Magnum Charger/Inverter Info

[Diplomat Don]

I replaced all of my batteries today with new Interstates (GC2's, formerly U2200 for the coach and 31MHD for the starters). I removed the battery pan, dressed up the metal box and added a Profill watering system. Once I was done I decided to double check my settings on the Magnum ME charger. One of the settings is the amp hour size. In the past I added the amp hours of the four batteries (4 x 232) for a total of 928 amp hours. The Magnum charger has a setting for 400, 600, 800 and 1000. I decided to call Magnum and ask if I was better off setting it at 800 instead of the 1000 it's allways been at. Apparently, I've been doing the math wrong. Magnum calculates the amp hours as if you have two 12 volt batteries when running four 6 volt batteires. They told me my amp hour setting was really 464 amp hours and to set the charger at either the 400 or 600 setting. He said the difference between the two was in the Absorption charge mode. At 400-600 the Absorption charge mode ran for 90 minutes. At 1000 it ran for 180 minutes.

I've always had acid issues and have done many things to slow down the acid buildup in the battery bay, including adding Thermoil which eliminated about 95%. I was really aggrevated by the fact that when I was shown the battery bay on Monaco Mama's coach it was dry and dusty .

I also asked about the percent charge setting. Mine was at 100% with the default being 80%. Magnum did the calculation on that also and said mine should be at 90%.

I'm sure a large majority of the coaches are running similar batteries to mine and I hope this helps a few in setting the Magnum charger correctly. (It's set at the charger panel. Push Setup and twist the dial to go to each setting).

Now the only question is how does all of this affect the charging of the chassis batteries. I added the MegaTech BIRD unit and now both banks are charging when on shore power. The sensor is only on the coach batteries. Soooooo, does the charger settings affect the chassis battery charging, particularly the amp hour setting?

[Sixpack98]

That would be an interesting question for Magnum. I suspect it would not make much difference in amp hour setting since most of the chassis load is parasitic (not huge amp draw compared to house load) when the engine is not running. I would think that the chassis batteries are seen (electrically) as a down stream load on the house batteries. Effectively, the house batteries are charging the chassis batteries if the chassis batteries voltage is lower than the house batteries. The MegaTech BIRD senses the voltage differential between the house and chassis batteries and if the chassis batteries are lower than the house batteries the BIRD allows current to flow thus charging the chassis batteries. I just looked at the Magnum panel and it is in float charge at 13.1v and 20 amps. I doubt there is 23 amp on the chassis side. My battery maintainer only outputs about 4 amp to keep the chassis batteries topped off.

I can't explain why MM battery tray is dusty clean. Mine certainly is not and my Magnum is set up at 400 amp/hr and 70% charge rate. If I don't clean the battery try with baking soda in water every 6 or 8 weeks the acid mist starts to corrode the tray. Cable lugs stay clean though. Lead acid batteries out gas and minute quantities of sulphuric acid escape with the bubbles. I do think the watering system will greatly reduce the problem since the caps are designed to recirculate the mist back into the battery and not the atmosphere.

[Diplomat Don]

The Interstate Workaholic batteries (12V starting batteries) use to have removalble cell caps once you cut the label. The new batteries I got today have a short breather tube coming out of the center/side of the batrtery. They said the new ones are almost impossible to remove the caps, but now have a vent tube. I added some tubing to the vent tubes and was able to extend the tubes down and out through the drain hole in the battery box.

[MonacoMama]

Dip Don...We have ours set at the 400 range I believe.. and also have had the percentage set at 85%.

Our battery bay is still dusty and dry but SacsTC did clean it out and put a coating on it. You can see the photo before and also one after below...

BEFORE



and AFTER below...


I hope you have better luck with the MegaTech BIRD than we did. I know we were not the only ones who had issues with it, either. I think we have gone back to the Echo~Charger.