The New Balmar SG200


A Self Learning Battery Monitor

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The Balmar SG200 is a revolutionary new battery monitor in that its feature set, capabilities and algorithms are a brand new concept in battery monitoring.

The Balmar SG200 is a self-learning battery monitor which was 100% developed in-house by CDI/Balmar. Compass Marine Inc. / worked quite closely with CDI/Balmar, along with other Balmar dealers, to identify what we wanted to see in a fresh new battery monitor. One thing we have grown to appreciate about CDI/Balmar is their willingness to identify what their dealers see as credible needs before pursuing a project.

While every feature we wanted to see, in a battery monitor, did not make it into the SG200, what we do have is a revolutionary new self-learning battery monitor that is flexible, remarkably accurate and incorporates a brand new SoH or State of Health calculation. SoH allows you to know where your bank stands in relation to the programmed or rated Ah capacity and has been previously non-existent in traditional Ah counters.

What is SoH?

SoH is a new feature in the SG200 that compares your banks current state of health to its “as new” factory 20-hour Ah capacity rating.

By industry standards batteries are considered dead when they can no longer deliver at least 80% of their factory rated Ah capacity. While 80% or lower does not mean they are “actually dead” it is where the battery industry sets the low safe level for continued use of deep-cycling batteries.

For setting up the SG200, let’s assume you have a 100Ah rated battery. You would simply program 100Ah into the SG200, regardless of the batteries age or current condition. Over time the *SoH will hone in and find your “percentage of new” state of health of the battery or bank. If the screen reads 77% SoH, after it has had ample time to learn the bank, then this would be an indication that the batteries are nearing end of life and replacements should be on the horizon.

*SoH is a function that only works with banks that are actively deep-cycled. In other words if you purchase an extra shunt for a bow or start bank don’t expect an SoH indication as the SoH feature is specifically engineered for banks that are cycled eg; house banks.

If you’re a coastal cruiser then this number may not be all that alarming but if you venture across the ponds you’ll want to give your bank much more serious replacement consideration when you start getting into the 70’s as a percentage of new.

Product Development

Like all good things the SG200 did not just happen over-night. All told, it took nearly 4 years to get from ideas on paper to an Alpha level product for testing. Here at Compass Marine Inc. we’ve conducted nearly an entire years worth of testing the SG200. It’s actually still on-going every time we come up with a new way to possibly trip it up or we come across a battery we believe can trip it up. Like most products the SG200 did not come out of the lab “prime-time” ready and a number of software tweaks were made along the way before the finished product began shipping. The engineers at Balmar were tremendous to work with and they responded quickly. While lab testing can’t always predict every single real-wold situation it can be used to develop a platform to start from.  Add in a learning algorithm, and the ability to update firmware for future proofing, and you’ve got a very simple to use product.

SoC, SoH, Amperage & Minutes Left

Recently, while up in Maine for a boat show, Chris Witzgall, Balmar’s Product Manager, stopped by our shop to get an idea of how we tested the SG200. Knowing Chris is far better than us with a video camera, we decided to take a different approach to our normal long diatribe of words and photos. We hope this video sums up & conveys how we tested the SG200 and why we were so interested to see yet another battery monitor hit the market.

What we like about the Balmar SG200:

  • Multiple shunts can be used with one display to monitor multiple on-board battery banks
  • The smarts or computer chip of the SG200 are housed inside the newly designed “Smart Shunt
  • SoH (State of Health) calculation lets you know when your bank is no-longer in a healthy state
  • SoC accuracy is quite good within half a dozen deep cycles and continues to get more accurate as time goes on
  • Self-Learning means no more cumbersome programming
  • Displays – SoC, SoH, Charge/Discharge Current, History, Faults & Alerts
  • Supports battery banks up to 1300Ah
  • Bluetooth capability via optional Bluetooth gateway
  • Firmware changes can be updated via Bluetooth
  • Supports Flooded Lead Acid, AGM, TPPL AGM, Carbon Foam AGM, GEL & *LiFePO4
  • Supports banks of 12V to 48V
  • SoC accuracy as good as 97% in just a few cycles
  • Auto-Calibrating
  • Remains accurate even as a battery ages
  • Less money than the SoC only Smartgauge
  • Our customers want simple, not complex, and the SG200 is simple, easy and accurate

*LiFePO4The SG200 may not work with certain “drop-in” Chinese LiFePO4 batteries. The SG200 has been tested with Lithionics, Battle Born, Relion, Mastervolt and numerous DIY built batteries with BMS protection operating on the positive bus.

What about Installation?

While the SG200 is a shunt based device, once you understand where the shunt needs to be, as close to battery negative as possible, and that wires that by-pass the shunt (sneaker wires) are not allowed, the installation is very straightforward.

The general installation is simple:

#1 Create a short negative jumper wire to go between the bank negative terminal and the battery side of the SmartShunt

#2 Wire all negative wires on the vessel to the “Cable” or “Load” side of the SmartShunt. Adding a heavy duty busbar can help with this

#3 Mount the display. It fits into a 2 1/16″ hole

#4 Run the SmartLink Cable then install the Deutsch terminal on the end and plug it into the display & SmartShunt

#5 Connect the orange wires to their respective banks (if applicable) and fuse within 7″ of battery positive.


