ecotrek batteries using 6 internal amps

[avanti]

I agree that on the surface at least, this report seems absurd. I recently carefully measured all of my loads. My entire TV consumes 1.5 amps; my propane solenoid valve consumes .7 amps (and most electrical relays typically use much less than that); my Fantastic Vent on "high" uses 2.8; my 2800 watt inverter on idle uses 2.3. The only DC load in the whole van that consumes anything like 6 amps is my large NovaKool compressor refrigerator, and that only when running. I don't see how you could make the battery controller consume 6 amps if you tried. There has got to be more to this story.

I've always thought that the RT design of separate controls for each battery was a kluge. I am no big fan of heavy automation in a B-van (one of the reasons we decided against an ARV), but that is too much even for me.

[gerrym51]

Originally Posted by avanti

I agree that on the surface at least, this report seems absurd. I recently carefully measured all of my loads. My entire TV consumes 1.5 amps; my propane solenoid valve consumes .7 amps (and most electrical relays typically use much less than that); my Fantastic Vent on "high" uses 2.8; my 2800 watt inverter on idle uses 2.3. The only DC load in the whole van that consumes anything like 6 amps is my large NovaKool compressor refrigerator, and that only when running. I don't see how you could make the battery controller consume 6 amps if you tried. There has got to be more to this story.

I've always thought that the RT design of separate controls for each battery was a kluge. I am no big fan of heavy automation in a B-van (one of the reasons we decided against an ARV), but that is too much even for me.

the Roadtrek engineer did not say it was the BMS system. people are inferring that. all he said was the battery uses 6 amps per hour internally. we really have no idea why.

[avanti]

Originally Posted by gerrym51

the Roadtrek engineer did not say it was the BMS system. people are inferring that. all he said was the battery uses 6 amps per hour internally. we really have no idea why.

I realize that. But, what are the other possibilities? The internal self-discharge of the batteries themselves is pretty well-understood. What's left? I guess there is the external control/display system, but I would consider that as part of the BMS.

[markopolo]

You'd likely feel heat from a 6 amp load unless it was disbursed over several contributing items. That's 72 watts (at 12v) - just think of how warm or hot a 60 watt incandescent bulb would feel.

As Avanti points out, it's not easy to produce a load like that in a Class B with LED lights and fans etc. I'd have to run both the furnace and the Fantastic Fan and maybe a few LED lights to produce a load like that.

A few not so great high resistance causing connections can generate heat (wasted energy) but that would show up under fairly large load conditions I'd expect not when the unit is basically idle.

As Avanti says: "There has got to be more to this story."

I know Gerry is just sharing info here. It will be interesting to hear of updates on this as more info comes out.

[booster]

As I mentioned earlier, the only load I can think of that would pull that much current would large capacity relays. I would compare them to the type used in the Surepower separator, which on the one we had pulled 3.5 amps continuously, and was killing our solar output if it was on. That is why the 12v relay in the van is a bistable design that only uses power while switching, and Blue Sea makes several different styles of bistable and magnetic hold, etc very low current use, high capacity relays. With separate in and out, Roadtrek probably as at least two large capacity relays in each module.

And Roadtrek did have self proclaimed relay failures early on, so they could have switched to something that works but uses more power.

[avanti]

Originally Posted by booster

As I mentioned earlier, the only load I can think of that would pull that much current would large capacity relays. I would compare them to the type used in the Surepower separator, which on the one we had pulled 3.5 amps continuously, and was killing our solar output if it was on.

I am not questioning your data, but 3.5 amps from any reasonably sized relay is out of line. I no longer have a separation relay, but as I said, my propane solenoid (which is similar) measures out at .7. According to this:

http://www.allbatterysalesandservice...SHEET_1315.pdf

a randomly-chosen Shurepower separator is spec's at .75 (sheet 4). At that current, they would need a lot of relays to get to the cited current.

I am guessing that your unit was somehow defective.

[Boxster1971]

Originally Posted by booster

As I mentioned earlier, the only load I can think of that would pull that much current would large capacity relays. I would compare them to the type used in the Surepower separator, which on the one we had pulled 3.5 amps continuously, and was killing our solar output if it was on. That is why the 12v relay in the van is a bistable design that only uses power while switching, and Blue Sea makes several different styles of bistable and magnetic hold, etc very low current use, high capacity relays. With separate in and out, Roadtrek probably as at least two large capacity relays in each module.

And Roadtrek did have self proclaimed relay failures early on, so they could have switched to something that works but uses more power.

booster - I think you have the answer. Roadtrek is using normally OFF relays that require considerable power to stay connected. From what I've seen Roadtrek generally uses cheaper parts in their designs. Airstream did the same recently with a Service Bulliten (SB164) on their Interstates. To solve a problem with parasitic drain from the Magnum inverter they added a cheap Normally OFF solenoid that requires a constant 1 amp to connect the inverter/charger.

That Roadtrek battery box probably has at least two powered relays causing a big part of the problem.

[booster]

Originally Posted by avanti

I am not questioning your data, but 3.5 amps from any reasonably sized relay is out of line. I no longer have a separation relay, but as I said, my propane solenoid (which is similar) measures out at .7. According to this:

http://www.allbatterysalesandservice...SHEET_1315.pdf

a randomly-chosen Shurepower separator is spec's at .75 (sheet 4). At that current, they would need a lot of relays to get to the cited current.

I am guessing that your unit was somehow defective.

