I understand the need for a battery monitor - certainly the analogy of monitoring your fuel level via a fuel pressure gauge strikes home (although it's a little bit off). I want to get one.What I can't get over is the price. They seem to hover at the $200+ level, and many don't even include the shunt. For things like battery and solar panels, it's pretty easy to understand how the material costs put some floor on the prices, and that once the cheaper manufacturers have come in and gotten close to the floor the prices are pretty reasonable.As I understand it though, the battery monitory is really just a cheap microcontroller reading the voltage drop across a shunt, and a cheap display + the (fixed cost) programming to do coulomb counting. A few dollars of parts all in all. Where are the vendors coming in to undercut these $200 units?Often you find the equivalent of battery monitoring technology built into inverters or other electronic devices, at no noticeable impact to the cost. So on top of the above reasoning from first principles, we know for a fact they are added to all sorts of devices at close to zero cost.Is the market just too small? There aren't enough units sold to bother entering the market? I guess the presence of small niche manufactures like Bogart would help justify that idea.It seems like it may be an interesting project for someone to develop the some open source battery monitoring software (that's the only "tough" part - i.e., not available off the shelf), and then pretty much anyone could throw together a monitor with a cheap microcontroller (e.g., TI launchpad for $5) and whatever display you want...

... another possibility is that I've just missed the decent < $50 battery monitor that exists out there in my searches. If that's the case, definitely LMK.

Hi,I have a "E-Meter" that was developed before the Tri Metric. Same person, but first or second 'stage' before the Tri Metric.I paid around $375 back in 1999, when wages and prices where much lower, so with inflation, the cost 'would be around $500 today'. Yes it is very accurate, and there is a lot to counting all those amp hours. I did not use 'twisted pair' wire, but instead used 8 wire thermostat wire (I had plenty sitting around). IT has worked great for over 15 years.You might want to check out this magazine, you might find a vendor who will sell them at a lower cost.HomePower.com Magazine. Look for an advertisers list near the back of the magazine. ALso check SolarOnSale.comSunElec.com is where you can buy solar panels for a great price.Overall, I had a pick. I could spend $375 for a 75 watt solar panel (well I bought 1 not 2) or spend $375 on this meter. My wife said 'Install the meter' - so I have the meter. The meter will not collect any more power, but can be handy in tracking down small loads that make the battery go dead over a week, just because a 1 amp load X 7 days X 24 hours is close to 200 AH, about what most batteries are rated at. My RV has a 0.8 amp load all the time when the battery switches are 'on'. It is running the CO meter and propane leak detector. Add the refrigerator, and it will go up to about 1.2 amps per hour. Or around 35 AH daily.My 400 watt solar system can put back about 21 AH per hour from 10 am to about 2 pm. Usually it is full before sundown.Good luck,Fred.

Here is what I have... $180... And includes the shunt...http://www.amazon.com/Victron-BMV-700-Battery-Monitor/dp/B00MJ9TAN8/ref=sr_1_1?ie=UTF8&qid=1452136448&sr=8-1&keywords=victron+battery+monitorI also have their MPPT controller with a similar looking remote...

There are cheapies from China on ebay. I have a couple installed but have not been able to use them yet. Hopefully soon.

Battery monitor pricing | Good Sam Community

60 Replies

Johno02
Explorer
Jan 07, 2016
I have been using one of these, and it works fine. I have a power port for the chassis battery, and one for the coach batteries. This is usually plugged in for the chassis battery, but works well on the other.

Battery monitor. Cheap!
Gerald55
Explorer
Jan 07, 2016
Do most of the "good" monitors have automatic zeroing (i.e., detecting the full state based on accepted current), or is it still mostly manual?

Note, I'm not disputing that a $200 monitor is "worth" it in terms of what you get out of it, but just not worth it in terms of cost of manufacture. Most items today are, at the cheap end, actually priced closer to the cost of manufacturing than what the marginal customer might pay.

It's the same way that I would still pay $10 for a ballpoint pen if that was my only chance, but in the real world they are actually priced at a few cents.
EsoxLucius
Explorer
Jan 07, 2016
The Trimetric 2030 and Magnum BMK are also about $180 with a shunt. Going rate I guess. The Blue Sky IPN-ProRemote is a bit more, but also does more in conjunction with a Blue Sky solar controller.
ktmrfs
Explorer II
Jan 07, 2016
Gerald55 wrote:
I understand the need for a battery monitor - certainly the analogy of monitoring your fuel level via a fuel pressure gauge strikes home (although it's a little bit off). I want to get one.

