Victron BMV702 Install

[chugchug]

If you are going to charge with jumper cables, you are probably better off looking at voltage to monitor the state of the battery and ignore Amp/Hours. An Amp/Hour meter such as the Victron BMV702 needs to calibrate itself to the full state of charge of the battery. If the battery is not brought back to full charge (as when charging with jumper cables), the reading will be getting increasingly wrong.

When calculating the amount of charge you are putting back in the Victron uses a parameter called "Charge Efficiency Factor", which is only an estimate.

[uncle_bob]

Originally Posted by CoorsLite

Once again Uncle Bob you have provided valuable guidance. Thanks very much.

You may have saved me an expensive battery (my Touareg TDI has an AGM battery with an imbedded chip), not to mention my new AS batteries (two Group 27’s).

My spidy sense told me that rapid charging with jumper cables may not be a good thing. You have just confirmed that. So why did I consider booster cables?

My Touareg has a 10AWG wire that leads to the 7Pin charging circuit. My worry was that heavy charging may overwhelm the 7Pin circuit, as I have at least a 150 Amp alternator. Hence the booster-cable approach. I have recently learned that the Touareg manages the 7Pin circuit to ensure correct current and if all else fails it is fused.

All of this points to alternative charging methods described well on the forum - Solar (I plan to install) and a generator (still considering but may be inevitable).

Thanks again.

Hi

No problem, we all thrash through this stuff ....

Simple way to look at it:

If both the TT and TV batteries are at the same voltage, no current will flow.

If they are at different voltages, the current is limited by the resistance.

Wire resistance is length times ohms per foot.

A 10 gauge wire is pretty small in terms of charging a battery. By the time you run all the way to the back of the SUV and then loop around in the trailer .... lots of resistance.

The wire on the 7 pin is there mainly to keep things topped up while rolling down the road.

Bob

[thiel]

Originally Posted by CoorsLite

Thanks for the advice and great pictures - these are helpful. Both examples illustrate my goal. It's the "remove furniture" part I am struggling with. The FC FB25 twin bed layout with center night stand shows only two visible screws in the entire forward area. My guess (and fear) is that the furniture is held together with pocket screws accessible only after removing the carpet liner from the front locker. I would like to confirm this before ripping-out the carpet-liner from the forward locker.

I'm going to do mine in a week or two and have the same question. If I get their first, I'll share pics.

[CoorsLite]

Re: Furniture removal in an FC25 FB twin: I will be interested what you find. After removing numerous screws from the walls, floor and both beds, the forward box enclosing the forward trunk would not budge for me.

IMO, as constructed, the FC25 FB Twin "wiring closet" is impossible to maintain. While the furniture can be removed with tons of work, this is not a practical approach for the long term, i.e. the need for maintenance or enhancements. For example, try removing the Inverter from the hatch or via the removable wall inside the front trunk. Or access the Distribution Box which is below the Inverter.

I enjoy woodworking and I have the tools. With one cut I made the forward curb-side hatch much bigger, exposing the entire wiring closet. I added one cleat from underneath to support the new removable hatch panel. It is all held in place with counter-sunk stainless screws when closed. You can DM me if you want to know more. Attached pictures are pre-modifications - they might help.