That is the 100 amp relay it appears, this is the 200 amp we had

http://www.allbatterysalesandservice...T_1315-200.pdf

It shows 1.5 amps, which is still more than we saw, but of course we don't know what voltage the rated them at, and we were charging wet cells at 14.7 volts. If they rated at 12v, we would be closer to 2 amps, but still less than we measured. I can tell you it would get too hot to touch. I may also be remembering from a time just before it failed, which it did.

I would think with the 200ah module of lithium, and an engine generator to charge them, they would need at least a 300 amp switching relay, and maybe more. The Blue Sea that I think we both have now (bistable) are rated at 500 amp continuous but only 300 amps for switching, which would apply here, I think. It pulls 7 amps switching, so if it wasn't a bistable, it would probably pull close to that all the time.

[booster]

Here is a 450 amp relay that Blue Sea sells that looks to have reduced current for holding once activated. It takes 3.6 amps to move, and then reduces to very low hold current. If it were a plain relay it would pull the 3.6 all the time, I think.

https://www.bluesea.com/products/901...12_24V_DC_250A

[avanti]

Originally Posted by booster

Here is a 450 amp relay that Blue Sea sells that looks to have reduced current for holding once activated. It takes 3.6 amps to move, and then reduces to very low hold current. If it were a plain relay it would pull the 3.6 all the time, I think.

https://www.bluesea.com/products/901...12_24V_DC_250A

Dunno, but it isn't hard to find 500amp relays that draw less than 1A when activated, e.g.:

https://www.amazon.com/PAC-PAC-500-5...=1&*entries*=0

If coil current really turns out to be the culprit here, it would represent some pretty sloppy engineering.

[booster]

Originally Posted by avanti

Dunno, but it isn't hard to find 500amp relays that draw less than 1A when activated, e.g.:

https://www.amazon.com/PAC-PAC-500-5...=1&*entries*=0

If coil current really turns out to be the culprit here, it would represent some pretty sloppy engineering.

I would totally agree, and it may or may not be the cause, or a contributor. Any way you look at, that kind of loss is sloppy engineering regardless of the cause.

[gregmchugh]

Originally Posted by booster

I would totally agree, and it may or may not be the cause, or a contributor. Any way you look at, that kind of loss is sloppy engineering regardless of the cause.

I could not believe the idea that there was a 6 amp internal draw in each Ecotrek module when it was first reported but the email indicates that it is not science fiction. The relays seem to be the only possible source fir the load. Each module has 4 amp battery heating pads but they were not included in the 6 amp draw as far as I can determine.

I really don't know what to say but this should be an embarrassing admission for any skilled electronics design group.

Yes, there is a complete BMS in each module including at least two relays to control the charge and load terminals on the module.

If there was a single set of relays for the complete battery bank you might forgive this somehow. As it is, the 470 watt solar option provides about the energy to power the internal 6 amp draw for a single Ecotrek module. No solar power left to power the compressor fridge or anything else. Solar is essentially useless and running the generator is the only option when boondocking to keep the batteries from completely discharging themselves in 30 hours due to the internal power draw.

What can you say, this is just a crazy story that appears to be true and not an urban legend...

[booster]

It does make you wonder how they rationalize all the hype when they have a fatal flaw like this (if they truly do). Has Hammil, Yan or anyone said anything about it other than the email from the (probably now fired) Roadtrek person. Nobody should make a mistake like this.

[booster]

Are the heaters strictly manual control?

[gregmchugh]

Originally Posted by booster

Are the heaters strictly manual control?

The 4 amp battery heaters in each module appear to be automatically controlled maybe by a simple thermostat of some sort rather than through the battery management controller since they seem to work when the module is shutdown. They get power from the charge terminal on the module before the relay so they can be powered from the engine generator by running the engine but cannot be powered from shore power, likely because the inverter/charger is connected to the load terminal not the charge terminal on the module.

[gerrym51]

Originally Posted by booster

It does make you wonder how they rationalize all the hype when they have a fatal flaw like this (if they truly do). Has Hammil, Yan or anyone said anything about it other than the email from the (probably now fired) Roadtrek person. Nobody should make a mistake like this.

i do not think this is a flaw to Roadtrek. they have so many configurations with agm and lithium it probably helps standardization.

Each battery has it's own built in bms and relay system. the only thing in the van is the on/off and reset switch for each battery.

If it didn't use so much power it would be 'brilliant'.

I'm surprised they told the guy. they could have just told him only use 1 battery most of the time and it would have worked with no one wiser.

by actually stating that is writing it has now opened a can of worms

[booster]

That sounds like the heaters would run off the AGM even with the lithium modules off? If they came on automatically you would think the would kill it?

[gregmchugh]

Originally Posted by booster

That sounds like the heaters would run off the AGM even with the lithium modules off? If they came on automatically you would think the would kill it?

I have also wondered about that, not many reports on the battery heaters so not much info to go on. I suppose they could only trigger at charge level voltages in order to prevent draining the AGM.

[gerrym51]

i do not think they use 4 amp heaters in the batteries. i have read about other types of internal battery heating

[gregmchugh]

Originally Posted by gerrym51

i do not think they use 4 amp heaters in the batteries. i have read about other types of internal battery heating

The internal pictures of Ecotrek battery modules show two silicone encapsulated heating pads located between the lithium cells and at least one owner has informed me that they are each 2 amp heating pads.

Not sure where you are getting different info Gerry...