Just got my 1917 Maxwell on it's wheels for the first time in over 50 years and the first chore was to wheel it outside and try jumping the starter off a 12 volt battery to see if the tight rebuilt engine would turn by the starter. I jumped it off a modern car because the Maxwell has two six volt batteries that start the car on 12 volts but runs it on 6 volts. Since the test jump failed to turn the engine, here's my question. Does the use of two 6 volt batteries in this manner double the cranking amps to the Maxwell starter? I'm trying to diagnose if I just didn't feed the Maxwell starter enough cranking amps or if what I did was correct and my problem lies with a too tight engine.
How are your jumper cables look like. Are they just to start a modern car or can you start a truck with them??
Car cables but they are old type fine strand copper that have always worked before.
In series, that is: pos to neg to pos to neg through the batteries you get 12 volts. In parallel: that is positives and negatives jumped together you get 6 volts and I believe increased crank amps.
Before you damage a good starter, why not pull the engine through compression by hand with hand crank and see how tight the motor is. If the bearings are well lubed you might be better off towing the car to loosen up the bearings a bit if needs be. If the cables are not heavy enough they will get very warm very quick but heavier cables might also just help you overheat the starter motor if the engine is really stiff. I am not sure what advantage there is in setting up motors so tight. I have never had one that wouldn't kick right off with the starter but those were T's.
Someone 50 years ago set this motor up and I'm worried it might be set up to "burn in" as some of the old-timers used to say. I can hand crank it but it is really stiff. It is wired as Charlie says in series, so does that mean I get more cranking amps from the 2 sixes or is it the same as a single battery?
I don't think 2 sixes in series increases the cranking amps. It doubles the voltage to 12. Pull the plugs and see if it's any easier to hand crank or try the electric starter with the plugs out. You could be fighting a slightly tight re-build and high compression.
The cranking amps from two sixes in series will be approximately the same as from one 12 volt battery assuming the batteries have the same internal resistance. The difference in the internal resistance from one battery to another can be from a number of factors including construction, physical size and load.
Twelve volts across the starter will give more amps than 6 volts,ie, more cranking amps, which is why they used two 6 volt batteries initially. I suspect the problem is the wire size and length of the jumper cables.
I don't know how difficult it is to access the bearings on a Maxwell engine, but it seems to me taking it on faith that the bearings were lubed properly 50 years ago and have remained so ever since is pretty risky. Dry babbitt bearings will quickly burn out.
Howard, to reiterate what Tom said, two 6V in series will act about the same as a single 12.
The current required to turn your starter over depends on battery internal resistance, cable size, starter motor resistance, and starter motor rpm.
Practically speaking, if it would have turned over with 2 sixes, it would have turned over with one twelve. So if the connections are OK and the starter motor is OK, and the motor isn't turning over, its because there's just too much mechanical resistance from the motor itself.
An old trick. How about draining the oil and refilling with kerosene (plus a couple quarts). Turn it over by hand and see if it turns easier. Then try the starter. Suggest you don't start the motor with the kerosene in the crankcase.
If it then seems easier to crank, drain & refill with lightweight oil (5w-30) and see if your starter will turn her over.
Just a question , is the clutch dragging ?
I would remove the plugs , pour some light oil down the cylinders put it in gear , and role it by turning the wheels
just to see if all is free
then if all is good tow it slowly , then try the starter ,with the plugs still out
There is not enough information given to answer the question "will two 6V in series will act about the same as a single 12". It really depends on the CCA of the batteries. You can buy a 12 volt battery with a CCA of 390 amps and yet at the same time 6 volt batteries run about 650 amps. In that case two 6 volt batteries would provide more power. If the CCA of the 12 volt battery is more then the CCA of the two 6 volt batteries, then the 12 volt battery would have the advantage.
That said, in this case I bet the problem is the tight motor even more likely bad connections and small wire on the jumper cables. The safe solution (for the starter at least) would be to hand crank start it.
Two 6 volt batteries in series will only give you 6 volts. The power will come from the strongest battery and the weaker one will serve no purpose, the two will not equalize. The two can be charged with a 6 volt charging system but it will take twice as long to fill them. They will not equalize with out an external source. There was some early sophisticated wiring methods to start on 12 volts and run on 6 volts but they proved to be troublesome over time. Early 6 volt batteries were not very good compared to todays batteries If your system requires 12 volt to start, I would suggest installing a 12 volt battery for that purpose and a 6 volt battery for the remainder of the system, charge the 6 volt battery with the charging system and charge the 12 volt battery from an external source. Two 6 volt batteries in series is a potential problem. I went through three years of grief with my motor home when I installed two 12 volt batteries in series thinking it would increase my power and time. It was no end of problems until I got rid of the second battery and continued to operate the system on only one 12 volt battery. If you have a vessel that is 1/4 full with 10 pounds of pressure and you have a second vessel that is half full with 10 pounds of pressure and you connect them together nothing will happen and they won't equalize. The 10 pounds of pressure is the same as voltage (electrical pressure) to overcome the 10 pounds in the 1/4 full vessel would require minimum 11, 12, 13 pounds respectively until they would equalize. A 6 volt charging system must put out greater than 6 volts to overcome the static pressure in the vessel/battery. Your system putting out 10 volts would appear to be correct. Consider the 10 volts as 10 pounds of pressure and consider the battery a pressure vessel containing only 6 pounds of pressure, the 10 pounds will effectively overcome the 6 pounds of pressure. The charging system on most vehicles will charge a "6 volt" battery to 7 or 7.5 volts. Two batteries are not any better without some kind of tricky wiring eg double pole double throw switch so as each battery can be charged independently. The one battery that the leads come off may be run down and may not have the capacity to maintain full power, the second battery will not provide any energy to the first battery and the trouble is perpetual.
