Thor Forums

[lwmcguir]

Originally Posted by DavidEM

I originally posted this thread to mine about my new Axis 24.1 purchase and pending delivery, but I thought it might also be useful here.





I read the Axis specific checklist referenced above. It was very comprehensive. But the engineer in me wants to go a little further. This takes one and preferably two electronic instruments: a digital multimeter and a clamp on DC ammeter. The former can be purchased for as little as $10 and the later can be purchased from $30+, the better ones $80+ like the Klein or Extech.



With all of the postings on this forum about batteries running down and not charging, either coach or chassis I think it is important to further check out the charging systems. An RV is not like a car and the odds of something wrong from the factory with these systems on anew car is almost non existent. Not so when a Ford chassis is married to a Thor coach with all of its various electrical systems and interfaces. So here goes:



The first one I mentioned above. With no shore power connected, measure the voltage at the coach battery terminals (under the step). If the shore power has been off for a while and the chassis engine hasn't been run in a while it should be near 12.6 V. Start the chassis engine and measure its voltage at the chassis battery terminals (where is it BTW?). It should be in the mid 13s. Then push the battery boost switch on the dash while measuring the coach battery voltage at its terminals. It should jump from 12.6 or whatever to the same voltage as the chassis battery. If not something is wrong- loose wire, burned out relay or solenoid, bad contacts on the solenoid.



The next check is the converter charging system. Again measure the resting coach battery voltage. Then plug in to shore power. The voltage should jump to the mid 13s or greater. If you have a DC clamp on ammeter, measure the current. If the batteries are fresh and haven't been used much recently it should show less than 10 amps or even in the low single digits with everything off in the coach except for a few lights. If the batteries are somewhat run down as evidenced by a resting voltage near 12.0 it ought to show as much as the converter's maximum output- 45 amps, slowly dropping as the batteries charge up.



Then turn off the shore power and the chassis engine. Turn off the use/store switch and let everything sit for a few minutes and measure the current from the batteries. It should be near zero or maybe a few tenths of an amp for the propane and CO detectors and other parasitic loads that may bypass the use/store switch.



Then turn the use/store switch on and with everything possible off: TV, fridge, lights, water pump, etc, the current shouldn't change much, still in the low tenths of an amp since the Axis does not have a propane switch which can consume a half an amp all of the time it is on.



This one has been added to my original posting because the Axis has no inverter: With the shore power disconnected turn on the inverter. Several outlets- the TV power outlet and one near the bed at least are powered from the inverter. Use a $5-10 outlet tester (or a small AC lamp or something similar) to verify that power is available at the expected outlets.



Once these systems all check out then the PDI checklist's approach of turn it on and see if it works is fine. But you need some instruments to see if the above systems work right and finding out can save you a lot of grief later.



David

Great overview and tutorial
Will help a lot of folks