Why do I keep murdering start batteries?

[belfert]

It looks like my start batteries are shot again.  This will be the fourth set in four years.  How do I stop murdering these things?  It gets expensive at $350 per set.  I doubt I would make it to Bussin' 11 with these batteries without resorting to the generator and a charger a few times.

I tried to start the bus last weekend and the batteries were too weak to start it.  I hooked up my Battery Tender plus that does 2.5 amp at 24 volt.  I ran that for a week.  I started the bus yesterday and it barely started even after charging for a week.  This morning the voltmeter was showing 16 volts even though I pulled the disconnect yesterday.  I hooked up my 24 volt charger and got the bus running today.

The alternator appears to charging as the voltmeter shows almost 28 volts when running and a digital multimeter shows 27.8 volts.  Now, the disconnect does not disconnect everything.  The turn signals, DDEC, passenger clock, and some other items get juice no matter what.

[HighTechRedneck]

Do you have anything maintaining their charge in between uses?  Either a maintainer or manually checking and charging them monthly?

[Len Silva]

Brian,

To begin with, that little charger is not going to anything if the batteries are too low to begin with.  It is intended only as a maintenance charger to keep good batteries topped off.

[gumpy]

.. Now, the disconnect does not disconnect everything.  The turn signals, DDEC, passenger clock, and some other items get juice no matter what.

I think I'd be looking at those "some other iterms" to see what's draining your batteries. Don't trust your disconnect, either. I've seen them leak when shut off. Test it.

Is  your bus 12v or 24v?


One of my starting batteries now has a bad cell. It's been installed for 8 years.  I had to replace the other one in spring 2009.  It came with the bus in 2000. I keep
them on float from my inverter when parked and plugged in. Seems to work well for my batteries.

craig

[bevans6]

What kills start batteries is a slow trickle discharge.  You need to store them fully charged and have a maintainer charge on all the time, or routine recharges every month or so.  Pull the ground cable off when you store them, that should stop the discharge.  Put couple of decent smart 12 volt chargers on and see if you can get them to recover - a week or so with a 10 amp charger smart charger may do wonders.  I had both my start batteries discharged almost to zero, and I was able to recover them both.

Brian

[belfert]

Do you have anything maintaining their charge in between uses?  Either a maintainer or manually checking and charging them monthly?

System is 24 volt with a vanner for 12 volt stuff.  I normally have a 2.5 amp Battery Tender Plus connected.  There was a period of about a week or so recently where I didn't have the charger plugged in and the bus wouldn't start after that week so I plugged the Battery Tender in and left it for a week.  The bus barely started yesterday.

I suspect the batteries are shot now as the bus sat for under 24 hours from yesterday to today and the voltage dropped to 16 volts or less.  The bus sat out in the desert for three days last month and it started just fine after three days with no charger.  Now, the bus had been driven more or less continuously for 2,000 miles prior to sitting for those three days.

[robertglines1]

Brian look for a separate switch for your ddec and other 12 volt needs.I have one on the 89 prevo in the top of the back bay close to the vanner..I use a set up like in a bass boat to maintain batteries has 4 separate 10 amp on demand chargers that charge batteries as needed individually.. my batteries last about 6 yrs without a problem.using 4 ea series 31 batteries 54$ each from local supplier:definitely not the high end batteries. add a total system batt disconnect switch to isolate batteries altogether..Bob

[belfert]

I should have plugged in my Battery Tender Plus as soon as we got home, but I didn't.  It is a pain to run an extension cord back there after every time the bus gets used so it doesn't always happen right away.

I really need to get an outlet installed for the charger so it just works any time the generator is going, or any time the bus is hooked to shore power.  Will it hurt to run the charger while the bus is running?

[robertglines1]

on some systems it will confuse voltage regulator if hooked up when running and you will get generator warning light on.try it

[Lin]

You could use a solar battery charger for float and save the effort of bringing out the cord right away.  However, it does seem that there is a load taking the batteries down.  I could leave mine for several weeks easily, and they still crank.

