E-Trek Battery Monitor Install

[gsm]

E-Trek AGM Battery Re-Configuration

1 - Sorry the pictures did not come trough. There is really nothing too earth shacking in them, but an illustration is worth a thousand words. I am very new at all this. I tried once again to send the pictures with this post, but I failed. I should also have numbered the paragraphs in my texts to make life easier for all.

NOTE – Markopolo –-- There is one problem with the red wiring in your schematic. The chassis ground on E- must be removed.

2 - I Should have explained why believe that in the series connection of the four, six-volt battery-blocks ( AB, EF, CG and DH), the hotter battery-block AB will consistently charge more quickly and reach full charge before the others when the blocks all experience the same charging current. Assuming four equally healthy blocks start charging from the same charge-state.

4 - The reason is that charging efficiency varies with battery temperature, in the range of 80 to 90 percent, over the temperature band mainly of concern to us.. It may be greater on some products than on others. This means that only 80 to 90 percent of the charging-current through the four battery-blocks is given over to the battery charge-state. Since the charging efficiency depends directly on chemical activity within the battery it will increase with temperature. The rule of thumb frequently used states that chemical activity roughly doubles every 10 degrees Celsius (21.2 degrees Fahrenheit) in temperature increase.

4 - This means that over the same charging period, the hotter battery-block AB will accumulate a higher state of charge than the colder battery-blocks, even though all are subject to the same charging current. And battery-block AB will reach the fully charged state first. At that time battery-blocks EF, CG and DH still have not reached full-charge, and if left that way for a prolonged period every usage-cycle, the capacity of the three colder blocks will decrease due to sulfation. I estimate that under these conditions right from the outset, the 24 volt battery-system would have the maximum Amp-Hr capacity effectively reduced by five to 10 percent. With each cycle the AB battery-block would begin charging from a higher charge-state, reach full charge earlier, and at charging cut-off leave blocks EF, CG and DH less and less fully charged.

5 - If the fully charged state of the AB battery-block is used as the determining factor for ending the charging process of the 24-volt battery system the system, six of the eight batteries will go into relatively rapid performance decline.

6 - That is why I asked whether Booster could confirm from his experience whether a bit of over charging is less harmful to AGM batteries then undercharging. The approach to exploit the economy of sticking with the exiting eight batteries is dependent on this. Booster basically confirms that it is likely possible for AGMs to bear some small period of over-charge. From this it appears that it is worth a try to allow the AB block to overcharge, and focus on the charge-state of the other three blocks.

7 - This why I recommended allowing a degree of overcharge of the AB block each cycle, to ensure that the three blocks EF, CG and DH are fully charged. This essentially happens if battery state of charge is sensed at the 24 volt terminal. I previous touched on this, and recommending that
battery temperature sensing be done at a terminal centrally located in the battery-nest at the rear, most likely the warmest spot back there. This will raise the charging source voltage, favoring fully charging the colder three blocks.

NOTE: - It would take a very complex battery-balancer with temperature sensing for each to the four battery-blocks to account for this, bypass the unnecessary current from block AB, and put it into the other three blocks.


Boosters idea of using six, Eight-Volt batteries in the rear compartment.

8 - I like Boosters idea of using Six eight-volt, 160 Amp-Hr AGMs, They could be quite large, and fill the entire floor area of the battery-compartment. The floor space is one limit, but the batteries could be a few inches taller, i.e. come above vehicle-floor with an appropriate sealed cover/hood. Venting to the exterior would remain below floor. Suitable taller batteries of greater Amp-Hr rating might be found and installed, with some sacrifice in storage space.

9 - One of the advantages of Booster's approach to the 24 volt battery system is that the series connected under-hood batteries A and B can be retained. This allows those batteries to continue as the prime or backup 12 volt system. It also gives the coach a backup starter-battery. The A and B batteries would be charged the conventional ways.

