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Daniel Wilson
Daniel Wilson,
Category: Ford
Satisfied Customers: 5552
Experience:  Owner at DJ Wilson
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I'm dealing with a 2001 Ford E450 with 7.3l diesel. The

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I'm dealing with a 2001 Ford E450 with 7.3l diesel. The problem is the truck battery is slowly discharging. The auxiliary battery system is a separate system using solar panels to charge the auxiliary batteries, which are 2 solar batteries in parallel. These are 30 amp batteries which means a potential of 60 amps. The positive terminal systems for the truck battery and solar batteries are separate, but both systems share the chassis as a ground for the negative terminals. Where exactly the solar battery system is grounded is not obvious, but my ohm meter used to check continuity says the solar batteries negative terminals are grounded to the chassis, as is the truck battery. My question is this: is it possible for the higher amperage potential of the truck battery to discharge into the solar batteries through the negative terminals? The positive terminals are indeed separate. The positive terminals are the usual route for back charging to take place but that's not possible in this case.

Hi my name is***** will be glad to help. Test the batteries with a digital tester for the internal condition such as for bad cells, internal shorts, low CCA, etc and also check the cables and connections that they are clean and tight and free from damage or corrosion. Check for voltage drops in the starting and charging system and do a battery drain test to isolate the circuit that is drawing the most voltage.

Click this link for how to perform this test on any automotive application

Parasitic drain test

Customer: replied 24 days ago.
You did not answer my question. I asked if it is possible for a battery of higher average potential to discharge into a battery system of lower potential through the negative terminals when the positive terminals are separated? Please answer this question.

No. Two different circuits.

If that were true in DC voltage you would never be able to separate any of your lighting circuits as they would bypass and drain from one another though the ground side. Please tale a moment to rate my service a that is how the site credits my time helping on the site. 5 star and bonuses are greatly appreciated and we can follow up as needed.

Daniel Wilson and other Ford Specialists are ready to help you
Customer: replied 24 days ago.
Thank you. That is the answer I wanted. I need the expert statement to convince a friend.

Pleasure to help. Convince him with OHMS law of electrical.

Here is some FYI to share with him. DC only flows one way or you have a short.


Some older trucks from long ago ran positive ground circuits but is obsolete in todays standards and caused too many problems. If you tried to wire a Negative ground circuit to that vehicle you would have an instant short. Both cant exist together. Pleasure to help and let me know if I can be of more assistance.

Customer: replied 24 days ago.
Farm tractors sometimes used the positive terminal as the ground in days gone by, Drove a few like that and remember it well.
My question was solely about my friends truck, and knowing that electrical current flows between higher potential to lower potential the question arose if the 2 grounded negative terminals would behave in the same way. That is from higher amperage to lower amperage potential. Your comparison to light circuits with varying resistance clarified this matter.

Ok great. Its been a pleasure to help. Enjoy the rest of your weekend.