(continued from Part I)

The first test was to check for a short in the system, which will also track phantom loads as well.  For this, I took my multimeter and set it to test for amps.  If you’re going to try this, make sure you set for DC amps and that you switch your positive lead to that one that you never normally use when looking for resistance or for how much charge a battery has.

Then, make sure that all your vehicle’s switches are off, no key in the ignition, etc.  You want to try and eliminate all EXTRA power draws and find just those that exist when the vehicle is just sitting there.

Next, unhook the a battery terminal connection to your bus (or car, or motorcycle), and bridge between the batteries and the connection with the multimeter. I chose the positive lead for my test because when I slide my battery box tray out, those leads are well exposed and really unlikely to short on anything, but you can choose negative and it will work the same way.   What you’ll see is a number of amps that are being drawn by the electrical systems of your vehicle from the batteries.

When doing this, start with your amp setting at it’s highest range, then slowly bring it down.  My draw came out at about .7 amps, which is what the ECM draws at rest.  If you come up with some higher number, you can try to pull fuses and see if you can find a system that’s drawing load when it shouldn’t.  If you come up with a fairly high amp load that you can’t account for through your existing vehicle systems, you might have a short, and then you have to start tracking your wiring harness(es)!

The next thing I did was to check the voltages of the batteries individually.  As I had already started on taking off the positive batter connection to the vehicle, taking the batteries out of parallel to test was simple.  And one of the batteries was only holding 10 volts while the other held 11, and this was after being on a charger for about 2 days.  I tried charging them separately, and while I could get the one holding 11 up to 12.6 volts of charge, it dropped really rapidly.  The one that was only a 10 volts just stayed at 10, but made boiling sounds that a sealed battery just shouldn’t while charging.

My multimeter doesn’t have a min/max function and I don’t have a load-tester (which basically creates a load using a high resistance draw),  so I couldn’t verify that neither battery dropped below 9.6 volts when trying to start.  But the fact that they weren’t holding the charge, or even able to charge to full showed that it was time for new batteries.

I ended up being able to get them from Batteries + Bulbs which had a couple of (basically) local stores.  This allowed me to order online and get a 10% discount, but go to the store and pick up the batteries.  I got two nice Group 31 sealed batteries which had more amps than the ones I removed! (And as an aside, they are Duracell batteries – which I didn’t realize they made such a big battery!)

So, how to actually change the batteries?  First, open up the battery box and make sure that the hatch is secured, so it doesn’t slam down on your head before you get ready to go out to the theater. (Yes, of course it has happened.)

Next pull the pins and pull out the battery tray. From the picture, you can see why I chose my positive terminals to disconnect – they’re  well away from any of the bodywork that might short.  Next, remove the main connection to the bus (I chose positive again), then the other and any ‘jumper’ cables that run the batteries in parallel (or series), but remember where they go (or went).

Then, remove the other connector line from the bus, then from the batteries themselves.  After that, it’s a matter of removing the means of securing the batteries into the tray.  On my bus, this is essentially a piece of angle iron with holes to fit a threaded ‘J’ rod that hooks into holes on the tray about halfway up the width of the battery.  These are easily removed, but otherwise secure because of the wingnuts that hold them in.

Once the batteries are loose, it’s an easy matter to remove the batteries. I took the time to clean out the tray, and put in a layer of the non-skid shelf liner that I had around.

  This is a sort of puffy and grippy foam screen. On the one hand, I thought this would help to secure the batteries, and on the other, it might provide them with a little shock-dampening.

Then it was simply a matter of doing all these things in reverse.  The new batteries went in and were secured.  I then reattached the negative jumper to the batteries, and then the negative contact to the bus.  Next came the positive jumper and the positive contact to the bus, and everything was ready to go!

I have to say that when I went to try everything out, I was amazed at how the new batteries spun the engine up.  The new batteries had a great charge and so much more power that the old ones.  I reattached the battery minder, and hopefully these will have the same life-span as the ones I just replaced.