#7 Pull the fuse from the red power + wire and connect it to the banks positive terminal.

#8 Reinstall the fuse and when the SG200 boots up program it with your banks information.

When wiring the Balmar SG200’s SmartShunt you may want to purchase a heavy duty busbar, as shown below, to collect all the vessels DC negatives.

Patience is a Virtue:

TIP: Once your SG200 is installed & programmed please be patient. The SG200 requires your bank to be deeply-cycled quite a few times in order for SoC and SoH to hone in. The deeper these cycles are, the faster the SG200 can learn the bank. Don’t be afraid to take your lead acid bank to 11.7V, if you want to speed up the learning process, just be sure you can recharge to 100% on the next cycle. Shallow cycling will just prolong the time it takes for the SG200 to “learn” bank behavior such as SoH.

Quote:Rod, I have had my new SG200 connected for almost four weeks and am still getting three dashes for SoH? We have not been able to leave the dock yet but was hoping to know my banks condition before we do?”


The SG200 can’t learn SoH while tied to a dock charging 24/7

The SG200 also cannot determine SoH while not charging and resting. To test this, we connected a lead acid battery to the SG200 and let it sit for two and a half months, with no charging or discharging, other than the SG200’s connection to the battery. At the end of 2.5 months the SG200 was still showing three dashes for SoH. Bottom line? The SG200 is smart enough to know whether you’re cycling or not. The good news is that the SoC prediction, at the end of 2.5 months, was accurate to within 3%, while just sitting there.

SoH Behavior:

At first the SG200 will show three dashes – – – for SoH. It will continue to do this until enough cycles have been completed, and they are deep enough cycles. You’ll want to discharge to at least 50% SoC. Once the three dashes disappear it will start to show a preliminary SoH. If your boat is dockside for a while SoH won’t begin to display until the bank starts being actively cycled. Unlike SoC, which responds more rapidly, SoH is not intended for rapid updating and really needs to learn your banks behavior. Expect upwards of a dozen or more deep-cycles for SoH to be accurate. Be patient!

Insider Guidance:

Please do not make the mistake of comparing the SG200 to a traditional Ah counter. They are not the same at all and not even close to being the in the same category ease of use wise. The SG200 is using multiple technologies to track the bank and doing so in a multiple cross-check fashion. The SG200 can measure and cross-check; battery impedance, internally stored battery behavioral models, voltage – measured many thousands of times per second, coulomb-counting, amperage/load, time *etc. and a self-learning algorithm to bring it all together.

*Etc. – There are other measurements & trade secrets going on inside the SG200 that we cannot publish.

The unique aspect of the SG200 is that each of these data measurements is cross-checked and is compared to the others so that no single measurement can control or skew the data. The SG200 can track both SoH and SoC and to do so very accurately without any cumbersome programming or manual re-sync being necessary.

The SG200 is the most accurate battery monitor for SoC & SoH we’ve tested here at Compass Marine Inc..

As I sit here typing this we have a Trojan SCS-225 130Ah flooded deep cycle battery on the test bench. It recently tested at 99.4Ah or 76.4% SoH. As can be seen the SG200 is reading 76% SoH. It honed in this accurately in just 10 deep cycles. This is about as perfect a prediction of SoH and you can get without an expensive or time consuming 20 hour test. This is rather amazing performance.That said, SoH has not proven to be as reliable in the field as it is in the lab. Balmar is dilligently working to improve SoH reliability

SG200 Do’s & Dont’s:

  • Do mount the Smartshunt as close to battery banks negative terminal as possible – less than 12″ is preferred
  • Do use the largest gauge wire you can between the Smartshunt and battery negative terminal
  • Do coat the shunt bolts or nuts with an anti-thread galling compound such as Tef-Gel. They are SS.
  • Do use crimping tools that result in the lowest resistance for any wire terminations
  • Do aim for the lowest possible voltage drop in your bank & shunt wiring.
  • Do connect the red fused wire directly to the battery banks positive terminal *only.
  • Do install the fuse for the red wire as the absolute last item installed.
  • Do wire parallel or series/parallel bank for optimal intrabank balance.
  • Do be patient. The Sg200 can’t work miracles, it needs to learn your bank during deep-cycling use.
  • Do cycle deeply on the first few cycles. The deeper you go the faster the SG200 will learn your bank
  • Do set it and forget it.
  • Do not keep changing settings hoping for it to speed the learning process, all you’re doing is slowing it down.
  • Do not depower or disconnect the SG200 from the battery, unless during winter storage.

*For LiFePO4 this decision will need to be weighed by the owner as to place it on the load side of a BMS switch or not. Drop-In LFP you have no choice in this matter. The SG200 will perform best with a direct red fused wire connection to the battery banks positive terminal.

Before you consider an Ah counting battery monitor, one that requires copious amount of human interaction/programming, to keep them accurately tracking the battery, consider the Balmar SG200 and let it do the work for you.

Good luck and happy boating!

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