My solution to the 24/12v battery equalizer conundrum

[kjurkic]

Many folks here like me have had issues with battery equalization. Under normal circumstance an equalizing device would keep the lower battery topped up as various 12v systems try to drain it down.

A replacement equalizer such as a Vanner are a very expensive repair option. Some folks here have installed a separate 12v alternator, which is likely the best long-term solution.

In my case, I had already purchased and installed a 24VDC to 120VAC 2400 watt inverter. I discovered a 12v, 30/80amp charger for $100CDN, so I installed it along with a 12v deep-cycle battery to power all the 12v systems. This has worked very well so far (the charger is rated at 100% duty cycle @ 30A). Even with high-beams on, my 12v gauge shows a steady 13+ volts.

HTH others with similar issues.

cheers
Ken

[Jeremy]

My bus doesn't have any 12v items on it as standard so didn't come with a Vanner etc, but I will be installing one or two 12v items myself as part of the conversion where 24v alternatives aren't available. Rather than buying an equalizer or installing another battery and running a charger off an inverter (electrically very inefficient) I have bought a commercial-grade 24vDC-12vDC converter, as used in trucks etc. It's a simple solution to the problem and to be honest I don't really know why some buses manufacturers wire the batteries in an unbalanced way in the first place, and then have to install equalizers to counteract the problem that creates. Or am I missing something?

Jeremy

[buswarrior]

An equalizer, such as Vanner popularly makes, doesn't let the batteries get out of balance, taking power from both to provide the 12 volt.

That's the point.

Every transit bus and motorcoach for close on 20 years has an equalizer in it.

If there was a more cost effective way to deal with the 12/24 volt supply issues in a coach, wouldn't the commercial, for profit, manufacturers and fleets be using it?

And, bonus for a busnut, some of them carry a pair for meeting whatever commercial capacity was needed.

The adoption, and knowledge base, for busnuts lags some 20 years behind, as we commonly don't get our hands on the coaches and the tech until it is beyond 20 years old...

For instance, the stories about how to check for MCI D model structural body upgrades will start shortly, once a few of us have them, learn the hard way, and post.

happy coaching!
buswarrior

[Jeremy]

An equalizer, such as Vanner popularly makes, doesn't let the batteries get out of balance, taking power from both to provide the 12 volt.

That's the point.

Yes I understand that, it just seems a bit strange to have to use a device to keep the batteries in balance when you could avoid causing them go out of balance in the first place. It may be that, since the current flowing between the batteries to keep them in balance is much lower than the 12v load you are taking out of the batteries, the Vanner is can simply be a smaller and cheaper device than a converter would need to be. Or it may be that because slightly different internal resistances etc can cause batteries to get out-of-sync anyway, so having a Vanner kills that bird as well.

I've no-doubt there are good reasons for doing it, I've just never understood what they are (or indeed why you'd build a bus with 12v headlights in the first place)

Jeremy

[kjurkic]

My bus doesn't have any 12v items on it as standard so didn't come with a Vanner etc, but I will be installing one or two 12v items myself as part of the conversion where 24v alternatives aren't available. Rather than buying an equalizer or installing another battery and running a charger off an inverter (electrically very inefficient) I have bought a commercial-grade 24vDC-12vDC converter, as used in trucks etc. It's a simple solution to the problem and to be honest I don't really know why some buses manufacturers wire the batteries in an unbalanced way in the first place, and then have to install equalizers to counteract the problem that creates. Or am I missing something?

Jeremy

I tried just such a converter, but it was limited to 60A surge, and being in a hurry to resolve the issue I installed it without a fuse or circuit breaker. You can guess the rest.

There are also a number of smaller inexpensive 24v/12v converters out there, with 10-15 amp capacity, which would work for powering individual components, rather than the whole 12V system.

I wasn't offering the "perfect fix" here, just food for thought if someone has already installed a 24v/120v inverter - those are very expensive, but allowed me an inexpensive fix for the 12v issue.

cheers

[Geoff]

kjurkic (real name?)

I am guessing that the 24/12v voltage regulator in your RTS quit working?.  That is what you needed-- a replacement regulator.  Or be like me-- dump the 300 amp gear driven alternator and use the V730 PTO drive to run separate 12v and 24v alternators.  I have no use for 24v except for the starter, driver's heater motor, and a few 24v relays.  My inverter is 12v with four golf cart batteries to run the RV house systems.

--Geoff