New Insight concerning Batteries/Chargers/Boondocking

[lewster]

Originally Posted by Sal2

Hey Lew,
Just wondering how you utilize the Inverter in a trailer? Not sure how it would tie in......or if you would want to tie it in. I have heard that inverter efficiency is below 65%? If so, is it better to directly utilize DC where possible. If this is the case, the only remaining AC items are the microwave? Hairdryer?

Anyway, if the choice of a Magnum Inverter is a by-product of the Converter/Charger choice, I was wondering if you would consider taking a look at the Sterling Pro Ultra and give me your critical analysis of the product. Your input is very appreciated.

Thanks,
Sal

Sal,

First, Magnum inverters run about 85%+ in the efficiency department, with the higher voltages (24 and 48 VDC units) running in the 90% range. Don't know what inverters are in the 65% range, but they are not made by Magnum.

It's always better to utilize direct DC power as there is no conversion loss. DC powered TVs are around, but most folks I speak with prefer the 120VAC units. These need the inverter, along with the microwave and hair dryers. The larger amp draw items like the microwave and hair appliances require larger inverters, more in the 2000 watt range and a minimum of 300 amp/hour (and preferably 400+) to power that larger items for any length of time. Some folks just haul around a Honda 2000 and the required fuel and call it a day.....others want no part of a generator. As always....YMMV!

The electrical connections are not rocket science, but Do require an installer with a good working knowledge of the AC and DC systems of an RV and their interactions.

I looked at the product description on their web site. Sounds impressive until I looked further into the exact pre-programmed charging profiles...none of which work much better for Lifelines than some of the converters that you mentioned. There IS a custom program, but being unfamiliar with the unit I have no idea of how adjustable it is. I also noticed the the lithium battery profile is off from what is generally accepted.

I also researched this unit a bit on some of the marine forums. There was a significant amount of dissatisfaction with these units from some folks that have had to replace them multiple times from failures. They seem to NOT be repairable.

They are also NOT CHEAP, as pricing that I saw was in the $450-$550 range. half the price of a similarly capable Magnum (50 amp PFC charging section), and I saw no mention about temperature compensation. I also assume that charging multiple battery banks is not an option that you require.

Let us know how it works and if it keeps on working. It will be interesting for sure.

[jbxx]

I do believe I saw that temperature compensation is an option on these.
They do seem to be on the expensive side.
I have kind of a low buget, lowtech/ high tech solution that worked great for me.
I got an old battery charger that had some switchable settings and added a variable regulator
circuit cobbed into one of the switch settings that allows me to set the voltage from 13- 16 V.
JB

[gecko]

Hi Sal-
We made the mistake of ordering the Airstream solar package from the factory, instead of adding it ourselves. It came with an inferior solar charger (one-stage), and the standard converter, which is also not optimum. They provided one outlet off the inverter--it's directly under the standard 110v outlet next to the door, which is handy because it's easily accessible from outside, too. The inverter itself is buried under the L return of the front couch along with the subwoofer, the BlueSky main unit, the grounding plate for the BlueSky, the converter, the hot water heater, and the second pair of 6volt AGM's that make up half of our battery bank. They also wired it to the bulkhead by the dinette where the TV lives, so that powers it, too. When we upgraded our solar, we changed out the solar charge to a BlueSky (great!) but stayed with the supplied inverter and converter for economic reasons. We had the guys pull a short line from the inverter supplied outlet into which the TV is plugged to a more convenient outlet under the dinette. This is where we plug our laptops in.

So we have a bit more convenient and cleaner setup, in that we have 100v where we are most likely to use it, instead of moving around your cig lighter powered inverter, which of course is not a big deal.

Now that we've worked with Lew, I would only work with him for this stuff. He's going to replace our 440 amp/hr AGM bank of four 6 volt AGM's that weigh 260lbs with a 300 amp/h lithium bank that weighs 84 lbs, plus 3.5 lbs for the required and provided BatteryManagementSystem. The lithiums can be discharged to 80% from full According to the battery manufacturer, our Airstream supplied converter and inverter will work fine with the lithiums. But we'll check with Lew as the definitive source on that.

