keeping batteries charged up

[82 MCI-9]

I just bought two new batteries about 3 weeks ago and was wondering what everyone else uses to keep them charged up? What are some good chargers out there that you would trust to just leave them pluged in all of the time to maintain the batteries. I was looking at one that is called the batterie tender it is just a trickle charger that turns itself on and of accordinglly to the batterie charge. I'am tring to eliminate someone forgetting to plug them in    Thanks for your help and advice Robert

[Buffalo SpaceShip]

I bought an automatic battery tender from NAPA for my genset batt. About an amp, I think. Cheap enough. I also saw some Schumacher unit at WalMart the other day. It has these quick disconnects that could be handy for an RV application. 6-12v only, though.

So if you have a 24v system and no equalizer (like myself), the start batts would require a 24v charger/ maintainer from somewhere like Battery Stuff if you want "set and forget" functionality. A 24v inverter/ charger could be set up to charge both house and coach banks, as well.

HTH,
Brian B.

[gumpy]

My bus is plugged in when parked. My inverter/charger is on float, and the crossover relay is always on, so my coach batteries are always on float with my house batteries. Works for me.

[Ace]

Craig when your bus is parked and plugged in how did you wire your start batteriesw into the inverter? Mine is always plugged in here at the house on a 50 amp service and would like to keep the bus batteries charged as well!

Do you have a diagram of the wiring?

Thanks

Ace

[gumpy]

Ace,

I don't have a diagram, but I can describe it. It's pretty simple.

I used a 200 amp relay out of a bus air conditioning system to connect the two. It's simply a 4/0 wire running from the house battery disconnect switch to the relay, to the coach battery disconnect. I have a manual toggle switch for now that activates it the relay. One side of the coil goes to ground, the other side goes to the switch and to 24 volts.

Effectively, I'm just adding the coach batteries onto the house batteries in parallel. Same voltage on both banks.

In the future, I will modify the toggle activation switch so it will deactivate the solenoid if either the coach or house battery disconnect switch is turned off. I also want to put a switch in the cockpit for convenience.

Here's photo of the relay when I was installing it.
http://www.gumpydog.com/bus/MC9_WIP/Electrical/Battery_Rack/040522.07.crossover_relay.JPG

I only have the house side connected here. I don't think I have one online of the coach side yet.

There are more photos at http://www.gumpydog.com/bus/MC9_WIP/Electrical/Battery_Rack/battery_rack.htm, near the bottom of the page.

[Ace]

Thanks Craig! Since i'm removing the a/c unit from my H3 I'll se if there is anything i can use like this relay thing!

I might not get it done right away but it would be a nice feature to have in the future!

Thanks again... and stay warm up there! 

Ace

[Lee Bradley]

Since my Neoplan is in the process of being gutted for conversion, it does get run enough to keep the batteries charged. I bought a marine three stage charger; it has two 12 volt, up to 5 amp outputs with each battery voltage sensed, the outputs can be connected to one battery for up to 10 amp output. Being a sealed marine unit, I mounted it in the battery compartment and wired it to the batteries after I removed the batteries for a good cleaning and scrubbed the battery tray. Cleaned the posts and terminals and did a little cable rerouting in the battery box. System voltage is now showing just over 24 volts when I turn on the switch.

[H3Jim]

24 volts is still under 50% charged, which is the very lowest you want to let a battery discharge.  Start batteries are not designed for deep discharge and should probably be maintained at 25 volts or higher.  Below is a table of % charged vs volts, one column for 12 volt batteries, the other for 24.

% charge   Volts   Volts

100%    25.44    12.72
90%    25.20    12.6
80%    24.96    12.48
70%    24.60    12.3
60%    24.36    12.18
50%    24.24    12.12
40%    24.00    12
30%    23.64    11.82
20%    23.40    11.7
10%    23.16    11.58

[sailerman]

 I do not run my engine enough to keep my batteries charged.  I used a 24 volt battery charger from NAPA hooked into shore power, and put it on a timer to come on for an hour each day. Even though it’s a three stage charger it was would charge more than the batteries need. I used to have to add water every 6 to 8 months. After putting the charger on the timer I have not had to add water for a year. I also wired a DC voltage meter to check battery voltage into the battery compartment, with a switch to push to test.  This has been very handy in checking on the condition of the batteries, and as an add bonus when the engine is running you can check the charging voltage at the batteries from the alternator easily.
 
  sailerman  NJT 6236