Charging inverter batteries off the alternator

Hi,

The most I've seen was 14.6 from the alternator. 13.9 take a heck of a long time to charge depleted house batteries--which is what is happening here (I think, the OP has not told us what the "fault" is for the inverter.)

More usually I see 13.2 to 13.4 in warm temperatures. That gets us down to as low as 12.5--in which case the house battery bank will never EVER fully charge.

I do see 15.4 (throttled to that level) from my Blue Sky solar controller.

wolfe10 wrote:


Said another way, the alternator may be putting out 14.9 and the batteries ("downstream" of the diode-based isolator) receive 14.2.

Hi Ronnie,

The isolator is unlikely to damage the inverter.

The OEM charging circuit for my "house" battery bank was fused at 60 amps. I replaced that fuse after the third failure with an automatic circuit breaker and added a 2nd charging path. I used continuous duty solenoids that draw 0.88 amps each when they are active.

Nascarcruzin wrote:
Pianotuna, would you recommend I disconnect the battery isolator to prevent any damage to the inverter?

the'bird' is a known headache
with failing boards and failing relays
there is a very good chance, that your house batteries charging problem is located at or related to the bcc/bird

Wolfe10, yes I have 2 sets of batteries, one cranking and one for the house/inverter. Like I said earlier, I am sure it was hooked up that way when it was new but I bought it used in 2009 and it was not working when I bought it.

i have to ask why it took 4 yrs to decide to fix the problem
this bcc charging issue has been discussed many times

house batteries Not charging is a routine question that pops several times a week

I had this problem and cured it in a very simple way. I hooked up a set of jumper cables from the house batteries to the chassis batteries while driving and un-hook them when not moving. Problem somewhat over. I had returned my inverter 3 times without success and the only thing I needed it for was to charge the batteries----it is now disconnected.

Nascarcruzin, you are correct, your rig originally used either the RV-CP or Intellitec BCC box that has the circuitry (called a Bi-Directional Relay Delay {BIRD} function) that controls the battery isolation/charging from alternate sources. (i.e. alternator or converter)

Your problem may be either the above referenced circuitry or the solenoid the circuits control.

QUESTION - Does your aux start function work? Pressing, and holding, the aux/emrg start switch should pick that same solenoid, which would give you a clue as to where the problem lies.

Now, just for clarification, the charging path is not the same path that the inverter uses to draw current from the batteries (unless it's wired incorrectly). You don't need a solenoid with much more than 150 amp continuous contact capability. Do make sure that the solenoid coil is rated for continuous duty, and I prefer using a 14volt rated coil.

If you locate the BCC box and need further troubleshooting documentation, just PM me. Good luck

Thanks Wolfe10, I will try your suggestions.

mena661 wrote:
I'm confused! You have an inverter fault but your fix is to make the alternator charge the house batteries?

If you will read ALL the posts you will understand!

I'm confused! You have an inverter fault but your fix is to make the alternator charge the house batteries?

Start at the alternator. Trace the large (usually red) B+ wire-- it will go to the battery isolator. Is the isolator a solenoid or a large rectangular device with aluminum fins (diode-based isolator)?

Let us know and with a simple voltmeter we can walk you through troubleshooting your system.

Wolfe10, yes I have 2 sets of batteries, one cranking and one for the house/inverter. Like I said earlier, I am sure it was hooked up that way when it was new but I bought it used in 2009 and it was not working when I bought it.