Roadtrek E-Trek Battery Setup

[photolimo]

I recently purchased an E-Trek and have had to do some work on the electrical. The dealer said that the batteries were setup in an odd way and I verified that the wires are done as shown below. Does this look right to others that have seen this setup?


https://docs.google.com/drawings/d/1oAN ... sp=sharing

[booster]

Haven't seen it before, but many of us have wondered how they are wired.

Most of it is pretty straightforward, if I read it right.

Single battery off of isolator is the van starting battery.

The two other 6v batteries in front, in series for 12v and the two 6v that are paired in the rear in series, are paralleled and run the coach 12v circuits.

The other 4 6v batteries are in series for 24v and run the inverter and are charged by the solar.

What I don't get is the balancer that would be on just two batteries it looks like.

I don't see a shore charger.

Very interesting, though. Thanks for putting it up for us to see.

[Caped Crusader]

There are two owners on the FB site waiting to have all their batteries replaced due to over charging. One has been waiting weeks, and the guess is Rt doesn't know yet what the problem is, so does not want to replace them till they have an answer.

[markopolo]

Thanks for posting the diagram. Looks well done and accurate.
The balancer is probably between the 24 volt battery bank and the 12 volt battery bank.

Like booster noted, it looks pretty straightforward. Dealer probably meant "unusual" instead of "odd". It is what I'd expect to see - I don't have an E-trek though. I think there was variance amongst the first builds. They may have standardized production now.

Looks like the battery capacity is 400 ah (approx) at 12 volts plus an additional 200 ah (approx) at 24 volts. The balancer would 'balance" the remaining capacity if one bank is drawn down quicker than the other I'd expect.

[booster]

Originally Posted by markopolo

Thanks for posting the diagram. Looks well done and accurate.
The balancer is probably between the 24 volt battery bank and the 12 volt battery bank.

Like booster noted, it looks pretty straightforward. Dealer probably meant "unusual" instead of "odd". It is what I'd expect to see - I don't have an E-trek though. I think there was variance amongst the first builds. They may have standardized production now.

Looks like the battery capacity is 400 ah (approx) at 12 volts plus an additional 200 ah (approx) at 24 volts. The balancer would 'balance" the remaining capacity if one bank is drawn down quicker than the other I'd expect.

I am totally not up to speed on balancers, and how they work, so I may be way off base here. I am assuming they are a variant of battery to battery charger, that works both directions between two banks? In this case it would be 12 to 24v one way and 24 to 12v the other way. If that is the case, I think I would expect to see the balancer positive connections to the first of the batteries in the series change for each bank, rather than the last one. The diagram would not charge the forward two coach batteries with the balancer, it appears, either. It may be just a line to the wrong spot, I know how hard it is to figure out where a maze of wires go, even if I just created them.

Interesting about the battery overcharge failures mentioned by the Caped Crusader. One of the big questions that I had from the beginning was how they handled the very high charge rates available form the huge engine generator and fairly large stock Sprinter alternator. To be kind to the batteries, these outputs would have to go through a very very big battery to battery charger to get "safe" multistep charging. With the two systems shown, they very well may have the van alternator going to the 12v batteries, and the engine generator at 24v and to the inverter batteries. The 12v system would be the same as any Sprinter in that configuration, and 400AH is a lot of coach battery, so overcharging would be less likely than with the 3500 watt engine generator into the 24v system. If they are running that straight in without modulation, it could do some damage, I would think. I know the AGM makers claim very high, or no, limits on amperage into the batteries at charging, but AGMs are also very sensitive to overheating and high voltages once full.

I am very glad some of this information is showing up, it will help all of us to understand the etrek, and our own, homemade, "improved" charging systems.

[mlts22]

A balancer does make sense... but it needs to be multi-stage in order to be useful in any way, shape, or form.

[booster]

There is an e-trek on ebay that had a long blurb about it. One of the things it said is that it has a 45 amp three step charger, which really surprised me in a rig with 800AH of 12v battery capacity. That is something like a 5% of capacity charger, which is way below even the quite low Trojan recommendation of 11-13%. It may also be their standard Tripplite, so it is likely it would not stay in absorption mode long enough to fill the batteries even if it was plugged in long enough. The 245 watt solar will probably do in the 90-100AH per day if sunny, and 1/2 that if it is not, so it looks like they are heavily relying on the engine generator for recharges. If that is the case, and it is a fixed voltage that is high enough to fill them quickly, it could help explain the damaged batteries mentioned earlier. I doubt there is any way the you could just find an electric site and plug in overnight to recover your batteries to full, as there would not be enough time.