After building a 230aH DIY lithium Battery for the canopy in our Isuzu Dmax, I decided that I needed a better way to monitor what it was actually doing, and purchased a Renogy Battery Monitor and Shunt.
Up until then, we’d been running a Projecta battery monitor, which simply displayed the battery voltage of our starter battery, and our secondary battery. Whilst this is a rather agricultural way to see how full your battery is, it works OK with an AGM battery, and with a battery and solar system that is sized correctly for the application it works just fine.
However, once you move to lithium, relying on battery voltage is almost useless, as its curve is not linear and will remain at a high voltage until its virtually dead. It will literally sit at 13.2V from about 20% to 90%, which doesn’t give you much of an indication of its actual state.
We have a Bluetooth module that connects to the BMS in the battery which works reasonably well too, but its not as good as a proper shunt, and for the minimal extra expense, I decided to purchase a Renogy unit.
It looks like you can get identical units that are not Renogy branded, so their units might not be anything special, but at least I know it has warranty and backup if needed.
What is a shunt and battery monitor?
Put simply, a shunt is a small device that hooks into the negative of your battery, and monitors all of the electrical flow through your battery. It will tell you what you are using at any given moment (or what you are charging), what percentage your battery is sitting at, and how many amp hours you’ve consumed, along with how long at that rate until its flat (or full) and a heap of other information.
I always thought that these were largely unnecessary, but since fitting one I don’t know how we lived without one for so long. They just make life so easy, with a simple glance telling you everything you need to know about your battery system.
Given that we’ve gone to a 2000W Renogy inverter, and run some pretty hefty appliances off the battery from time to time, its really helpful to be able to see what the battery is doing.
In conjunction with the shunt and battery monitor, I installed a 50 amp Renogy DCDC and Bluetooth dongle, and can see the battery voltage of both the starter and house battery, along with the charge going to both (as it back charges) and how much solar or alternator current is going into the battery from my phone, anywhere within a 20 metre radius of the vehicle.
We paid for this
I always include this little snippet in each of our reviews, so you know how we received the product (it was not gifted, or sponsored), and know with 100% certainty that our opinion is our own. We paid our own money (full RRP) for this shunt, and have no commercial interest in promoting, or degrading it.
Looking online now, they are $104, and we paid somewhere around that, with a heap of other Renogy gear that we’ve purchased.
Renogy Shunt Review
I’m really pleased with this unit. It’s small, easy to read, easy to use and has all of the information on one page without having to cycle through a million pages. We also have a Victron BMV 712 in our Reconn R2 (another shunt), which is great, except its much harder to use, and to see all of the information you have to cycle through a heap of pages.
The Renogy Battery monitor flashes when its charging, and you can easily see whether power is going in, or you are consuming energy.
Overall, we’re really happy with the Renogy Battery monitor and shunt, and would get another one. It gives me peace of mind that we are caring for our lithium battery, and is absolutely worth the money it costs to get one.