option to restore the bus to its original configuration later, with minimal reduction in capabilities.

      Additional question:

      How long would the fridge run on 2 larger Lifeline 8D batteries with the inverter? Someone help with the math!

      #2358
      MyPrevost
      Keymaster

      For those with older coaches considering how far to downsize comfortably:

      If you’re thinking about scaling down, keep in mind that you might not need a massive battery bank or multiple inverters. I frequently use my inverter overnight to keep the fridge cold and never come close to deep cycling my batteries. My setup includes two Deka 8D batteries, and I don’t plug in or run the generator.

      If the main constant load is the fridge, and other power needs are intermittent (like outlets, microwave, or TV), you don’t need a huge battery bank or two inverters. In my motorhome, where the fridge is the only constant load, I cycle the inverter on and off. I run the inverter for about half an hour, watch the load meter, and once the fridge compressor turns off and the fridge is sufficiently cold, I turn the inverter off. I can easily go an hour or two before needing to turn it back on. When cooking and accessing the fridge frequently, I keep the inverter on while cooking and turn it off after.

      This approach also works for boondocking. With just two 8D batteries, I can keep my fridge cold for days before needing a recharge. I’ve comfortably managed three days of boondocking on only two batteries.

      For other appliances, turn the inverter on only when needed. If conserving power is a priority, use the TV while the fridge is cooling. A couple of hours of TV with a dish uses very little power. The inverter stays off while I sleep, keeping the freezer frozen until morning. In the morning, I turn on the inverter for the fridge and coffee pot, then turn it off again.

      Understand how your fridge operates—how often and how long it runs. This knowledge can help you maximize your inverter and battery bank performance with less equipment and cost.

      I’ve adapted my 30-amp power cord to a 20-amp and plugged it into a 2500W Heart inverter. It successfully starts and runs the roof air even with the engine off, though it’s limited by battery capacity if the engine isn’t running. While I don’t use this as an OTR AC (I have a Red Dot system), I’ve tested it and it works well with only a slight change in the AC motor’s tone.

      Another surprising fact: I moved a Cruise Air to a 2000W Heart inverter, and it worked fine despite the Cruise Air’s hard start. This was with a 1st Gen Heart, which was a factor too.

      I know this might be unconventional for many in the Prevost community who prefer to never turn off their inverters and think you need two 4000W units to be “cool.” I’m not worried about that. These are proven methods I use myself. I don’t full-time, but in the past five years, I’ve spent more time in my camper than at home, staying comfortable and happy with minimal inverter and battery setup. Just keep it in the 70-degree range, and that’s what the wheels are for.

      #2359
      MyPrevost
      Keymaster

      Lifeline 4DA’s are 525.00 and 4DL’s are 530.00 each Joe, shipping depending on zip commercial or residential.

      #2360
      MyPrevost
      Keymaster

      Having two 4KW inverters is probably not the best choice. If the owner runs too many loads on the inverters while driving, they might find out the hard way how costly a 50DN alternator can be. Plus, don’t forget the cost of new 4/0 battery-to-inverter cables, which can run $10 per foot for marine-grade options!

      As coaches age, modifications often have less impact on resale value, especially when they can be clearly explained. For one owner, I removed one of two Trace 4KW inverters and replaced it with a transfer switch. The coach’s usage didn’t justify a full inverter replacement, and it allowed the owner to downsize the battery bank. At $500+ per battery and 120-160 pounds each, cutting down on unnecessary weight and cost makes sense.

      For an older coach, it’s best to modernize the electrical system to meet the owner’s specific needs rather than going overboard with upgrades.

      #2361
      MyPrevost
      Keymaster

      Thanks for the info, everyone.

      Finding 12R22.5 tires is becoming increasingly difficult. It’s been a while since I last checked, and it looks like their availability is waning.

      If you’re switching to 315/80 tires, be ready to either mount them on 8.5-inch rims or upgrade to 9-inch rims. On older, lighter buses where excessive pressure isn’t needed to carry the load, the steer and tag positions should wear correctly. For duels on the drive axle with 8.5-inch rims, 100 psi is preferable to prevent the sidewalls from touching each other at the bottom when the tires squat. With lower pressure, the tires might touch or kiss each other on rough roads.

      If you do switch to 9-inch rims on the drives, make sure the inner rim is steel. The extra thickness of the flange on an aluminum inner rim can push the outer tire’s sidewall against the rubber fenders when the suspension is working.

      I know Michelin advises against putting 315/80 on 8.5-inch rims, but for what it’s worth, I had them on an ’84 with 8.5-inch rims, and they worked fine for the current owner too.

      I’m not sure about the cost of new 9-inch polished aluminum rims, but personally, I find them unattractive, with their small style holes making it tough to air up the inner tire. Just a disclaimer—buyer beware.

      This chassis will serve as a great example of what it takes to properly manage an older bus. I’ll break it all down as I go, which should be helpful for those of you with older models and new to this community, including part numbers, prices, and labor involved.

      #2362
      MyPrevost
      Keymaster

      Joe, will 295s carry the load? Just a thought given the rim width.

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