House Batteries Upgrade to AGM ... and other Related

[Hallen01]

I thought our 2013 Berk house batteries might be prematurely near the end of their useful life because every time I had a fault and cleared it, the inverter/charger went to bulk charge, which I had incorrectly interpreted as the batteries having fully discharged (bad thing – causes the battery plates to become heavily sulfated, shortening their life). Also, when we travel with the inverter on, I noticed that the batteries go to bulk charge immediately after plugging in to shore power upon hooking up at the destination.

In fact, the inverter has circuitry to not let the batteries fully discharge, and modifies the set point voltage discharge limits with actual battery temperature sensor information.

After rereading the Magnum Inverter-Charger MM-1212 and Magnum Remote Panel Model MM-RC manuals online, I called Magnum Dimensions tech support, and found out:
· That the batteries go to bulk charge immediately after clearing the fault (by cycling the inverter on, then back off) only means that the batteries dropped below 12.5v, not that they went flat;
· Same thing is true when I have the inverter on while traveling, and I see that the batteries go to bulk charge immediately after plugging in to shore power
· Our MM-RC remote indicator (lights on the panel) does not have the push-button feature that the replacement/upgrade ME-RC50 remote has, that of allowing the batteries to be equalized (intentionally overcharged) once every six months or so, to knock the sulfates off the plates
o equalizing is a “controlled overcharge” performed after the batteries have been fully charged
o equalizing helps to mix the battery electrolyte (to reverse the buildup of stratification) and to remove sulfates that may have built up on the plates
o if conditions are left unchecked, the overall capacity of the battery is reduced
· If you are replacing a MM-RC remote with the ME-RC50 remote, installation is “plug-and-play”
· The shore button on the ME-RC50 should be used to change from the default 30A breaker setting to the 20A setting upon installation
· The ME-RC50 remote is required for use with AGM batteries, so that the charging profile can be reprogrammed properly for your make and model of AGM battery

I do not plan to convert this season to the ME-RC50, but may do this post season, or later in the season for the following reasons:
· Allows manual, periodic intentional overcharge to equalize the batteries, extending the life of the present batteries
· I was planning to eventually upgrade to Lifeline 6V AGM batteries which require the ME-RC50 remote for programming, using either
o four Lifeline 220 Ah GPL-4CT @ $308.00 each (10” high, total 264 lbs) recommended if inverter only used to power entertainment center/computers, recharging phones, etc., and shore power used almost all of the time, or
o four Lifeline 300 Ah GPL-6CT @ $435.55 each (13” high, total 360 lbs) recommended if residential refrigerator added or if dry camping frequently
§ requires reprogramming the ME-RC50 remote to a value other than the default 220 Ah battery capacity
§ probably also requires an additional ¾” plywood liner on the battery compartment floor to accomodate the additional 96 lbs; slide weight bearing capability and axle rating should also be checked for additional refrigerator and batteries weight; AC receptacle that powers the residential refrigerator needs to be connected to a circuit powered by the inverter output, not the GFCI AC shore power pass-through circuit which the LP gas refrigerator supply was connected to
§ would be necessary only if dry camping frequently, or if residential refrigerator installed; if latter installed, then a 2000 mA pure sine wave inverter is strongly recommended*
o The battery type should entered into the ME-RC50 remote per “Set Battery Type”, page 26 of the remote manual (select AGM-1 for Lifeline Batteries)

I plan on avoiding the entire residential refrigerator upgrade scenario primarily for weight rating and space considerations, but I do plan to eventually replace my flooded cell lead-acid batteries with the Lifeline 220 Ah GPL-4CT batteries just to avoid servicing battery water levels; I also would necessarily have to replace my Magnum Remote Panel Model MM-RC with a ME-RC50 remote, which will also give me the equalization option which extends the life of the AGM batteries.

I recommend consulting Magnum Dimensions tech support during setup to go over all the settings you think you need to make, after reading the manual

* A residential refrigerator will work with AC supplied by a modified sine wave inverter, and a 1200 mA inverter (e.g. the MM-1212) is probably sufficient if there are no other major loads; however, without a pure sine wave inverter, AC motors run at decreased efficiency and overheat, which shortens their life.

[ScottBrownstein]

I follow your narrative, however, I would be concerned that your system goes into bulk charge mode after travelling. Unless you have a huge load on the inverter when on the road, your alternator should be keeping the batteries up when travelling and the inverter should not go into fault mode (indicating that it believes that the batteries are getting too low to continue to output power.) When you arrive at your destination and hook up to shore power, the inverter's charger section should find the batteries up to snuff, unless they were very seriously discharged when you left.

