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6V92TA cold weather battery modification

January 08, 2015, 07:51:40 pm

It got down to 5 degrees last night and I'm still attempting to recover. One thing I finally proved to myself is that with straight 40 weight motor oil the engine will not start at 19 degrees even with the block heater running all night and using all 3 batteries with the boost solenoid closed. I kinda knew the block heater was useless and that I really need an oil heater for cold weather starting. This is the first time it's ever gotten cold enough to prove it. I will definitely be installing an oil pan plug heater as soon as practical. What I did today was remove the cranking battery, move the two coach batteries forward, then reinstall the cranking battery behind the two coach batteries. I then wired the two former coach batteries as the new cranking batteries and the one former cranking battery as the new coach battery. I doubled my cold cranking capability and cut my coach battery run time in half. I realize my charger was designed to charge two batteries, not one. Will it boil off more water than normal from the single coach battery with this modification? I presume the isolator and alternator will be fine with this modification. I really don't need two 8D batteries for my coach but I certainly do need two for cold weather cranking. I doubt the boost solenoid is capable of carrying enough amperage to get the full cranking power of all three batteries, so my modification seems very practical to me. I put an electric heater on the ground underneath the oil pan and by the time I was done with the battery modification the engine started right up on the first try. I'm gonna leave it this way permanently unless someone can convince me that it's gonna do damage or something? I'll probably call Foretravel tomorrow and ask if there's any reason they can think of why I can't leave it this way permanently. Plan A was to never drive anywhere cold enough to need two cranking batteries, but since that plan didn't work out for me, this is plan B.

What prompted this discovery was the water apparently froze in the bottom of my fresh water tank. I normally drive with very little water, but I didn't consider how cold it would be when I arrived, and of course all the water in the campground is frozen, so I couldn't fill my water tank upon arrival as I normally do. I'm guessing my tank froze because the level was low. If I could have filled it as planned it probably would have been fine. So I'll drive with a full tank of water from now on if it's extremely cold at my destination, which in theory should never happen, but unfortunately this is plan B. I woke up several times during the night and ran the rear furnace, and the water still worked in the morning. It was mid day before it quit. I jumped to the conclusion I was out of water because nothing came out of the tank drain valve when I opened it. When I attempted to start my engine at 19 degrees to go get some water it didn't start and that's how this story began. After the battery modification I got it started and filled the water tank at a friendly local car wash, but it's apparently still frozen in the bottom of the tank. The rear furnace has been running a while now. I cut out a square of thick wafer board plywood to cover the opening where the power cable comes up into the utility bay. I cut a slot that's just the right size for the power cable to pass through without letting air through. I noticed there was ice on the inside of the plywood even though the charger was running all night and I started the rear furnace several times during the night. The short water hose I leave permanently connected to the fill spout was frozen even though it was rolled up and stowed inside the utility bay, just a couple feet from the charger with the charger's fan blowing on it all night. The charger obviously doesn't make enough heat to keep even a hose from freezing inside the utility bay. I just put one of those tent candle lanterns inside the water pump bay, but I don't think the pump is frozen. I think it's the bottom of the tank that's frozen. I have no idea how I'm gonna get it thawed out if filling it with water and running the rear furnace doesn't work. I drove back from the car wash where I found the water. I thought all the sloshing would help melt the ice but it's still frozen.

Back to the battery modification. Please don't attempt this unless you've got the skills, the understanding, the need, heavy lifting strength, and a healthy fear of high amperage electric incineration. The batteries are 150 pounds each and full of very strong acid. A spark can ignite the hydrogen from the batteries and cause a minature Hindenburg explosion. Definitely wear goggles with side protectors when working with batteries and wash your hands immediately afterward. If you spill any acid on your clothes or shoes take them off and wash them immediately or they'll be ruined... This is not a casual modification for the faint of heart.

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Re: 6V92TA cold weather battery modification

Reply #1 – January 08, 2015, 08:31:51 pm

Scott,

Check to see if there is an plate and gasket under the AC to block mount down on the lower right side of the engine. Some earlier Detroits have a block heater there and it works 10X better than the useless non-block thermostat housing heater. I think a couple of members with the 6V-92TA have the heater in that location with the same year as yours.That failing, buy an external heater with pump that circulates warm coolant to both sides of the block. This is the best route to take as it takes a short time to bring the engine up to starting temperature.

I also run SAE 40 and have started at 8000 feet when the temperature was in the teens without using anything other than the generator running and the boost solenoid on . Took a while and killed anything alive within a couple of hundred feet when it finally started. (my block heater was bad).

A 9 liter Detroit will need two 8Ds or three 34 or 31 series for the engine batteries. We tried starting on one 8D at the fire dept but then turned the battery switch to the "both" position every time to start. One battery would usually do the trick but occasionally it would kick back and the engine would run backwards (mechanical Detroit) The non-turbo Detroits have a higher compression ratio so start well at low temperatures. My 4107 bus had two 8Ds for starting the 8V-71.

