Battery Charger - 12V to 24V

[Oonrahnjay]

    The diagram above shows my battery setup (two Type 31's, in series to give 24V).  The two main battery cables (on the left side of the diagram) go to a master disconnect switch.  Is it OK to attach a battery charger as shown, without removing the series connector cable?



    This diagram show a "Y" arrangement for the wiring from the battery charger.  The series connector has been removed.  Will this work to allow both batteries to be charged at the same time?

     All comments appreciated.  BH   NC   USA

[Lin]

Looks to me as if you have essentially changed the batteries from series to parallel.  In that case, a 12v charger will work for both.

[buswarrior]

Both pictures appear to be correct.

On the top one, you may also move the charger to the other battery,  once the top one is charged, observing proper polarity.

You may also employ a second 12V charger, and connect one each to each battery, observing proper polarity, and works fine.

Busnuts will always find other things to deploy a battery charger to, seems you can't really have too many of them around...

happy coaching!
buswarrior

[Lee Bradley]

I would charge them separately. Connected to gather as shown a weak battery will draw down the system.

[Oonrahnjay]

I would charge them separately. Connected to gather as shown a weak battery will draw down the system. 

     Thanks, Lee.  That's the kind of "warning" info that I was looking for.  Appreciate it.  BH

[Jeremy]

I would charge them separately. Connected to gather as shown a weak battery will draw down the system.

Not sure I understand that - a weak battery will draw down the system during charging? To my thinking, even if one battery is flat and one fully charged, connecting them together in parallel gives a total 'amount' of charging required which is identical to the sum of charging each battery separately. I may be wrong though.

BTW, In the first illustration I'd want make sure the main disconnect switch was disconnected. I'm not entirely sure what difference it would make, but it seems better to remove the complication of external circuits and loads

Jeremy

[PSmith]

One little word of caution.  Sometimes(most) the Battery Charger wiring (internal) will have the negative side connected to the case of the Charger and this will cause some surprises.

I found a Marine style charger/maintainer that has 2)two separate sets of output cables that allows you to charge both batteries at the same time without worrying about interconnections.  The outputs are completely isolated from each other and are both independent. The charge rates are small at 3 amps each, but work well for keeping the engine/starting batteries happy and healthy. The Charger is of the 3-stage variety and I have it permanently mounted in the battery bay.

just my way

[Oonrahnjay]

(snip)  I found a Marine style charger/maintainer that has 2)two separate sets of output cables (snip) 

      Sounds perfect.  Brand/model/model number please?   Thanks a lot!

[robertglines1]

Source : marine battery charger   I got mine from bass pro shop.   Has 4 charging stations (I have 4 group 31's) maintains each individual at full charge then shuts that circuit off.  been using last 3 coaches.   15 yrs.  will let you know when one of 4 is getting weak(charging light stays on constant)  10 amp per circuit.  Bob

[Oonrahnjay]

Source : marine battery charger   I got mine from bass pro shop.   Has 4 charging stations (I have 4 group 31's) maintains each individual at full charge then shuts that circuit off.  been using last 3 coaches.   15 yrs.  will let you know when one of 4 is getting weak(charging light stays on constant)  10 amp per circuit.  Bob 

      Sweet!  Thanks for this info, there's a BPS just down the street from my bus shop.

[PSmith]

trying to find the invoice for the charger-

I'd look at the unit - but the bus is in the paint shop 125 miles away  

sounds like you already have a good lead from robert's post.

[PSmith]

I do remember the brand - it was Guest.

has worked great for 5 yrs. for what its worth

good luck

[stevet903]

I have one of these permanently mounted in the battery compartment - you can charge 2 12V batteries or combine the outputs to a single 24V output.  I have 4 batteries so I combined the outputs to a single 24V.  I've had it for 4 years and no problems!!

http://www.marinco.com/product/10-amp-dual-battery-chargepro-charger-0

They also make a 3 and a 10 amp dual charger.

http://www.marinco.com/productline/battery-chargers

[buswarrior]

For a busnut on a budget, there is no need to buy anything more than one inexpensive 12V automatic battery charger, and swap it around your various 12 volt batteries, without disconnecting anything.

Yes, the fancier chargers are terrific, and convenient, but I wouldn't want a newnut thinking they have to spend money on one of those early in the process. Lots better stuff to spend on at that point!

Also, a warning: A battery charger, in this day and age, that has the case connected to the output when we darn well know the vehicle body is grounded to the battery is dangerous and should be banished. I'd suspect some unauthorized modifications, a failure, or unintended use, might be in play?

I am assuming that the original poster is wanting to perform battery charging for maintenance purposes in a storage setting, as opposed to using the charger to supply loads in an operational setting.

If there will be loads applied while charging, then there are issues of imbalanced consumption, and the potential to harm the uncharged battery portion, unless you appreciate what you are doing to the battery bank as a whole and swapping connections in a timely manner to keep things closer to balance. That is a more complicated issue.

Unfortunately, there are thing$ to do with battery maintenance that have taken on mythical proportion$, which u$ually lead to more money being $pent than nece$$ary.

In a storage setting, for maintenance purposes, as long as there is 12 volts worth of battery between the two alligator clips, that's all the charger will worry about, and it will do its best to charge that 12V worth of battery.

When the charger indicates it has done its job on that portion, then move on to the next 12V worth of battery and repeat.

When funds allow, you may also put a second inexpensive charger into use on another 12V worth of battery at the same time. They don't even have to be identical, as they just work away at their own portion of the bank until done. You can also plug them both into the same extension cord without tripping the circuit, which is nice.

happy coaching!
buswarrior

[Oonrahnjay]

(snip) I am assuming that the original poster is wanting to perform battery charging for maintenance purposes in a storage setting, as opposed to using the charger to supply loads in an operational setting.   (snip) 

      Yes, exactly.  Sorry I didn't make that clear in the beginning.  Thank you all for comments, I guess i was on the right track but it's good to have confirmation from the more experienced.