Lithium Batteries / voltstart.

[<<B-Guy>>]

As I research features we might want in a B van, I am thinkimg that Lithium batteries might well be a desirable thing, but not sure that we need or want "Voltstart." Especially when I learned that it is an option priced in excess of $1800!

We don't have pets any more, and I don't foresee needing to run the AC any time we are away from the trailer.

What I am wondering is whether - without voltstart - it is possible to set up a simple voltage drop monitor with an audible alarm to tell me I need to run
the engine - or generator to recharge the batteries,

I gather Lithium batteries hold their voltage and can be discharged much deeper than AGM's, so I'm not sure how well a simple voltage monitor would work.

Would that be what triggers "Voltstart," or does it use some more sophisticated means to determine when to charge?

I was thinking about a simple device like this

https://www.amazon.ca/dp/B00N6L8SMW/...a1d70caad2d6_S


You can set the alarm trigger voltage to whatever you like within range.

Any thoughts or advice?

Brian.

[mikes47]

Originally Posted by Wingeezer

As I research features we might want in a B van, I am thinkimg that Lithium batteries might well be a desirable thing, but not sure that we need or want "Voltstart." Especially when I learned that it is an option priced in excess of $1800! ...

Brian.

I agree, this is a feature that is "Really Nice To Have"; but not critical. We don't have a RoadTrek so our configuration uses different labels, but we do have 600 AH of Lithium as well as the feature that starts the engine when the batteries fall to a personally configured State of Charge. Like you, we don't have pets. We tend to drive most days and that keeps the batteries charged. But we have done some rally-type events where we boon docked for several days in a row without driving. It was nice to know that if we were out and about, the batteries would be kept at a healthy charge without our constantly checking. Nice; not critical.

[cruising7388]

Originally Posted by Wingeezer

As I research features we might want in a B van, I am thinkimg that Lithium batteries might well be a desirable thing, but not sure that we need or want "Voltstart." Especially when I learned that it is an option priced in excess of $1800!

We don't have pets any more, and I don't foresee needing to run the AC any time we are away from the trailer.

What I am wondering is whether - without voltstart - it is possible to set up a simple voltage drop monitor with an audible alarm to tell me I need to run
the engine - or generator to recharge the batteries,

I gather Lithium batteries hold their voltage and can be discharged much deeper than AGM's, so I'm not sure how well a simple voltage monitor would work.

Would that be what triggers "Voltstart," or does it use some more sophisticated means to determine when to charge?

I was thinking about a simple device like this

https://www.amazon.ca/dp/B00N6L8SMW/...a1d70caad2d6_S


You can set the alarm trigger voltage to whatever you like within range.

Any thoughts or advice?

Brian.

The discharge curve for lithiums is relatively flat so using voltage readings for interpolating SOC provides a rougher metric than a true shunt driven SOC meter. The accuracy and usefulness of a volt meter reading is improved if you use a four digit meter which will indicate voltage changes of 10 millivolts whereas the the three digit meter will only register 100 millivolt changes. We replaced the factory meter with a Blue Sea 1733 OLED which unlike LEDs or LCDs is visible under any lighting conditions.

Early Etreks didn't have any voltmeter at all. Subsequent production did include one which evolved from a mini 3 digit round meter to the current configuration which is a four digit LCD meter which doesn't have any alarm feature.

The conventional wisdom is that voltage interpolation is a clearly inferior way to measure battery state of charge. As a generality, this is indisputable, but ironically with the Roadtrek's design, it turns out to be just the opposite because of the internal parasitic drain inherent in their BMS design. A state of charge meter like the Trimetric et al depends for accurate reading on current passing through it's shunt but with the Roadtrek BMS design, the parasitic losses are internal to the battery and are never registered by the shunt. Consequently, you can be dissipating somewhere between 75 - 100 ah of battery suds in 24 hours while your SOC meter tells you that you are good to go.

Whether to spend the money for Voltstart is a vexed question. It uses a preset voltage rather than SOC as for the trigger. Compared to the Autostart features you see in the ARV where you can control the set point and depth of discharge, you have no control over this with Voltstart. Additionally, the factory has reconfigured the Voltstart trigger from 12.4 volts to 12.8 volts which means there is pretty little run time before triggering it.

[booster]

If you are not a huge power user, and considering the problems Roadtrek has had with the lithium (including the not fixed, it appears, big parsitic losses) you might want to consider going with AGM batteries. You could still do an auto start if you wanted to, but without pets and unattended AC it is likely you wouldn't need it. The high parasitic losses in the lithium batteries makes the auto recharging much more necessary.

I think the 210 still has the option of two or 4 AGM batteries.

[gerrym51]

Originally Posted by booster

If you are not a huge power user, and considering the problems Roadtrek has had with the lithium (including the not fixed, it appears, big parsitic losses) you might want to consider going with AGM batteries. You could still do an auto start if you wanted to, but without pets and unattended AC it is likely you wouldn't need it. The high parasitic losses in the lithium batteries makes the auto recharging much more necessary.