Use two sets of jumper cables at the same time. Just don't leave them connected for very darn long if the engine doesn't turn over almost immediately. You could also do as I do with a tight T engine. Get someone to jump that starter while at the same time you get on the hand crank. Also, be careful!
I think you are correct that a system that used both 6 and 12 volts sounds like problems. However you are in error, two 6 volt batteries in series will give you 12 volts, not 6 volts. Two 6 volt batteries in parallel will give you 6 volts.
I have old dozers that are a 12 volt systems and originally had two 6 volt batteries. They work fine but I use a single heavy 12 battery because they are cheaper.
I've worked too hard chasing and rebuilding original parts to keep this thing as built to just butcher it now at the first sign of trouble. You are all right about it being complicated. It has a starter/generator that starts on 12 and senses when the engine starts it switches to a 6 volt generator. When the engine starts you release the foot pedal that engages the starter gear and also an electrical/mechanical switch that tied both batteries together is disengaged to allow the 2 batteries to return to separate 6 volt function.
If you can hand crank it I doubt it is too tight but I would be concerned that there is no lubrication on the bearings and a dry start up is not a good idea. Every engine I have rebuilt was so tight that I had to pull them to start. On all of them I could not hand crank but if I stepped on the crank handle at 3:00 position the crank would turn. Unless you are way stronger than I am if you can crank it the starter motor should be able to do it too if it is getting 12 volts and the starter motor is OK. Did you try cranking by hand while someone hits the starter? Sometimes you need to break that initial resistance and then it will start to spin freely.
The IHC TD24 crawlers in the 50ís started on 24V and switched to 12V in the same way.
No starter solenoid there, you stood up and jumped on the switch with your heel.
If the batteries were a bit low you got the engine barely turning on the starter and then
got off the starter switch and hoped the resulting available current surge would trigger
the coil quick enough to fire a spark plug.
To add to that complicated system, they started on gas and then switched over to diesel.
Sorry Jim I got my series-parallel incorrectly referenced I will be more cautious next time, thanks
I know the late '10s Maxwell (and a few others) had a convoluted electrical system. I too would prefer and recommend it be kept as original. Once you get it sorted out and running, trying to convert it to something more common will not help you much and may lead to other problems. Just like model T coils, once you figure it out, it is not so bad.
Sorting it out can be tough. There are many options, many tests, and many things you could or should try or do that may work or not. I wish I could come by and help for a few hours. I am very "hands-on" and making suggestions over the forum is sometimes tough without looking at some detail first. I would speculate that jumper cable issues coupled with engine tightness may be the main reason you couldn't get it to turn over enough.
The engine being too tight, and of unknown assembly lubrication, may be a case of "tear it down now", or " tear it down later". IF you chose to start it "as is", it may work out fine. On the other hand, it could eat up the main and/or rod bearings in the first minute. How much is known about the person that assembled the engine? Many engines have been "burned in" and turned out fine. Again, on the other hand, if the pistons and rods are too tight, you may have over-heating issues followed by severely scored cylinders and maybe knock out Babbitt bearings later.
An opinion based upon past experience. If you can crank it over by hand? It probably is not too much too tight. Some of the best engines I have ever experienced, required towing to start them. Sometimes the starter system just isn't strong enough to start the engine tight and fresh.
I would love to see photos of your Maxwell. Probably others would, too.
Drive carefully, and enjoy, W2
I think the engine is becoming easier to turn, I can get about two or three revolutions before I tire out. The fellow that had this rebuilt was known for cost no object restorations so I'm pretty sure no shortcuts were taken. I'm going to change the starter with one I've gone through and know what's inside. Then I think I'll finally get a set of battery cable ends and make a set of heavy duty jumpers out of the old welding cable I've been saving. If all this fails it's time to pull the head and pan and see what is so tight. The picture doesn't look like much but it's all rebuilt and together for the first time since the early 1960's. I plan to duplicate the ambulance shown in a 1916 Maxwell company magazine if I can.
Here's the ambulance:
Howard, yesterday I asked you about the kind of jumper cables you are using. Car cables can't give you the current (+600A) to make the engine turn.
