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Foretravel Motorhome Forums => Foretravel Tech Talk => Topic started by: WS6_Keith on June 26, 2024, 10:19:57 am

Title: No [not chassis, HOUSE] battery power at inverter
Post by: WS6_Keith on June 26, 2024, 10:19:57 am
It's been hot in Vegas for the last week or so.  109 is the high today.  I run two 10k BTU portable A/C's plus two circulating fans in my coach to try to keep the load off the roof A/C's, which are set to come on at 90*F.  The portables are set to 75*F, to get ahead of the heat.  The coach is plugged in to my shop, which also has A/C's and the pool pump runs from it.  Monday, all the load popped the breaker and the coach started running on the inverter.  The roof A/C's don't run, but the fans and portables kept going.  Got home and it was about 100*F inside.

Reset the breaker and shore power is restored.  I noticed that the Xantrex is reporting that it's only charging 1amp and the dash cig lighter is showing 12.8V.  I checked the Victron BMV-712 and it's showing -1amp draw, not charging.  I discovered that there is not 12V at the end of the cables from the house batteries to the inverter.

I checked continuity across the 350A fuse in the front bay, curb side, and it's good.  Have not yet got to the batteries, and did not have a ground to check for voltage at the fuse, I'll get to that tonight (in the 105*F it will be at 8pm).  The BMV-712 shunt is showing proper voltage, so I don't think it's a battery or connection issue.

My question is, what else is in-line between the batteries and inverter besides the fuse?  The schematic in the owners manual doesn't show anything else.

[Edited topic title - Michelle]
Title: Re: No chassis battery power at inverter
Post by: craneman on June 26, 2024, 10:25:22 am
Continuity might not show that the fuse isn't passing load. I spent 2 days last year trying to find the same issue and it turned out to be the fuse.
Title: Re: No chassis battery power at inverter
Post by: dsd on June 26, 2024, 11:28:57 am
Back to the basics. This is in the no start category for me. I still like using a test light bulb with two leads and clips at the end. If you put across a cable that is good, light bulb out. Go across a resistance or open and it lights up. Dont forget this could also be a ground issue too. Keith dont forget I have that DC clamp on amp meter if you need it. We are leaving Saturday to North Carolina though and its part of the coach tool kit
Title: Re: No chassis battery power at inverter
Post by: WS6_Keith on June 26, 2024, 05:48:17 pm
Thanks guys, I'm suspecting the fuse as well.  It was the only thing I saw that it could be.  I'll pull it out tonight and look it over closer.  I should have a spare and don't.  Anyone know where to get this 350A thing?
Title: Re: No chassis battery power at inverter
Post by: Pamela & Mike on June 26, 2024, 06:08:03 pm
  Anyone know where to get this 350A thing?

I would check Digi Key, Allied, or Dell City. There are several styles so the one you have could be different than ours. So in other words it is a Easter egg hunt but those electric supply companies will have them.

Mike
Title: Re: No chassis battery power at inverter
Post by: Michelle on June 26, 2024, 06:51:35 pm
My question is, what else is in-line between the batteries and inverter besides the fuse?  The schematic in the owners manual doesn't show anything else.

Noting that you're asking about chassis batteries, unless you have something like a Trik-l-start or other added charging relay, or are using the boost switch, the OEM Xantrex inverter/charger and wiring in a 2003 does not charge the chassis batteries, only the house ones.

