Almost ready to convert to 12v

Shakinboxcarjoe · Post by **Shakinboxcarjoe** » Sat Feb 14, 2015 2:34 pm

Totally rebuilt motor, I finally have spark, timing correct...I hope, but the starter seems slow in turning motor over. Both batteries fully charged and even connected a 12 v booster. I'm guessing starter now needs rebuilt or conversion. So it will not start....opinions? Thnx!

Post by **wesk** » Sat Feb 14, 2015 3:09 pm

Since about 1920 our planet has kept moving forward from the hand crank, thru the 6 volt systems, 8 volt batteries in 6 V systems, 12 volt, 24 Volt and now 48 volts is on the horizon. Yes this was all FORWARD movement. It seems whenever something fails to function we blame the designer and the system and not the failed component or the guy maintaining the failed component. The suggestion to move backwards makes absolutely no sense.

I am old enough to have been quite used to 6 volt systems. All the whiners back then blamed the system instead of the worn out components or in some cases their own mistakes (putting 6 or 8 gauge 12 volt battery cables on a 6 volt system that demands 2 gauge.). Or forgetting to insure the ground strap was connected between the engine and the frame.

When a 24 volt starter cranks slow you must ascertain what is causing it. It is a symptom of a problem and not an operating characteristic of all 24 volt systems. Where should you start? Well the TM's 9-8012 and -8014 have great troubleshooting charts that take you all the way through the possible causes in an organized manner starting with the easiest and cheapest first.

You mention the engine was just overhauled. Was the crank turning resistance within limits? A too tight engine will beat your starter to death. If the rebuilder doesn't understand the question on crank rotaing resistance then it's time to find a real rebuilder and have him look your engine overhaul over.

Some basics of any slow turning electric motor issue are:

1-Circuit resistance high. This means open each (YES EVERY) connection and insure it is clean and tight. Insure no ground straps are missing loose or corroded (yes these are also called connections) This includes the start switch where age results in severe arcing, deposits, resistance and shorts. It pays to secure a solid understanding of electrical principals and learn how to do voltage drop checks.

2-System voltage is low. Don't be fooled here. Get a good digital VOM and check battery voltage across each 12 volt battery and across the pair for 24 volt. Both 12 volters if fully charged should read ate least 12.5 volts. Across the pair should read at least 25. Less means they are not taking a full charge or they have internal cell issues. When you crank the starter the voltage across both should not drop below 20-22 volts. If it does suspect bad battery or two bad batteries.

3-If the above two paragraphs check out then pull the starter and haul it to a shop where either the shop guy is over 40 years old or a younger fella shows that he can read above the 8th grade level. Hand him the starter and your copy of TM 9-1825B and if he follows the test instructions he should have an answer for you in less than 10 minutes on the condition of your starter.

4x4M38 · Post by **4x4M38** » Sat Feb 14, 2015 3:34 pm

Yeah, if you are fully converted to 24 volts, if it was me I'd do anything to keep from switching to 12 Joe.

There are plenty of us out here that would give a left well, you get the idea, to have a 24 volt vehicle, but many circumstances are preventing and may forever prevent having a 24 volt unit.

Just my two cents.

Shakinboxcarjoe · Post by **Shakinboxcarjoe** » Sat Feb 14, 2015 3:42 pm

Thanks guys. Ill l keep you posted.

BullRun · Post by **BullRun** » Wed Feb 18, 2015 6:17 am

You mention the batteries are charged... I am having doubts as to the quality of how new lead and acid batteries are constructed if that is what you are using.

My recent experience with modern lead batteries is they do not take very well to charging before they are seriously diminished in power output. I read some literature with one of my recent battery purchases that with each recharge after being fully drained of output that at the next full charge, lets say for illustration, only 80% power output is available. At two recharges only 60% power output is available and so on. Probably not that extreme but you get the idea. The plates inside the battery gunk up really fast causing a power loss. The literature sheet said this.

I do not remember lead batteries being like this years ago. I have had a few brand new batteries fail to hold charges after only 1 or 2 charges after being fully drained and being put on a home charger. Brand new duds.

24 volt is way better. On top of that it is a waterproof system. Right now is probably the easiest time ever to keep them operating with original equipment. Most of those 12 volt conversions were done years ago because original 24 volt jeep parts were hard to find on the civilian market.

oreo3156 · Post by **oreo3156** » Fri Feb 20, 2015 1:12 pm

My jeep was already 12 volt when I bought it and have never worked on the 24 volt, but is it possible to have the batteries hooked up in parrallel instead of in series?

Post by **wesk** » Fri Feb 20, 2015 1:21 pm

24 V system must have batteries in series for 24 volts. 12 volt systems that want to use two 12 V batteries must connect them parallel for 12 volt output.

oreo3156 · Post by **oreo3156** » Sun Feb 22, 2015 10:46 pm

I'm wondering if Shakinboxcarjoe has them hooked up wrong (in parallel), is it possible to do so?

Bretto · Post by **Bretto** » Mon Feb 23, 2015 5:20 am

Anything is possible.

Xamon · Post by **Xamon** » Mon Feb 23, 2015 8:11 am

Well the difference is simple, Series it goes connection of positive line to positive battery terminal, negative terminal to positive terminal of next battery, negative to ground. Parallel connects positive to positive and negative to negative. more wire involved in hooking up a parallel system, although I did see once on a cat dozer where a guy ran the series setup with one battery backwards, fried the batteries right quick.

Shakinboxcarjoe · Post by **Shakinboxcarjoe** » Mon Feb 23, 2015 7:18 pm

I believe it is in series. From the starter, it's wired to positive in firewall box, negative from same battery to positive terminal of battery in engine bay, negative on same battery to ground. I also have ground strap from frame to engine block. I have a 24 volt storage charger hooked up to keep both charged....hooked up with the positive to starter terminal and negative to engine bay battery neg terminal. I have spark in all cylinders, it sparks on every compression stroke on each cylinder, so I'm getting close. Not running yet. Fuel pump bad so using starting fluid just trying to get to show some life. Not ready to convert yet! Thanks for all your help!

Post by **wesk** » Mon Feb 23, 2015 11:42 pm

Then your jeep is correctly wired in series for 24 volt.

Shakinboxcarjoe · Post by **Shakinboxcarjoe** » Sat Mar 07, 2015 3:10 pm

Finally got my jeep running! Had to adjust distributor, oil pump so the timing was correct. Once that was done, it purred like a kitten. I ended up keeping it 24 volt with one exception. My starter is worn so I bought a new 12 volt starter and wired it this way: from the engine bay battery, cable frm starter to positive post and wire for foot switch I bought at tractor supply. 2nd Wire from foot switch to solinoid. So, the starter and switch only pulls from the 1st battery which reads 12 volts. I wired the positive from the cowl battery to the ignition switch and regulator. Question is am I hurting anything wiring like this? Thanks for all your help. I just need to finished putting front clip on and it ready!!