Vanner Equalizer

[richard5933]

I've read through lots of posts about this, and I've read through the instructions for the Vanner equalizer. I still have questions.

In the instructions for the Vanner there is an example of an RV setup. Looks to me that this is designed for having 24v systems for both the chassis and house systems. It also looks like they show two equalizers - one each on the chassis batteries and the house batteries. Then I found an example of a system where there were just extra 12v batteries added to handle an additional 12v load. That seemed like what I needed.

There are no 12v loads on the chassis side of my coach. They are all in the RV (house) side of things. I'm pretty sure that means I don't need the Vanner on the chassis side.

Is it possible to just use one equalizer if my goal is to be able to charge the house batteries from the chassis battery/alternator? My thought is that I could connect a Vanner to the chassis 24v battery bank, and then run a 4/0 cable from the 12v post to the house batteries. To keep the systems isolated when the engine is not running, I'd incorporate a constant-duty solenoid in the connection between the Vanner and the house batteries.

If my house batteries are set up as a 12v battery bank, is this a workable solution?

I've attached a modified diagram from the Vanner instructions to show what I have in mind.

[gumpy]

I don't think you want to do the 4/0 cable thing. You're going to severely deplete the lower side of your coach batteries, and that can cause the upper side to get overcharged by your alternator.

Do it the way Vanner shows, with the output from the equalizer. It will be limited to whatever amperage the Vanner is, but over time it will charge your house bank, and will keep the coach batteries equal.


Second thoughts. Initially I thought you were going to run the 4/0 from the battery post, not the vanner post. I reread and looked at your diagram again, and maybe you meant attaching it to the Vanner 12v post. That's correct, however, you don't nee a 4/0 cable. You can size the wire to whatever the Vanner amperage is. if it's a 60 amp Vanner, you can use a 2 ga wire. Solenoid where you show is a good idea, also.

[richard5933]

I don't think you want to do the 4/0 cable thing. You're going to severely deplete the lower side of your coach batteries, and that can cause the upper side to get overcharged by your alternator.

Do it the way Vanner shows, with the output from the equalizer. It will be limited to whatever amperage the Vanner is, but over time it will charge your house bank, and will keep the coach batteries equal.


Second thoughts. Initially I thought you were going to run the 4/0 from the battery post, not the vanner post. I reread and looked at your diagram again, and maybe you meant attaching it to the Vanner 12v post. That's correct, however, you don't nee a 4/0 cable. You can size the wire to whatever the Vanner amperage is. if it's a 60 amp Vanner, you can use a 2 ga wire. Solenoid where you show is a good idea, also.

I think we're talking about the same thing. I was going to connect the 12v batteries to the Vanner post. I think you're correct though, that the 4/0 would be overkill and probably more difficult to run through the chase than something smaller.

[Frank @ TX]

Richard,
For 17 years and counting we have the power form the alt go to the coach bats and thru a relay and then the house (24v ) bats.  The Vanner is needed only to keep the four house bats equal and supply 12v to the house.  A bit different than your drawing I think.
Works for us.
Frank

[bevans6]

A Vanner is, at it's most basic, a switching power supply that outputs a 12 volt supply that is exactly half of it's input 24 volt supply.  Your application is using it as a 12 volt supply from a 24 volt source, so completely allowed.  It will supply up to it's limit, and I suggest you fuse/breaker the output to the 12v batteries at maybe 75% of the rated output of the Vanner, like 45 amps if it's a 60 amp model.  The reason is that the Vanner is quite stupid, and doesn't have current limiting circuitry in the same way that chargers do - it will simply put out the power to the extent that it is able, and with three large batteries, it might get asked for a lot if they are well discharged and want to be charged up quickly.  My Vanner does have a resettable breaker on it as well.  I would include a way to disconnect the ground from the Vanner to turn it off if it is not being used, since it will continuously discharge the bus start batteries as long as it's connected to them, at a very low rate, but a very real possibility of damaging the start batteries.

[richard5933]

Richard,
For 17 years and counting we have the power form the alt go to the coach bats and thru a relay and then the house (24v ) bats.  The Vanner is needed only to keep the four house bats equal and supply 12v to the house.  A bit different than your drawing I think.
Works for us.
Frank

Would there be any advantage to setting up our house batteries at 24v instead of 12v? Of course then I'd have to use the Vanner to supply current to the 12v systems, but it would allow me to keep the current 24v lighting that is in the bus already. Other than the 24v lighting, the only items on the house system currently are two 12-volt radios and a 12v fridge.