I think the 210 still has the option of two or 4 AGM batteries.

i thought the parasitic losses got better booster. where did you read this?

[cruising7388]

Originally Posted by booster

I think the 210 still has the option of two or 4 AGM batteries.

That's correct, the option for two additional AGM batteries is available. One of the redeeming virtues of the RT Chevys is that they still allow you to pick and choose among the options. The rest of their line requires choosing packages which IMO sucks.

[booster]

Originally Posted by gerrym51

i thought the parasitic losses got better booster. where did you read this?

I think it is more of not hearing that it had been fixed. The last discussion here was a few months ago IIRC, and there didn't seem to be any information on it getting better. I think somebody may even have had information from a Hymer engineer giving the amount.

BBQ follows this stuff pretty closely, he will likely have more details.

[booster]

Here is the post that said the losses were still high. 60 watts continuous, 24/7.

http://www.classbforum.com/forums/f7...html#post63685

[<<B-Guy>>]

Hmmm - all that info takes this retired old mech. eng. some time to digest!

So are you saying that despite the fact that it isn't normally the best way to go, Rt does in fact use voltage readings to trigger the voltstart charging?

If so, do you know if an accurate enough monitor with audible alarm (ie more precise than the one I linked to) is available to monitor manually and start the gennie as and when required?

I haven't read up much about lithium batts (guess I should!), particularly on this issue of internal parasitic load. What is the figure you quote of 75-100 AH loss in 24 hrs? Surely a typo? no?!

Maybe as "Booster suggests I should just forget about not only voltstart, but also lithiums as well, and just stick with AGM's.

I believe RT still offers a set up with either 2 or 4 6v AGMS for the 210.

I have two AGM coach batts in our Airstream trailer - 8 years old and still seem fine for use!

Unless we change our camping style dramatically (could happen if / when we swap our trailer for a van!) then at least, 90% of the time we camp with shore power available.

Now and then we stop overnght at a Flying I and then I use my Honda 2000 gennie as needed. Works fine for us. May of course do a bit more stealth camping with a van!

Many thanks for your detailed response - very helpful!

Brian.

[booster]

Yep the parasitic in the Roadtreks really is that high. 60 watts, 5 amps, 120ah per day wasted. It is not a function of lithium batteries in general, just the poor design of Roadtrek's system.

From the way you describe your travels, two or four AGMs and an engine generator would probably do just fine for you, and you avoid the wasted power and monitoring and cold weather charging questions.

[<<B-Guy>>]

Thanks Booster,

This forum with knowlegeable folks like you is extremely valuable to people like me - especially in comparison to info given by (hopefully well-meaning but not always correct) RV sales people.

I shouldn't generalise, I'm sure some RV sales personnel are very good, but you can never be sure which ones they are!

For many of them, I expect just selling the most expensive options is the objective!

Caveat emptor!

Brian



PS - by the way, I gather Pleasure Way are now pushing lithium
batteries, not sure if they are standard or an option.

Any idea if they have the same parasitic issue as RT?

[cruising7388]

Originally Posted by Wingeezer

Hmmm - all that info takes this retired old mech. eng. some time to digest!

So are you saying that despite the fact that it isn't normally the best way to go, Rt does in fact use voltage readings to trigger the voltstart charging?

If so, do you know if an accurate enough monitor with audible alarm (ie more precise than the one I linked to) is available to monitor manually and start the gennie as and when required?

I haven't read up much about lithium batts (guess I should!), particularly on this issue of internal parasitic load. What is the figure you quote of 75-100 AH loss in 24 hrs? Surely a typo? no?!

Maybe as "Booster suggests I should just forget about not only voltstart, but also lithiums as well, and just stick with AGM's.

I believe RT still offers a set up with either 2 or 4 6v AGMS for the 210.

I have two AGM coach batts in our Airstream trailer - 8 years old and still seem fine for use!

Unless we change our camping style dramatically (could happen if / when we swap our trailer for a van!) then at least, 90% of the time we camp with shore power available.

Now and then we stop overnght at a Flying I and then I use my Honda 2000 gennie as needed. Works fine for us. May of course do a bit more stealth camping with a van!

Many thanks for your detailed response - very helpful!

Brian.

RT uses voltage degradation for their Voltstart trigger because they don't employ any SOC metering. It's preset by the module for which in current protection is 12.8 volts which is IMO absurdly high since even 800 ah of lithium batteries won't discharge very long before dropping to this voltage.

Remember that Voltstart does not start the engine directly. It is tethered to a remote start module that does this. I believe that they are both supplied to RT by a third party source so it's possible that you could install a remote start module yourself.

