Rewiring Aktiv's Ecotrek System

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STOP!!! this is a work in progress and a total draft. Its published so others can review and comment on its progress.

Is this project for your RV?

This project applies to Aktiv 1.0s with Ecotrek batteries of any revision. Accompanied by correct programming of inverter/charger, solar controller and Balmar, this project should result in reliable cabin DC power and higher EcoTrek Battery life. This project will be adapted Aktiv 2.0 and Loft by others.

What is the technical goal of this rewiring?

This project achieves two goals.

1) Move all Aktiv chargers to the Ecotrek battery's charge-side. Lithium batteries require a Battery Management System (BMS) to protect the Lithium cells from damage resulting by under-voltage and over-charge. The BMS stops charging by opening the charge-side relay. The BMS stops under-voltage by opening both the charge-side and discharge-side relays. Hymer mistakenly connected the solar charger and inverter/charger to the Ecotrek's discharge-side and charging continues even after the BMS opens the charge-side relay. This leads to revision H batteries being overcharged and sometimes even shutting down for days. KS2 added a unique software feature to the L1 battery; opening the discharge-side relay to stop over-charge if chargers are mistakenly connected to the discharge side. This is an important protection of the valuable lithium cells but it also turns off the DC power to the main cabin. This leads many owner to believe the L1 battery is broken when in fact it is mis-installed.

2) Accurately deliver UHG voltage to the Ecotrek batteries (optional). The reference figure below reveals that lithium battery charge voltage increases as little as 0.06 volts between 20% and 80% State Of Charge (SOC). The Balmar is a voltage controlled charger so its vital it accurately senses EcoTrek battery voltage for quick charging. The Balmar reference ground and ecotrek voltage sense the UHG voltage rather than the Ecotrek voltage thus introducing a voltage error as much as 0.2 volts. Yes, the error is ten times higher than the voltage being measured. The re-wiring corrects this measurement error. Marine How To has a great explanation for why to fix the sense wiring error. https://marinehowto.com/alternators-voltage-sensing/

Overview of What is Changing

The projects details a procedure to move the inverter/changer and the solar charger to the charge-side (red lines) of the EcoTreks while leaving the battery ON/OFF latching relay on the discharge-side (blue lines) of the Ecotrek batteries. As an overview, the four changes are lettered and depicted with curving wires in the following figure:

Move all Aktiv chargers to the Ecotrek battery's charge-side

A) An existing cable is moved from a discharge junction to a charge junction.

B) An existing cabinet cable and new 70 amp sealed circuit breaker are relocated under the ProMaster beside an Ecotrek discharge-side. A new 6-gauge cable is routed from the 70 amp CB, through the floor and to the battery ON/OFF latching relay.

Accurately deliver UHG voltage to the Ecotrek batteries (optional)

C) The Balmar grounded to the chassis next to the Balmar.

D) The Balmar's voltage sense line is routed to the Ecotrek's charge terminal with a dedicated 14 gauge wire and an inline 10-amp fuse.

These are not original SUIET Hacks, LLC concepts. The Aktiv is only being wired per the vendor's installations instructions and best practices.

Do you have the expertise to safely complete this project?

This project includes making cable assemblies using 14 and 6 gauge wire, crimps, and heat shrink. Cabling is routed under the Aktiv, in the engine compartment and in the Aktiv's rear electrical equipment cabinet. This is mainly a mechanical task of routing cables, crimping wires and tightening terminals. There is no electricity involved between the initial disconnection of the battery power and its final re-connection.

Does Hymer Approve of this Project?

The reason this needed electrical work was never performed is lost to Hymer's receivership. This work is best left to your dealer or a RV repair technician if they are willing.

Is the Project Effective and Safe?

Yes. The added wires are accompanied by a circuit breaker or fuse sized to protect those wires.

Instructions to Move Solar and Inverter/Charger to the Ecotrek Battery's Charge-side

Special Tools:

Wire terminal crimping tool
drill with 3/32 bit

Parts

Installation