I will start with what my system consist of
9 canadian solar 270 watt panels wired 3 strings 3 panels in series
midnite classic 150 charge controller w/wiz bang jr. making a average of 65 amp to charge 24 volt battery bank
8 ub121100 110AH batteries series in pairs for 24 volts and then paralleled to a large copper buss bar with 00 cable making a 440ah bank
reliable 3000 watt 6000 peak inverter also wired with 00 cable
Ok so everything is good as far as charging, the problem I have is I am trying to run a hallmark 1hp deep well pump. The inverter has no problem starting the pump and running it as long a the sun is out and putting 30 or more amp to the battery bank. but if the charge controller is turned off then the battery voltage slowly drops (about 10 mins) untell the inverted alarms at about 21 volts and then shuts off at 19 to 20 volts. Once it shuts off it only takes about 5 seconds for the voltage to rise again to 25 volt and the inverter will try to restart but with in seconds drags the volt back down and shuts off again. The pump when running is drawing 8 amps a 120vac not possitive shut what the start draw is but seems to be around 25 amps but once again it has no problem starting and even running as long as the charge controller is putting a decent amount of power to charge the batteries, on the the input side of the inverter I am see a 55 amp draw when the pump is running.
So my question is how is the the voltage dropping so quickly without the controller putting amps to the batteries? The cables are plenty big and the batteries are rated at 60 amps each max draw so that should be 60 x 4. The batteries a only losing a few % soc before the inverter starts shutting off.
thanks for any ideas
Standard things to check are - all connections are tight ? Crimps on lugs good ?
Almost sounds to me like a battery problem. Are all the batteries the same age ?
I would put volt meter on each battery under load before inverter cuts out and see if any of them are dropping voltage compared to others. You could disconnect the batteries and load test each one while monitoring voltage and see if voltage takes a dive.
It can be hard to balance all the batteries in so many parallel strings - are all connecting cables the same length ?
I have seen bad AGM batteries voltage look fine but it takes a dive under load.
Of course if batteries are capable of delivering load and holding voltage then it could be an inverter problem.
That is very inexpensive inverter. Make sure the cables are well connected there.
My 24v 3500 watt Outback inverter calls for 4/0 wire size. So maybe the wire size you have is dropping the voltage on the surge startup of the pump ? There are online calculators.
I know I threw out a lot of things there but you are going to have to put volt and clamp meter on your system to evaluate your system and start to be able to find problem.
here are the things I looked up for your system in case anyone else wants to make suggestions they won't have to find them.
Larry
https://www.amazon.com/Reliable-Inverter-Voltage-Converter-Display/dp/B01M5L0A5L/ref=pd_sbs_23_8?_encoding=UTF8&pd_rd_i=B01M5L0A5L&pd_rd_r=018G6TNBBW44AVMSSCGC&pd_rd_w=WBASp&pd_rd_wg=nLdvn&psc=1&refRID=018G6TNBBW44AVMSSCGC
https://www.amazon.com/110AH-Replacement-Battery-UB121100-Replaces/dp/B00BHLLLBS
Thanks for the Links, Larry,
Hi supra..,
Welcome to this Forum,
Only a couple of comments;
This does seem most likely a battery problem.
As Larry noted, parallel battery strings can be trouble, especially when they are AGMs.
What are the settings for Absorb and Float voltages, and Absorb time, and End Amps, if used?
How did you find these settings, from the battery manufacturer?
Are all of the batteries the same age? Same Date Code?
If you do not already have a DC Clamp Ammeter, you will find one useful to monitor the charge and discharge currents on each string. Ideally, these currents should be close to identical.
Often, AGM batteries do like a L O N G Absorb stage, particularly if they are paralleled.
The Amazon Link for the inverter state that it is "true pure sine wave" or similar, this would be good, if true ...
Just a drive-by, FWIW, Vic
I agree, this is a battery problem. You either have a bad battery or many bad batteries. No magic here. I believe the batteries are toast. You just can't have what you are sting if the batteries are good.
Sorry,
Robin
beware the simple AC ammeter when measuring loads.
My 1/2 hp 240VAC pump pulls 1,000VA (about 1Kw) as logged by my inverter, which has watt and VA metering. Taking that to a 1Hp, would be 2K w or about 100A consumed by the inverter at 24V, if no other loads. I question the accuracy of your measurement of only 55A
This is for mike90045
https://www.amazon.com/Hallmark-Industries-MA0414X-7-Submersible-Stainless/dp/B00NTT2JO4/ref=sr_1_3?ie=UTF8&qid=1499557544&sr=8-3&keywords=hallmark+deep+well+pump
I've measure it says in there manual 10.5 amps max, I'm only down about half the max depth and measure around 8 amp, even when running it with a generator.
I'm thinking I need to check all the batteries again
Thanks for all the input everyone!
Supracoolguy,
Others have said it.....batteries in parallel are a big problem...especially AGM's , they have a vey low internal impedance and are very difficult to balancing when wired in parallel.
Also high frequency inverters have very low overload capability. For largely inductive loads such as a water pump (squirrel cage motors) Need a inverter with a large transformer such as the Outback and MagnaSine units. Most of the consumer grade units are high frequency switch mode units which have problems with hugely inductive motors. If at all possible get a pump with a capacitor start capacitor run motor. They have less inductive loading than a standard motor and are more efficient.
But your bigger issue is AGM's in parallel.....that will be problematic!
David