If you don't have the OEM setup, the above may not apply.
Title: Re: No chassis battery power at inverter
Post by: WS6_Keith on June 26, 2024, 06:53:39 pm
From a bit of searching, it looks like the fuse is a Class T format, 350A.  My Xantrex inverter is supposed to provide 3000w continuous and 6000w peak.  At 12V, that's 250A/500A.  It could never produce the peak with this fuse in place.  Should I be considering getting a higher amperage fuse?  I assume the fuse is really there to safeguard a dead short during an accident or something similar, so it would pop a 500A as easy as a 350A, but under load, you wouldn't pop a 500A as easy as that 350A.  I've had this thing 3 years and this is the first issue, but I don't want to repeat it either.  The fuses look to be around $75ish.
Title: Re: No chassis battery power at inverter
Post by: WS6_Keith on June 26, 2024, 06:54:49 pm
Noting that you're asking about chassis batteries, unless you have something like a Trik-l-start or other added charging relay, or are using the boost switch, the OEM Xantrex inverter/charger and wiring in a 2003 does not charge the chassis batteries, only the house ones.
You're right.  Edited.  HOUSE batteries.
Title: Re: No chassis battery power at inverter
Post by: Michelle on June 26, 2024, 06:56:58 pm
You're right.  Edited.  HOUSE batteries.

I've edited the topic title  :D
Title: Re: No [not chassis, HOUSE] battery power at inverter
Post by: Pamela & Mike on June 26, 2024, 07:34:12 pm
Should I be considering getting a higher amperage fuse? 

Keith,

Look at the size of your cables, Will they handle that many amps?  If not then the cable will become the fuse if you put in a larger size fuse.

Mike
Title: Re: No [not chassis, HOUSE] battery power at inverter
Post by: WS6_Keith on June 26, 2024, 11:49:37 pm
The fuse is definitely the issue.  I ran a wire from the ground to my meter and then probed both sides of the fuse.  Input has 13.04V, output had 12.6, then started dropping.  Still being connected to the inverter at the other end, I'm guessing there was a charged capacitor back feeding some voltage.  It's 0V now and shows no continuity.

Those cables are 3/0.  I'll just stick with the 350A fuse and get a spare. 
Title: Re: No [not chassis, HOUSE] battery power at inverter
Post by: WS6_Keith on June 30, 2024, 12:58:21 pm
Replacing the fuse seems to have put everything back in working order.  The old one does show discoloration indicating it's been hot, maybe that was part of the issue.  No idea how old it is, it could be original for all I know.

Title: Re: No [not chassis, HOUSE] battery power at inverter
Post by: craneman on June 30, 2024, 01:44:56 pm
I spent 2 days trouble shooting the blown fuse issue and should know do the simplest things first. I even ordered 2 spares after that.
Title: Re: No [not chassis, HOUSE] battery power at inverter
Post by: WS6_Keith on June 30, 2024, 06:43:20 pm
I have added a spare to my stash as well.  I'm slowly catching up to DSD with the "spare coach in the coach" plan.
Title: Re: No [not chassis, HOUSE] battery power at inverter
Post by: dsd on July 01, 2024, 01:19:10 am
I have added a spare to my stash as well.  I'm slowly catching up to DSD with the "spare coach in the coach" plan.
please send me a link to the fuse. I don't want to be left out without one.
Title: Re: No [not chassis, HOUSE] battery power at inverter
Post by: WS6_Keith on July 01, 2024, 01:36:22 am
please send me a link to the fuse. I don't want to be left out without one.
Haha!  Here you go Scott:

Amazon.com: Blue Sea Systems 5120 FUSE A3T (CLASS T) 350-AMP : Tools & Home... (https://www.amazon.com/dp/B000MMH1J4?ref=ppx_yo2ov_dt_b_product_details&th=1)
Title: Re: No [not chassis, HOUSE] battery power at inverter
Post by: Michelle on July 01, 2024, 09:14:13 am
I have added a spare to my stash as well.  I'm slowly catching up to DSD with the "spare coach in the coach" plan.

 :coffee:  *wondering how to create a usable "spare parts by generation" info repository...  need more  :coffee:  *
Title: Re: No [not chassis, HOUSE] battery power at inverter
Post by: WS6_Keith on July 01, 2024, 10:25:35 am
:coffee:  *wondering how to create a usable "spare parts by generation" info repository...  need more  :coffee:  *
Some of the basics would be: