there is a small drain on my battery

[markopolo]

peppster - if you haven't already ruled out the isolator as the cause of the problem then take a look at this pdf - http://www.grampianowners.com/Links/...or_Trouble.pdf - to see if a short circuited diode #1 failure mode matches the symptoms you're seeing.

[mkguitar]

Originally Posted by cruising7388

Yank the positive cable from the battery.

Usually best practice is to disconnect the NEGATIVE cable as it is less likely to spark.
ESP if your wrench happens to contact the chassis

This is important if a conventional wet cell lead/acid battery is charging it will release hydrogen gas- Hindenberg.

So when puling a battery, disconnect - first.

installing a battery - last.




Interesting info on later ecm/ alternator controls- that all makes sense to me in using motor power to drive the wheels when it is most needed.

my 05 Chev chassis is the newest thing I own and my ASE training is over 20 years in the past...

some smart cookies on this forum.

Mike

[cruising7388]

Originally Posted by mkguitar

Usually best practice is to disconnect the NEGATIVE cable as it is less likely to spark.
ESP if your wrench happens to contact the chassis

This is important if a conventional wet cell lead/acid battery is charging it will release hydrogen gas- Hindenberg.

Yep. Thanks for the point well taken.

[peppster66]

thank you for all your replies, I have disconnected the battery, fully charged it, and will wait until tomorrow to see if there is a drop in volts, start there, hopefully find the problem soon, thank you all,,,,,,,

[cruising7388]

Originally Posted by peppster66

thank you for all your replies, I have disconnected the battery, fully charged it, and will wait until tomorrow to see if there is a drop in volts, start there, hopefully find the problem soon, thank you all,,,,,,,

What did you find out?

[peppster66]

well, it appears not to be the battery, if its disconnected, it will hold a full charge, I have checked the isolator, and it is not the problem either, so I am checking all the fuses and relays , then on to the alternator as a last try, this has me stumped so far, but I will keep trying, thanks,,,,

[cruising7388]

Originally Posted by gregmchugh

Because the Ecotrek modules do not require regular full charges like AGM batteries do. If they don't get to full charge it is not going to effect the life of the battery cells. The critical factor in lithium battery packs is cell balancing and this is handled internal to each 4 cell Ecotrek module by the Battery Management System. If the charge voltage is high enough and long enough then all the Ecotrek modules will reach full charge even if there is unbalanced charge voltage at the modules due to varying cable lengths. If some modules are not at full charge when the charge voltage drops it is not critical, only effect is likely some, probably small, reduction in usable capacity for that charge.

The more critical issue is the type of charge profile used which seems to be set up to be the most optimum profile for the AGM battery life and not the 14+ volt optimum charge voltage for the lithium cells. Roadtrek does not discuss the charge profile strategy and you don't have a reading of actual charge level for the ecotreks so hard to actually assess how well the charge strategy actually performs.

Thanks for pointing this out. I've seen some multiple battery tabulations that showed some startling differences in charging rates to the individual batteries from the failure to provide a balancing network but I guess the significance of this largely depends on the length of the charging cycle and as you point out, the worst case for a lithium array would be some capacity loss in some of the batteries but without damage to the battery itself.

With respect to the charging profile, I thought the implementing of the programmable Balmar regulator was to enable defining the optimum profile for whatever batteries are employed. Doesn't Roadtrek program the Balmar to meet the charging profile desired for lithiums?

[booster]

Originally Posted by cruising7388

Thanks for pointing this out. I've seen some multiple battery tabulations that showed some startling differences in charging rates to the individual batteries from the failure to provide a balancing network but I guess the significance of this largely depends on the length of the charging cycle and as you point out, the worst case for a lithium array would be some capacity loss in some of the batteries but without damage to the battery itself.

With respect to the charging profile, I thought the implementing of the programmable Balmar regulator was to enable defining the optimum profile for whatever batteries are employed. Doesn't Roadtrek program the Balmar to meet the charging profile desired for lithiums?

