Battery Monitor choices

I used the Bogart Trimetric for a number of years, but when I updated to lithium this year I switched to Victron, both for the monitor (712) and solar controller (100/30). Both can be monitored & parameters set using Bluetooth from my phone. It is handy to watch the battery charging from the tow vehicle or sitting outside, and the history functions are useful. That said, the Trimetric gave me the same information, but only at the device.

Here is a general tip for simplifying an installation and reducing voltage losses.

You can often use the ground cable on the battery as a substitute shunt. Choose the length of wire with resistance equal to the shunt. Tap into the cable by simply screwing in a small brass screw at the correct length. Most units have current calibration capability that can compensate for variations.

BFL13 wrote:

So until you get AGMs you only need the four lights on the range hood monitor, or else splurge on a DMM for $10, but you don't need a monitor at all.

All you REALLY need is a digital voltmeter connected directly to the batteries and an understanding of what the voltage readings MEAN under various circumstances.

That's it. Around $20 or less.

And even if you don't adjust your thinking when you get AGMs, you should still get a longer service life from them than from wet cells.

OP---"We mostly boondock so I think all I need is SOC. (Real solar and lithium batteries are coming, but not quite here.) Do I run the generator yet? Time to go to a hookup site? What else matters??"

With flooded batts you don't need a monitor at all to do that. All you need is your "morning voltage" while camping. Pretend that is a "resting voltage" (take it when the furnace is not on and before the solar jacks up the voltage) and get your SOC from that.

Observe your daily change--with no solar, this will be fairly steady. Let's say you want to stay above 50% SOC and you pick 12.1v for that SOC (same as Trojan does) You start with 12.7 and next day it is 12.5, then 12.3. So you know that tomorrow it will be 12.1 and time to recharge the bank.

If it is 12.4, 12.2, and you figure 12.0 tomorrow, you can recharge "early" today or go another day and recharge at 40% SOC (which will not kill your batts)

I used to do that with the four lights on the range hood and no DMM even. I noticed that after a while the light would be green but go to yellow when the furnace came on but would bounce back to green when the furnace stopped. Then it stayed yellow no bounce back, and could go red if furnace came on and some lights. That was the signal to recharge the batts, since a DMM comparison showed yellow was about 12.2v.

I then got a Trimetric, more as a toy than as a need. But then got AGMs and now it is vital. Need the ammeter to tell when down to 0.5a/100AH (proper full for AGMs) and the voltage to know at proper Vabs to hold at while amps taper to that amount.

So until you get AGMs you only need the four lights on the range hood monitor, or else splurge on a DMM for $10, but you don't need a monitor at all.

I built mine up in a PVC Junction Box with the large three position Speciality Switch Cover...


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I have two battery zones BAT1 and BAT2 and then I use a DC AMP METER off the Battery Selector Switch...

I have this mounted just inside my door to the POPUP trailer...

I glued the meter movements to the inside of the speciality cover...

No electronics involved here just two DC VOLMETERs and one DC AMP meter...


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I did add an ON-OFF switch on the inside of the cabinet as these mounted meters sure are bright at night... My plan was a night light but didn't realize how bright they would be haha...

If I ever bought one it would probably be the BOGART TM-2030RV-F...


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Roy Ken

I just did a conversion to LIFePO4 batteries. The voltage and other readings IMHO will be useless, you really want to focus in on Amps in/out. I have a Victron 702 with the Bluetooth dongle (equivalent to the 712). Good unit and the phone app is very useful. As mentioned you'll have to run a cable for the shunt, but any monitor worth it's salt will have one too.

The nee plus ultra for everything except LI batteries is the SmartGauge. It is the only one that actually becomes more accurate as you use it.

I have been extremely pleased with the Clipper BM-1 compact battery monitor. High quality and very aesthetic, too. ....or the BM-2 with larger display unit.

Clipper battery monitor by NASA Marine

I bought the Tri Metric 6 years ago to better understand my battery usage as a prelude to solar. It makes the case that the Puerk Effect is not necessary which starts the Tom Toms. I preferred it's mounting vs the Victron which is also a good unit IMHO. Both require a wiring cable and the Victron has a small circuit board on the shunt which bothered me. My shunt is very exposed to water and dirt from under the MH as are the batteries.

Perhaps the Victron is "better" but the Tri Metric has served me well. After the initial love affair I rarely look at any of the parameters except voltage, amps and SOC (I use %) which I can cycle on the display. This includes a second battery bank voltage.