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Old 02-25-2010, 01:47 AM   #11
RodeWorthy
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OVervoltage Problem

Thom,
I am having trouble understanding what your problem is. You have mentioned going through a lot of 12V fixtures and water pumps. I too have had water pump problems with the Shurflo Extreme 5.7 GPM variable speed pump. I am on 3rd pump. However, the symptoms of the failure were not related to voltage issues.

I also recall that you have gone through one or more Trombetta relays associated with the hydraulic pump. I too have had failures of those devices. I have never determined what caused those failures. I took them back to Trailair and they were going to open them up to determine what failed but I never heard back from them. I really suspect over current problems. The hydraulic circuit requires very high current level -- greater than 80A in some modes. If I could get a look at the terminals inside it would be easier to determine what is happening in there.

Are you having components "burn-out" or quit all together? Is there a symptom of the failed units that lead you to believe it is over voltage?

It is possible to have very high voltage spikes that cannot be detected by a meter attached to the circuit. Spikes of this nature are generally very short duration, in the order of milliseconds, and will not be detected by in-line meters. Sensitive electronic apparatus are usually more susceptible to this phenomenon than motors, relays or light fixtures. In our rigs the refrigerator circuit board can be affected.

I still maintain that voltages up to 15 volts or even higher should not be considered excessive for 12VDC rated components. All 12VDC charging systems exhibit voltage levels in that order. It is required in order for the battery to charge. The charging voltage has to be higher than the battery voltage in order to induce charging current into the battery bank. It is normal.

Only recently I was directed to an FAQ on Interstate's site that indicated they want the U2200 battery Absorption charge voltage to be 15.5V. The charge current is specified as C/10 where C is the AH rate of the battery system. In our 4 battery banks, wired in series-parallel and Interstates rating of 232AH per battery, this means 464AH. C/10 then means limiting charge rate to 46.4 Amps.

The RS3000 battery charger is rated at 150 Amps, not 100. The SCP (System Control Panel) provides for current limiting through the AH setting for your battery bank and through the Maximum Current Setting. Xantrex has fixed the current rate at C/5. So in order to achieve the C/10 specified by Interstate you would put in 464AH as the size of the battery bank and set the Maximum current rate to 50%. Xantrex fixes the Absorption charge rate at 14.4 volts - well below the specified voltage in the FAQ. Personally I think the 15.5V Absorption Voltage is too high. They specify the equalization voltage as 15.6V - only .1V higher. Generally we want to isolate loads (to protect them and to keep the load off the battery while overcharging) when we equalize the batteries but we can't do that when in absorption mode. This is the only place I have found these specs. Other batteries such as Trojan specify 14.8V as the absorption volltage and that is what I have been using.

I monitor voltage with a Tri-Metric 2020 battery monitor. Almost all my battery charging is done via my solar controller. I rarely enable charging from the Inverter. In the past 3 days my log shows I have had max volts of 14.7 to 15.3 Volts. Again I consider this normal and necessary to fully charge my batteries.

I hope this diatribe has not strayed too far from your issue. I would be interested to know what the nature of the failures are.
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Old 02-26-2010, 12:02 AM   #12
Thom
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RodeWorthy
So far I have had no problems with the Trombetta relays associated with the hydraulic pump. Must have been someone else I went through 4 5,7 pumps and then installed a dirt garden variety 2.3 and it has lasted the longest but is starting to act up. I am now in the habit of carrying at least one extra water pump, no water in the desert sucks.

The florescent light fixtures are becoming a problem, I now have had 6 or so just quit working, I have gone through more than 24 tubes during this process as well

Sorry about misstating the charger amp capacity, right now between the engineers and the technician that is trying to help me my mind is basically mud

My 4 six volt battery bank is set up in the zantrex menu system correctly according to Zantrax .

I am monitoring with a TM 500 and the RS 3000 remote. Now they think I may benefit from a software upgrade on the RS, after I check out a couple other things for them.

Are you using any florescent lighting fixtures in your rig, I have a total of 7 with only 4 working at this time

At this time we are just trying to figure out why the light fixtures keep failing and the tubes burn out, this is starting to get costly
Thom
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Old 02-26-2010, 11:40 AM   #13
Motor31
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I could be all wet about it but IIRC charging voltages much above 15 volts start to get into the equalization range for batteries and are not intended for maintenance charging purposes. That means excessive boiling of the electrolyte in the batteries and shortened life span as well.

I would think that voltages above 14 volts isn't very good for 12 volt applications. I haven't seen any "appliances" indicating a volt range over 14 volts on the specs.

Does anyone have the installation manual and spec sheet for the inverter in question to look what the factory indicates is normal operation?
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Old 02-27-2010, 01:04 PM   #14
RodeWorthy
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Thom,
Sorry about the Trombetta failure comment. I had you mixed up with Lauren. Also no problem on the current rating of the RS3000 charger. I just wanted to point out it is plenty capable and able to charge at a rate that is too high for the 4 x 6V Interstate U2200 battery set (according to Interstate). I will deal with the charging issue in a separate post.