[gumpy]

Would there be any advantage to setting up our house batteries at 24v instead of 12v? Of course then I'd have to use the Vanner to supply current to the 12v systems, but it would allow me to keep the current 24v lighting that is in the bus already. Other than the 24v lighting, the only items on the house system currently are two 12-volt radios and a 12v fridge.

The primary advantage would be if you are using a 24v inverter on the house battery. 

Brian has a good point on the house batteries exceeding the output limits of the equalizer if they are deeply discharged. Unfortunately, a fuse is not going to help much, because once they are at that level, they will blow the fuse every time a new one is installed. You will have to charge the batteries up with another source first. You really need a way to limit the current being allowed to be drawn. Unfortunately, that exceeds my limited electrical knowledge. I know there's a way. Adding resistance or something. I just don't know how it's done in a practical sense.


This would actually be another advantage of having a 24v house battery as you could then connect the coach and house batteries using that 4/0 cable and then the alternator will charge them both when connected together. That's how I do mine. Then your equalizer can be used for the minimal 12v loads you have.

[Toolman]

I do the same as Frank above, 24v House with a centre tap for 12v, the Vanner keeps the two 12v sides equal. By far the best way to handle your 12v loads

[richard5933]

Not sure I understand completely. Let's say that I spend a night dry camping and run my house batteries down to 50%. They would take a charge as fast as they could get it. The Vanner would only be able to output up to its limit - in this case 60 amps. Seems like it would be the same thing as plugging in a tiny 10-amp battery charger to a really large battery bank. The charger just keeps plugging along providing 10 amps till the bank is charged.

Wouldn't the Vanner just continue to output its maximum until the house batteries are charged? My understanding is that discharged batteries don't pull current to them, but rather they'll take whatever they can get. Of course I could be wrong.

The Vanner draws 17 milliamps while on standby according to their specs. There is some concern in the instructions about using a negative-side disconnect due to reversed polarity issues. Couldn't a disconnect between the Vanner and the 24v chassis battery bank accomplish the same protection against drawing down the chassis batteries?

I'm going to try and contact Vanner directly to get some additional information about all this as well.

[bevans6]

A bit more about Vanners.

A Vanner can certainly be used as a charger, but it isn't designed in the same way as modern smart chargers.  It just outputs a voltage equal to half of it's input voltage (nominally 12 volts out and 24 volts in, but it has a range of possibilities).  When it's being used as a 12 volt charger in a 24 volt bus, it will pull from the supply side - the bus alternator, which would be running at around 27.5 - 28 volts normally - and charge the house batteries at 13.75 - 14 volts.  If the alternator is not running and the Vanner is left connected to the house bank, any 12 volt loads will be shared between the house bank and the bus start bank - the Vanner will be driven by the 24 volt input from the bus start batteries to keep the house bank at exactly half of the bus bank, and supply sufficient current to do that.  That may or may not be what you want to happen, so you need to have a switch to turn off the Vanner.

If a Vanner is being used to equalize, it supplies a current equal to the load current on it's 12 volt output.  The current is generated by the Vanner being powered by the 24 volt battery, so in an odd way the 12 volt load current is being supplied by both of the 12 volt source batteries, so it acts as though the 12 volt batteries are in parallel to supply the load current, when of course they are in series and actually supplying the 24 volt volt power to run the Vanner.  Kind of neat in my opinion.

My Vanner is connected to equalize my 24 volt house bank, to supply relatively low house 12 volt current loads like lights, a radio, the fridge computer.  My 24 volt house bank also supplies my inverter, which I use to run the TV, microwave, etc, and to run the rooftop AC when the bus is running.  It will run the AC unit when the bus is off, but not for long.  I have a switch to connect the house bank to the bus bank.  That lets me run the inverter from the bus alternator, lets the bus alternator directly charge the house bank, lets me boost the start batteries with the house bank, or even lets me fully disconnect the start batteries and run everything from just the house bank.  Very flexible, very useful.  Many excellent reasons to have a 24 volt house bank in a 24 volt bus, and to use a Vanner to supply small house 12v loads, but you have to design it that way to make it work.

A Vanner can be a charger, but it doesn't work in the same way as a modern smart charger does.  A modern three stage smart charger has a bulk stage where the current is limited and the voltage varies, then an absorption stage where the voltage is limited and the current varies, and then a maintenance mode where the voltage is reduced and the current is limited to a trickle charge.  All the Vanner can do is an approximation of the absorption stage, with a constant voltage controlled by the bus alternator, and a reducing current controlled by the increasing state of charge of the house bank over time.

