Which is the correct value to enter in this Renogy setting please?

CJW

2016 T6.0 T32 SL-to-Camper
VIP Member
T6 Guru
Hello. I’ve got the Renogy Battery Monitor attached to a LB with 95Ah capacity. Set up of the monitor includes manually setting the Ah capacity of the battery directly as a value. I had put in 95Ah. I read the manual again and it says to set this value to the ‘usable capacity’ - so should this value be 47.5Ah instead of 95?

986325EB-53D7-47E2-8E1D-2F6AF8749DDC.jpeg

Two online vids I found both set it to the total capacity:



And the actual Renogy video does the same (equivalent to 95Ah).

Is this just sloppy language in the manual? What value do other forum members use please - 100% or 50%

Many thanks.
 
use 100% if its a lithium.

use 50% If its a SLA (acid) battery.

because you can only use 50% of a SLA batterys capacity. - that way the monitor will count down 100%-0 ( for the SLA 50%)
 
  • Like
Reactions: CJW
that is unless the unit compensates for the 50% DOD when you set the unit to SLA?

does it have the option for setting the battery type?
 
  • Like
Reactions: CJW
Thanks @Dellmassive - no, the battery type is set with the DCC50S but there’s no way the monitor can receive that info from the DCC50S as the monitor is connected only to the shunt. You must be right because the ‘usable’ changes from one battery to another and either the YouTube users are using lithium or they’ve got it wrong. I’ll set it to 47.5Ah and see how we get on. Thanks again.

Edit - should have said, mine’s an AGM.
 
just checked . .

no mention of battery chemistry on the Renogy shunt . . .

just voltage and current in Ah capacity. (0.1-9999 Ah)

as as above id try for thr 50% method for a SLA AGM battery type and test.

if your LB is 95Ah - you can only use 50%, so thats 47.5Ah.

so watch your monitor and sync to 100% when fully charged.

then discharge to empty . . .

you should see the meter drop from 100% to 0% and show the consumed Ah as 47.5Ah ish.

that will prove you have tyhe correct setting.

voltage can be a bit iffy metering out %SoC, but id assum the AGM will be down to 12.00v

refence chart for AGM.


1648221956121.png



++++++++++++++++++++++++++++








1648221504810.png







1648221592241.png

.



I can get you a discount at Renogy United Kingdom

+
 
  • Like
Reactions: CJW
one odd thing is the install guide states the same. .

for LFP and SLA.

so i think that might not be exactly correct.

but they do state about setting a 0% marker for the LFP battery.


2. Capacity calibration: On first use, the percentage and capacity are not the actual value, you need to calibrate the capacity to either 100% or 0%.

First set the usable AH capacity of the battery as the preset AH capacity.

For Lithium and Sealed Lead Acid batteries to calibrate to 100% charge the battery fully and hold the "up" key for 3s to set the capacity to 100%

For Lithium batteries to calibrate to 0% discharge the battery completely and hold the "down" button key for 3s to set the capacity to zero. This will only have to be done on initial installation of the Renogy Battery Monitor or if the Battery Bank is replaced


.

1648222241406.png
 
  • Like
Reactions: CJW
Agree. I think the manual would be much clearer if it hinted that the manual capacity setting might be different depending on battery chemistry for batteries that have the same number of Ah stamped on the casing of the battery. Ultimately, I know I’ve got 47.5 usable Ah, and the rest of the family would benefit from a clear 100 to zero reading rather than having to remember that 50% discharge is the limit, which could easily result in a damaged battery.
 
yep . . well i guess your the guy to test this setup.

so test away and report your findings back here for the good of the people. ( any my personal curiosity now you've asked the question)


+++

dont forget the pics,

before - during - after.


good luck with the testing.

+++
 
  • Like
Reactions: CJW
Hi @Dellmassive - the fairest test I could think of (with the equipment and time I have) was this:
  • Photograph the battery monitor display
  • Run a constant and known load for exactly one hour without interfering with it.
  • Photograph it again
  • Check the readings make sense
My shunt is the only connection to the LB negative terminal and all return earths run through the chassis, into a 150A busbar, then into the P- of the shunt.

Isolating all other loads, including the control panel, I usually see 0.01A reported on the monitor. This is either the DCC50S or the monitor itself. Either way, 10mA is not going to cloud the readings. Turning the isolator back to on, I see 0.04 draw, which is another 30mA being drawn from the Control Panel.

The constant load is four light circuits with 20 fittings overall. Manufacturer‘s info for all lights combined is almost exactly 2A. Switching all the circuits on, the shunt monitor reports 2.07A, which can be seen in the photos. This is as expected.

The monitor is set with the ‘Capacity’ at 47.5Ah - 50% of the AGM battery’s sales pitch capacity of 95Ah @ c20. AGM battery tables show (as does yours) that 50% DOD is typically associated with 12.1v. The sticker on the Exide EP800 says not to discharge below 12.1v, so everything is aligning nicely.

The battery was discharged slightly before the test to remove any unusual behaviour around the higher limits. I’m not sure if this was necessary.

The first photo at the start of the test shows the load of 2.07A, battery voltage (under load, obviously) of 12.5V, a reported power of 26W being output. 12.5V x 2.07A = 25.875W, which rounded up to 26W on the display. The charge is showing as 46Ah and time remaining (at static load) as 22 hrs 23 mins, which is 22.38 hours. 22.38hours x 2.07A = 46.33Ah. 46.33Ah is 97.53% of 47.5Ah, shown rounded up to 98% in the display. Again, everything as expected.

F9341154-8191-467E-86E6-0BEBEB7C55B0.jpeg

Wait an hour which, incidentally, is just long enough for DubDog Lotta to fall asleep with her gob open:

482107EF-E25A-4259-BA63-D4BDD0B37DF5.jpeg

The second photo, exactly one hour later, shows 21 hours and 22 minutes remaining, which is almost exactly one hour less, which is terrific. The load and voltage haven’t changed, but the power is reported now at 25w, which I assume is a minor drop in voltage, not enough to trigger a decimal drop on the display. 2.07A have been drawn for one hour, so I’d expect the charge level to have dropped by a 2Ah, which it has. The percentage follows suit.

20733F21-9252-47B7-8ABA-91E1629D6E04.jpeg

I think I’m right in concluding that the monitor isn’t trying to do anything clever like detecting an AGM battery and halving the available charge. Therefore, for AGM batteries, there is no benefit to setting the ‘Capacity’ to that stated on the battery label, and in fact there is a significant downside - that non-technical users of the van would see ‘time remaining’ and ’percentage remaining’ values that give a wrong impression if maintaining battery health is a given. I’d like make it really clear for the rest of my family (who use the van without me) that they can trust the 100%-reducing-to-0% display like any iPhone or iPad, without worry, without finding that things misbehave, and without inadvertently damaging the battery.

It is possible to set a charge level alarm on the monitor, which I’ve got set at 5Ah remaining. It would be possible to enter the sales pitch 95Ah value into the ‘capacity’ setting, and set an alarm at, say 50Ah. If the user understands why an alarm is going off at over 50% level being reported, then fine, but it wouldn’t make sense to the uninitiated, and I’d get a phone call from a campsite.

Lithium, as you say, is a different matter altogether.
 
Back
Top