10 - One might view the 24 volt to 12 volt converter as optional or as an independent source, when a second isolated 12 volt source is advantageous, or a back up is needed. One is no longer seriously impacted by a 12 volt system failure.

11 - If possible at least two of the six batteries might kept healthy as replacements for A and B when needed. All six batteries might be used in a small power back- up system. Waste not want not.


Three Pictures and a Schematic should follow


Regards All
GerryM

[markopolo]

Just trying to fully understand the existing setup:

24V Solar float voltages: (assumed/expected 26.6V or 6.65V at each battery if perfectly balanced)

A: 6.33v
B: 6.43v < New battery
C: 6.94v
D: 6.88v
E: 6.43v < New battery
F: 6.34v
G: 6.94v
H: 6.88v

Existing series connections:

DCAB 6.88V + 6.94V + 6.33V + 6.43V = 26.58V
HGFE 6.88V + 6.94V + 6.34V + 6.43V = 26.59V

Existing parallel connections:

6V parallel: AF 6.33V
12V parallel: BE 6.43V (both new batteries)
18V parallel: CG 6.94V
24V parallel: DH 6.88V

Cooper Equalizer:

Equalizer attaches to series connected FE at F+ and AB at A+. Both are at 12.77V. The equalizer also supplies positive voltage to C-.

I'd expect to see half of D+ (or H+) being 13.3V at both F+ and A+ if the equalizer is working correctly. Source: http://www.allbatterysalesandservice...0C00-SPECS.pdf

Maybe A&F are nearly dead? Could they be causing a load sufficient to pull down the two new batteries B&E?

[markopolo]

Back to the new design from GerryM.
Summary:

New parallel connections:
AB 6V
EF 12V
CG 18V
DH 24V

New series connections:
BA / EF = 12V
CG / DH = 12V
BA/EF / CG/DH = 24V

Ground to BA to EF = 6V ground & 12V ground.
Ground to BA/EF to CG/DH = 24V ground.

I removed the ground at E-.

Image attached:

E-Trek Battery balanced layout equalizer.jpg

Please review for accuracy and errors.

[gregmchugh]

Did not notice before that there are two versions of the Cooper, the equalizer that outputs 1/2 of the input and the converter that has a fixed output voltage, nominally 13.5v. So you can also use the equalizer for handling 12v loads at the 12v point if you accept the voltage variation which would be greater anyway I expect at the 12v tap from the batteries without the equalizer.

[markopolo]

Good catch.
C in model # = converter
E in model # = equalizer

No confirmation whether it is an equalizer or converter (installed wrong) from photolimo's post here: http://www.classbforum.com/forums/f5...html#post35816

[booster]

I looked at the Cooper site a couple of days ago, and it appeared that the units that are called equalizer/converter show two wiring diagrams, one if it is used as an equalizer, and another if it is used as converter. Can't do both?

I did finally get back on the original topic about installing a battery meter in the system. One of the big hangups is the two, far apart negative connections for using a shunt.

I found the information the inductive pickups from Inpower, and if I am reading it correctly you should be able to use one of the inductives with any meter that needs a 50mv shunt output and has over 20 ohms internal resistance. That would include Trimetric, Magnum, Blue Sky, Victron, etc AFAIK. The sensor can go in any line, positive or negative. The only extra wiring is a small power and ground circuit to run it. You eliminate the big wire connection issues of adding a shunt, so you come out way ahead on work.

Of course, I would call whatever meter manufacturer you want to use to confirm compatibility, but is looks pretty good from the literature.

http://inpowerdirect.com/docs/OM-23C.pdf

[photolimo]

Originally Posted by markopolo

Where does the positive 12v line to the fuse panel come from? (I see negative 12v in the schematic)

Not sure what your asking here. The positive 12v in the front battery bank goes to the 12v loads.

Originally Posted by markopolo

Are there any really large 12v loads? Fridge, pump, fan & lights could be handled easily by an equalizer. Does your etrek have instant hot water? Is that AC or DC? If DC is it 12v or 24v? Is the solar 24v also?