When you run your engine you should see something like 14 volts on the house bank. If there is no change to the house battery bank voltage when you start up, your battery isolation solenoid is having problems and is not connecting the alternator to the house bank when the engine is running. This will also mean that your "boost start" switch may not work either. This solenoid gets a lot of use and is a failure mode part in most RV electrical systems.

[Mmnsc]

Where is the battery isolation solenoid. Not sure my engine is charging the house batteries.


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[ScottBrownstein]

Originally Posted by Mmnsc

Where is the battery isolation solenoid. Not sure my engine is charging the house batteries.

Based on your narrative...it isn't! The isolation solenoid is in the Battery Control Center (BCC). If you have a boost switch, you have one. It measures battery bank voltage and when it rises over 13.3 volts or so it puts all batteries in parallel, house with chassis when the engine is running and chassis with house when you are hooked up to shore power and the converter is running (also on generator.)

There is no way that the inverter should go into fault mode when the engine is running with an alternator that offers at least 175 Amps of 12 volt.

It is a black box (really!) that has the positive battery cables running to it from the house bank. It contains the battery disconnect switch as well and a bunch of fuses for things like the steps, etc.

There are lots of brands, but most recently it seems that FR is using one from Intellitec. You can find the manual here http://www.intellitec.com/assets/pdf/5301087new3.pdf

Since the solenoids are always powered when connected to shore power, they tend to eventually die from heating. Almost any RV dealer carries lots of spares in stock. If it is bad you want a continuous duty solenoid, not a starter solenoid.

[Hallen01]

Originally Posted by ScottBrownstein

I follow your narrative, however, I would be concerned that your system goes into bulk charge mode after travelling. Unless you have a huge load on the inverter when on the road, your alternator should be keeping the batteries up when travelling and the inverter should not go into fault mode (indicating that it believes that the batteries are getting too low to continue to output power.) When you arrive at your destination and hook up to shore power, the inverter's charger section should find the batteries up to snuff, unless they were very seriously discharged when you left.

When you run your engine you should see something like 14 volts on the house bank. If there is no change to the house battery bank voltage when you start up, your battery isolation solenoid is having problems and is not connecting the alternator to the house bank when the engine is running. This will also mean that your "boost start" switch may not work either. This solenoid gets a lot of use and is a failure mode part in most RV electrical systems.

Scott: Thanks for your reply. I'm learning more about this subject every time I talk to someone.

I had thought that everything you stated would have been the case, but I was advised by someone in the FR warranty department during a visit out there that the house batteries charge when the engine is running, only after the chassis batteries have been topped off (whatever voltage that is, I don't know), unless the spring loaded emergency start switch is depressed, which reverses the situation. I have never gotten a fault condition while travelling (either with the inverter on or off), and I can only assume that the chassis batteries needed continuous charging while travelling, not allowing the house batteries to get their turn.

[ScottBrownstein]

Originally Posted by Hallen01

Scott:...I was advised by someone in the FR warranty department during a visit out there that the house batteries charge when the engine is running, only after the chassis batteries have been topped off (whatever voltage that is, I don't know...

Well, that is correct, however it is not really a state of charge situation but a system voltage issue. The BCC will bring on the house after starting the engine when the system voltage rises above something like 13.3 or 13.4 volts. Most engine alternators are HUGE and their voltage regulators are set to around 14 volts, so if your chassis battery is in reasonable shape, the house should come in within 15 or 30 seconds after starting. It isn't about "their turn" its chassis or chassis + house, two choices only, at least on a Ford gasser chassis. When you plug into shore power its house and then house + chassis, same voltage level.

You indicated that whenever you plug in after a drive your inverter/charger immediately goes into boost. If it stays there very long, your house bank is low and the alternator didn't do its thing during your drive.

I know, I know this all sounds very complicated.In reality, once you know how it works, its really quite simple. Another way to check what is happening is to start your engine and verify that all 4 red leds on the battery panel light. It isn't as good a test, and doesn't tell you much if they were all lit before you started up.

[camaraderie]

Originally Posted by Mmnsc

Where is the battery isolation solenoid. Not sure my engine is charging the house batteries.


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Turn the engine on and take a voltage reading at the battery posts...if it is 13.2 or greater...they are being charge by the engine alternator. If it is less...you might want to look at the battery disconnect switch and make sure it is in the connected position & check again.

[NV245]

On Berkshire it is easier to see if the "emergency start" switch lamp glows or blinks indicating that battery voltage is 13.3 and the chassis and house batteries are linked together, it happens when drive engine is running and chassis batteries are 13.3 or above, or when plugged in and house batteries are 13.3 or above.


