Hi everyone,

Recently I acquired a broken down SOLA 1500 sinewave UPS which I was
able to repair. Since I already have a UPS for my PC I decided to use
it solely as an inverter. I replaced the internal 24v battery pack
with 2 external 65AH deep cycle marine batteries connected to the unit
with 2 80cm 300A high grade welding cables to minimise losses.
Problem is; when the unit is running under a light load, it
immediately sounds the "low battery" alarm. It can run for hours like
this, but the thing that makes me uncomfortable is when looking at the
battery voltage on my CRO, I can see very pronounced "dips" approx
every 9mS; alternating between 2 distinct "dips" of 4-5 volts and 2
volts with apparent high frequency harmonics. Either my batteries are
damaged, they were bought as new factory seconds with cosmetic
defects, or these types of batteries simply cannot supply the heavy
surges of power needed, fast enough. Under load, they steadily supply
around 24.6 volts which is probably why the UPS is complaining.
However, I do not like these dips in voltage since I can hear the unit
struggle when a large monitor is switched on, which does not happen
with the internal batteries. I doubt they are defective though, so I'd
like to build a capacitor and choke filter close to the UPS unit to
"support" the batteries. An LC filter would help, I suspect, however I
have never built one even remotely as powerful as this unit needs.
Could anyone please point me to a schematic or describe a simple
filter that would be cost-effective? How many turns of what gauge wire
would I need and would I be able to salvage the inductors found in
wrecked PC power supplies?
If you read through all this; thank you. I'd be grateful for your help
and post an update with any success or failure stories.

It should suffice to use a few large capacitors. Start with perhaps 10 x
2200uF 35V in parallel, at the inveter, and finish it off with one of those
1F caps across each battery (or both, if you can find a 25-35V unit). Maybe
1F is a bit much, even 100,000uF will help. Heck, even just the smaller
caps will help, since it sounds like the inverter, remarkably, has little or
no filtering inside it to begin with!

Tim

--
Deep Fryer: A very philosophical monk.
Website @ http://webpages.charter.net/dawill/tmoranwms

Thank you for your response.
I was "afraid" of ending up having to use large and expensive
capacitors to help keep the voltage steady. I assume this UPS has so
little filtering because the small 7Ah SLA batteries, combined with a
shorter cable run, are more adept at handling the "surges" of current
required, without dropping the voltage too much. These high current
draws from the batteries last only around 1-2mS.

Tim Williams wrote:
It should suffice to use a few large capacitors. Start with perhaps 10 x
2200uF 35V in parallel, at the inveter, and finish it off with one of those
1F caps across each battery (or both, if you can find a 25-35V unit). Maybe
1F is a bit much, even 100,000uF will help. Heck, even just the smaller
caps will help, since it sounds like the inverter, remarkably, has little or
no filtering inside it to begin with!

Tim

--
Deep Fryer: A very philosophical monk.
Website @ http://webpages.charter.net/dawill/tmoranwms

mrdl@cooltoad.com a écrit :
Thank you for your response.
I was "afraid" of ending up having to use large and expensive
capacitors to help keep the voltage steady. I assume this UPS has so
little filtering because the small 7Ah SLA batteries, combined with a
shorter cable run, are more adept at handling the "surges" of current
required, without dropping the voltage too much. These high current
draws from the batteries last only around 1-2mS.

Tim Williams wrote:
It should suffice to use a few large capacitors. Start with perhaps 10 x
2200uF 35V in parallel, at the inveter, and finish it off with one of those
1F caps across each battery (or both, if you can find a 25-35V unit). Maybe
1F is a bit much, even 100,000uF will help. Heck, even just the smaller
caps will help, since it sounds like the inverter, remarkably, has little or
no filtering inside it to begin with!

Tim

--
Deep Fryer: A very philosophical monk.
Website @ http://webpages.charter.net/dawill/tmoranwms



So why don't you just keep the internal SLA as a bypass?

--
Thanks,
Fred.

So why don't you just keep the internal SLA as a bypass?

Hi Fred,
What do you mean by "bypass"? I have replaced these batteries since
they only give me 20-30 minutes run-time. When the power fails, the
UPS connected to my PC will keep it running until I use the 2nd UPS
with the large external batteries to power the UPS protecting my PC.
This way I could keep my PC running for up to 12 hours without
interruption.

Is there any other way to solve my problem, besides using very large
caps?

So why don't you just keep the internal SLA as a bypass?

Hi Fred,
What do you mean by "bypass"? I have replaced these batteries since
they only give me 20-30 minutes run-time. When the power fails, the
UPS connected to my PC will keep it running until I use the 2nd UPS
with the large external batteries to power the UPS protecting my PC.
This way I could keep my PC running for up to 12 hours without
interruption.

Is there any other way to solve my problem, besides using very large
caps?