[lewster]

Just a quick comment. Lithiums require a very specific charging regimen called CC/CV, which means constant current constant voltage. The lithiums we are using need a bulk charge of 14.3VDC and float at 13.5VDC.

The only charging equipment that can handle this very specific requirement is a high quality solar charge controller like the Blue Sky with the iPN PRO remote and a Magnum inverter/charger.

The stock Parallax, or any available converter will kill the very expensive lithiums in short order.


Lew Farber
RVIA/RVDA Nationally Certified Master Tech
Master Tech Energy Systems, Inc.
AM Solar Certified Installation Center
Lifeline Batteries**Magnum Inverters
541-490-6357

[BoldAdventure]

Poor Lew, this has been an interesting topic. But I feel like Lew is having to repeat himself.

[Lance M]

Originally Posted by BoldAdventure

Poor Lew, this has been an interesting topic. But I feel like Lew is having to repeat himself.

Yes. He is very good at repeating himself, however

He's been doing it for years around here. Awesome asset to this forum.

He's a very patient man. Even when someone insists on addressing him as "Lester" That is a good thread to read.

Thanks Lew!

[lewster]

No problem! It happens a lot as many folks never read the entire thread.


Lew Farber
RVIA/RVDA Nationally Certified Master Tech
Master Tech Energy Systems, Inc.
AM Solar Certified Installation Center
Lifeline Batteries**Magnum Inverters
541-490-6357

[BoldAdventure]

Originally Posted by lewster

No problem! It happens a lot as many folks never read the entire thread.

OMG YES! This is my biggest internet pet peeve. Inserting opinion without reading the discussion before giving said opinion to ensure it was on topic.

Is there a thread anywhere detailing the installation of the Magnum. I noticed some of the other units seem to get installed in the same place as the Parallax, where as with the Magnum units I've seen them installed elsewhere. Usually closer to the batteries.

[SteveSueMac]

Originally Posted by BoldAdventure

OMG YES! This is my biggest internet pet peeve. Inserting opinion without reading the discussion before giving said opinion to ensure it was on topic.

Yeah, but imagine being Lew and having to repeat yourself all the time. Or being Lew and being called Lester. Man - that's enough to start its own thread!

;-)

(Yes, I'm being a wise guy...hope that was obvious...)

[Rocinante]

Very helpful topic, thanks Lew and Sal. I'm now convinced that if / when we switch to AGM batteries, we'll also be swapping out our relatively new PD 4655 for a Magnum converter/inverter. Thank you for this point of clarity regarding the insufficiency of the smart PD4655 when it comes to the proper care and feeding of AGM batteries. Somehow that point had not previously clicked for me.

[lewster]

Originally Posted by Rocinante

Very helpful topic, thanks Lew and Sal. I'm now convinced that if / when we switch to AGM batteries, we'll also be swapping out our relatively new PD 4655 for a Magnum converter/inverter. Thank you for this point of clarity regarding the insufficiency of the smart PD4655 when it comes to the proper care and feeding of AGM batteries. Somehow that point had not previously clicked for me.

Don't want to be picky, but that's inverter/charger

[TheCabin]

Is it just Airstream or do all Thor Ind. RVs use single stage chargers?

[TheCabin]

I have been looking over the manual for the MMS and it does appear to be very good at providing both the ac inversion and an excellent battery charger (which is what I really want). Does anyone know if it is a simple plug-in to its remote control port (RJ-11 connector) of the existing cable coming from the stock wfco inverter control switch installed on the AS? The standards involved in rv electronics appear to be somewhat of the wild west at this time.

