Replacing a UPS battery with a higher capacity one.
How practical is replacing a UPS battery with one with higher capacity in order to get longer battery life using same equipment. Say I want a 1kva ups to last 6hrs or over. WIll it work or will i have to change a circuit?
I dont know. What circuit are you changing, the mother boards? On Sun, Apr 18, 2010 at 11:54 PM, Job Muriuki <muriukin@gmail.com> wrote:
How practical is replacing a UPS battery with one with higher capacity in order to get longer battery life using same equipment. Say I want a 1kva ups to last 6hrs or over. WIll it work or will i have to change a circuit?
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I believe you'll have to modify the charging circuit as usually most UPSs have an IC as a charge controller controlling rate of charge and preventing overcharging etc...discharging may not be a problem but the charging might require a mod...maybe due to a higher charging current? I'm not an elec guru though...just my thots... On the other hand if you want to support a higher wattage than designed then you also have to mod the discharging circuit as well to accommodate the higher current...maybe the charge/discharge controller is built into one IC so that might be tricky. You could also consider going for inverter solutions like the ones on http://chekelea.com/index.php?_a=viewCat&catId=28 So confirm first from an electronics buddy before you hook up a 1kva UPS to 6 12-volt car batteries in parallel... :) You could undercharge them, burn your charging circuit, or end up generating crazy amounts of hydrogen (maybe unlikely) On Sun, Apr 18, 2010 at 23:54, Job Muriuki <muriukin@gmail.com> wrote:
How practical is replacing a UPS battery with one with higher capacity in order to get longer battery life using same equipment. Say I want a 1kva ups to last 6hrs or over. WIll it work or will i have to change a circuit?
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Or it could work... some circuits are idiot circuits...
I have seen someone do it with an automotive battery but didn't get a chance to ask if the charging circuits had been changed.
Hello @Job, I'll add to what others have mentioned so far. Pls avoid extra batteries for a system that has not been designed to handle extra time. A few points to consider : a) UPS transformer : Extended time will cause the transformer to heat up, internal flux can melt and shortout the copper windings b) Charging circuit : The built-in circuit is designed for the normal one/two battery operation and will cause the charger circuit to burn out on extra amp charging load. c) Power Mosfets : These drive the two/more windings of the invertor tranformer and drain a large current from the battery. On a small UPS they are rated at around 30amps surge load/ 10amps running load. By increasing the available current using an additional battery, the mosfets will drain more current at load startup surge and blow. The safety circuit on these has an overload mechanism, thus if the load is increased the ups will shut down because it is related to drain current. But the damage to components takes places in micro-seconds which is not enough to protect your equipment from taking a severe hit. A fuse blows in milli-seconds and will break the wire under short circuit conditions i.e the load across the wire exceeds the rating. I'd highly recommend you to go for the correct UPS which allows for your scenario below, else you will be putting your equipment at a severe risk of damage or even start a fire. Pls be careful and consider the outcome should the system fail. But you are welcome to innovate by adding extra cooling fans, change the power mosfets and at minimum double the transformer copper gauge with safety fuses all the way. HTHs. Rgds. On Sun, Apr 18, 2010 at 11:54 PM, Job Muriuki <muriukin@gmail.com> wrote:
How practical is replacing a UPS battery with one with higher capacity in order to get longer battery life using same equipment. Say I want a 1kva ups to last 6hrs or over. WIll it work or will i have to change a circuit?
@Job, I forgot to add that most modern UPS have a thermo-fuse built into the transformer which break circuit if when the transformer reaches a certain temperature. In your innovation, when you build the transformer, pls do literally bury in the core a thermo-fuse but you will need to find the manufacturers heat rating for the tranformer. I did these things many years ago, so its all trickling back, one by one.... sorry for the piece meal thots. :-)
Thanks ya all, I think i will go for the inverter/charging systems with higher capacity I dont want to risk lossing any equipment.
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