Your pump issues are not untypical. I have met or read posts from many people who have had multiple failures of the Shurflo Extreme 5.7 GPM pump. Some as many as 5 and now you report 7. Wow! I am on my 3rd one. My problems were not over voltage. My pump problems were related to 1) electronics control -- pump would continuously hunt and run on at very low speed without shutting off; 2) internal check valve failure causing pump to backfill the fresh water tank when connected to c.g. supply. I never had an outright failure of the pump where it would not run. But I agree -- being without water in not an option -- and it is our only source when dry camping. I came close to buying a spare but did not. I may regret that.

The loss of the fluorescent lamps is another matter. The number of failures you have is very high. I would suspect a problem too. My first thought about a possible cause is very high voltage spikes from the inverter due to failed capacitors in the inverter/charger. They exist to filter such spikes. You are already in touch with the right people to make that assessment so I won't speculate further on that. We have 5 fluorescent fixtures in our '07 rig and have never experienced a failure. We do not use those fixtures very often. In fact, I cannot recall any light bulbs failing.

We have the same setup you have but I have modified the factory battery wiring considerably. PM me If you would like a diagram of the changes. My converter is not connected and never has been. It is available as a stand by in case the inverter has to be removed for service.

My RS3000 is model 809-3000. Firmware revision is 1.09.00. I would be very interested to know the specifics of how your battery bank is set up in the Xantrex. Especially since they have approved it. This is a bit of a confusing area. Would also be interested to know what F/W revison they are suggesting and what they think that might fix.

I am still of a mind that the voltages (mid-14V) you are seeing are not abnormal when charging and should not be causing your problem. The values are within the range for the charging algorithm of the inverter/charger.

I am not sure what more I can offer. If there is something you would like me to check to compare my system to yours let me know. Hope you get to the bottom of this soon.
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Old 02-27-2010, 02:58 PM   #15
RodeWorthy
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The Compromises of Battery Charging

Quote:
Originally Posted by Motor31
I could be all wet about it but IIRC charging voltages much above 15 volts start to get into the equalization range for batteries and are not intended for maintenance charging purposes. That means excessive boiling of the electrolyte in the batteries and shortened life span as well.

I would think that voltages above 14 volts isn't very good for 12 volt applications. I haven't seen any "appliances" indicating a volt range over 14 volts on the specs.

Does anyone have the installation manual and spec sheet for the inverter in question to look what the factory indicates is normal operation?
Battery Charging is a tricky thing. There are comprimises that must be understood. Two of the things we need to consider are: Overcharging and Undercharging. Both can prematurely destroy the battery.

Overcharge the batteries and risk damage from excessive heat, gassing of electolyte and depletion of the positive grid. Gassing is not the most serious for a flooded cell battery. Within reason that is a maintenance issue. Plate buckling due to heat and depletion of the grid is another matter and can prematurely shorten the life of the battery.

Undercharge the batteries and risk sulfation of the battery plates which reduces capacity, incomplete charging and consequently a lot less battery capacity available -- capacity that you paid for and are lugging around. Sulfated plates will shorten the useable battery life.

RVers probably break down into two camps when it comes to battery charging philosophy:

Those who most always use FHU and need only concern themselves with battery maintenance. Their batteries are most always connected to a charger (converter) when under heaviest use.

Those who regularly dry camp for long terms and rely heavily on the deep cycle capabilities of their battery set while disconnected from the grid. They need to be able to fully charge their batteries quickly and not deplete them below 50% of their AH capacity to preserve battery life. Staying at least 70% of full charge is even better.

Charging Voltage and Current parameters for the two scenarios are aptly discussed at BatteryUniversity.com. This site ofers a great deal of practical information about batteries of all types.

Installation and User manuals for the Xantrex RS3000 Inverter/Charger are available on the Xantrex web site. Refer to Appendix B of the User Manual for the Battery Charging Reference including the charge algorithm for this device.

Complications arise when we compare those values to the requirements stated for the Interstate U2200 battery. Decisions must be made - it is a bit of a tightrope walk. Who do we believe: the inverter/charger supplier or the battery manufacturer?.

I have quoted charge values earlier so no need to do it again. They were the manufacturers values - not mine.

I will leave you with this to ponder. If 13.8 Volts will charge a battery to 75% capacity how could we utilize that battery in a system that needs to work on the top 30 to 50% of the battery capacity? It would be seriously impaired. The need to increase charge voltage and duration to complete the last 25% of charge and do it quickly becomes paramount. It requires higher charger voltage to do that.

Mike, I agree with you that 15.5 volts sounds too high for an absorption charge rate. That value is what the battery mfr states but it is only 0.1V below their equalize rate. It is puzzling and I have avoided it. My absorption voltage is set at 14.8V on my solar charger. That is what Trojan specs are and is about half way between the Xantrex and Interstate specs. It is at the high end of the Battery University rate for aggressive charging of sealed lead-acid batteries.

When equalizing it is important to isolate the batteries from their loads so I have no problem with the 15+Volts there.

Lest anyone think the difference between 14.4V and 14.8V is trivial - it is not. At the micro-ohm battery resistances involved there is a great deal of change in current flow between these values.

Can't say if my appliances are at risk because of this but every off-grid user that uses batteries to store energy is faced with the same scenario. I would think the subject would be widely discussed if it was a problem. I have not seen that discussion.
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'07 Mobile Suites 36RS3 #3910
Mor/ryde IS, Trailersaver TS3 hitch
Level-Up with Remote Control
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'08 Chevy 3500 dually Duramax/Allison
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