On the other hand, I think there is a problem in the way you are hooking up the 12V battery.
A few year ago, in one of the Mercedes vans here in Europe, there was a similar starting system. The van runs on 12V and started on 24V. To get it started with a jumper system you needed 24V so two 12V batteries. It didn't work with the jumper batteries hooked up together to get 24V and hook them to the van batteries. You needed to hook up each battery one by one to the car batteries to make it work 4 heavy jumper cables were needed to to connect the batteries.
I don't know how the 6 - 12V system on the Maxwell is working but I think you will need 2 good 6V batteries and 4 heavy duty jumper cables.
Andre, there is only one way to hook up the battery to test if it will turn the motor over. The two 6 volts are dry new old stock so I haven't even tried them as I want to see if it will turn with 12 volts as it was designed. I hooked the jumper cables directly to the starter from my running 12 volt car battery and it didn't turn. That's why I asked if I could expect any better results from the two 6 volt batteries if I go ahead and activate them.
Good to see the Maxwell coming along. Have you had the pan off? It would be fairly simple to take it off and check the bearings for fit and lubrication to make sure there isn't a problem before taking a chance on harming them.
Good luck with the Maxwell.
WAHOO!! Early Thanksgiving! It was the old starter! Swapped in the one I rebuilt years ago, hooked up the same old jumper cables and RRRRRRRRRR she spun over with the plugs out. Put the plugs in and she still spins. I've been sweating this tight engine for 10 years and now no problem. It's still tight by hand cranking but I guess I underestimated the gearing in this starter. There is a flywheel ring gear as usual, then a few inches to the right of the ring gear is the stationary starter gear, and when you push the starter pedal a third gear slides into the mix at the same time as the starter electrical switch is engaged. Boy am I doing a Happy Dance!
Now I can pull the pan and see how things inside are.
Thanks for all the help,
Check it out and then give it a little gas and a little spark and voom voom!
I used to have a Simms mag for a Maxwell. Used dry cells to boost the starting spark in lieu of an impulse coupling. I gave it to a guy who wanted it for his T speedster.
Tom, did you find out if he ever used that Simms Magneto? I ask because during my Maxwell research I found an old book that said a Simms used those dry cells because when hand cranked they didn't produce enough spark to start the car. Once at running speed the dry cells disconnected. My late 1917 was built when Simms was in a labor strike and left Maxwell with no supply of magneto's. Luckily Atwater-Kent had just introduced a modern distributor/coil system that was designed to be a direct bolt-on replacement for magneto's. All Maxwell's had this option from that time on.
He hasn't used it yet. Here is a picture of it.
Also, here is a schematic if anyone is interested in the goofy 12V/6V thing. Kind of hard to see, but the starter switch changes the batteries from parallel to series whilst cranking, then back when released.
FWIW This DU4 was on the '16 engine in my '15 Maxwell and after cleaning and adjusting it fired right off after a couple of choking turns. I don't know why they needed dry cells with the Simms. They still had the 6V/12V.
I knew I had this somewhere.
April 5 1917 Motor Age Magazine:
Simms Generating Speed
Why will a Simms-Huff magneto as installed
on the Maxwell 25 furnish ample current for
ignition at the slowest possible speed, and
yet not furnish spark for the starting motor
when cranked by hand, no matter how fast the
motor is cranked, unless the auxillary dry cell
circuit is used? The magnets are strong, and the
armature alone throws a hot spark with the dry
cell curcuit, and upon testing all secondary
insulation with high tension current no leakage
can be detected. This car operates entirely
satisfactorily at all speeds but cannot be started
by hand cranking alone unless the starting switch
is also closed to close the auxillary dry cell
Answer: The lowest speed that the Simms-Huff
magneto is designed to deliver sufficent current
at a high enough voltage to produce a efficent
spark is 75 R.P.M. . It has been Maxwell's
experience that one could not crank the engine
at this speed.Therefore the magneto will not
deliver an efficent spark by cranking the engine
by hand unless assisted by the dry cells.With
the car idled down to 4 m.p.h.in high, the car
is still turning 160 r.p.m. .As can be seen,
this speed is considerably above 75 r.p.m. at
which speed a good spark is obtained from the
It appears we need to know if you have an SU-4 or an SU-4D Simms Magneto.
If the above question was for me, the DU4 I showed was a Bosch and may not have been furnished with the car when new. Also the easy starting I spoke about was hand cranking. I have not delved into the starter generator yet. This thread is very interesting to me.
Just wanted to take this opportunity to publicly thank Richard Eagle. Not only do I enjoy his posts and paintings on here but if it hadn't been for his gift of spare rear axle parts my picture of my Maxwell up on it's feet would have never been possible.
Happy Thanksgiving to you and yours and that goes for all you guys & gals on this forum.
Howard, that is very nice of you to say. The folks on the forum have a generosity like the guys who have helped me for 50 years. It was nice to meet you here and learn more about Maxwell's.