Lithium Batteries / voltstart.

[booster]

Originally Posted by wincrasher

I don't see why the chassis battery isn't sufficient for monitoring and an autostart system. The draw is in milliamps, not unlike the stereo.

The Promaster also has an unusually large and robust AGM chassis battery.

You certainly could monitor the coach batteries with power to the Voltstart, as long as the Voltstart has a separate "sense" wire to determine SOC.

Unfortunately having it that way would allow the engine to start when a coach battery was not visible to the charging systems, alternator, solar, shore, so you would still have the issue of a runaway alternator burning things out.

If you had relay to connect the starting and coach batteries together to accomplish the activation, you would be able to get the engine to start, and the alternator to turn on with the coach batteries offline. You would, however, need to have a 12v to 12v charger inline from the stock alternator to limit current when the lithiums came online, as they would severely over tax the stock alternator, I think. To me, this sounds like the most practical recovery, and heat when in cold shutdown, method to have.

[avanti]

Originally Posted by wincrasher

I don't see why the chassis battery isn't sufficient for monitoring and an autostart system.

...or a 9V radio battery.

[gregmchugh]

Originally Posted by cruising7388

RT employs a beefy group 24 battery which seems to me to be overkill for the task it performs; has a shorter practical life span than solid state alternatives and since this AGM is common to the other charging sources, it's always being charged as if it's a lithium battery.

From the reports I have seen from owners, it seems that the lithium’s are being charged using an AGM charge profile rather than the other way around. Not optimal charging for the lithium’s but good enough for this application (most owners won’t notice the resulting small loss in battery capacity) and not going to harm the AGM...

[cruising7388]

Originally Posted by gregmchugh

From the reports I have seen from owners, it seems that the lithium’s are being charged using an AGM charge profile rather than the other way around. Not optimal charging for the lithium’s but good enough for this application (most owners won’t notice the resulting small loss in battery capacity) and not going to harm the AGM...

I don't believe there was any control panel voltmeter in a Roadtrek before the later 2016-2017 production. For owners predating the voltmeter inclusion, how would they have any way of determining the lithium battery charging profile? RT offers a six year warranty on the lithiums and only a one year warranty on the AGM. Although anything is possible, I find it difficult to believe other than that the programming RT orders order for the Balmar regulator and sets up in their Powerstar charger is geared toward the optimal life of expensive lithium batterys rather than the AGM.

[gregmchugh]

Originally Posted by cruising7388

I don't believe there was any control panel voltmeter in a Roadtrek before the later 2016-2017 production. For owners predating the voltmeter inclusion, how would they have any way of determining the lithium battery charging profile? RT offers a six year warranty on the lithiums and only a one year warranty on the AGM. Although anything is possible, I find it difficult to believe other than that the programming RT orders order for the Balmar regulator and sets up in their Powerstar charger is geared toward the optimal life of expensive lithium batterys rather than the AGM.

The owners who were interested in the details plugged a voltmeter into one of the 12v outlets long before RT ever installed a voltmeter. Reported voltage readings seemed like a standard AGM charge profile not the optimum lithium profile...

All reports I saw indicated that the charger profiles were set to one of the AGM settings, at least for the inverter and solar.

No harm to the lithium’s with an AGM profile, just a reduction in usable capacity if they don’t get a full charge...

You can check yours to see what charge voltages are being used, could be AGM or could be lithium...

[cruising7388]

Originally Posted by booster

I would certainly hope that the Voltstart won't start the engine unless there is a battery connected to the alternator, so the alternator doesn't go way high and destroy stuff. Even Roadtrek wouldn't be that foolish to allow starting under those conditions, so they needed the AGM so the Voltstart sees a battery. Of course the Balmar will also not activate without seeing a battery, so even if the Voltstart did start the engine, there would be no charging from the Nations alternator.

If this is true, is it correct to state that there would be no potential damage to the Balmar/Nations equipment if the engine starts and merely spools up the GU alternator because the Balmar would suppress alternator field winding current unless it senses a battery. However, once the GU alternator is delivering power to the battery a BMS shutdown can subject the alternator and regulator to damage?

[booster]

Originally Posted by cruising7388

If this is true, is it correct to state that there would be no potential damage to the Balmar/Nations equipment if the engine starts and merely spools up the GU alternator because the Balmar would suppress alternator field winding current unless it senses a battery. However, once the GU alternator is delivering power to the battery a BMS shutdown can subject the alternator and regulator to damage?