I'm sure there are some 4 digit meters with alarm features. I'm partial to Blue Sea meters with alarms that are expensive but superb in quality. There is room on the control panel to mount a thru panel meter where the switches for an Onan generator are deleted when a Nations GU is installed. But actually, you could install the meter anywhere in the coach upstream of an appliance load.

https://www.bluesea.com/products/1833/M2_DC_Voltmeter

The actual parasitic loss amount from the BMS is murky. A primary suspect for this loss is that RT apparently doesn't use energy saving latchers to control their BMS relays.The anecdotal reports are as high as 5 amps continuous drain. In extrapolating from the voltage degradation over a 24 hour period I gestimate the loss to be closer to three amps but which still amounts to over 75ah per day. And for multiple battery setups this is for each battery. A solar panel might offset the loss from one battery but not from multiple batteries which is why RT recommends that while not in transit, that you turn off the inverter if not required for 120V and also shut down the batteries not required for the appliances you are using. By comparison, the BMS drain on the Galleria Li3 has apparently been reduced in the whereabouts of 15ma.

For the way you indicate you will be using the RV, if you are going for the 210, Booster's suggestion that you use AGMs rather than lithiums is a good one if for no other reason that I think it's likely that competition will force RT to scrap the Etrek configuration for a more up to date design similar to the Xantrex setup in the Galleria or the 48 Volt system just introduced by WGO.

[Davydd]

Parasitic loss is not a lithium battery problem it is a Roadtrek problem. There is very little parasitic loss in lithium ion batteries if the systems are designed right and if you have high amp hour battery capacity you wouldn't need Voltstart if Roadtrek gave you a SOC readout. And if you don't go with high amp hour battery capacity then you are wasting your money with lithium ion batteries. 400ah or better you shouldn't have problems if designed right. You definitely could use a second alternator (underhood generator in Roadtrek terms) to fast charge your batteries while driving. Idleling to charge batteries is stupid thus Voltstart is stupid.

[avanti]

Originally Posted by booster

Yep the parasitic in the Roadtreks really is that high. 60 watts, 5 amps, 120ah per day wasted.

You know, if there really is 60 watts of continuous parasitic loss, that would translate to a LOT of heat. It would be like having a 60 watt light bulb burning full time inside the enclosure.

I am not saying that it isn't true, but if it is, I would think that it would be pretty obvious what is consuming the power.

[booster]

Originally Posted by avanti

You know, if there really is 60 watts of continuous parasitic loss, that would translate to a LOT of heat. It would be like having a 60 watt light bulb burning full time inside the enclosure.

I am not saying that it isn't true, but if it is, I would think that it would be pretty obvious what is consuming the power.

The 60 watt figure was from the Hymer engineer that a poster talked to, and was in the link I to another thread I posted earlier. It would be a lot of heat, and if they allowed you to open the case, I would certainly think it would be easy to find.

When the lithium first came out there was talk of 5-6 amps of parasitic, and then IIRC Hammil said they got it down to 3ish amps, but now we have a Hymer engineer back at 5 amps, so shaky information to be sure. I do know that I have read of several systems that claimed that a module that was turned on, but will all loads turned off would be dead in two days of running nothing.

[gerrym51]

Originally Posted by booster

I think it is more of not hearing that it had been fixed. The last discussion here was a few months ago IIRC, and there didn't seem to be any information on it getting better. I think somebody may even have had information from a Hymer engineer giving the amount.

BBQ follows this stuff pretty closely, he will likely have more details.

I'm waiting for BBQ to clarify about the Roadtrek ecotrek announcement he said was coming- he said that monday

[gregmchugh]

Originally Posted by gerrym51

I'm waiting for BBQ to clarify about the Roadtrek ecotrek announcement he said was coming- he said that monday

I predict that the announcement is...

“We have decided to stop producing the Ecotrek, Voltstart, and underhead generator products and will now be installing the Volta system. Winnebago has the right idea and we have no qualms about following in their footsteps...”

or maybe not...

[gerrym51]

Originally Posted by gregmchugh

I predict that the announcement is...

“We have decided to stop producing the Ecotrek, Voltstart, and underhead generator products and will now be installing the Volta system. Winnebago has the right idea and we have no qualms about following in their footsteps...”

or maybe not...

i'd be shocked

[booster]

Originally Posted by gregmchugh

I predict that the announcement is...

“We have decided to stop producing the Ecotrek, Voltstart, and underhead generator products and will now be installing the Volta system. Winnebago has the right idea and we have no qualms about following in their footsteps...”

or maybe not...

That might be close, but I think it would be more likely to be "We have decided to stop producing the Ecotrek, Voltstart, and underhood generator and now will be installing a private label copy of the Volta system that will be 1/2 the price (for us to buy, but the same to sell to you) and 1/4 the quality, but it will say ROADTREK on it so you know it will the best, even though it will be made in place you have never heard of!!!"

[gerrym51]

Originally Posted by booster

That might be close, but I think it would be more likely to be "We have decided to stop producing the Ecotrek, Voltstart, and underhood generator and now will be installing a private label copy of the Volta system that will be 1/2 the price (for us to buy, but the same to sell to you) and 1/4 the quality, but it will say ROADTREK on it so you know it will the best, even though it will be made in place you have never heard of!!!"

Booster-BBQ piqued our interest in this on monday-he said it was coming shortly and now friday is here and zilch. BBQ you should either clarify or retract.