Brian

[richard5933]

I spoke with the folks at Vanner today. Sounds like there would be no problem using a 66-100 as a charger, but it's certainly not the cheapest thing in the world. It also doesn't provide any type of smart charger features.

Right now I'm leaning towards having a 12v house battery bank. I will install separate 120v chargers for both the house and chassis battery banks for use when on shore power/genset. The main goal of installing the Vanner was simply to be able to charge the house battery bank while on the road. The only 24v loads in the coach right now are interior lights and water pump, and they will be converted to 12v soon. Lighting will be changed to LED and I'll simply install a 12v pump.

For just over half the price of the Vanner, it looks like I can purchase something like this:
http://www.sterling-power-usa.com/SterlingPower24volt-to-12volt-dc-to-dc-batterytobatterycharger.aspx

Seems to me that this would be a better way to go all around, especially since this will provide smart charging for the house batteries while on the road. From the manual, it looks like it won't pull any current from the chassis batteries unless the alternator is providing charge, and in many ways sounds like the Xantrex Echo Charger but on steroids.

Thoughts?

[buswarrior]

Do you have any of this equipment yet? If not...

A Vanner Equalizer is not the first thing I would buy as a 12 volt house bank charger.

That isn't their purpose, even if it "functions" It gets used as a power supply in buses, not as a charger. As already written, it will make a pretty dumb charger. Dumb = abusive to your batteries, compared to the other marvelous options available.

The coach alternator quickly goes to minimum voltage after a start, as the start batteries are effectively fully charged. the house batteries get half of that... mess with the regulator, and you start boiling the starts in a feeble attempt to charge the house.

You have a big alternator already, why not access all that available power and design the house bank to that voltage?

Or, if committed to 12 volt, why not add a proper externally regulated alternator and smart regulator to the engine?

Lots of ways to do this without complicated and perhaps uncharted area using a Vanner EQ?

happy coaching!
buswarrior

[richard5933]

Do you have any of this equipment yet? If not...

You have a big alternator already, why not access all that available power and design the house bank to that voltage?

Or, if committed to 12 volt, why not add a proper externally regulated alternator and smart regulator to the engine...

Haven't bought anything yet...

I'm definitely leaning against the Vanner. Not smart enough to charge the house batteries properly.

Definitely want the house batteries to be 12v. Everything we're going to run is 12v, so it makes no sense to have a 24v house system - we'd still need a Vanner to supply the 12v devices.

Right now that leaves me to figure out how to charge the house batteries while driving. Unless there is a pre-made kit to add a 12v alternator, that is out. I'm not ready to engineer something like that right now.

Which is why I'm leaning towards the 24v-to-12v battery charger. I linked to the Sterling one earlier. It looks like it would provide up to 70 amps for the 12v house system as long as the bus alternator is running.

Any one have experience with one of the 24v-to-12v battery chargers like the one I linked to?

Or, does anyone have photos they can post that show how to safely mount an auxiliary 12v alternator to the 8V71? If it can be done with off-the-shelf parts I might be up for that.

Richard
1974 GMC P8M4108A-125 (Current bus)
1964 GM PD4106-2412 (totalled Sept 2017)
Located in beautiful Wisconsin
KD9GRB

[bevans6]

I think the reason Vanners are so ubiquitous in the hobby bus world is that they usually come for free with the bus, or are obtained very cheaply used.  I think the reason most people with a 24 volt bus lean towards a 24 volt house bank is so they can charge it for free from the bus alternator, so they can run a 24 volt industrial sized inverter with reduced cable sizes, and because they already have a Vanner for free.  Carefully analyze your downstream power needs to make sure you don't need a 24 volt inverter.  If you don't, then a 12 volt battery bank starts to make a lot of sense.  Adding a second alternator for your 12 volt house bank can be the cheapest way, but your DC to DC chargers look well thought out.

As stated earlier I personally went with a 24 volt house bank, for two killer application reasons.  One is I use a large 24 volt inverter to run my air conditioner while driving, powered from the bus alternator.  The second - and it's saved my wallet big time several times - is that I can run my bus off the house bank if I lose a start battery (which I did) and I can use the house batteries to boost the start batteries when it's cold out and the engine is hard to start.  Those two applications make a 24 volt house bank mandatory for me.

[sledhead]

when I 1st built the coach I set the house system bank 12 v and it worked ok but it was a big drain on the batteries when I was using the inverter and it took a lot longer to charge the 12 v bank . when it was time to change the batteries I redid the system to 24 v for coach and 24 v for house and a new hybrid inverter
and added a 24 v to 12 v converter for all the 12 volt stuff and in amps it was not much

1000 times better

dave