Good battery dying regularly

I could use some help here. 2007 144 low roof. Was a panel van that with the amazing help of this forum I have slowly converted. Here's the problem. When the van sits for a week (not my daily driver) the battery is getting run down and making it tough to start. I had the battery charged on a trickle charger and then tested and it looks good. I know it has to be one of 3 things; starter, alternator, or electrical problem. As I was converting the back and before I had read up on the canbus system I pulled out the rear dome and sliding door lights (I have LED's on a backup battery system) and clipped the terminating resistors. I am wondering if it's possible I have an open loop problem and am losing power because of my mistake. Thoughts? I plan on testing voltage across the battery when running to test alternator but currently can't get it started.

-Noah

Craves_Waves said:

I had the battery charged on a trickle charger and then tested and it looks good.

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When you say that you've "tested", what exactly does that mean? Have you taken specific gravity readings with a hydrometer after letting the battery stabilize for some time after coming off the charger?

Please elaborate.

Hey vertigo, by tested I mean I took it to Les Schwab, had them trickle charge over night and then they tested it. I believe that is the method they used but am not certain. They were able to tell me that the cells were still 80%+ good so I assume they checked the cells. Additional info, the alternator light does not go on when I am driving and after a long drive it appears to be charging because after sitting overnight it will crank right up.

There have been a few other electrical anomalies such as right rearview mirror indicator going out (I assume turn signal relay) and the dome in front went out after having just been replaced.

Then there is the infamous Y cable.

Measuring charging voltage while under way..........spec would be about 13.9 to 14.2.

If the Y cable has an issue charging voltage might be 13.0-13.5. Testing is the best measure.

There are several post dealing with the issue. It is the battery cables from the positive battery to the alternator and starter.

You are correct besides the Y cable the general battery condition, alternator, parasitic draw ( key off drain) even dirty battery terminal and loose or dirty ground cables ( both chassis and engine ground) can be at play.

showkey said:

Then there is the infamous Y cable.

Measuring charging voltage while under way..........spec would be about 13.9 to 14.2.

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Very good point. I've been working through some LHM DPF issues on my 2007, and in the process discovered that my Y cable was horribly brittle, and voltage (from almost new alternator to almost new battery) was only 13.7v. After installing the latest version of the cable (revision #4 according to Europarts' website), my van's operating voltage is back in spec at 14.2v. I also replaced the engine ground strap (which appeared to be equally suspect) with a new one.

Unfortunately it didn't solve my odd DPF trouble codes, but wow, the engine sure starts up fast now!

Ah, I have read about Y cable problems and will put that on my check list. Do either of you know if you can get current/voltage leak by cutting the end resistors that the rear dome and sliding door lights plug into? I'm hypothesizing that perhaps cutting those and not terminating the lines properly gave me a ground fault or some other open circuit that is leaking voltage. Originally my plan was to cut the connectors and wire the lines directly into my new LEDs. After reading some posts on here I learned that without the proper current draw the canbus system would show a fault.

Craves_Waves said:

Ah, I have read about Y cable problems and will put that on my check list. Do either of you know if you can get current/voltage leak by cutting the end resistors that the rear dome and sliding door lights plug into? I'm hypothesizing that perhaps cutting those and not terminating the lines properly gave me a ground fault or some other open circuit that is leaking voltage. Originally my plan was to cut the connectors and wire the lines directly into my new LEDs. After reading some posts on here I learned that without the proper current draw the canbus system would show a fault.

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I don't have any personal experience with that situation. Others will no doubt have abundant knowledge on it.