Xantrex Battery Monitor Product Review

[Maine Sail]

Hi All,I thought I'd post a product review of the Xantrex XBM battery monitor. After years of guessing the state of charge and how long I should run my engine I decided to buy a Xantrex XBM battery monitor. This monitor was easy to install and is very easy to operate although set up was slightly confusing but I managed.The Xantrex Battery Monitor uses unique microprocessor technology to provide total battery status information for your battery bank. A simple display shows volts, amps, amp hours consumed, and operating time remaining. It also displays a "fuel guage" for your batteries. One fun feature is to set it to amp draw and see what different items draw per hour. I know my stereo and VHF combined draw about 4.5 ah, my chart plotter about .8ah and my anchor light 1 ah.If I have learned anything using the XBM it's that I now understand how a battery charges and how when it gets to 92% full it starts accepting very little amps from the alternator. The last 10% of charge can take upwards of 7 hours of running the engine to achieve a 100% charge. At 92% charge my batteries are accepting less than 5 amps per hour! At a 60% charge they accept about 45-50+ amps. The size of your alternator can do nothing to "force" current into the batteries if they won't accept it. If I draw my batteries down to 60% I can get back to 90% with my 90 amp alternator in about an hour but the last 10% takes a long, long time.In hind sight I wish I had bought the XBM before the bigger alternator because I could have saved a lot of money. I rarely, draw my two 4D battery bank below 70% and that's running a fridge, stereo, plotter, auto pilot and cabin lights at night. I now know that I really have no real need for a 90amp alternator and that the stock 51 amp alternator would have been fine.My advice to anyone planning an alternator upgrade would be to add a Xantrex XBM first and then decide if you need a bigger alternator. I actually physically swapped my 90 and my 51 amp alternators, mid summer, to see if there were any differences and guess what? It took the stock alternator, with built in regulator, about 15-18 minutes longer to reach a 90% charge from a 70% charge than with the 90 amp, externally regualted, alternator thats it! At a 90% charge the 51 amp alternator and the 90 amp alternator performed identically because the battereies were controling the rate of charge not the alternator or regulator. The other thing to note is that my 90 amp uses one of those fancy high dollar multi stage Balmar regulators. I now know that these regulators are mostly a bunch of BS as far as I'm concerned. The standard built in regulator on the stock alternator charged at the same rate at 90% and up as the expensive Balmar multi stage! I highly recommend the Xantrex XBM battery monitor and also Jack Rabbit Marine. I ordered my XBM from Jack Rabbit and it was on my door step the next day and I did not pay for next day Fed-X...The XBM is one of the most usefull devices on my boat!!

 

[Don S/V ILLusion]

good info

It's always useful to hear reviews of good products. I can't help wonder if you would see the relatiely small charge rate differential between the 2 alternators if your battery bak was larger.Regardless, on to my question - after your review, I'm thinking of installing the monitor too but have a somehwat unique wiring system such that it may make the monitor useless. Before I ask you the questiohn, I need to describe the system:500amps house bank comprised of 6V Trojans plus a separate start battery, all charged via a Xantrax 40 amp Smartcharger with remote panel. The complication, which makes me think the mnitor won't work, is that I have a separate inverter leg of the wiring directly off the house bank, separately switched and fused, which does not share the same wiring to the electric panel at the nav station. Basically, two branches from the house bank, one to the nav panel and the other to the inverter. Not sure if that's a clear description...Because the branches are isolated, I can't figure out how I'd wire the shunt such that it would read the current draw through both branches. Without doing so, the monitor couldn't read everything.Question - can you eplain either where you placed the shunt on your boat or, assuming I described this clearly, where I'd put it on my situation?Thanks

 

[Maine Sail]

The XBM will...

Read current draw between the negative terminal and the positive terminal (input+ & output - of your combined bank). It should not matter if you have two seperate hot wires going to the batery + side because the shunt measures between the + terminal and the negative terminals. What it won't do is measure your start battery too.

 

[Captain Bob]

Jave Jim, who is a shy and timid individual,

did something similar with a Link 2000 and a Heart Inverter.I am always thrilled to se folks tackle projects on their sailboats, and publish their success.Great job Maine Sail!