[belfert]

Brian look for a separate switch for your ddec and other 12 volt needs.I have one on the 89 prevo in the top of the back bay close to the vanner..I use a set up like in a bass boat to maintain batteries has 4 separate 10 amp on demand chargers that charge batteries as needed individually.. my batteries last about 6 yrs without a problem.using 4 ea series 31 batteries 54$ each from local supplier:definitely not the high end batteries. add a total system batt disconnect switch to isolate batteries altogether..Bob

What kind of supplier has group 31s that cheap?  Sam's Club charges closer to $100.  The cheapest I have found is at a local heavy truck dealer for about $80 each.  Even the $80 ones only have a 1 year warranty.

I'm pretty sure there isn't a second switch.  The manufacturer wants that stuff to stay powered.

[eddiepotts]

belfert, My batteries won't last 3 days from my drains I have. I keep a 1/2 wrench next to my batteries and disconnect them when I park. I do not have a 24v charger so I use my 12v smart charger and jumper cables to charge both batteries at one time. I have let my bus sit a month and it starts up just fine when I get back to it. When I bought the bus my alternator did not work. The PO had a 24v charger wired in because he always ran the genny. It is an entertainer. But even still I could drive the bus for about 2 days before I would have to charge the batteries. When I would stop for the night I would just hook up the charger to the genny and be good a couple of more days. I just had the alternator rebuilt the other day so I hope that is over.

[Busted Knuckle]

Brian we've been also experienced the same problem with our Dina draining the batteries while parked for any more than a week even with the disconnect turned off!

While trying to find/fix the problem we've discovered Dina did some weird S**T with the way they set up the batteries and shut offs!

Because of their mixed voltage set up they needed more amps than the vanner supplies at the 12 tap so what they really did was basically a center tap between the tow 12 volt banks! But they have many small 12-18 gauge wires tied into where these hook up on the coach which literally makes it impossible to  shut the power off completely!
I found this out when I thought I'd be slick and put a disconnect in the main ground cable. Wrong still connected through that center tap and all the little grounds still feeding the chassis system!

Now what I saw about two weeks ago on on of Carl's Dina's was he took out the 4 group 31's took the sheet metal battery box cover and cut the back half off. (took the hinged lid off, and cut the small piece still left at the back inside {toward engine} wall and then cut it loose around the back side toward the rear of the bus out) Then took and slid an 8D in the opening and toward the front of the bus and then the second 8D slides straight in the new cut out! Used one of the original wooden block hold downs in between them to secure them and put MCI (knife blade) style battery cut off switches in line on 12V tap and the main 24 positive connection. Seems to work!

Evidently I'm seeing that this "phantom draw" is a common problem on a Dina after some time and Carl has literally owned 30-40 of them over the yrs! So if Carl believes this is the best way to eliminate it, I sure ain't the one to argue with his experiences! ( I plan to duplicate his set up on ours in the near future! In the main time we make it a point to start all the buses at least once a week and let them run about 10 mins after starting them before shutting them off!)

FWIW  BK  

[Ed Hackenbruch]

I have 2 group 31's for my start batteries, (5A-8V71) they only get charged off of my 24v alt. when running down the road. They are 4 years old, i don't use the disconnect switch, (probably should) and have never had a problem firing up. We just got to Yuma a little over a week ago and i will probably not start the bus again until the end of January if we go up to Quartzsite. If not then it will be either April or May when we leave. My last set of batteries were 8D's which were 8 years old when one died. I guess i am lucky.

[Ace]

Prevost is the same way. The 24/7 current from a phantom drain killed my 4 group 31's every year for the first 3 years until I talked to my buddy Nelson about what they do for this problem and since he advised me to simply install a 24 volt on-board marine battery charger. The best 200 bucks in the whole conversion. Keep in mind my bus stays plugged into my 50 amp service and after I get back from any trip, I plug the bus up and then plug my charger in the outlet in the bay and it stays on until I leave. I never keep it plugged in while the engine is running. It will overvharge if the genset is running. Ever since float charging my batteries, they stay fully charged a lot longer and all my lights are brighter!
That or just run the bus more often.