Pierce

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Re: 6V92TA cold weather battery modification

Reply #2 – January 08, 2015, 09:21:39 pm

Scott,

John Fitz posted about using the lower coolant access in this post. Alternate Block Heater on 6V92 Detroits

Also be careful when selecting your oil heater if you go that route. I'm pretty sure the oil pan is baffled and getting a heating coil up the drain hole might be an issue. I've seen stick on oil pan heaters that might work but with all the curves in the oil pan it might be tough to get good contact. Here is one that I thought looked interesting. Wolverine Engine Heater Oil Pan Tank Heater 500 Watt Model 40 W40 120 Volt...

Heading south is the best strategy but funny how life gets in the way.

see ya
ken

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Re: 6V92TA cold weather battery modification

Reply #3 – January 08, 2015, 09:39:40 pm

I think it would be more efficient to warm the oil directly rather than warming the coolant and hoping it somehow finds a way to warm up the oil way down in the bottom of the pan also. I need to warm up the thick 40 weight oil from the bottom of the pan so the engine will crank fast enough to start. For now I'll put the electric heater on the ground under the oil pan for an hour or so before I crank the engine. That combined with the dual cranking battery modification worked well. I also have a portable propane heater with me that can sit on the ground under the oil pan. I want to leave the dual cranking battery modification permanently unless it's going to cause some problem, but I can't think of anything other than the charger possibly boiling off more water than usual from the single coach battery. I normally leave the boost solenoid closed when I'm home to charge the cranking batteries but I open it when I leave or go to sleep. I don't want to drain the cranking batteries if there's a power failure in the campground. I looked to see if I have the block heater mount by the AC compressor but I didn't know what I was looking for. I don't want to use the water heater anyway. I want to use an oil heater. It's the thick oil in the bottom of the pan that prevents the engine from cranking fast enough to start. Warming the water won't start the engine if the oil in the pan is too thick for fast cranking. The only way I'll ever use the water heater again will be in conjunction with the oil heater in extremely cold weather or in the event the oil heater is inoperative. Both situations seem unlikely so the water heater will just be abandoned but left in place permanently.

Still no progress getting the water tank thawed out... (sigh)

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Re: 6V92TA cold weather battery modification

Reply #4 – January 08, 2015, 09:52:12 pm

I kinda like that Wolverine pad heater. I was surprised to read in the listing that 500+ watts is needed to warm up 7 gallons of oil. I was intending to install a 300 watt plug heater in my oil pan. If the Wolverine will actually stay attached to the oil pan I'm interested... Did you buy one and did it work properly?

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Re: 6V92TA cold weather battery modification

Reply #5 – January 08, 2015, 09:57:32 pm

I haven't done anything yet. Still researching. Right now the Kim Hotstart is at the top of the list.

see ya
ken

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Re: 6V92TA cold weather battery modification

Reply #6 – January 08, 2015, 10:24:24 pm

Scott,

My take is slow cranking does not have that much do do with SAE 40 oil as with a starter, cable, terminal or battery CCA problem. We crank just about as fast in the teens as at 80 degrees.

All diesels are compression ignition engines. They need the compressed gas to be hot enough to cause the diesel to explode when it is injected. A dip stick heater is just not going to be able to heat the rest of the engine enough to get the diesel to ignite when injected. Heating is done three ways, conduction, radiation or convection. The steel oil pan will not give much conduction to the block. The warm oil will not be an effective form of radiation to the rest of the engine. This leaves only convection to bring the block up to temperature for compression ignition. Heating the oil will see a lot of loss through radiation to the sub-freezing air on three sides so the same wattage will have less of an effect as heating the block directly. A magnetic heater on the bottom of the pan would be marginal and you would need at least 1000 watts to have much of an effect at really low temperatures.

A circulation coolant heater is the choice of truckers in cold climates. A little harder to install as you have to run hoses to fittings on either side of the block or heads but worth the effort. Finding the reason other than the SAE 40 oil for slow cranking would be my first to solve. Using a digital voltmeter, you can check the voltage at the starter while cranking vs the voltage at the battery in the starting condition. A starter with poor contacts, drag from worn bushings could also be the reason for your slow cranking. As I said, ours spins like a top hot or cold using the same oil you do. Since Detroit did not install glow plugs or heated intake screens, you have to have all your ducks in a row with maintenance to get good, quick starts in sub-freezing weather.

Pierce

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Re: 6V92TA cold weather battery modification

Reply #7 – January 09, 2015, 06:56:53 pm

My water tank did thaw out last night after several hours of running the rear furnace. If your tank is frozen keep running your rear furnace and it will eventually thaw out.

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Re: 6V92TA cold weather battery modification

Reply #8 – January 09, 2015, 07:12:33 pm

I have a 6V92TA in my Wanderlodge with the lower block heater (behind the AC ). I started mine last year at -12F. No extra batteries. Ran the heater about 4 hours. Those high mounted heaters are about worthless.

TOM

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