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#1
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Battery charger
Why not use a traditional split charge relay.
Alternator output then becomes the limiting factor |
#2
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Battery charger
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#3
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Battery charger
On Nov 16, 4:42*pm, wrote:
Why not use a traditional split charge relay. Alternator *output then becomes the limiting factor I didnt think you could charge a deep cycle battery in an automotive system without damaging the battery. Its my understanding that car batteries are designed for a quick charge at realativly high current while deep cycle batteries require a long low current charge. To make it work thought you had to have a special charge regulator for the deep cycle battery. Jimmie |
#4
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Battery charger
Howdy,
What type of deep discharge battery do you mean? Gell vs AGM vs VRLA vs Flooded battery generally require different care. I use low maintenance flooded deep disharge batteries and charge them at 20% of their AHr capacity rating. I'd have no worries about mounting one of these remotely from the alternator (like in the trunk) and letting the vehicle system charge it. Gell or AGM I'd charge at 10% capacity or less. These would require some current limiting circuit. The volts per cell for full charge and float charge will be different too. Though if you keep the battery between 80% and 20% of full charge it's not an issue. 73, Grumpy JIMMIE wrote in news:8795bf5a-715c-4a24-8290- : On Nov 16, 4:42*pm, wrote: Why not use a traditional split charge relay. Alternator *output then becomes the limiting factor I didnt think you could charge a deep cycle battery in an automotive system without damaging the battery. Its my understanding that car batteries are designed for a quick charge at realativly high current while deep cycle batteries require a long low current charge. To make it work thought you had to have a special charge regulator for the deep cycle battery. Jimmie |
#5
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Battery charger
On Nov 17, 1:58*pm, Grumpy The Mule wrote:
Howdy, What type of deep discharge battery do you mean? Gell vs AGM vs VRLA vs Flooded battery generally require different care. * I use low maintenance flooded deep disharge batteries and charge them at 20% of their AHr capacity rating. I'd have no worries about mounting one of these remotely from the alternator (like in the trunk) and letting the vehicle system charge it. Gell or AGM I'd charge at 10% capacity or less. *These would require some current limiting circuit. The volts per cell for full charge and float charge will be different too. *Though if you keep the battery between 80% and 20% of full charge it's not an issue. 73, Grumpy JIMMIE wrote in news:8795bf5a-715c-4a24-8290- : On Nov 16, 4:42*pm, wrote: Why not use a traditional split charge relay. Alternator *output then becomes the limiting factor I didnt think you could charge a deep cycle battery in an automotive system without damaging the battery. Its my understanding that car batteries are designed for a quick charge at realativly high current while deep cycle batteries require a long low current charge. To make it work thought you had to have a special charge regulator for the deep cycle battery. Jimmie- Hide quoted text - - Show quoted text - Im not sure but they are sealed 100Ahr batteries and the max recharge rate is 10amps so definitly not FLOOD. I have recharged them from my aux power connector in my truck bed but this took a lot more care and effort than I wanted to give. Wife and kid thought I was paying more attention to the batteries than them.. I thought about feeding them from a constant current source. In this case it would act more like a current limiter. Jimmie |
#6
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Battery charger
Howdy,
Ok, the minimum you'd need to charge these is a voltage and current regulated supply limited to less than 10A and 13.62 for AGM or 13.50 for gell (check the manufacturer's stated the float voltage). No more than 14.1V in any case. The vehicle voltage is not much higer than this with the engine is running. It's possible to build a low drop linear regulator to serve this function. Linear Technology or Micrel should have an app note you can work from. This is the one device solution. You'll get a couple of hundred milliamps to an amp at 13.6V from as low as 14V maybe a bit less. Good for keeping the auxilliary battery topped off but not so good for recharging. If you want faster recharge (which still won't be very fast since 120%-140% of 100Ahr is is going to take 12H-14Hr at 10A) I suggest a SMPS running off the vehicle battery it can charge the gell cell even when the engine isn't running. Try National Semiconductor's Web Bench power design tool and roll your own with their parts. http://www.national.com/appinfo/power/webench.html For minimum recharge time a bigger SMPS (maybe a nice push-pull) is required. I might try a simple switcher boost converter or switched capacitor converter and raise the vehicle supplied voltage to about 24V at a few milliamps to bias a series pass MOSFET linear regulator. The output current and drop-out voltage are then only limited by the mosfet pass device(s) .... virtually unlimited! Though