What I can't get over is the price. They seem to hover at the $200+ level, and many don't even include the shunt. For things like battery and solar panels, it's pretty easy to understand how the material costs put some floor on the prices, and that once the cheaper manufacturers have come in and gotten close to the floor the prices are pretty reasonable.

As I understand it though, the battery monitory is really just a cheap microcontroller reading the voltage drop across a shunt, and a cheap display + the (fixed cost) programming to do coulomb counting. A few dollars of parts all in all. Where are the vendors coming in to undercut these $200 units?

Often you find the equivalent of battery monitoring technology built into inverters or other electronic devices, at no noticeable impact to the cost. So on top of the above reasoning from first principles, we know for a fact they are added to all sorts of devices at close to zero cost.

Is the market just too small? There aren't enough units sold to bother entering the market? I guess the presence of small niche manufactures like Bogart would help justify that idea.

It seems like it may be an interesting project for someone to develop the some open source battery monitoring software (that's the only "tough" part - i.e., not available off the shelf), and then pretty much anyone could throw together a monitor with a cheap microcontroller (e.g., TI launchpad for $5) and whatever display you want...

pricing is determined by percieved customer value and expected sales usually set to maximize profits. Mfg cost is part of the equation, but seldom is selling price set as a multiple of mfg cost.

And the pricing needs to take into account the development cost amortized over the product life.

It isn't that uncommon for products to sell for 10X or more of mfg cost
landyacht318
Explorer
Jan 07, 2016
Keep in mind that they are often wired improperly, and often not programmed correctly, and not rezeroed properly, but the human watching it might still see 92% and get that seratonin filled headrush and a burst of confidence, when the batteries are 74% and aching for a full recharge.

But when they are wired properly, recently rezeroed, well I love seeing a XX AH from full, and when charging my battery watch it reset to ) from full right when the battery is actually full, determined by a hydrometer or determined by how much current the AGM is accepting at absorption voltage.

Heres some good reading on battery monitors:

http://www.pbase.com/mainecruising/battery_monitor

http://www.pbase.com/mainecruising/programming_a_battery_monitor

http://www.pbase.com/mainecruising/smart_gauge
Snowman9000
Explorer
Jan 07, 2016
There are cheapies from China on ebay. I have a couple installed but have not been able to use them yet. Hopefully soon.
Trackrig
Explorer II
Jan 07, 2016
posted in error.

Bill
KRumm
Explorer
Jan 07, 2016
Here is what I have... $180... And includes the shunt...

http://www.amazon.com/Victron-BMV-700-Battery-Monitor/dp/B00MJ9TAN8/ref=sr_1_1?ie=UTF8&qid=1452136448&sr=8-1&keywords=victron+battery+monitor

I also have their MPPT controller with a similar looking remote...
Golden_HVAC
Explorer
Jan 07, 2016
Hi,

I have a "E-Meter" that was developed before the Tri Metric. Same person, but first or second 'stage' before the Tri Metric.

I paid around $375 back in 1999, when wages and prices where much lower, so with inflation, the cost 'would be around $500 today'.

Yes it is very accurate, and there is a lot to counting all those amp hours.

I did not use 'twisted pair' wire, but instead used 8 wire thermostat wire (I had plenty sitting around). IT has worked great for over 15 years.

You might want to check out this magazine, you might find a vendor who will sell them at a lower cost.

HomePower.com Magazine. Look for an advertisers list near the back of the magazine.

ALso check SolarOnSale.com

SunElec.com is where you can buy solar panels for a great price.

Overall, I had a pick. I could spend $375 for a 75 watt solar panel (well I bought 1 not 2) or spend $375 on this meter. My wife said 'Install the meter' - so I have the meter.

The meter will not collect any more power, but can be handy in tracking down small loads that make the battery go dead over a week, just because a 1 amp load X 7 days X 24 hours is close to 200 AH, about what most batteries are rated at.

My RV has a 0.8 amp load all the time when the battery switches are 'on'. It is running the CO meter and propane leak detector. Add the refrigerator, and it will go up to about 1.2 amps per hour. Or around 35 AH daily.

My 400 watt solar system can put back about 21 AH per hour from 10 am to about 2 pm. Usually it is full before sundown.

Good luck,

Fred.
Gerald55
Explorer
Jan 07, 2016
... another possibility is that I've just missed the decent < $50 battery monitor that exists out there in my searches. If that's the case, definitely LMK.

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Battery monitor pricing

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