I do think that the Balmar stuff could be damaged from a BMS shut down with the engine running, for whatever reason, if there were no AGM. Even shutting of the manual switches on the modules might do it if the allow all of them to go offline without shutting off the alternator field first. Most systems with manual disconnects warn against shutting off the charging while running if the there is no other battery in the system. We have one of the few big systems around that can be shut down while charging, although it probably is not a good idea if the amps are really high as you can still get s spike while the regulator reacts, because ours has both alternators in parallel. That way the starting battery is always in the alternator charging system.

[Reed]

[QUOTE=gregmchugh;71767]Yes, very true.

There is still the issue of powering electric battery heating pads from the underhood generator or shore power or solar for a cold van with the lithium battery bank below operating temperature which could still be a reason for keeping a small AGM battery in the system.

Winnebago is using cabin heated air to warm the lithium battery bank.

We went six weeks on Mexican West Coast without utilizing into line power or using integral Oman generator. 415 W of solar was more than sufficient.
Line power in Mexico can be chancy as noted in a previous post of ours on this thread. We now always drive in a grounding stake when we do plug in. Discussed this more fully on post #55 in this thread.

Our son did the design and fabrication of our solar/LFP system. The Manzanita Micro LFP batteries of 180 Amp-hrs each (12 V nominal) were installed under the bed. He. Installed a blower that turns on at about 40 F and blows cabin air into the battery compartment.

It got to 18 F at Balmorhea State Park on our way to Yucatan in December 2016. The blower came on about 1 am for the first time and startled us awake. Ignored this afterwards. We have installed an Olympic Wave 3 which kept cabin fairly warm (see parallel thread on this forum concerning poor insulation in a RT)

Reed and Elaine

[avanti]

Originally Posted by booster

I do think that the Balmar stuff could be damaged from a BMS shut down with the engine running, for whatever reason, if there were no AGM. Even shutting of the manual switches on the modules might do it if the allow all of them to go offline without shutting off the alternator field first. Most systems with manual disconnects warn against shutting off the charging while running if the there is no other battery in the system. We have one of the few big systems around that can be shut down while charging, although it probably is not a good idea if the amps are really high as you can still get s spike while the regulator reacts, because ours has both alternators in parallel. That way the starting battery is always in the alternator charging system.

In our rig, the master battery shutoff is one of the BlueSea latching relays with the nice remote pushbutton switches. That switch has an "On/Off" indicator light that is controlled by a small ground feedback wire from the relay. I checked with BlueSea, and they approved using that feedback wire to power a small signal relay. I use this relay to disable the Balmar properly. So, if anyone were to shut off the disconnect while running, the Balmar would shut down correctly and no harm would be done.

I mention this by way of saying that IMO, any BMS system that could EVER automatically disconnect the battery simply MUST provide an output that can be used to implement an orderly shutdown of an external alternator system.

[booster]

Originally Posted by avanti

In our rig, the master battery shutoff is one of the BlueSea latching relays with the nice remote pushbutton switches. That switch has an "On/Off" indicator light that is controlled by a small ground feedback wire from the relay. I checked with BlueSea, and they approved using that feedback wire to power a small signal relay. I use this relay to disable the Balmar properly. So, if anyone were to shut off the disconnect while running, the Balmar would shut down correctly and no harm would be done.

I mention this by way of saying that IMO, any BMS system that could EVER automatically disconnect the battery simply MUST provide an output that can be used to implement an orderly shutdown of an external alternator system.

Interesting that you can run the relay off the little indicator output, good information.

What we need is for Blue Sea to come out with a bistable relay like the yours and ours, but that does the progressive switching of two circuits, like their special manual switch does. Those appear to be specifically designed to address the alternator sense on first, off last problems we are talking about.

[avanti]

Originally Posted by booster

Interesting that you can run the relay off the little indicator output, good information.

Just for the record, this is the information they provided in 2015:

I have an application in which I need to generate a signal based on whether the ML-RBS is ON or OFF. Because of the possibility of a back-feed, I can't just use the output terminal of the switch. The yellow wire ("LED output") appears to satisfy this need. Is it alright for me to use this signal to control a small relay? Can you give me a ballpark as to how much current this wire can safely sink? Thank you.

