Personally i would give a rest. You are in range with the highest electrical load on, so why fuss? _________________ '52 Dodge M37, '42 GPW, '48 FrankenJeep CJ2A/M38, '50 CJV-35(U), '51 M38, '42 WC-57 Command Car, '44 WC-51 Weapons , (2) M1941 Sperry 60" Anti-Aircraft Searchlights, John Deere M-gator, '44 White M3A1 Scout Car
Never trust the photos on pin locations. Get a good light and a magnifying glass if necessary and read the pin letters inside the plug just in case your plug was indexed differently then the one in the photos.
Interesting, I did not understand how the ground worked, which is why I need the extra ground when disconnected and running the test. You will turn me into a sparkey yet!!
The main reason for the grounding struggle are the rubber shock mounts used at the two pivot bolts. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
So with the generator being in range I hooked up the new/second hand tested voltage regulator and it gave the same results as the first, idle 28.1V Rev 29.9V lights on 29.8V. not the 28.5V expected.
It came with an updated S W Battery Generator gauge which works spot on.
When running she sits on the little peg in the top green band, so it can not be that far out unless the gauge is not very accurate.
When does the damage to batteries lights etc kick in as I have none of these problems.
I can see why Wes likes the very original adjustable ones as I would be able to knock it back a bit.
Boiling of the batteries usually does not occur until above 30 volts or if the 29.9 is continued long after the battery charging is complete. Try not to forget the original gauge which had a different function. The amp meter was able to show the relative rate of charge going into the battery during the normal start and charge cycle. With the amp meter you watch the initial high charge rate just after start then watched it slowly drop to the lower rate of charge as the battery reached maximum capacity. If the rate of current flow is not reduced the battery will boil over. There is a relationship between Voltage and Amperage but the two gauges actually show two different events. Voltage is the measurement of the pressure in your electrical charging system. Amperage is the amount of work or amount of current resulting from the pressure. Although most modern vehicles have long since dropped the use of the amp meter in favor of a voltmeter or color scale volt meter the amp meter still was a very helpful gauge and offered the rest of the information. To better explain all this we need only look at a DC/AC generator test bench which has both gauges to enable complete and more meaningfull data to troubleshoot with. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Thank Wes, I did not make it clear I think that my original voltage regulator, the one you posted a photo for me has been replaced by the same but tested unit. The gauge is the same as the original but a little larger on the colours so you are able to see the needle position better. Now I know a little more about Volt and Amp meters.
So short runs only until I can find a regulator which gives the correct readings I think.
Meanwhile I have put my original Voltage regulator back on.
Some interesting readings.
Engine bay battery Stood not running 12.6V in range for a 12v battery
Other battery stood not running 12.6V in range for a 12v battery
So this shows , I think batteries are good and charged.
Engine running with revs on, measure for 24V engine bay battery 29.1V( dropped a bit from my previous post of 29.7)
Other battery with revs on, measure for 24V 30.3V
Does the voltage regulator regulate the power to each battery as well as dropping the power from the generator or is it slight inconsistencies in the batteries?
In all operations the M38 is a 28V electrical system. The combined nominal voltage of the two batteries is 24V. In all system operating troubleshooting you must treat this PAIR of batteries as just that, a paired 24 volt battery pack. When troubleshooting the system while it's operating you must always record only the voltage reading at the + side of the cowl battery or the other end of that cable at the starter.
I suggest you avoid adding complexity and confusion to the troubleshooting process by attempting to treat these batteries as individual 12V batteries. They are only really individual when they are no longer paired together (all cables disconnected). The strongest single battery will always be drawn down by the weaker single battery as long as they are connected in series or parallel.
The only time we treat these two batteries as individual batteries is when we suspect them of being weak or damaged. Then they are taken to the bench and properly tested as individual 12V batteries. At the bench each will get the standard regimen of charging, testing the electrolyte, individual cell readings and load banking to see how each measures up. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
I should have also mentioned that when selecting replacement batteries they should always be purchased in pairs from current stocks so they can be as close as possible in production dates and as evenly matched as humanly possible. NEVER replace one battery alone! The weaker, old battery will only shorten the life of the newer battery by constantly draining it when the jeep is not operation.
Another high value accessory in this business is a quick disconnect for the engine bay battery's ground terminal in either a switch style or the battery top terminal style. This can be taken one step further by having two quick disconnects, one at each battery's ground cable/terminal.
Thanks for the battery advice, I have the second type of cut off,may be a good idea to fit the first type as well, belts and braces as we say on this side.
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