AGM to Li

[T1 Terry]

The manufacturer specifies 33 amps / 100AH @ 3.2 volts for 182 minutes
At 12.5 volts that load needs to be increased 132 amps for 182 minutes.
So I need to find something that will draw about 1500 watts ...a 240V toaster plus the 325watt fridge comes to mind.
That will also test my wiring for any hotspots and my whole installation....will do that.

Will let you know, Paypal will refund if they are not to specification.
I dont understand the manufacture specifies the dischage test at 33 amps and 100 amps on 100AH, where does .2C test come from cant find it the specifications supplied with the Battery.
Do I have it right the test the manufaturer is specifying between .33C and 1.0C.

33amps per 100Ah is 0.3CA and 100 amps per 100Ah is 1CA. So it appears they have improved their test conditions, 33amps for 1 hr = 33 Ah or 0.55 amp minutes or 0.55Ah per minute. Multiply that by the 182 mins = 0.55 x 182 = 100.1Ah.
The 33 amps @ 12.8v nom. = 422.4w per 100Ah so the 12 cells connected 2P4S will build a 200Ah @ 12.8v nom. battery. This means the load test will need to be 845w, allow roughly 10% loss for the inverter the plugged in load will need to be roughly 760w and a constant load for 182 mins ...... Possibly a 500w and a string of 100w bulbs you can turn off one at a time to hold the load at 66 amps till a cell drops to 2.5v under load. You will need to constantly monitor the cell voltages through the test and stop as soon as a group drops below 2.5v.
If you run the inverter through a Victron BMV, the latest 712 has a Bluetooth output to a computer or smart phone, so the total Ah drawn could be measured, a continuous read out of the load and an alarm set for 12v to give you a warning to go and sit with the battery and watch the cell monitor to catch the 2.5v end of test mark. Set the Victron BMV to a 1.0 Peukert Factor and 100% charge efficiency so the reading will be accurate and you should be set to do a reliable and repeatable capacity test.

I use various watt capacity 12v and 24v water heater elements in a galvanised garbage can full of water as my load with a Junsi 8S running a log and the alarm set to disconnect the load when a cell drops below 2.8v under load and calculate the time x load get the remaining battery capacity. Because the battery bank capacity I need to test can vary between 100Ah and 700Ah the cabling to the heater elements can look a tad agricultural at times and the bigger batteries need me to swap out some of the water every so often to avoid boiling it, but fortunately the voltage curve is reasonably flat once the test is under way so it doesn't require a lot of monitoring. The fall off from below 3v under a 0.5CA load (Winston cell specs) is fairly quick because the capacity is exhausted by that point so I had to build a control to cut the load rather than risk missing it, that gets a tad expensive and not something I want to repeat

T1 Terry

[Barboots]

How do you plan to keep a toaster or kettle running for this extended period? I'd put money on them retiring before the test is complete.

Terry's method sounds like it's worth the time rigging up [emoji106]

[cruiserxxx]

The 33 amps @ 12.8v nom. = 422.4w per 100Ah so the 12 cells connected 2P4S will build a 200Ah @ 12.8v nom. battery. This means the load test will need to be 845w, allow roughly 10% loss for the inverter the plugged in load will need to be roughly 760w and a constant load for 182 mins ......
T1 Terry

Just double checking, with 12 cells I think I will have 300AH at 12.8V see intended wiring method. therefore a 1140 watt load for 182 minutes.
Yes had the thought about a toaster not hacking it, maybe the fan heater a couple 100 watt bulbs to fine tune.

[jon_d]

The test might be considered invalid.

Using kettles, fridges, globes is ok, but the inverter efficiencies, fidges cycling etc need to be considered.

As Terry said, the best and 'only' way is a resistive (pure) load connected at DC and measured at DC.

Unless traceable calibrated equipment is being used, the manufacture is likely to reject any claim.