The only 12v load on top of what you listed is the gas water heater/furnace. It is wired in before the rest of the loads meaning it is connected under the drivers seat just before the battery disconnect relay and not at the main 12v fuse load panel. So when "battery disconnect" is not lit up "the batteries are not connected", the gas heater is still connected to the bank. I think they do this to prevent freezing water failure but not sure.

We do have the instant hot water heater but it is 120v.

Solar panel comes in to the solar charge controller at 24v.

[gregmchugh]

Originally Posted by booster

I looked at the Cooper site a couple of days ago, and it appeared that the units that are called equalizer/converter show two wiring diagrams, one if it is used as an equalizer, and another if it is used as converter. Can't do both?[/URL]

The descriptions and installation diagrams for the equalizer version of the Cooper show that loads can be powered from the 12v connection point. A difference between the two is that for the the equalizer, the voltage at the 12v connection is 1/2 the voltage of the 24v connection and for the the converter version, there is regulated 13.5v (nominal) at the 12v connection point where the loads are powered. So, the equalizer can be used as a converter but the converter cannot be used as an equalizer.

[markopolo]

Originally Posted by photolimo

Not sure what your asking here. The positive 12v in the front battery bank goes to the 12v loads.



The only 12v load on top of what you listed is the gas water heater/furnace. It is wired in before the rest of the loads meaning it is connected under the drivers seat just before the battery disconnect relay and not at the main 12v fuse load panel. So when "battery disconnect" is not lit up "the batteries are not connected", the gas heater is still connected to the bank. I think they do this to prevent freezing water failure but not sure.

We do have the instant hot water heater but it is 120v.

Solar panel comes in to the solar charge controller at 24v.

Thanks, I figured out the +12v to panel.

Where does the solar controller output connect to the batteries?

[gsm]

Getting The Maximum From AGM E-Trek Batteries

Markopolo and All

1 - I should have noticed that 'G'-terminal of the Equalizer has to remain connected to chassis/ground.

2 - I believe that the battery configuration shown as a stack/totem-pole would be visually clearer/cleaner. Battery-pair AB with chassis ground and current-monitoring shunt if used at the bottom, block EF above it, followed by CG, and DH at the top. I agree with Booster that rather than a shunt better and more flexible solution is to use a Hall Effect current monitor such as the InPower LLC Model DCS30-300-1. It can be placed around a cable, anywhere along the battery stack, wherever total current flows.

3 - The battery-stack is best, centered in the schematic, to minimize the number of crossing lines/wire-runs. To the left the Equalizer and 24 volt alternator charging source, etc.. To the right loads, converters (for 12 volt and other voltages), inverters, any other charging source (such as solar, power-line etc.).

4 - The connection from A+B+ (under hood) to E-F- (in the rear) could be shown longer, and as two connections (to reflect the two paralleled cable- runs. As on the current schematic, a dashed line across this cable-pair, separates under-hood form from rear-compartment stuff. The use of diagonally opposite tap-points on each battery pair/block could be included for illustration, as well as the theoretical voltages at each level of the stack.

5 – Another version of this new schematic could show Booster 's suggest approach with six eight-volt AGM by opening/eliminating the long cables to A+B+, and grounding E-F- to chassis. Batteries A and B could be shown series connected and configured as a conventional 12-volt system, either primary or backup.

6 - Booster's suggested setup certainly minimizes the losses from jumpers, terminal clamp-points, and cable length. This should give the 24-volt battery-system very low impedance and losses. One could maximize benefit from Booster's approach by connecting the two, now unused cable-runs in parallel with the charging-cable from the high current alternator.


More On The Suggested Battery Configuration

7 – On RT's configuration, I previously viewed the separator at points A+and F+ as main ON/OFF switch for all 12-volt power to the coach, the connection between the separator and the starter battery was not shown in the first drawing bearing letter-names for the batteries. (I expected that there would likely be another separator between the battery-systems 24-volt terminals and the coach electronics.)

