RoadTrek's EcoTrek

[gerrym51]

Originally Posted by cruising7388

Now that's a classy installation

Is the outside container metal or plastic?

Do you know if ARV employs the battery cable balancing arrangement described by Smartgauge?

do lithium batterys need battery balancing?

[Davydd]

Originally Posted by cruising7388

Now that's a classy installation

Is the outside container metal or plastic?

Do you know if ARV employs the battery cable balancing arrangement described by Smartgauge?

I snapped this photo midway through assembly. It is an insulated honeycomb fiberglass box. That is all protected by a steel cage and then an aluminum skid plate is under all that.



There are 16 3.2v 200ah cells arranged in four in series for a nominal 12v battery and then 4 in parallel to create the one discreet nominal 800ah 12v battery. Cell balancing is done by I don't know how (above my knowledge) but I have observed it once on the Silverleaf controller. It was kind of scary in how it was churning away and the batteries were getting hot. The only thing proprietary about ARV is its computer programming to make everything work together and they have partnered with all the companies involved. I don't know if it is so much proprietary but just custom that can't be just handed out and expect to work for anyone else.

This is a typical status readout on the Silverleaf screen. The little flame means the electric heating pads are on to keep the batteries above freezing. I believe it was -10F when I took this photo. So you get the temperature of each cell and the voltage.

[Davydd]

I should mention my batteries are first generation. I got the first pack like this. Now they are putting them in two metal boxes in the same location and doing something different. That's about all I know until I go to Advanced Fest in May. I've said before, if you really want to know the latest, anyone can go to Advanced Fest. They don't keep secrets. How do you think theFitRV got all their ideas?

[gregmchugh]

Originally Posted by cruising7388

Now that's a classy installation

Is the outside container metal or plastic?

Do you know if ARV employs the battery cable balancing arrangement described by Smartgauge?

I don't believe there would be any need for battery cable balancing for an integrated lithium battery bank like ARV uses or even for the modular lithium battery design used by Roadtrek.

The lithium battery cells are kept in balance in both these designs by local cell balancing circuits.

In the integrated design (ARV) there is a single positive and single negative connection to the overall battery bank so cable lengths are not relevant.

For the Roadtrek modular design, each Ecotrek module operates independently of the others and the BMS in each module protects the lithium cells from over charge, over discharge, over temperature, and under temperature. There will be different charge/discharge voltage levels at the modules due to different cable length connections to the modules but these voltage differences will not result in any major issues. If the modules are at different states of charge due to the voltage differences it will not cause any problems with the lithium cells that have no requirement to reach full charge regularly like an AGM battery.

Again, just my view on it...

[gregmchugh]

Originally Posted by gerrym51

do lithium batterys need battery balancing?

The lithium cells need balancing and this is done with a local balancing circuit on each cell. In a modular system like the Ecotrek design, I don't see any need for balancing the modules since the lithium cells are protected by the BMS. There is no need to get the module to full charge regularly like AGM batteries. The battery equalizer installed on the 8 battery AGM Etrek design insures that the AGM batteries all get charged to the same level even when there is uneven discharge due to the 12v power draw on half the batteries in addition to the 24v power draw on all the batteries.