Getting 12 volts

Mike in GA · April 17, 2019, 07:11:00 PM

What's the preferred way to get 12 volts for various house needs (lights, fans, water pump)? I have 4 L-16 Lifeline AGMs wired to feed 24 volts to my Trace 4024.
Should I add a 12 volt battery and feed it with a Vanner equalizer from the 24 volt bank?
Add a 12 volt battery and hook it up to a 3 stage smart charger?
Center tap the 24 volt bank?
Mike in GA

buswarrior · April 17, 2019, 08:37:47 PM

Vanner battery equalizer on a centre tap from the house bank.

Happy coaching!
Buswarrior

richard5933 · April 18, 2019, 02:21:44 AM

Agree - a Vanner will allow you to get power to your 12v loads without damaging your batteries. No need for a separate 12v battery for this.

Here's a manual from Vanner - may not be the for the model you get but it has lots of wiring diagrams to show the options.

Mike in GA · April 18, 2019, 11:19:43 AM

I have a spare Lifeline 12v battery I could work into the system.
Use a 24 to 12 Vanner or use a 12v converter charger?
Mike in GA

Utahclaimjumper · April 18, 2019, 12:13:20 PM

Quote from: buswarrior on April 17, 2019, 08:37:47 PM
Vanner battery equalizer on a centre tap from the house bank.

Happy coaching!
Buswarrior

It would be from your chassis bank TO your house bank.>>>Dan

buswarrior · April 18, 2019, 01:02:51 PM

His house bank is 24 volt, the loads mentioned seem to be 12 volt house loads? Keep 'em all clear of the chassis so self inflicted no-starts are avoided?

No mention of a chassis 12 volt need?

Mike?

Happy coaching!
Buswarrior

richard5933 · April 18, 2019, 01:15:29 PM

What is your chassis system - 12v or 24v?

Utahclaimjumper · April 18, 2019, 01:59:30 PM

If he has a 24 volt system, he has to be charging it some way. More than likely a 24 volt alternator and starter, which means a 24 volt chassis system. I can't imagine it being the other way,, no benefit.>>>D

luvrbus · April 18, 2019, 02:09:49 PM

Says he owns a MCI it will be 24v and his inverters are 24v sounds like the post reads he looking for 12v supply,the Vanner has a 12 outlet I can pull 40 amps 12v from mine

richard5933 · April 18, 2019, 02:52:15 PM

That 12v battery can be connected as a second house battery bank. Follow the diagram at the top-left of page 8 of the manual I posted earlier. It shows the correct way to add the additional 12v battery. You'd use the Vanner to tap into the existing 24v battery bank, and then connect the 12v battery to the 12v post on the Vanner. The 12v load would connect to the 12v battery as normal.

I suppose the extra 12v battery would also help if there was ever a short-term load on the 12v system larger than the Vanner could supply.

Not sure what the current draw is from the Vanner when it's connected to the 24v battery bank, so it might be necessary to install a disconnect of some type for times you don't need to have any 12v loads or times when you want to maximize the 24v battery bank life.

buswarrior · April 18, 2019, 07:05:10 PM

A Vanner battery equalizer is typically attached directly to the batteries in a stock coach or transit bus. Battery cut-off switch is beyond those connections.

No loads, it can sit there for months with no ill effect.

He wants a few boring 12 volt accessories for camping use. The loads don't justify anything else.

Adding a battery in the 12 volt side would be a waste of lead, it won't contribute anything unless the 24 volt is allowed to run down, which would be a mistake in itself.

Happy coaching!
Buswarrior

MagnoliaBus · April 19, 2019, 05:26:52 AM

What i see on newer transit buses is step-down 24V-12V converter. No center tapping, no battery imbalance.

Mike in GA · April 19, 2019, 07:45:55 AM

Thanks everyone. For the last 16 years I have used a Vanner equalizer to split 24 volts and send 12 volts to an auxiliary 12 volt battery that powers my fans, water pumps, etcetera.
But lately the 12 volt side has been less than half of the 24 volt input and this has caused my house water pump to stop functioning when the voltage is hovering around 12 volts or less. I am presuming a failing Vanner since the 12 v battery load tests as sound.
Some have told me that the 12 volt load should be powered right off the 12 volt lug of the equalizer rather than going to an auxiliary 12 v battery. But the diagram shown on the Vanner manual (page eight) suggests that the equalizer go to a 12 v battery to charge and power a 12 v system.
Thanks again for your help
Mike in GA

Dave5Cs · April 19, 2019, 10:18:48 AM

Mike what about a dirty ground? On vanner or battery.

sledhead · April 19, 2019, 02:09:04 PM

after I changed from a 12 volt inverter to a 24 volt inverter and changed all the interior lights to led 12 v there was not much 12 draw other then the water pump and the slide out motor . I used a converter 24 v to 13.6 volt 30 amp and it worked great for the water pump and all the lights but the slide was to much for it .so I put a 12 volt screw gun lithium battery in the system and never had a problem after that . it could handle the large draw for the start up of the slide motor

dave