8 – I do not see the necessity of the link shown in the schematic, from E+F+ via the separator to the stater-battery. In the my suggested revision, it cannot be achieved unless one of the two low resistance cable-runs to the rear is sacrificed, which would not be a good thing for the battery system.

9 - Finally, if RT's battery-configuration indeed has a separator connected to the 12-volt point, it was likely connected under the hood, at what is now a six-volt point. Is this separator an unfortunate hang-over from the 'RS Adventurous'? If part of the E-Trek design, it is not clear to me under what condition RT allows the separator to close. I have some suspicions why it is there , but have nothing solid to go on. The obvious use of of the separator is for emergency staring, however if closed during vehicle operation the separator would impact battery charging in a number of ways, some more bearable than others. And it would feed back into the Sprinter's charging system.

A Note On My Suspicions Regarding The Functional-Failures Of The Original Configuration

10 - It is possible that RT noted that in their configuration, battery string A & B was severely overcharging. (Of the charging current passing through CG and DH, A & B got much greater proportion than E & F.) RT may have tried to ameliorate the problem by using the separator to switch in the starter battery to bypass some charging- current around string A & B, but to some extend it bypassed string E & F also, and drew down the terminal voltage. This meant that string E & F charged even less. Only the batteries in blocks CG and DH had a chance to charge completely.. In use the 24-volt battery system could only deliver the charge in the A & B and E & F strings, and the 12 volt out would diminish first. This is what the balancer/ egualizer is expected to fight against.

11 - I am confident that creating battery blocks, AB and EF, makes a satisfactory solution. Batteries E and F are no longer starved for charge, and A and B are no longer seriously overcharged.

NOTE: - The connection between the separator (if it is indeed present) must be removed, even before other changes are made.

NOTE: - I discount the possibility that connection of string A & B via the separator to the starter battery could have been used in attempted compensation to increase charge on battery strings A & B and E & F.


Best Regards All

GerryM

[photolimo]

Originally Posted by markopolo

Maybe A&F are nearly dead? Could they be causing a load sufficient to pull down the two new batteries B&E?

Just a note about the new batteries, they are a completely different brand and have slightly different voltage properties from the original.

[gsm]

I just noticed Booster's sketch of the stacked battery totem-pole. Sorry Booster! I Seem to always be hundred miles behind you.

Best Regards
GerryM

[gsm]

photolimo

Did you replace all four bottom batteries (A, B, E & F) with the same type? They are all severely undercharged, certainly compared to the top pairs, according to Markopolo's data in post #142. For how long have the batteries sat like this? If you changed all four, I would not expect the large voltage difference compared to the CG & DH blocks from a different brand of similar capacity. The whole bottom 12-volt section is being discharged held-back by some parallel load. Might not allow that section to charge properly. Have a look at my last post Approx. #150, where I talk about the separator and the connection to the starter battery. If this connection is actually there, and closed while the engine is running, it would divert current, and prevent proper charging of the lower 12-volt battery-blocks.

Best Regards
GerryM

[photolimo]

Originally Posted by gsm

Did you replace all four bottom batteries (A, B, E & F) with the same type? They are all severely undercharged, certainly compared to the top pairs, according to Markopolo's data in post #142. For how long have the batteries sat like this?

No, Roadtrek only replaced two batteries when the bank went dead the other day. This is why we would like to install a proper battery monitoring system.

Here are the latest voltages after resting without the solar charger hooked up.

[photolimo]

Originally Posted by markopolo

Good catch.
C in model # = converter
E in model # = equalizer

No confirmation whether it is an equalizer or converter (installed wrong) from photolimo's post here: http://www.classbforum.com/forums/f5...html#post35816

Had to dig deep but finally had the time/opportunity to find the model number.

MODEL: 21100E00
Rev: E

The wires they used are 2AWG and are exposed, so I will be covering them up.

Breakers were labeled 70AMP and also exposed terminals, so I will be covering those up as well.