Thank you for the question. Our Engineering tells me 250 m Amps would be safe for the 7700 ML-RBS. The 7713 ML-RBS would only be able to support 30 m Amps.

[cruising7388]

Originally Posted by booster

I do think that the Balmar stuff could be damaged from a BMS shut down with the engine running, for whatever reason, if there were no AGM. Even shutting of the manual switches on the modules might do it if the allow all of them to go offline without shutting off the alternator field first. Most systems with manual disconnects warn against shutting off the charging while running if the there is no other battery in the system. We have one of the few big systems around that can be shut down while charging, although it probably is not a good idea if the amps are really high as you can still get s spike while the regulator reacts, because ours has both alternators in parallel. That way the starting battery is always in the alternator charging system.

The Balmar excerpt in Avanti #84 acknowledges the potential for damage if after engine start, the GU alternator is up and running and charging and the battery is subsequently disconnected. But what about the more likely scenario which is when the engine starts and the alternator spins up only after the battery BMS disconnects? Balmar doesn't address that scenario one way or the other.

[avanti]

Originally Posted by cruising7388

The Balmar excerpt in Avanti #84 acknowledges the potential for damage if after engine start, the GU alternator is up and running and charging and the battery is subsequently disconnected. But what about the more likely scenario which is when the engine starts and the alternator spins up only after the battery BMS disconnects? Balmar doesn't address that scenario one way or the other.

I think it depends on exactly how the Balmar is wired. It should be getting its "enable" input from the battery, I think. If this is the case, it will never start up and all will be well. The worrisome case is when the alternator is producing power and so keeps the regulator going absent the battery. At least this is how I understand things. It's been a while since I looked carefully at this.

[booster]

Originally Posted by cruising7388

The Balmar excerpt in Avanti #84 acknowledges the potential for damage if after engine start, the GU alternator is up and running and charging and the battery is subsequently disconnected. But what about the more likely scenario which is when the engine starts and the alternator spins up only after the battery BMS disconnects? Balmar doesn't address that scenario one way or the other.

That would pretty much depend on how the Balmar is hooked up, I think.

If the "on (ignition)" wire for the Balmar is coming off the coach batteries, the Balmar will not activate and there should be no problem as there would not be voltage or current to the field. Of course, there may be timing issues with everything coming on line at the same time in the alternator, when it is already spinning. That doesn't normally happen in alternator systems. I think the Balmar, like many other regulators, uses a soft start feature to ease in the charging when you start the engine, so there must be some concern with just turning things on. If the soft start still happens if the regulator is turned on after the alternator has been running a while, it would likely make everything well protected.

Probably still in question is what would happen if the batteries were reconnected with motor running if wired that way, as the amperage would go up very quickly and I don't know if the regulating would be able to control it fast enough.

I think by far the safest method of protecting everything is to always have a battery in the system, if the engine is runnable. Next safest would be to only turn on the alternator with the on input from the batteries that are going to be charged, and have the voltage sense wire to the same batteries and active first. Switching things on and off that are moving hundreds of amps can really do some odd stuff, so better to avoid it all if possible.

[cruising7388]

Originally Posted by avanti

I think it depends on exactly how the Balmar is wired. It should be getting its "enable" input from the battery, I think. If this is the case, it will never start up and all will be well. The worrisome case is when the alternator is producing power and so keeps the regulator going absent the battery. At least this is how I understand things. It's been a while since I looked carefully at this.

For the installation to work properly there really aren't any choices in the wiring configuration. The Balmar installation instruction indicates that the regulator itself gets powered from ignition, not the coach battery. But the battery sensing terminal only looks at the coach battery and at startup, if it doesn't sense voltage, the regulator will prevent any field winding current to the alternator and as you indicate, it won't damage anything. The dicier condition that Balmar warns about is a battery disconnect after the alternator is charging the battery.

http://www.balmar.net/wp-content/upl...ion-Manual.pdf

[cruising7388]

Originally Posted by booster

That would pretty much depend on how the Balmar is hooked up, I think.

If the "on (ignition)" wire for the Balmar is coming off the coach batteries, the Balmar will not activate and there should be no problem as there would not be voltage or current to the field.

I think the Balmar, like many other regulators, uses a soft start feature to ease in the charging when you start the engine, so there must be some concern with just turning things on. If the soft start still happens if the regulator is turned on after the alternator has been running a while, it would likely make everything well protected.


