Posted: 5/22/2012 6:52:25 PM EDT
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I was at my local Rural King today buying a car battery and came across a solar battery maintainer. It is a small 2.4 watt (.2 amp) trickle charger designed specifically for keeping a battery topped off.
I picked one up, since they were only $30, to give it a try. After reading the manual, I have a couple questions. The manual says that it is only to be used as a maintainer and that charging a partially discharged battery with it may cause the battery to lose capacity. Anyone here know why or how that would happen? I was under the impression that a trickle charge was the best way to prevent a battery from losing capacity, not the other way around. Also, it mentions that it must be unhooked prior to starting or running a vehicle because electrical surges from the alternator may damage it. Would I be able to get around this by using a relay that breaks the circuit whenever the ignition is on or by using a diode to prevent current from backfeeding into the maintainer? Would this be a problem with a system that doesn't have an alternator? I was thinking about using this on my upcoming HAM EMCOMM box build which obviously will not have one. |
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Quoted:
The manual says that it is only to be used as a maintainer and that charging a partially discharged battery with it may cause the battery to lose capacity. Anyone here know why or how that would happen? Recharging a lead-acid battery requires a considerably higher voltage than simply maintaining it: Charge voltage: approx. 14.5 V Maintenance voltage: approx. 13.5 V If the solar maintainer only produces 13.5 volts under load, it will not bring the battery up to anywhere near a full charge - and chronically undercharging a lead-acid battery can result in a permanent loss of capacity. |
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Quoted:
Quoted:
The manual says that it is only to be used as a maintainer and that charging a partially discharged battery with it may cause the battery to lose capacity. Anyone here know why or how that would happen? Recharging a lead-acid battery requires a considerably higher voltage than simply maintaining it: Charge voltage: approx. 14.5 V Maintenance voltage: approx. 13.5 V If the solar maintainer only produces 13.5 volts under load, it will not bring the battery up to anywhere near a full charge - and chronically undercharging a lead-acid battery can result in a permanent loss of capacity. The specs show "Optimum Working Voltage" at 17.5 volts. Would this vary based on sun conditions or would voltage remain constant while amperage would vary? ETA: Also, am I on the right track with wiring with a diode or relay? |
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Quoted:
Quoted:
Quoted:
The manual says that it is only to be used as a maintainer and that charging a partially discharged battery with it may cause the battery to lose capacity. Anyone here know why or how that would happen? Recharging a lead-acid battery requires a considerably higher voltage than simply maintaining it: Charge voltage: approx. 14.5 V Maintenance voltage: approx. 13.5 V If the solar maintainer only produces 13.5 volts under load, it will not bring the battery up to anywhere near a full charge - and chronically undercharging a lead-acid battery can result in a permanent loss of capacity. The specs show "Optimum Working Voltage" at 17.5 volts. Would this vary based on sun conditions or would voltage remain constant while amperage would vary? ETA: Also, am I on the right track with wiring with a diode or relay? It's too small to produce anywhere near 17.5 volts with a partially-discharged battery - which is why they recommend only using it to maintain fully-charged batteries. |
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The solar panel will act as a current source per it's current rating.
Depending on the size of the battery, it could possibly over charge it at the point 2 amp charge rate. If it's limited to 13.5 VDC, this won't happen tho. The information you're providing seems uncertain. Yes, you could use a relay to take it out of the circuit when your ign sw is on. No, putting a diode in series with it will drop the voltage from it .3 to .7 volts and sort of defeat it's purpose. You need to connect it to a smallish battery and take some readings as it trickle charges the battery and post them here. |