BAC Forum
General Boards => Technical Support => Topic started by: marty christensen on March 15, 2018, 04:59:40 PM
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I have a question on my inverter. It seems to operate normally, but 1 volt low. With AGM house batteries and a Magnum 3000 inverter, the book shows 14.1 bulk, 14.3 absorption and 13.1 float. The settings have been programed for 400 amp AGM batteries. My remote shows 1 volt lower than the above. The book says at 13.1 float charge the charger turns off until the voltage drops to 12.9 and then starts the float charge again. Since the most I get on float charge is 12.2 to 12.4, the inverter is always charging on float. My question is..... can the inverter be adjusted to charge approx 1 volt higher or is running as it is normal or OK?? I think it has always work this way since I purchased the coach. I seem to having trouble now getting the patio awning to retract. Not enough voltage. I have just replace the batteries yesterday
Marty Christensen
08 Contessa, 400hp cat
Magum inverter
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Marty,
It sounds like you have a defective (shorted) battery temperature sensor. Check your inverter, if you have a battery temperature sensor plugged into the battery temp sensor port, unplug it, and see if it cures your problem. If there is no battery temp sensor or if it does not correct your problem, call Magnum Technical Support, and they will help you diagnose the issue.
Gerald
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Gerald, thanks for the response. I see a battery temp port, so I will unplug it and give it a try. Is this something I can leave out if it cures the problem?
Marty
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Gerald, I did remove the cable and the charging immediately jumped up to 13V where it is supposed to be. I looked at the batteries and also around the inverter for the actual sensor and could not find it. Where would it be? Do I really need a sensor?
Marty
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Marty,
There are several possibilities here. First, there could be a bad temperature sensor that was taken off your negative battery post (intended location), and just stuck back in a corner. Second, and I have seen this, the inverter was replaced and the shorted control cable for the old inverter was plugged into the battery temp sensor port.
As you can see, the inverter will function well without at battery temp sensor, but if you want to spend a little time (depending on distance and obstructions between the inverter and batteries) and a few dollars on installing a new temp sensor, the inverter can charge your batteries at the optimum rate for their temperature which can be a benefit to you batteries and extend their life, especially in a high temperature environment. However, if you spend all of your time on full hookups in a location that never gets above 70 degrees F, you do not need a battery temp sensor.
Gerald
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Gerald, I think I will contact Magnum and order a new sensor. I am the original owner of the coach and this is original inverter. I remember it always working like this. Probably the factory connected the cables and never installed the sensor.+
Thanks for your help.
Marty
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Marty,
I do not think that Magnum will sell you a sensor, since they want you to use their retailers. The Magnum battery temp sensors are available online from Amazon and numerous other retailers. The thing that you need to know before you order one is the length of cable that you need since they come in 15, 25, or 40 foot lengths. The sensor is made into the cable end and sealed, so a length adjustment is not easy. You can look for the correct sensor by Goggling ME-BTS- and the cable length you want like ME-BTS-40 for a 40 foot cable.
Gerald
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I have a similar situation with a Magnum 2812 inverter/charger. I looked at the charging current with and without the temp sensor connected. I did see the correct voltage change (depending on ambient temperature) when doing this. Also in doing a lot of checking previously I found the DC connection at the inverter loose. Caused almost a full volt drop across the loose connection.
My short term solution was to use the AGM2 battery seclection on the Magnum which is a little higher voltage output. I monitor the charging voltage and current regularly so I am not overly concerned about this setting. Do find it frustration though.
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Some comments in this thread have me thinking..(not sure that's a good thing). When my batteries are low, and either the AGS starts the generator or I plug in to shore power, the first charging mode is always bulk...then absorption...then float. As long as I am plugged in the status remains float when it gets there. I have always assumed that meant my house batteries were fully charged. The OP mentioned "float charge". Is there charging going on while in the float status?
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Stan,
From the manual:
Float Charging – At the end of the Absorb Charging time, the charger reduces the charge voltage and tries to maintain the batteries at the Float Charge voltage setting. This is determined by the SETUP menu’s 04 Battery Type setting as shown in Table 3-4. Info: If the battery voltage falls ≤12.1 VDC (12-volt models), ≤24.2 VDC (24-volt models) or ≤48.4 VDC (48-volt models), the unit will begin Bulk Charging.
Steve
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Our Xantrex Freedom PSW 3000w inverter goes through the three steps as described - bulk, absorption and float - then sits on float to maintain the batteries (both the house and chassis batteries) showing 13.6v to 13.7v indefinitely on the Aladdin screen.
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Our Xantrex Freedom PSW 3000w inverter goes through the three steps as described - bulk, absorption and float - then sits on float to maintain the batteries (both the house and chassis batteries) showing 13.6v to 13.7v indefinitely on the Aladdin screen.
I have the exact unit, so I guess I'm okay. Thanks.
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Guys, I have one more question on BTS. I have ordered a new cable and of course it is not going to be easy to install a new cable from the inverter to the batteries. Is there any problem in cutting about 1' off the sensor cable at the battery contact point and just splicing the new sensor to the old cable?? The wire from the inverter is surely going to be good. It is just wire. The sensor is the defective part. I thought I could solder the 2 wire parts together for good contact and just seal it up. Turns an all day project into 1 hour or less.
Marty Christensen
08 Contessa, 400hp
MAGNUM INVERTER
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Marty,
In theory you idea works, but in the real world, there may be problems. The first issue is how good are you at soldering wires? If the connection is not really good, there will be a change in resistance that will affect the accuracy of your BTS enough to make it problematical, and in that case, you might as well not have one connected at all. The other problem will arise if the connection is not sealed well enough because it will be in a very corrosive area that is also exposed to high moisture at times. If you are confident that those things are not a problem in your case, go for it.
Gerald
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Gerald, thanks for the reply. I will have to think about it a while.
Marty Christensen
08 Contessa 400 hp