I think by far the safest method of protecting everything is to always have a battery in the system, if the engine is runnable. Next safest would be to only turn on the alternator with the on input from the batteries that are going to be charged, and have the voltage sense wire to the same batteries and active first. Switching things on and off that are moving hundreds of amps can really do some odd stuff, so better to avoid it all if possible.

Actually, per Balmar specs, the regulator itself is powered from ignition. But battery sensing looks at the coach batteries which is the important thing.

The regulator does have both a delay and also a soft start feature. The delay is set at one second to ensure that the alternator has spooled up to an acceptable rpm. Soft start is a single shot process that slowly ramps up alternator voltage to the target voltage, that value being determined by whether the regulator selects bulk or absorption charging which is probably determined by battery sensing. The ramp up is pretty slow (40 millivolts per second) so it can take as much as a minute or so to meet the target.

Consequently, there is no reason to be concerned if full alternator output doesn't develop immediately on a monitoring voltmeter. The primary purpose of soft start is to preclude hammering the alternator bearings plus the belt squealing and premature wear that would otherwise occur with an instantaneous heavy load demand.

IMO, the safest way to protect the alternator is not an external battery. There is something faintly hilarious about the fact that Balmar, after sternly warning about the dire consequences of a battery disconnect, proceeds to offer you an extra cost device (Balmar TSP-12) that guarantees that it won't happen! It's nothing more than a heavy duty avalanche diode aka Transient Voltage Suppressor, (TVS) that clamps any spike delivered to the alternator diodes to a safe voltage. Short of 1.5k dissipation, the TVS is undamaged by the event. In the very unlikely event that the energy from the spike exceeds this value, the worst case is that the protective device is sacrificed. Balmar adds a couple of ring terminals and some wire and it ends up at West Marine for $29. But the device itself can be found at electronic supply houses (Mouser, et al) as a Vishay 1.5KE18A-E3 for chump change.

I think the historic leading cause of alternator damage in RVs was the use of manual battery switches that would break-before-make which would result in a brief interval where there was no battery connection which could damage an alternator in rotation. I think they are pretty uniformly designed now to make-before-break. Also, during this period, the diodes used in alternators had relatively low peak inverse voltage ratings because back then the cost of a diode was sort of keyed to its voltage rating. That doesn't hold very true now and I believe the diodes in modern alternators have far higher voltage ratings than they use to and while it's always possible to blow them, in the RV application, I think it's a lot less likely.

[booster]

The only battery disconnect switch that I know of is the BlueSea one. It will connect the alternator field after the batteries connect and disconnect the field a before the batteries connect.


https://www.bluesea.com/resources/91

[cruising7388]

Originally Posted by booster

The only battery disconnect switch that I know of is the BlueSea one. It will connect the alternator field after the batteries connect and disconnect the field a before the batteries connect.


https://www.bluesea.com/resources/91

That certainly is an effective way of protecting the alternator from spiking during a battery disconnect period but it results in a virtually instantaneous shift between a no load condition and full squash for the alternator, so if there is a heavy load demand during the shift, isn't this going to play hell with the belts?

Also, with the current Canbus network that typically controls alternator output, I dimly recall that the field windings are internally controlled within the alternator and respond to logic inputs from the computer. If this is the case, what pick off point is available for interrupting the windings by the manual switch?

[avanti]

Originally Posted by cruising7388

Also, with the current Canbus network that typically controls alternator output, I dimly recall that the field windings are internally controlled within the alternator and respond to logic inputs from the computer. If this is the case, what pick off point is available for interrupting the windings by the manual switch?

I though this conversation was exclusively about second engine alternators. Connecting to a modern LIN-controlled OEM alternator is a fools errand, IMO.

[cruising7388]

Originally Posted by avanti

I though this conversation was exclusively about second engine alternators. Connecting to a modern LIN-controlled OEM alternator is a fools errand, IMO.

That's true, but the immediate focus was on how a manual battery change switch might briefly open all battery paths to the alternator and Booster described a model that incorporated a field winding interrupt feature to keep the alternator stable during the transition. With current alternator developments, I was simply wondering if you can even access field winding terminal any longer on the alternator itself

If these alternators are better described as LIN-controlled, thanks for the heads up. I assume that what you describe as a fools errand would be trying to maintain house batteries from one?