Charging "profiles" most often refer to the voltages they run at, and then the charger uses either an algorithm or amps from a shunt to know it the batteries are fully charged. AFAIK, the Balmor looks at field % of the alternator to try to figure out where it is at in the charge cycle, with no input of amp hour capacity of the bank or any other battery modifiers except type. It also won't know if any of the amps are going to loads. As with very many chargers and smart regulators, getting the batteries to not be over or undercharged is very unlikely, so most of the systems are set way to the undercharge side, as they feel the hazard to the batteries is lower. If you have a shunt based battery monitor, you can easily tell if any of the systems is doing a good job, or not.

[cruising7388]

Originally Posted by peppster66

well, it appears not to be the battery, if its disconnected, it will hold a full charge, I have checked the isolator, and it is not the problem either, so I am checking all the fuses and relays , then on to the alternator as a last try, this has me stumped so far, but I will keep trying, thanks,,,,

It helps to determine that internal battery discharge isn't the problem.

The next thing to check is the parasitic load on the battery which can be done if you have a digital meter that can read amperes. Put the meter in the ampere measuring mode. Disconnect the negative battery cable and with the meter in the ampere mode, put one lead on the negative battery terminal and the other lead on the disconnected negative cable. Start with the highest ampere scale, (typically 10 amps) and measure the amperage draw. Then disconnect the cable running to the input terminal on your isolator and see if it changes the meter values. If it doesn't, selectively pull the engine (not coach) fuses and observe any changes in meter values.

[gregmchugh]

Originally Posted by cruising7388

With respect to the charging profile, I thought the implementing of the programmable Balmar regulator was to enable defining the optimum profile for whatever batteries are employed. Doesn't Roadtrek program the Balmar to meet the charging profile desired for lithiums?

A charging profile for lithium would be a constant 14+ volts which would not be good for the AGM battery that is in parallel with the Ecotreks. It appears that the three chargers are set up with AGM charge profiles to improve the life of the AGM and the lithiums seem to get charged adequately. Though, without any readout of battery charge level in an Ecotrek van it is hard to know how full the charge is on the lithium batteries.

[cruising7388]

Originally Posted by gregmchugh

A charging profile for lithium would be a constant 14+ volts which would not be good for the AGM battery that is in parallel with the Ecotreks. It appears that the three chargers are set up with AGM charge profiles to improve the life of the AGM and the lithiums seem to get charged adequately. Though, without any readout of battery charge level in an Ecotrek van it is hard to know how full the charge is on the lithium batteries.

This is a little confusing to me.

Fully chargedAGM (coach) and engine batteries are often subject to hours of 14+ volts during lengthy driving periods without damage. Furthermore, I thought the Balmar regulator is employed to drop alternator voltage down to a 0 charging state to avoid damage to a fully charged lithium battery. BTW, if the lithium BMSs never shut down from battery depletion, is there ever any load placed on the Etrek AGM?

[gregmchugh]

Originally Posted by cruising7388

This is a little confusing to me.

Fully chargedAGM (coach) and engine batteries are often subject to hours of 14+ volts during lengthy driving periods without damage. Furthermore, I thought the Balmar regulator is employed to drop alternator voltage down to a 0 charging state to avoid damage to a fully charged lithium battery. BTW, if the lithium BMSs never shut down from battery depletion, is there ever any load placed on the Etrek AGM?

AGM batteries do get overcharged from prolonged charging by a regular alternator and this is probably one of the factors along with cases where the AGMs are not brought to full charge regularly that lead to reduced life in RV usage.

The Battery Management Sysytem should prevent overcharging of the lithium cells no matter what the charger is doing.

Yes, it is likely that the AGM battery only discharges when the lithium cells get down near the 80% discharge so it may not happen regularly.

[booster]

Originally Posted by cruising7388

This is a little confusing to me.

Fully chargedAGM (coach) and engine batteries are often subject to hours of 14+ volts during lengthy driving periods without damage. Furthermore, I thought the Balmar regulator is employed to drop alternator voltage down to a 0 charging state to avoid damage to a fully charged lithium battery. BTW, if the lithium BMSs never shut down from battery depletion, is there ever any load placed on the Etrek AGM?

Subjecting fully charged AGMs to driving voltage over 14 volts is not good for the batteries and is likely one of the reasons they never last as long as the manufacturers charts show. Depending on who you believe, gassing point is around 14.1v which is very often exceeded while driving.

You could probably set the voltages in the Balmar to give a constant output of near 14v, as I think you can do manual setting of the bulk, absorption, and float voltages. Normally, using the preset programs, they do turn down to float.