[idroba]

Originally Posted by Sal2

Began to look at specifications for Progressive Dynamics and noticed that although Bulk voltage is listed as 14.4V, the converter can only achieve 12.6V at rated current output. If this is the case, you would likely never obtain full converter current into the battery on Bulk charge because the battery is voltage dependent in order to force current. So buying a larger converter may not help recharge time. Hummm

Called Progressive Dynamics and spoke with an Engineer who confirmed that the highest current possible into a 50% discharged battery is approximately 47 amps. (regardless of having larger converter ie(55amps, 60amps, 70amps).
As was explained to me, the only advantage to a larger converter is the ability to support higher DC loads ie(appliances & lighting) my thought....so what

I'm looking for the quickest recovery time to recharge my batteries ..... not looking to run bigger loads and so the saga continues, I turned to IOTA

Batteries will only take current at a given rate and the charge tapers off rapidly in even the bulk rate stage. That is why PD says there is a limit to the current in the bulk stage. Batteries cannot be forced to accept charge faster than they want to (no, they are not human, but it is a chemical reaction situation). They don't mind being filled reasonably fast if they are mostly empty, but as they fill up, they take less current as the "nature of the beast". The last 20% goes slower. The last 5% is really slow. They are not like a glass of water that can be filled faster with a bigger hose. Your quest for a charger which will give you "the quickest recovery time to recharge my batteries" is going to run into this normal flooded cell battery charge issue every time. No one makes a charger which will fire hose fill a battery without damage to the battery.

[BoldAdventure]

Unless you go with Lithium batteries, you can charge them really fast.

[Rocinante]

Not as fast as they discharge your wallet when you buy them.

I kid, of course. I'd love a set of those lithium babies!

[Sal2]

Originally Posted by lewster

Sal,

First, Magnum inverters run about 85%+ in the efficiency department, with the higher voltages (24 and 48 VDC units) running in the 90% range. Don't know what inverters are in the 65% range, but they are not made by Magnum.

It's always better to utilize direct DC power as there is no conversion loss. DC powered TVs are around, but most folks I speak with prefer the 120VAC units. These need the inverter, along with the microwave and hair dryers. The larger amp draw items like the microwave and hair appliances require larger inverters, more in the 2000 watt range and a minimum of 300 amp/hour (and preferably 400+) to power that larger items for any length of time. Some folks just haul around a Honda 2000 and the required fuel and call it a day.....others want no part of a generator. As always....YMMV!

The electrical connections are not rocket science, but Do require an installer with a good working knowledge of the AC and DC systems of an RV and their interactions.

I looked at the product description on their web site. Sounds impressive until I looked further into the exact pre-programmed charging profiles...none of which work much better for Lifelines than some of the converters that you mentioned. There IS a custom program, but being unfamiliar with the unit I have no idea of how adjustable it is. I also noticed the the lithium battery profile is off from what is generally accepted.

I also researched this unit a bit on some of the marine forums. There was a significant amount of dissatisfaction with these units from some folks that have had to replace them multiple times from failures. They seem to NOT be repairable.

They are also NOT CHEAP, as pricing that I saw was in the $450-$550 range. half the price of a similarly capable Magnum (50 amp PFC charging section), and I saw no mention about temperature compensation. I also assume that charging multiple battery banks is not an option that you require.

Let us know how it works and if it keeps on working. It will be interesting for sure.

===============
Hi Lew,
I have been pondering whether or not to respond because I don't want to butt heads with anyone. However, seeing how much interest there is in this subject, it would seem unfair not to provide any info I have gathered.

Its appears inverter efficiency is indeed on the order of 85+% as you pointed out. I plead ignorance on this count. In my mind I remember inverters being very in-efficient. Perhaps I was looking at older portable inverters such as my Trip-Lite 200watt. Anyway, sorry for the mis-information.

As concerns Inverter Chargers, they seem practical when coupled with a supporting Solar energy source but not so good without it. As most trailer owners have no such system, conventional wisdom suggest finding ways to utilize 12VDC directly from the batteries and finding practical ways to recharge the batteries when needed.

When I travel, I have found that my vehicle charging system does a fair job of maintaining batteries when on the road. If I boondock for more than two days, I have to recharge. The idea behind getting a high quality marine charger/converter is to use a portable generator to recover to 90% charge. From what the folks at Lifeline tell me, this is very feasible with the right charger in approximately 3 to 4 hours, depending on the state of discharge.

My hope is to pump 60amps into the battery bank until it switches to Absorption phase. The batteries should be at 90+% at this point and allow for 2 more days boondocking.