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[ScottBrownstein]

Originally Posted by NV245

On Berkshire it is easier to see if the "emergency start" switch lamp glows or blinks indicating that battery voltage is 13.3 and the chassis and house batteries are linked together, it happens when drive engine is running and chassis batteries are 13.3 or above, or when plugged in and house batteries are 13.3 or above.

Wow...that is a nice feature. Definitive!

[Hallen01]

[QUOTE=ScottBrownstein;1131716]It isn't about "their turn" its chassis or chassis + house, two choices only, at least on a Ford gasser chassis. When you plug into shore power its house and then house + chassis, same voltage level.QUOTE]

[Hallen01]

I like your system better than my system, or at least what I think my system is, as described to me by Berkshire Diesel Division Warranty Department. I'm not really knowledgeable enough to be able to prove if mine really is an "either/or" system.


As far as seeing the "Bulk Charge" indicator light on the MM-RC remote panel upon pulling into a campground and hooking up, following a trip with the inverter in the "On" position; that just means the house batteries dropped below 12.5v enroute, which isn't all that bad.

[Hallen01]

Originally Posted by NV245

On Berkshire it is easier to see if the "emergency start" switch lamp glows or blinks indicating that battery voltage is 13.3 and the chassis and house batteries are linked together, it happens when drive engine is running and chassis batteries are 13.3 or above, or when plugged in and house batteries are 13.3 or above.

So specifically is this how you run the test:

• Start engine
• Press and hold "Emergency Start"
• Emergency Start switch blinks: house batteries are above 13.3v and not linked to the alternator (along with the chassis batteries)?
• Emergency Start switch glows steady: house batteries are 13.3v or below, and have been linked to the alternator (along with the chassis batteries)?

So then the chassis batteries or a FR Berk are always on charge from the alternator if the engine is running?

[ScottBrownstein]

Originally Posted by Hallen01

So specifically is this how you run the test:

• Start engine
• Press and hold "Emergency Start"
• Emergency Start switch blinks: house batteries are above 13.3v and not linked to the alternator (along with the chassis batteries)?
• Emergency Start switch glows steady: house batteries are 13.3v or below, and have been linked to the alternator (along with the chassis batteries)?

So then the chassis batteries or a FR Berk are always on charge from the alternator if the engine is running?

I really doubt that is the procedure. Start the engine, if the emergency start switch glows that means that the BCC has already connected the house to the chassis and that the system voltage is above 13.3 (that is the reason why the BCC connected the two banks!)

On my past rigs, if you hear the solenoid click when you press the emergency start switch, the solenoid wasn't engaged. When you run the engine and for at least a minute after you shut down, when you press the switch you won't hear the solenoid "clunk" since it was already engaged by the BCC using the 13.3 volt system voltage.

Now, as far as the inverter discharging the batteries during a long drive, that just shouldn't be possible if the alternator was charging the house. I would bet that you have at least a 175 amp alternator and that would mean that the inverter was supplying more than 2,000 watts of AC all the time you were driving. Even a really big residential refrigerator only draws half of that and it only runs 4 or 5 minutes out of each hour anyway.

Virtually all modern RVs charge the house with the engine whenever it is running (MB Sprinter aside.)

Your coach is trying to tell you something...

[gordonsick]

Originally Posted by Hallen01

four Lifeline 300 Ah GPL-6CT @ $435.55 each (13” high, total 360 lbs) recommended if residential refrigerator added or if dry camping frequently
§ requires reprogramming the ME-RC50 remote to a value other than the default 220 Ah battery capacity
§ probably also requires an additional ¾” plywood liner on the battery compartment floor to accomodate the additional 96 lbs; slide weight bearing capability and axle rating should also be checked for additional refrigerator and batteries weight; AC receptacle that powers the residential refrigerator needs to be connected to a circuit powered by the inverter output, not the GFCI AC shore power pass-through circuit which the LP gas refrigerator supply was connected to

Wow, this thread is very informative and well-reasoned, so I'll archive it. Thanks.

I've been thinking about some of these issues of a battery upgrade, and I'm thinking of getting L16 batteries, which are nominally 16" high (and 6volts), but have basically the same footprint as a golf cart battery. They are available flooded or AGM and would weigh about 500 pounds for a set of 4. They would deliver 700+ nominal amp hours. My Berk has enough height for them and enough slack in the footprint to take their bases.

One issue of concern is whether this overloads the house battery bay. I'd hate to have it break while going over a bump on a road. I'm planning to ask the Diesel Division folks about the weight rating. The golf cart batteries are about 250 lbs for the set, I think.

The other issue is cost. In Canada, the AGMs would be about $2K for the set.