Unusual Electrical Issue With Dead Starter Battery

[marklg]

I had an unusual electrical issue in my 2007 Great West on a 2006 Chassis. After sitting for some time, the starter battery was very dead. I attempted to use my boost switch that provides 12V from the house batteries to the original solenoid connecting the house battery circuit to the starter battery circuit. I have installed a Sterling B2B to charge my LiFePO4 from the engine. Both are not used at the same time.

I turned on the boost switch but no current was flowing. All of the electrical devices on the original house battery panel were not working. The B2B, solar charge controllers and inverter that I wired up were all working fine. I charged the starter battery, not an easy feat as the voltage was so low the charger had to be started on the 6V position, then switched to 12V after a while. After the battery was charged, the rear appliances and the air ride compressor still would not work.

I came back a couple days later, and tried to see what was working and what wasn't. As part of that, I ran the generator, part of the original installation. After that, everything was working. I did no repairs.

The original 12V house system is somewhat of a mystery. I know what I added, but don't have any info on the original system. For example, there is a resettable breaker under the vehicle and I have no idea what it does. It is quite rusty. The wiring is substandard, thinner than it should be and with poor connections, but I don't see any specific issues. In the past, a bad house water pump caused a huge voltage drop on the wires without blowing a fuse, so I know the wires are too small. With everything working, there is nothing to troubleshoot now.

Does anyone have any suggestions as to what might have happened. Does anyone know more about what Great West installed originally?

Regards,

Mark

 

[ECU]

Two things come to mind about the jumping. Was the house battery also dead (cause of why it didn't work)?
The jump relay is powered by something. It sounds like your's is wired from the starter battery, thus no relay triggering when you really need it. That is the logic behind my wiring of the jump button being powered from the house side of power.

 

[autostaretx]

As a sheer guess: does the generator operate a transfer relay (on the 12v side)?
If so, firing up the genny may have "exercised" that relay, releasing either "stuck" contacts or cleaning their faces.

--dick

 

[Kajtek1]

I am not getting clear picture of the events from the topic, but what I know for sure that battery discharged below 6v should be replaced.

 

[marklg]

Two things come to mind about the jumping. Was the house battery also dead (cause of why it didn't work)?
The jump relay is powered by something. It sounds like your's is wired from the starter battery, thus no relay triggering when you really need it. That is the logic behind my wiring of the jump button being powered from the house side of power.

The house batteries that I installed were fine, charged and running the inverter just fine. I am running the boost relay from the house batteries. It was connected to D+, but when I installed the LiFePO4s and DC-DC converter, I repurposed the relay connections to a boost function, driven by the house batteries as they would not be depleted. I did not check if the relay actually clicked when I hit the switch. The switch is in the back and the relay under the hood and I had no helper.

Regards,

Mark

 

[marklg]

As a sheer guess: does the generator operate a transfer relay (on the 12v side)?
If so, firing up the genny may have "exercised" that relay, releasing either "stuck" contacts or cleaning their faces.

--dick

I am not getting clear picture of the events from the topic, but what I know for sure that battery discharged below 6v should be replaced.

There is a 120V automatic transfer switch for the generator, no 12V transfer switch I know of, but I don't have info on the original system.

I'm worried about it, but it still seems to hold a charge. It is a Napa AGM. I replaced my broken RC charger that can count amp hours and discharge and charge. I can discharge it down to maybe 12V and recharge and see how much capacity that is. I know it is dependent on temperature and rate of discharge, but it should give me some idea. It certainly has enough current capability to run the glow plugs and the starter robustly.

Regards,

Mark

 

[Kajtek1]

There are lot of gizmos who suppose to test battery stage, but none of them will do full test alone.
I have load tester + Solar tester, who test CA electronically. Between 2 of them I can pretty well tell battery stage.
Simple test is observe voltage drop when you turn all the headlights and blower on max.
Now how to test your boost switch is another story.

 

[ECU]

I did not check if the relay actually clicked when I hit the switch. The switch is in the back and the relay under the hood and I had no helper.

Flick your switch and test the voltage at the start battery. It should be up to the house battery level if the relay is hot.

 

[WinnieView1]

Our 12 volt Boost switch is momentary and must be held down the entire time it's needed, luckily it's where MB would have placed the tray slot in the dash below the radio. Most Boost switches will also work in reverse.

 

[marklg]

Our 12 volt Boost switch is momentary and must be held down the entire time it's needed, luckily it's where MB would have placed the tray slot in the dash below the radio. Most Boost switches will also work in reverse.

I installed the boost switch and ran a line from it to the contactor coil in front. I reused the wiring from the contactor to the rear. That wiring I'm not sure of.

Flick your switch and test the voltage at the start battery. It should be up to the house battery level if the relay is hot.

I installed a big red switch in the back but I could see no current being provided by the house batteries. I could recheck now to see if that path is working again.

I installed the stuff on these two pages and they continued to work.



This is made up of the original wiring. I'm not 100% sure of it. I'm starting to suspect F9 and F10. They are rusted and unreadable, so I don't really know what they are. If they opened up, that would cause my problem, but they normally should reset quickly.


Regards,

Mark

 

[ECU]

I have had the reset-able fuses go bad.