This is based on a 250 amp-hr Lifeline Battery bank.
Using 4amps/hr, 8 hrs/day = 32 amp-hrs / day

Of course, a solar charger would also be an excellent solution for recharging the batteries and one to be considered.

But either case, I don't have a need or desire to install an Inverter/Charger.
And yes, I suggest the $500 Sterling is much more cost effective than spending $1000 for a Magnum Inverter/Charger + Solar system + Installation.

Concerning the charge profiles, the selectable profiles beat the pants off of having no selection and from what I understand, the profile offered for AGM batteries is very useable. I spoke with Dave at Lifeline and he indicated that the profile they provide looks good. (14.4 Bulk, 14.4 Absorption, 13.4 Float, 13.0 Maintenance) His only suggested improvement is to lower the Float voltage to 13.2. A change I can easily accommodate with this charger.

This charger does include a temperature compensation sensor module so no problem there.

Concerning Owner problems. I found two threads about on this subject, both threads written by the same person (Yofy) back in April 2011. In that same thread, (FlyingCloud1937) comments:

You just bought one of my preferred chargers, from one of my preferred manufactures.

I have recommended that charger to all of my commercial clients for the past 9 years.

Todate I haven't seen one failure in over 100.

lucky you.

Lloyd

[Sal2]

Originally Posted by idroba

Batteries will only take current at a given rate and the charge tapers off rapidly in even the bulk rate stage. That is why PD says there is a limit to the current in the bulk stage. Batteries cannot be forced to accept charge faster than they want to (no, they are not human, but it is a chemical reaction situation). They don't mind being filled reasonably fast if they are mostly empty, but as they fill up, they take less current as the "nature of the beast". The last 20% goes slower. The last 5% is really slow. They are not like a glass of water that can be filled faster with a bigger hose. Your quest for a charger which will give you "the quickest recovery time to recharge my batteries" is going to run into this normal flooded cell battery charge issue every time. No one makes a charger which will fire hose fill a battery without damage to the battery.

========================
Hi idroba,
Not true. During bulk charging, the current into the battery is limited by three variables.
1) Charging voltage supplied by charger. This is the reason why Bulk Charge Voltage is typically 14.2V and higher. All things being equal, lower charging voltage will result in lower current, (less energy) longer recovery time, to charge the battery.
2) Internal resistance of the battery. In the case of LifeLine batteries they have very low internal resistance and therefore will accept high charging currents on the order of 250% of battery amp-hour rating. As the Lifeline Tech told me,"you probably couldn't afford the charger that this battery would accept".
3) The rated current output of the subject Charger. (assuming the charger can achieve full rated output current at the target voltage i.e.(14.2V or higher)

This is the reason why a charger that does not produce full rated current at the target charge voltage (14.2 or higher) will result in reduced charging current (and therefore longer charge time) into the battery. Probably over simplied but you get the idea.

Hope this helps.
Sal

[Sal2]

A little more information I found out today.

Folks at Lifeline said that with a 60amp charger on a 250 amp-hr battery bank (LifeLine Batteries). With the batteries discharged to 50%, recovery time to 90% would take 1 to 1-1/2hrs.

So I believe this would allow me to boondock for two days. Then running the generator for 1 to 1-1/2hrs to recover to 90% providing for another two days running off grid.

They tell me this is acceptable practice for a month or more as long as I return the batteries to full charge at some future time. Not exactly specified but indicated approximately every 1 to 1-1/2 months. Doesn't sound too difficult to live with.

Just another bit of info to consider.

[idroba]

There was no mention of a specific battery type in the original post (s). I assumed the normal flooded cell battery. Others may be different and are different.

Flooded cell batteries have a recommended maximum charge rate which depends on their total capacity. Most RV type chargers take the typical battery and capacity into account in their design as they are general purpose devices built by the thousands at an affordable price. You can build custom anything and fine tune it with big budgets, but most people and manufacturers look at some compromises and costs for the job they generally have.

You are talking about bulk charging only. I wrote about total charging.

I wish you well with your quest.