Tri-Metric programming help

Tee hee, never mind the battery and the hydrometer, just fiddle with the Trimetric until it says what you want. :)

BTW, the Trimetric reads high on its rounding off to one decimal point on voltage, so that 13.7 is maybe 13.65.

Also, on your amps setting for how far down the amps get by the time you are "full." Our rig has a standing minimum amps draw of 0.3a except when the fridge cycles on at another 0.5a for 0.8a standing amount then. So if I decided that my low amps setting for "full" would be 1 amp, that would be when the charger is doing 1.3a or maybe 1.8 I guess.

All too confusing for me. It works fine without ever setting those "three things." It still does the accumulated AH, volts, and amps. (that is the NET amps in and out showing remember, not just your charging amps)

The Tirmetric shunt needs to be as close to the negative post as practical. Mine is on top of the AGM battery. You would want a flooded battery shunt further away due to corrosion.

Display wires: There are 2 wires on the negative side of the shunt. One is for display power and the corresponding wire is connected to the battery positive post with a fuse. The second wire and it's corresponding wire on the positive side of the shunt are the sense wires.

It's important to have no loads on the sense lines due to the low voltages which is why there are 2 wires on the negative shunt post. A 500A shunt has a 50mV drop. So to measure 10A the voltage would be 10/500*50mV=1mV (ie 1 millivolt).

BF13 is correct that the display voltage resolution is single digit but that does not mean that the calculations use a single digit.

WOW, I feel like the dumb kit in high school class. Maybe I shouldn't have partied as hard as I did. :D I am learning however. I know that the battery I have has no chance of surviving at all, with a power jack and a powered rear slide it will die in no time. I have started to look at dual 6v and that will happen sooner than later. However I have made some notes and have a question for you guys. Tri-metric has been installed for 3 days and the battery has been charging through the trailer converter for over a week. The tri-metric displays 13.7. Should I change P1 to 13.6 so it shows complete charge?

The instructions for the Trimetric (on line somewhere in bogart's site) have a good explanation for how they do it. They say that until gassing starts the heat loss is actually less than the 4% they use.

Point again is that, say, 10% loss for AH returned for the 80-100% SOC, is 10% of that 20%. Say 440AH bank, 20% is 88AH and 10% of that is 9AH. 9/440 is 2%. If loss over 80% SOC were 20%, that would be 4% of capacity. When you combine that with their vague notion of "full" as something under 100%, it hardly shows for one cycle, but gets off track after a few cycles.

The shunt has the thin wires (some braided) in a cable to where the read-out panel is mounted and one of those wires goes off to the battery pos terminal at the shunt end. The shunt has to be close enough to the battery for spreading those wires at that end of the cable to their locations. I suppose you could separate the pos wire so the shunt could be farther from the battery. I am not clear on that.

Interesting. I'm not sure many batteries are 96% efficient at getting back to truly fully charged, but at least it tries to account for that. I think to get back to really full can take more like 10%-15% extra amp hours, or even more depending on charge rate.

Is the shunt right at the battery post typically?

Jim

The Trimetric uses 96% (allows 4% for losses) on recharges. This is mainly till you get up to gassing voltage, then it does not try to stay even with heat losses. However, the amps are low at high SOC so the "percentage of what?" is low too, so it doesn't get far off until you do a number of cycles, then it needs a reset.

You have some idea of your bank's capacity, so when it gets to, eg, est 50% SOC by "morning voltage" being 12.1 (with 6s) you can see if you are close to half the AH as a cross-check. Anytime, if your "no load" (parasites only) voltage and AH figures don't match, you know the AHs need a reset or you have a load running you didn't know about.

(Outside lights left on, converter on inverter, tank heaters, etc, etc :( )

It is all "close enough" for camping- not meant to be a science lab. The situation would be much better if it had its volts to two decimal places, but you need a shunt that can go with high amps so that means one decimal place on the volts. You can use a voltmeter if you need more accuracy on voltage.

Interesting except for putting back AH you have taken out. You know if you only put back what you took out from a full battery that you are definately not yet recharged. There is loss in the recharge cycle. If you are back to nearly the same SG as you were before starting out with the same amp hours, you started from a considerably discharged state. I would guess <90% charged.

Jim

Just for info, you can get very good value from your Trimetric without ever setting the "three things."

I have an idea of my battery bank's capacity, which is always changing due to temperature, which is always changing. So IMO the Trimetric idea of "percentage charged" is totally bogus.

Nevertheless, right out of the box, it can do accumulated AHs, amps, and volts, which is all I ever need.

For solar, be aware you need to kill the "auto reset" of AH as suggested in the instructions, or it will reset every time it gets dark.

You can kick off with battery full according to its SG, and reset the AH. Then get down to 12.2v for your "morning voltage," and note the minus AH you are at. Call that 50% of capacity, so now you know what the full AH capacity is at that temp. Recharge by whatever means you have and carry on.

If you ever get recharged back to zero AH or more, confirm by SG, and reset the AH to zero and carry on. You will need to reset the AH to zero every so often. Just how it is.

If you think that is all nuts, read the Trimetric instructions of how to under-shoot your actual capacity, so the battery never gets to "true full" before the Tri says it is full after using your phony "three things." :)

I love my Trimetric, but it works for me; I don't work for it!

Perfect! Flip off the main CB, use the battery and compare the battery and Trimetric readings. When done - CB on and post the results.

Thanks for the help, Ya kinda mad at myself when I forgot to check what battery it had in it when we picked it up. It was on my list but with cold weather I guess I wanted warm food and beer and wasn't worried about what they sent me with. In the scheme of things probably not a huge issue as I was planning on dual 6v even before I bought the TT. I think I can get it close for now as we are not really replying on the batteries just yet, we are still at the plug and play step with it. I am excited about the tri-metric with the future upgrade of better batteries and solar in the future. Again thanks for the help up to this point.
Shawn