 

[ruedi ross]

Maine Sail, you have some of the

basics slightly misunderstood. The shunt measures current flow into and out of the battery bank by monitoring current flow at the negative connection to the battery bank. Amps in = Amps out, less the effeciency factor of your batteries, which can be programmed into your meter typically 85-90%. Because it measures at the negative terminal, it doesn't matter if the current source comes from a charging source such as your alternator, solar panels, shore power charger, or draws such as your DC sub panel, inverter, or whatever. they all flow thru the negative connection to your battery bank. this is why the instructions say that the shunt be wired DIRECTLY to the negative terminal of your battery with NOTHING connected to your negative battery connection between the battery and shunt. Don, this means that unless you have more than one house bank, if it is wired up this way, your "unique" wiring system will still work with this system. Having separate positive wiring systems to the inverter and to the DC panel mean nothing, they all use the common negative connection to the battery via the shunt. Another thought, a 50 amp alternator operating at full capacity will not last as long as a 100 amp alternator operating at 1/2 its rated capacity. You always want a "cushion" when rating your operating ranges of these components. A 100 amp alternator is designed to have more cooling capacity at a given RPM, larger diode banks, etc., You don't run your engine wide open all the time, why do you want to run your alternator wide open all the time? A 100 amp alternator operating at low engine RPM's will put out significantly more current than a 50 amp at the same RPM. Your comment about the "fancy balmar 3 stage regulator being a bunch of bs" indicates a lack of understanding of how flooded lead acid batteries work. One of the worst things you can do to your house batteries is overcharge them for hours on end with a "dumb" regulator that comes stock on most alternators. It's not all about stuffing amps into your battery, it's about maintaining a specific voltage at a certain charge rate and tapering that charge rate off as the batteries near the upper end of this charge cycle. To just charge the batteries with a Dumb regulator will work with a starting battery, but will cause your expensive, quality deep cycle house batteries to die an early death.One last thing, if your VHF draws one amp and you leave it on for one hour, this is one amp hour removed from your battery bank. If your sterer and VHF combined draw 4.5 amps, but are only on for 30 minutes, this removes 2.25 amp hours from your battery bank. This maay seem like I'm nitpicking, but it is an important concept to understand. A good example would be if you are running your microwave off your inverter. lets say your inverter draws 100 amps from your batterys to run your microwave, but it only runs for 6 minutes. This would suck 10 amp hours from your battery.Hope this helps, Ross

 

[Don S/V ILLusion]

thanks Ross

I said "unique" in the context there are separate neg leads for the panel and inverter respectively - not a good idea I know but easily remedied by connecting both to the load side of the shunt. thanks guys for all the input

 

[Maine Sail]

No Sh#t Ross....

All I was trying to say was that in his particular situation with two loads off his + battery terminal it would work. I know how a shunt works and was not trying to get into a confusing discussion about in/out solar, alternator or shore power in regards to the shunt or the fact that any load grounded prior to the shunt will not be read by the XBM.As for your comments about dumb regulators frying my main bank in short order I really have to question that? I've owned numerous boats over the years with so called dumb regulators and had house banks last at least a minimum five years or more! I usually run 6v golf cart batteries but on this boat I'm waiting for the factory 4D's to kick the can first and unfortunately they are still working perfectly. In case you did not read my post entirely I have actually tested, compared and physically done the comparison between my Balmar ARS 5 regulator with my 90 amp alternator and my stock alternator with the "dumb" regulator. The float voltage & amp output on both regulators, according to the XBM, is virtually identical from 90% of charge and up (and yes I'm using the right setting, FDC, on my ARS 5). So how is it if they both put out the same voltage and same amps when the batteries are almost full am I going to fry them when the XBM and my Fluke DMM tell me the output is the same (within +/- .1v)? I'm not trying to bash the external regulator, I own one, and it certainly has it's place with certain battery types but the $300.00 difference plus the cost of the alternator hardly seems worth it for coastal cruising when I can get 5 or 6 years out of $190.00 worth of 6V golf cart batteries using a so called dumb regulator. Even with a smart regulator I replace batteries every 5 years or so anyway if they need it or not..On my old Catalina 30 I never bothered to upgrade the the alterntor or regulator. It had a stock 51 amp Motorolla alternator and a house bank consisting of four 6V Trojan 105's. According to the Balmar site this alternaotr was grossly undersized for the 440ah bank. I had installed these batteries in April of 1999 and intended to upgrade the charging system too but I sold the boat in October of 1999 prior to upgrading it. As of August 2006 the current owner still had the same alternator and the same Trojan T105 batteries! Yes those poor Trojans sustained seven years of being charged with an undersized alternator and a dumb regulator! I know this because the current owner, the guy I sold my boat to, found my long lost Dewalt 14v cordless drill battery under the battery box while he was changing the rubber fuel lines. He saw me on my boat, hailed me on the VHF, and I went over in the dink to get my drill battery. While I was there, sniffing the leaking diesel fuel, I noticed the Trojans and asked if those were still the Trojan batteries I had installed in 1999 and they were. Unfortunately my Dewalt battery was toast but the Trojans were still going strong dumb regulator and all. According to boating logic the alternator should have fried long ago and the batteries should have lasted a season and a half at best. Companies like Balmar have done a tremendous job at marketing external regulators and huge alternators. Hell I bought into it! Please feel free to educate me on my wayward thinking.

 

[ruedi ross]

Didn't mean to piss you off

And I think I'll pass on trying to educate you.

 

[Maine Sail]

Don't worry about it...