not as efficient as the switcher. Maybe a good idea to throttle back the current limit from 10A when the engine is running to a few hundred milliamps when it is not. Though even that's too much if the vehicle sits unused for too long. Which causes me to ponder... you'll drain the vehicle battery unless the engine is running. Even at 10A charge current a full recharge requires a fair amout of driving! Perhaps it's better to plan on recharging the battery from "dock side" power and only trickle charge the battery from the vehicle to keep it topped off. One of the low drop regulator IC's set to 13.6V or a simple switcher(tm) would be all you need for that. 73, Grumpy JIMMIE wrote in news:0309608e-8c61-4bac-a667- : Im not sure but they are sealed 100Ahr batteries and the max recharge rate is 10amps so definitly not FLOOD. I have recharged them from my aux power connector in my truck bed but this took a lot more care and effort than I wanted to give. Wife and kid thought I was paying more attention to the batteries than them.. I thought about feeding them from a constant current source. In this case it would act more like a current limiter. Jimmie |
#7
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Battery charger
On Mon, 17 Nov 2008 09:06:28 -0800 (PST), JIMMIE wrote:
I didnt think you could charge a deep cycle battery in an automotive system without damaging the battery. Hmmm mine is 7yrs old |
#8
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Battery charger
JIMMIE wrote:
On Nov 16, 4:42 pm, wrote: Why not use a traditional split charge relay. Alternator output then becomes the limiting factor I didnt think you could charge a deep cycle battery in an automotive system without damaging the battery. Its my understanding that car batteries are designed for a quick charge at realativly high current while deep cycle batteries require a long low current charge. To make it work thought you had to have a special charge regulator for the deep cycle battery. ========================== 'Deep Cycle' batteries should be charged with a current not exceeding 0.1C , meaning that a 80Ah battery should be charged with a current not exceeding 8 Amperes. Frank KN6WH |
#9
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Battery charger
The UC3906 is temp compensated unlike zeners which go up with temp
rise and down with temp decrease. Believe me 1/10 of a volt change will fawk up the charge rate. Been there done that. I've quick charged deep cycle marine batteries at work when I forgot to put my battery on charge on my electric bike. 55 amp in one hour no problem. Now I was using this my electric bike every day to gits to work. I got 2 years out of that deep cycle marine battery before my brushes on my motor were no longer available from Grainger. I didn't count the times I quick charged the battery at 55 amp rate but it was quite a few. If this isn't any everyday thing make it simple, no frilles But a automotive in car charging system is the worst thing anybody to do to a battery. I'd let my battery sit on cold concrete before I'd charge it with an automotive charging system in a car. 73 OM n8zu I didnt think you could charge a deep cycle battery in an automotive system without damaging the battery. Its my understanding that car batteries are designed for a quick charge at realativly high current while deep cycle batteries require a long low current charge. To make it work thought you had to have a special charge regulator for the deep cycle battery. ========================== 'Deep Cycle' batteries should be charged with a current not exceeding 0.1C , *meaning that a 80Ah battery should be charged with a current not exceeding 8 Amperes. Frank * KN6WH |
#10
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Battery charger
Howdy,
There are a of couple newer devices that you might like even more than the UC3906. Check out the UC3909 and BQ2031. All zeners are not created equal! The 1N825 is a common temperature compensated diode and it's uncommonly good. Transfer standards built in the 1960's and 70's often used zeners... and they were good enough by golly. The venerated Fluke 335D used an ion implanted or burried zener diode and it's still one of the most stable units available. Here's the deal, the battery voltage varies with temperature. About minus 3 to minus 5 milivolts per degree C. Not very stable! (However for temperatures between 5C to 35C it can be safely ignored.) Now if the circuit is exposed to the same ambient temperature as the battery and your reference drifts about the same amount and in the same direction as the battery, it can be only a good thing. A true zener has a negative temperature coefficient. An avalanche diode has a positive temperature coefficient. The cross over point between the two effects is around 5.6V A common silicon rectifier diode has a negative 2 milivolts per degree C coefficient. It's not difficult to select a couple of parts that when combined in series will produce the minus 5 milivolts per degree C desired. A 6.8V zener in series with three 1N4001 running 1 milliamp of bias current is in the ball park. Honest to god temperature compensated charging requires a temperature sensor in the battery (thermistor usually) but it's only needed where you're charging at a rate that heats the battery or when charging over a very wide range of ambient. The above is just my opinion and all that jazz... 73, Grumpy |
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