Charging House Batteries
- Thread starter mattdanger
- Start date
Bikersmurf
Expedition Leader
On a related matter. For flooded led Acid batteries, what is the recommended charging voltage?
The reason I ask is that the stock Ambulance setup used a Diode Isolator. I know, Evil, Evil, Evil. However, that said, the Alternator puts out up to 15 v and I routinely see 14.4 v at the house batteries. If I swapped in an ARC, would 15 v be too much? BTW at Idle 100+ amps and somewhat above idle, 215 amps (24/7).
The reason I ask is that the stock Ambulance setup used a Diode Isolator. I know, Evil, Evil, Evil. However, that said, the Alternator puts out up to 15 v and I routinely see 14.4 v at the house batteries. If I swapped in an ARC, would 15 v be too much? BTW at Idle 100+ amps and somewhat above idle, 215 amps (24/7).
Mwilliamshs
Explorer
Trojan says 14.8v bulk charge for a 12v flooded system. Some mfg's differ.
dwh
Tail-End Charlie
Diode isolators cause a voltage drop through the diode.
Let's use .6v drop as an example. And let's also use 14.4v as an example of the voltage regulator set point.
Now, if the regulator senses voltage at the alternator, then it will see 14.4v and hold the alternator there, and after the diode, the battery only sees 13.8v.
That's evil.
But if the regulator senses voltage at the battery, it will hold the alternator wherever it has to be in order for the regulator to see 14.4v at the battery. In this example, that would mean the alternator would have to be at 15v for the regulator to see 14.4v after the .6v drop through the diode.
I suspect that's what is happening with your truck. That's probably why you see 15v on the alternator side of the diode.
(And if the regulator senses voltage after the diode instead of before the diode, then the diode isolator is not evil.)
If that is the case, then after replacing the diode isolator with something else, the regulator won't be holding the alternator at such a high voltage.
Let's use .6v drop as an example. And let's also use 14.4v as an example of the voltage regulator set point.
Now, if the regulator senses voltage at the alternator, then it will see 14.4v and hold the alternator there, and after the diode, the battery only sees 13.8v.
That's evil.
But if the regulator senses voltage at the battery, it will hold the alternator wherever it has to be in order for the regulator to see 14.4v at the battery. In this example, that would mean the alternator would have to be at 15v for the regulator to see 14.4v after the .6v drop through the diode.
I suspect that's what is happening with your truck. That's probably why you see 15v on the alternator side of the diode.
(And if the regulator senses voltage after the diode instead of before the diode, then the diode isolator is not evil.)
If that is the case, then after replacing the diode isolator with something else, the regulator won't be holding the alternator at such a high voltage.
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Bikersmurf
Expedition Leader
The 15 v is on an analog guage... 14.4 v is what the power inverter digital guage is showing at the inverter. I suppose if I bridge the diode isolator with a heavy jumper, I can see what would happen if I had an ARC.
Sounds like 14.8 can be viewed as acceptable... Not sure if it's worth a wad of cash to redesign a setup that's giving me 14.4v. Perhaps when I get the 7+ months of pay I've been shorted.
Sounds like 14.8 can be viewed as acceptable... Not sure if it's worth a wad of cash to redesign a setup that's giving me 14.4v. Perhaps when I get the 7+ months of pay I've been shorted.
_hein_
Observer
System sounds right and agree that there is no need to isolate the charge sources with the relay. Best practice is to connect two charge sources to opposite ends of the battery bank if possible. Make sure that all the negative 12V leads congregate on one side of the shunt with other side as the only connection to the negative post of the battery bank. We make a direct mount tower kit that attaches directly to the RNG-100D and then mounts to the Sprinter roof rails. Below is a link to a layout showing how two panels can be mounted with 4 towers. Very common setup for us.
http://www.impact3d.com/Impact_direct_mount_2xRNG100D.pdf
dwh
Tail-End Charlie
Or just bypass the isolator by moving the input wire from the alternator over and connect it to the wire that runs out to the starter battery. Then you're back to a factory setup for testing purposes.
14.4v is fine. Going to a higher voltage will shave some time off a full charge cycle, but not all that much. 10%-20% would be a halfassed ballpark guess.
Bikersmurf
Expedition Leader
If I'm needing to minimize recovery time, I'll keep it in mind. For now I plug it in every night so it's not a concern.
A bigger concern is the 5 A that the current fridge drains constantly... Although, I've also not got the budget for a higher efficiency one at this time.
A bigger concern is the 5 A that the current fridge drains constantly... Although, I've also not got the budget for a higher efficiency one at this time.
5Amps is a big draw for a fridge, I assume a DC cooler like a Coleman or other cheap unit, not the ARB one? Batteries will never survive unless you are charging them daily. If solar, then you need a big bank, maybe 300 watts in summer with good sun.
I tried with a 4 amp draw with 100 watt solar panel in SoCal in summer and killed batteries after 3 days. 200 watt solar panels in cloudy NE and killed batteries in 2-3 days. Now, Im just getting rid of the cooler - not worth the hassle.
That said, re-charging batteries was a pain. My trailer's converter was only 2amps, so I am adding a 10 amp home garage charger when I have shoreline or generator power. Anyone know how this will play with the 2amp charger on top of the solar charging all together? I can set the garage 10amp charger on "Manual" mode, so it should just put out the 10amps no matter what, I think.
What should I be aware of?
I tried with a 4 amp draw with 100 watt solar panel in SoCal in summer and killed batteries after 3 days. 200 watt solar panels in cloudy NE and killed batteries in 2-3 days. Now, Im just getting rid of the cooler - not worth the hassle.
That said, re-charging batteries was a pain. My trailer's converter was only 2amps, so I am adding a 10 amp home garage charger when I have shoreline or generator power. Anyone know how this will play with the 2amp charger on top of the solar charging all together? I can set the garage 10amp charger on "Manual" mode, so it should just put out the 10amps no matter what, I think.
What should I be aware of?