All,
I have an unknown drain on the coach batts when all is shut down. Not sure where it is but it slowly pulls the coach batts down. I try and charge the the starting batts and coach batts when the coach is in storage with a Battery Minder. I've found the starting batteries will "top off" but the coach batts never reach full charge. I am charging both sets with the terminals still connected.
The starting batts top off and go to float with the terminals connected, the house batts won't due to my unknown draw. I bought the inexpensive negative terminal disconnectors and will install this evening.
My question: with the negative terminals disconnected from the batteries, but the positives still connected, can I charge the batts sufficiently. The unknown draw shouldn't be able to draw with only the positives connected: CORRECT?
Thanks, just checking.

Correct.

Got a little different problem. Went camping in May and all was fine. Begin of July found coach battery dead (step did not retreat). Replaced battery (marine deep cycle 4 years old), next day dead battery again. Back to Wallyworld and they tested the battery, said it had a bad cell, got another one. Went camping and noticed the waterpump running constantly. Acc manual a sign of low voltage. Battery loads and goes dead in matter of 10 minutes. Where should I start? Starting battery/motor cranks fine. Genset runs (used it on the way to run A/C). Camped plugged in shore power.

quote:

Originally posted by Marvin+Doris:
Battery loads and goes dead in matter of 10 minutes. Where should I start?

I would fully charge the battery with a known good charger. Test it with a hydrometer or conductance tester. A hydrometer is cheaper, but many battery sellers have a conductance tester or a load tester. I am not in love with automotive load testers on deep cycle batteries, but they do tell you something.

You should have a hydrometer, anyway.

Once the battery is verified good, let it sit disconnected for a day and verify that it stays charged.

Then, check the drain with an ammeter. A round automotive dash ammeter with clip leads should be good for the heavy drain you seem to have. I fear your drain might be too much for a multimeter.
Once you are reading the drain, remove the fuses one by one until an observer tells you that the drain is stopped. Then, work through that particular circuit, looking for shorts to ground or something really draining. You might need to disconnect things one at a time. A clamp on DC ammeter can be handy for this. The genset could have a drain from a stuck contacter. The step might have its own fuse in line. The water pump might also. Perhaps disconnecting the step will tell you something.

Does the genset start from the coach batteries or from the starting battery?

Welcome to the forums!

Almost always from the coach batteries.

Does the genset charge the coach batteries when it is running?

Just bought our 1990 Barth special built. I came with NO manuals.

It was originally a mobile computer lab for a local school district but those went out of style many years ago and I just bought it for a mobile command center for my police dcepartment.

ANY assistance is appreciated.

Genset charges the coach batteries, but not the engine battery.

The Barth commercial coaches were even more customized than the motorhomes, so there is likely nothing typical about your unit.

Best to take photos, because members here own coaches with a variety of origins, and somebody may be able to figure things out.

I would like to add we found the problem: the round 80 amp breaker was defect, we replaced it with a new 100 amp one and all is fine now.

One step often missed is to disconnect the positive connection then check that connection to ground for ohms. If you are lucky the ohms will be high enough to indicate loads that should not be on line normally. If it is 1 or less ohms you are left with tracing the coach wiring diagram or opening a disconnect, my option. I ran out of intelligent things to do or find so I just disconnect the starboard bank from its load when on the hook.

Going to a larger breaker could deprive the wiring of proper protection. This would depend on wire size. An overload that would pop an 80 amp breaker might overload your wiring and cause it to melt or start a fire without popping the breaker.

I'm gonna take a wild guess and say that Barth sized the breaker properly for the wires.

quote:

replaced it with a new 100 amp one and all is fine now.

Is that something like putting a penny in the fuse socket?

Guess so, but the 80 AMP is no longer available (unless TJ sends me his old one

quote:

Does the genset charge the coach batteries when it is running?

Typically, unless equipped with a transformer (Onan QD) or alternator (Kohler or Onan DKD), the GenSet itself will not charge the batteries, the AC to DC converter or Inverter/Charger it is powering will maintain the batteries. I moved my GenSet DC source to the Chassis batteries just in case I screw up and run the house batteries down.

Same here; the Honda has a charging coil that will replace the power it uses from the chassis battery. The Honda's designed to run off its own battery; I have one installed that is the emergency source.