Hello. I just bought and installed 2 brand new deep cycle 105Ah batteries on Monday from West Marine. The no load voltage on the terminals was 12.4 & 12.39. I flicked the shore power, checked my Xantrex 10 TB was on (it is wired through the isolator switch, and Xantrex say it should go straight to the battery terminals??) and the lights lit, and then left them to charge overnight.I went back today check on them, expecting to see around 12.6v : They both had the same voltage : 12.40 v??. Now I know I had not let them 'settle' for any period of time, but I expected them at least to have increased slightly. I physically measured the same voltage at the Xantrex Output terminals as at the battery terminals. So I switched to #2 Battery and started up the motor and measured the Voltage under engine charging : 13.65 max at the terminals at any rpm, which, I have read, is not good in that it will lead to chronic undercharging of the batteries. Is it likely that the alternator is sensing the near full chage of the batteries and regulating down? although I thought 14-14.4 v was norm from the alternator while charging. I am expecting 12.6 volts at the terminals, but will I have tho let them settle first? Any advice on what to do or am I worrying about nothing?? Neil
Battery Charging Query
- Thread starter Neil Hodgson
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Ahoy Neil
The lower voltage could be caused by the combiner. If it is the type that uses diodes there will be a voltage drop. The relay typ combiner has very little voltage drop. That is why Xantrex wants the charger hooked direct to the batteries. Fair winds. Cap'n Dave
The lower voltage could be caused by the combiner. If it is the type that uses diodes there will be a voltage drop. The relay typ combiner has very little voltage drop. That is why Xantrex wants the charger hooked direct to the batteries. Fair winds. Cap'n Dave
12.4 from a charger
is not going to cut it. 13.65 from your alternator COULD be OK but that would depend on the state of charge on the bateries. Most new batteries are shipped dry and you have to add the electrolite to activate them. WM does this for you. So the now fully charged battery is sitting around the WM store for a few months self discharging. With that said, you should see 14.1-14.2+ initial charging voltage from any source that is connected to any 12 V battery. This may only last for 15-30 secs as the "regulator" adjusts the current output. The "charging" voltage is dependant on a lot of things but you have to have a higher than no load voltage to charge any battery. Try this, measure the no load voltage and then turn on the charger. You should see the voltage go up about 1.5-2 volts for at least a few seconds. If the charger is not doing this then take the charger leads off the battery and measure the open circut voltage from the charger. You should see something like 15 volts (depends on the charger). If you don't the charger is bad. Another check for wetcell batteries (this is another reason I love these things) is to take the cell caps off while the charger is on and see if there are bubbles. Sometimes you can hear them better than see them. If there are bubbles when the charger is on and the bubbles stop a few minutes after the charger is switched off and no load on the battery then the battery is charging. If the bubbles continue after the charger is off and no load is being drawn from them then that battery has a short. It will probably be just two adjacent cells but that is all it takes. I have seen new batteries with shorted cells. Not very often but it does happen. Also check your alternator belt for the proper tension. If you can grab the pully and turn it by hand it is too loose. If it makes a squeel right after starting it is too loose. The rule is not more than 1" of movement in the plane of the belt at the midpoint of the longest run between pullies.
is not going to cut it. 13.65 from your alternator COULD be OK but that would depend on the state of charge on the bateries. Most new batteries are shipped dry and you have to add the electrolite to activate them. WM does this for you. So the now fully charged battery is sitting around the WM store for a few months self discharging. With that said, you should see 14.1-14.2+ initial charging voltage from any source that is connected to any 12 V battery. This may only last for 15-30 secs as the "regulator" adjusts the current output. The "charging" voltage is dependant on a lot of things but you have to have a higher than no load voltage to charge any battery. Try this, measure the no load voltage and then turn on the charger. You should see the voltage go up about 1.5-2 volts for at least a few seconds. If the charger is not doing this then take the charger leads off the battery and measure the open circut voltage from the charger. You should see something like 15 volts (depends on the charger). If you don't the charger is bad. Another check for wetcell batteries (this is another reason I love these things) is to take the cell caps off while the charger is on and see if there are bubbles. Sometimes you can hear them better than see them. If there are bubbles when the charger is on and the bubbles stop a few minutes after the charger is switched off and no load on the battery then the battery is charging. If the bubbles continue after the charger is off and no load is being drawn from them then that battery has a short. It will probably be just two adjacent cells but that is all it takes. I have seen new batteries with shorted cells. Not very often but it does happen. Also check your alternator belt for the proper tension. If you can grab the pully and turn it by hand it is too loose. If it makes a squeel right after starting it is too loose. The rule is not more than 1" of movement in the plane of the belt at the midpoint of the longest run between pullies.
I used to get...
... some relatively low voltage readings when testing my unloaded batteries with a cheap DVM that I keep on board for trouble-shooting purposes. One day, I brought my expensive DVM from home and tested the batteries. Bingo. They were right on the money reading 12.6 - 12.8 vdc. The cheap DVM was reading about .2 - .3 vdc low. I have since made a "deviation" table for it. So, you may want to try another DVM on your batteries before doing anything else.
... some relatively low voltage readings when testing my unloaded batteries with a cheap DVM that I keep on board for trouble-shooting purposes. One day, I brought my expensive DVM from home and tested the batteries. Bingo. They were right on the money reading 12.6 - 12.8 vdc. The cheap DVM was reading about .2 - .3 vdc low. I have since made a "deviation" table for it. So, you may want to try another DVM on your batteries before doing anything else.
I don't charge through a switch
I think that the charger should be connected directly to the batteries. Just my two cents.
I think that the charger should be connected directly to the batteries. Just my two cents.
float charge
HI neil 13.6 sounds like a float charge your batterys start chargeing at 14.4 volts and the voltage slowley drops untill it reaches 13.6 then holds there .My solar chargers keep my baterys chargeing at 13.6 volts the alt never works all summer long beccouse the voltage never drops down low enought to kick the alt on John
HI neil 13.6 sounds like a float charge your batterys start chargeing at 14.4 volts and the voltage slowley drops untill it reaches 13.6 then holds there .My solar chargers keep my baterys chargeing at 13.6 volts the alt never works all summer long beccouse the voltage never drops down low enought to kick the alt on John
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