You didn't piss me off in the least but yes I was a little sarcastic in my tone. I was trying to keep it as simple as possible because I know marine electrical issues are a tough pill to swallow for many DIY guys. I do understand the concept fully about the multi stage regulators but I think the hype is way to overblown for your average coastal cruiser. My question is not if they do or don't work, they do bulk faster, but rather is it worth the $650.00 upgrade if you DIY or the $1500.00 upgrade to pay the yard to do it? For what most people spend on upgrading an alternator they could by and new main or genoa.. The XBM is just a way to get a better understanding of current draw and alt output vs. using a digital multi meter and guessing how long that light was left on in the head.....

 

[ruedi ross]

Agreed...

And thinking about it a little more I think the real situation where a 3 stage external regulator would be beneficial is in a power boat where you are running the engine for hours and hours at a time. There a constant voltage regulator would have a better chance to overcharge batteries and cause damage. Sailboats rarely motor for that long. My experience comes mainly from off grid solar applications and I have seen a few where poorly regulated charging systems that have been neglected and allowed to overcharge for long periods of time have done substantial damage, both to the batteries and to the structure that they were stored in. I definately agree with you that a battery monitor such as the XBM, Link, Bogart trimetric, or similar will give you a very intimate understanding of your systems and how they perform in various situations and are a must have in my humble opinion.Again, my apologies, I know sometimes I don't come across the way I want to.

 

[Bill Roosa]

DIY and marine anything

Well if you are a DIY kind of guy/gal then perhaps you should take the time to understand the system you are working on. So lay it on us.As for 3 stage vs dumb charging, a flooded cell battery can live with a dumb charger just fine, you will just not have the full battery AH available unless you leave it on for a long time. A dumb charger will be set for the trickle charge voltage if you have any sense. It will charge more initially when the batteries are low but will, in short order, go to a trickle charge rate as the battery voltage comes up. The whole point of going to a 3 stage charger is to charge the batteries QUICKLY without destroying them. That's why solar and wind chargers work (more fully charged battery) better than an alternator on a sail boat. They continue to work for long periods of time at trickle charge rates and the batteries don't take a deep discharge.

 

[Maine Sail]

Yor're right about solar...

Quote:"My experience comes mainly from off grid solar applications and I have seen a few where poorly regulated charging systems that have been neglected and allowed to overcharge for long periods of time have done substantial damage, both to the batteries and to the structure that they were stored in."An unregulated solar panel connected to any battery can fry it in short order even a very small one. They can also suck power out of the batteries if not used properly. A friend put a solar panel on his boat three years ago and by accident left it up side down under his dodger and not on the deck in the sun light. In one unattended three week period his batteries went totally dead because he had not installed them with a blocking diode or a charge controller. Between the draw from the panels and the numerous cycles of his bilge pump, from a poorly adjusted stuffing box, he almost lost his boat. Solar panels must be installed with blocking diodes at a minimum but a charge controler is really whats needed.Solar panels work better than a alternaotr on a sailboat at fully topping off the batteries. An alternator will get you back to 90% relatively quickly but the remaining trickle charge to 100% takes a very long time...

 

[Scott21120]

I've seen a product similar to the XBM

for under $200, but I have thumbed through a dozen of my old magazines and can't find the ad now, or remember the name of the company. My question is, where would you use a Link 2000 instead of an XBM? I have a single 105ah battery for starting as one bank, and 2) 240ah 6v batteries for the house. I installed a Trucharge 20 last summer, but we are on a mooring and don't plug in often. It would be nice to know the battery state other than via the voltmeter on the panel.

 

[Stu Jackson]

Good electrical input

Could simply be that the discharged batteries took the charge from the essentially unregulated internally regulated charger as well as a smart three stage charger would. Perhaps I missed in the input about what the voltages were at those charing regimens. If it was a mere 13.8, the batteries were not being charged properly even though the amperage may have been fine. r_ oss makes a point.Is the ARS5 a true three stage regulator? It could well be that it is only a 13.8 V "float" voltage charger. That could be why there's little difference between that and the "dumb" internally regulated charger from your old alternator. Our M612 does all three stages of differing voltages.We installed a new alternator & regulator last April. Alternator was less than $180, regulator $280, plus parts at $50. Somewhat shy of $650, maybe not far off.Also, boats with old dumb regulators on OEM alternators will keep the batteries going depending on how the boat is being used. If it's a marina-hound, and plugged in all the time, the alternator does little on the charging regimen, almost m=nothing, in fact unless the boat's been anchored out. Don't know how the C30 was, or is, being used.Based on off-the-grid cruising, the idea is to minimize engine run hours when on the hook. So, smart charging saves engine run hours by charging the batteries faster, like Bill mentioned. It's rather that simple.The nicest part about this thread is that it exhibits knowledge that is beyond most turn-the-key-and-go boaters.