Many of us just disconnect the coach batteries from the engine charging when they get full to prevent the long drive damage.

[eric1514]

Originally Posted by booster

...
Many of us just disconnect the coach batteries from the engine charging when they get full to prevent the long drive damage.

I'd like to see a show of hands to back up that "many" claim. It's not that I disagree with your findings re overcharging and battery life, but I don't know of anyone, except you, who has a disconnect switch and the instrumentation to know when to throw it.

Eric

[booster]

Originally Posted by eric1514

I'd like to see a show of hands to back up that "many" claim. It's not that I disagree with your findings re overcharging and battery life, but I don't know of anyone, except you, who has a disconnect switch and the instrumentation to know when to throw it.

Eric

I guess it would depend on how you define "many" . I know of at least 3 others, but will let them speak for themselves, if they choose to. I would think that the vast majority don't disconnect them, as B's don't normally come with either a disconnect method or a way to tell the batteries are full, so it isn't even possible unless you add it yourself. Those with standalone engine generators are far more likely to use an external regulator to just turn down the the voltage when it thinks the batteries, which is still fairly inaccurate, I think, but better than putting full voltage on the batteries all the time. It also eliminates the need for the disconnect.

With the battery banks getting bigger and using the much more expensive AGMs (compared to wet cells), I think the the whole issue of battery care will be better addressed in the future. Shore chargers are already drifting away from timers to a basic amp controlled stage transition style (not very accurate at this point because not adjustable) and improvements will continue, I hope. I think the same will happen with the charging off alternators. The solar manufacturers appear to be much more modern in the accurate charging methods, as you can get even modestly priced charge controllers that have a built in monitor and settable amps controlled stage transitions.

What will be very interesting is what the OEMs are going to do about charging the larger AGM banks (200ah+ are getting very common) that can accept a lot of amps when low. The new vehicles with PCM controlled charging systems appear to have problems with the large currents that aren't being used by the chassis even if the alternator has enough capacity. I don't know how they can handle that without either limiting the charge current to the coach, or using a second alternator like the engine generator systems do now. Most are still staying with old ways of having something like an 80 amp auto resetting breaker in the line to the coach, which is not a good solution, and the PCM would then see high amps that were cycling on and off which might be even worse.

[avanti]

Originally Posted by booster

What will be very interesting is what the OEMs are going to do about charging the larger AGM banks (200ah+ are getting very common) that can accept a lot of amps when low. The new vehicles with PCM controlled charging systems appear to have problems with the large currents that aren't being used by the chassis even if the alternator has enough capacity. I don't know how they can handle that without either limiting the charge current to the coach, or using a second alternator like the engine generator systems do now.

I am betting on second engine alternators. Not that expensive (cheaper than a genset), takes less space, and not that hard. Makes everything SO much simpler. ARV, RT, and the lamented GWV all went this way. The others will catch up.

The only real negative is lack of A/C while boondocking. But, my guess is that there is relatively little overlap between boondocking and A/C use. (Yes, I know there are exceptions).

The only other obvious answer is real DC-DC chargers. I don't quite understand why they aren't more popular. They don't help with charging speed, but they are safe both for the battery and the vehicle.

[booster]

I agree on the DC-DC chargers as they would seem to be a logical solution, especially if you wanted to be able to use an internally regulated alternator. I don't recall if the output of them can be turned down or not, I will have to look at the Sterling site to see. They would also be a natural for the manufacturers to use an existing shunt to control them, which would be a huge plus IMO.

The cost of the second alternators does compare very favorably to the regular generators, and would do even better in mass production and if they used the significantly less expensive, high output alternators available rather than the very expensive XP ones. Folks with PCM controlled setups would wind up being limited to whatever the system can handle without problems, which might not be very much, unless they go to a second alternator, or someone comes up with a workaround for the PCM control.

[cruising7388]

Originally Posted by booster

Subjecting fully charged AGMs to driving voltage over 14 volts is not good for the batteries and is likely one of the reasons they never last as long as the manufacturers charts show. Depending on who you believe, gassing point is around 14.1v which is very often exceeded while driving.