[T1 Terry]

The 33 amps @ 12.8v nom. = 422.4w per 100Ah so the 12 cells connected 2P4S will build a 200Ah @ 12.8v nom. battery. This means the load test will need to be 845w, allow roughly 10% loss for the inverter the plugged in load will need to be roughly 760w and a constant load for 182 mins ......
T1 Terry

Just double checking, with 12 cells I think I will have 300AH at 12.8V see intended wiring method. therefore a 1140 watt load for 182 minutes.
Yes had the thought about a toaster not hacking it, maybe the fan heater a couple 100 watt bulbs to fine tune.

Brain fade, 300Ah so 99 amps x 12.8v = 1267w, so roughly 1300w less 10% for inverter inefficiency = 1170w, so a 1000w bar heater and a string of light bulbs to hold the discharge rate measured by the Victron at 99 amps or better still, 1200w +/- 5%. I believe the new Victron BMV712 will output via Bluetooth to a computer so a plot can be draw and the Junsi 8S will plot a graph of the cell voltages to give you a hard to argue with set of test results. Plotting both the charge and discharge curves and repeating the test 3 times will match the test regime used by Winston battery Co. so should be plenty for Sinopoly, they were both the same company once upon a time and traded as Thundersky with Winston Chung being the technical brains behind the set up.

T1 Terry

EDIT: Missed a bit, the battery pack must be connected in a way the loop goes through all the cells, at the moment only the first 4 cells are in series with each group having 3 cell hanging off them in parallel, the first 4 cells will do all the work until deeply discharged and serious risk a reverse current flow towards the end of the test.

[cruiserxxx]

I might be overcomplicating things, Attached is a wiring diagram for the Dingo 2020 to upgrade the capacity I intend to follow, except will put some thought into measuring charge currents twice, will use the Dingo to test the batteries.

I have a Dingo 4040 and in the back of head I think someone told me years ago it switches the negatives, therefore should I be switching the negatives thru the SSR?
Also think it would be a good idea to run a 240v to 2.5 - 15v 40 amp power source thru SSR terminal 2 with a blocking diode so the Dingo controls all charging.

[bagmaker]

dont worry about it Cruiserxxx, you cannot get relays to do the job

[T1 Terry]

dont worry about it Cruiserxxx, you cannot get relays to do the job

You can, but not for a reasonable price unless you can handle converting a lot more of your solar to heat than desirable. If you source SSR's from evil bay at least halve the quoted handling capacity and consider that to be its max handling capacity and aim to run at 50% of that most of the time. If you construct a wet back heat sink you could use them at the 50% of rated capacity and directly convert solar panel energy into water heating energy, that way the heat generated isn't wasted .... well until the water reaches 50*C on the intake side, then you will need to add a car heater core and fan controlled by a thermostat on the heatsink.

As far as the Dingo 20/20 and Dingo 40/40, the 20/20 is positive switching and the 40/40 is negative switching as are all the PL series. If you can get your head around how the Dingo drives the SSR's and just what the - and + on the SSR terminals really mean, you won't have a problem wiring it up. The SSR's all have an internal diode to protect damage from back current/voltage spikes, so no need to add a diode across the load side.

T1 Terry

[Barboots]

There is also a Dingo 20/20N which is negative switching.

Cheers, Steve

[bagmaker]

dont worry about it Cruiserxxx, you cannot get relays to do the job

You can, but not for a reasonable price unless you can handle converting a lot more of your solar to heat than desirable. If you source SSR's from evil bay at least halve the quoted handling capacity and consider that to be its max handling capacity and aim to run at 50% of that most of the time. If you construct a wet back heat sink you could use them at the 50% of rated capacity and directly convert solar panel energy into water heating energy, that way the heat generated isn't wasted .... well until the water reaches 50*C on the intake side, then you will need to add a car heater core and fan controlled by a thermostat on the heatsink.

As far as the Dingo 20/20 and Dingo 40/40, the 20/20 is positive switching and the 40/40 is negative switching as are all the PL series. If you can get your head around how the Dingo drives the SSR's and just what the - and + on the SSR terminals really mean, you won't have a problem wiring it up. The SSR's all have an internal diode to protect damage from back current/voltage spikes, so no need to add a diode across the load side.

T1 Terry

So you reckon the Jaycar ones at 50% would live?
Gonna be 150 amps.......