Cheers,
Ben



Fred Bartoli wrote:
m...@cooltoad.com a écrit :
Thank you for your response.
I was "afraid" of ending up having to use large and expensive
capacitors to help keep the voltage steady. I assume this UPS has so
little filtering because the small 7Ah SLA batteries, combined with a
shorter cable run, are more adept at handling the "surges" of current
required, without dropping the voltage too much. These high current
draws from the batteries last only around 1-2mS.

Tim Williams wrote:
It should suffice to use a few large capacitors. Start with perhaps 10 x
2200uF 35V in parallel, at the inveter, and finish it off with one of those
1F caps across each battery (or both, if you can find a 25-35V unit).. Maybe
1F is a bit much, even 100,000uF will help. Heck, even just the smaller
caps will help, since it sounds like the inverter, remarkably, has little or
no filtering inside it to begin with!

Tim

--
Deep Fryer: A very philosophical monk.
Website @http://webpages.charter.net/dawill/tmoranwms

So why don't you just keep the internal SLA as a bypass?

--
Thanks,
Fred.- Hide quoted text -

- Show quoted text -

On 16 Feb 2007 03:25:20 -0800, mrdl@cooltoad.com Gave us:

So why don't you just keep the internal SLA as a bypass?

Hi Fred,
What do you mean by "bypass"? I have replaced these batteries since
they only give me 20-30 minutes run-time. When the power fails, the
UPS connected to my PC will keep it running until I use the 2nd UPS
with the large external batteries to power the UPS protecting my PC.
This way I could keep my PC running for up to 12 hours without
interruption.

Is there any other way to solve my problem, besides using very large
caps?


Yes. Get and USE a power supply that can handle the demand. You
don't need all those cap banks if your supply rail doesn't have all
that ripple in it to start with.

Refrain from top posting in Usenet.

On Feb 16, 6:25 am, m...@cooltoad.com wrote:
So why don't you just keep the internal SLA as a bypass?

Hi Fred,
What do you mean by "bypass"? I have replaced these batteries since
they only give me 20-30 minutes run-time. When the power fails, the
UPS connected to my PC will keep it running until I use the 2nd UPS
with the large external batteries to power the UPS protecting my PC.
This way I could keep my PC running for up to 12 hours without
interruption.

Is there any other way to solve my problem, besides using very large
caps?

Cheers,
Ben



Fred Bartoli wrote:
m...@cooltoad.com a écrit :
Thank you for your response.
I was "afraid" of ending up having to use large and expensive
capacitors to help keep the voltage steady. I assume this UPS has so
little filtering because the small 7Ah SLA batteries, combined with a
shorter cable run, are more adept at handling the "surges" of current
required, without dropping the voltage too much. These high current
draws from the batteries last only around 1-2mS.

Tim Williams wrote:
It should suffice to use a few large capacitors. Start with perhaps 10 x
2200uF 35V in parallel, at the inveter, and finish it off with one of those
1F caps across each battery (or both, if you can find a 25-35V unit). Maybe
1F is a bit much, even 100,000uF will help. Heck, even just the smaller
caps will help, since it sounds like the inverter, remarkably, has little or
no filtering inside it to begin with!

Tim

--
Deep Fryer: A very philosophical monk.
Website @http://webpages.charter.net/dawill/tmoranwms

So why don't you just keep the internal SLA as a bypass?

--
Thanks,
Fred.- Hide quoted text -

- Show quoted text -

He means leave the internal batteries in place and connect the
external batteies in parrallel across the internal batteries...

The internal batteries supply the ripple current and the external
batteries suply the average current.

I have done this and it works OK as long as you keep the batteries
charged/discharged together.

Mark

Hi everyone,

Recently I acquired a broken down SOLA 1500 sinewave UPS which I was
able to repair. Since I already have a UPS for my PC I decided to use
it solely as an inverter. I replaced the internal 24v battery pack
with 2 external 65AH deep cycle marine batteries connected to the unit
with 2 80cm 300A high grade welding cables to minimise losses.

Problem is; when the unit is running under a light load, it
immediately sounds the "low battery" alarm. It can run for hours like
this, but the thing that makes me uncomfortable is when looking at the
battery voltage on my CRO, I can see very pronounced "dips" approx
every 9mS; alternating between 2 distinct "dips" of 4-5 volts and 2
volts with apparent high frequency harmonics. Either my batteries are
damaged, they were bought as new factory seconds with cosmetic
defects, or these types of batteries simply cannot supply the heavy
surges of power needed, fast enough. Under load, they steadily supply
around 24.6 volts which is probably why the UPS is complaining.
However, I do not like these dips in voltage since I can hear the unit
struggle when a large monitor is switched on, which does not happen
with the internal batteries. I doubt they are defective though, so I'd
like to build a capacitor and choke filter close to the UPS unit to
"support" the batteries. An LC filter would help, I suspect, however I
have never built one even remotely as powerful as this unit needs.