There seems to be a wide range of opinions regarding the consequences of this. From the Powerstream website:

SLA Battery Quick-Charging

Question: Why do sealed lead acid manufacturers specify that you can't charge at a rate higher than C/3? And why are they wrong?



First let's define the C/3 term. If the capacity of a battery is C amp-hours and you want to charge in 3 hours, you would be charging at C/3 amps (C amp-hours/3 hours = C/3 amps). If you want to charge in half an hour you would charge at C/0.5hours, or 2C. A 15AH battery would have a C/3 charge rate of 15AH/3H = 5 amps.

As we discuss below, it has been shown that the dominant sealed lead acid technology, VRLA AGM, can be charged at high rates without damage. But the battery manufacturers often say to charge below C/3.

The reason for this is found in Linden's Battery Handbook. He says "The VRLA battery is capable of recombining the oxygen produced on overcharge up to the C/3 rate of constant current charge. At higher rates the recombination reaction is exceeded by the rate of gas generation." [my italics]

To fully understand this statement you also have to realize that no oxygen is generated during the charging of the battery. Oxygen is only generated when the battery is being overcharged. So what the battery manufacturers are thinking is that if you don't charge a battery at higher than C/3, you also won't overcharge the battery at higher than C/3. So even if you use the dumbest charger on the planet it won't cause the battery to vent.

This completely discounts the fact that a quality battery charger will never overcharge the battery at all. In fact to overcharge the battery at C/3 you have to be at a much higher voltage than is normally available from a 12 volt charger. To force a current of only C/5 through a fully charged battery requires 16.2 volts. (I couldn't find the voltage necessary for C/3, but it will be much higher).

Typically a multi-stage charger will run at 14.4 volts during the fast charging phase and 13.8 volts during the float charging phase. At 13.8 volts it is impossible to generate oxygen even for a fully charged battery, and even at 14.4 volts the oxygen generation rate for overcharge is about C/100.

[booster]

That information about the charging rate recommendations is starting to change, with Lifeline tending to be one of the bigger manufacturers recommendations of higher rate charging. For deeper discharges (50% or more), they recommend AT Least C/5 to C/2.5. with the higher end starting to need temperature compensation. When I have talked to them about it, they said they are OK temp controlled all the way up to C/1.25, as long as monitored. They won't accept that much for long, like 1/2 hour or less before they start to taper acceptance, assuming normal charging voltage of 14.3-14.4v for bulk and absorption and you have enough amps available to hold that voltage.

As far as a charger not overcharging at C/3, that is not true, because the battery is not full at that charge rate. it is the voltage that counts, and only once the batteries are full. The amps are determined by the battery SOC if the voltage is held constant and will be hugely less than C/3 when the battery is full. I don't particularly agree with Powerstreams increasing of voltage by a bunch to force in more amps for longer before the acceptance drops, as the manufacturers don't want you to that, except for a short, current control, stage after they get full which is basically a mini equalize. By the time a Lifeline is full it will be at C/200 or .5%C. That is 2.2 amps on a 440ah bank. Leaving it at 14.4 volts after that will dry it out and oxidize the anode per most manufacturers. If you have it at 16v to force more amps in, you could blow past that point quickly and do bad things, plus be oxidizing and gassing more while getting there and have extra heat gain. So, basically charge rate is totally irrelevant to overcharging in most cases, if you have the voltage right for the battery type and brand, and temp controlled. It is how long you are at that voltage once you get the battery full, before going to float that will be how much you are overcharged. If you stop before the .5%C, you are undercharging, which is pretty usual with most most chargers as they try to prevent overcharging. It is easy to over charge with any dumb charger, regardless of it's capacity.

There some that are saying that you will be at absorption voltage longer if you have a high charge rate, and they are correct. It is likely that this extra time at full absorption voltage will cause more gassing and oxidation, which may be true. As soon as you get to the gassing point, and have extra amps available (you know because the amps start to taper to the battery) the battery will use some of those amps to gas, including oxygen. You will get to gassing voltage (about 14.v) when the battery is likely only 60% full at C/3. At C/1.25, you might get there by 50% full as you have the amps available to hold the voltage up. The high charge rate will have less time at bulk and longer in absorption because of that, so it will see gassing point longer than a lower charge rate. The consensus, at least according to Lifeline, is that downside of the higher rate is much less than the benefits they get from the higher rate.