So why don't you just keep the internal SLA as a bypass?

Hi Fred,
What do you mean by "bypass"? I have replaced these batteries since
they only give me 20-30 minutes run-time. When the power fails, the
UPS connected to my PC will keep it running until I use the 2nd UPS
with the large external batteries to power the UPS protecting my PC.
This way I could keep my PC running for up to 12 hours without
interruption.

Is there any other way to solve my problem, besides using very large
caps?

Please don't be rude.

As I said, the power supply is 1500VA which is
more than powerful enough to start a monitor without straining.

I have
a 425 unit which can do the same. My PC uses around 20% of the power
the 1500VA unit can deliver.

This post is about solving a problem, not buying another unit.

So why don't you just keep the internal SLA as a bypass?

Hi Fred,
What do you mean by "bypass"? I have replaced these batteries since
they only give me 20-30 minutes run-time. When the power fails, the
UPS connected to my PC will keep it running until I use the 2nd UPS
with the large external batteries to power the UPS protecting my PC.
This way I could keep my PC running for up to 12 hours without
interruption.

Is there any other way to solve my problem, besides using very large
caps?

Cheers,
Ben

Fred Bartoli wrote:

mrdl@cooltoad.com a écrit :

Thank you for your response.
I was "afraid" of ending up having to use large and expensive
capacitors to help keep the voltage steady. I assume this UPS has so
little filtering because the small 7Ah SLA batteries, combined with a
shorter cable run, are more adept at handling the "surges" of current
required, without dropping the voltage too much. These high current
draws from the batteries last only around 1-2mS.

Tim Williams wrote:

It should suffice to use a few large capacitors. Start with perhaps 10 x
2200uF 35V in parallel, at the inveter, and finish it off with one of those
1F caps across each battery (or both, if you can find a 25-35V unit). Maybe
1F is a bit much, even 100,000uF will help. Heck, even just the smaller
caps will help, since it sounds like the inverter, remarkably, has little or
no filtering inside it to begin with!

Tim

--
Deep Fryer: A very philosophical monk.
Website @ http://webpages.charter.net/dawill/tmoranwms


So why don't you just keep the internal SLA as a bypass?

--
Thanks,
Fred.

On 16 Feb 2007 03:25:20 -0800, mrdl@cooltoad.com wrote:

So why don't you just keep the internal SLA as a bypass?

Hi Fred,
What do you mean by "bypass"? I have replaced these batteries since
they only give me 20-30 minutes run-time. When the power fails, the
UPS connected to my PC will keep it running until I use the 2nd UPS
with the large external batteries to power the UPS protecting my PC.
This way I could keep my PC running for up to 12 hours without
interruption.

Is there any other way to solve my problem, besides using very large
caps?

Try reducing the loop area of your cables. If they are twisted/wrapped
around each other, their inductance will be reduced. Multiple smaller
cable pairs, similarly twisted, might work better as a more easily
manipulated substitute.

Local capacitive decoupling at the load is the simplest first step.
Fill up the area where the batteries used to be with low esr parts.
Low impedance, not high capacitance is the goal.

RL

mrdl@cooltoad.com wrote:
So why don't you just keep the internal SLA as a bypass?

Hi Fred,
What do you mean by "bypass"? I have replaced these batteries since
they only give me 20-30 minutes run-time. When the power fails, the
UPS connected to my PC will keep it running until I use the 2nd UPS
with the large external batteries to power the UPS protecting my PC.
This way I could keep my PC running for up to 12 hours without
interruption.

Is there any other way to solve my problem, besides using very large
caps?

Cheers,
Ben


It may be that your big batteries are not fully charged.
The charger in the UPS was capable of charging 7 AH
batteries, but may not be able to give the 65 AH batteries
a full charge.

Ed


Fred Bartoli wrote:

mrdl@cooltoad.com a écrit :

Thank you for your response.
I was "afraid" of ending up having to use large and expensive
capacitors to help keep the voltage steady. I assume this UPS has so
little filtering because the small 7Ah SLA batteries, combined with a
shorter cable run, are more adept at handling the "surges" of current
required, without dropping the voltage too much. These high current
draws from the batteries last only around 1-2mS.

Tim Williams wrote:

It should suffice to use a few large capacitors. Start with perhaps 10 x
2200uF 35V in parallel, at the inveter, and finish it off with one of those
1F caps across each battery (or both, if you can find a 25-35V unit). Maybe
1F is a bit much, even 100,000uF will help. Heck, even just the smaller
caps will help, since it sounds like the inverter, remarkably, has little or
no filtering inside it to begin with!

Tim

--
Deep Fryer: A very philosophical monk.
Website @ http://webpages.charter.net/dawill/tmoranwms


So why don't you just keep the internal SLA as a bypass?

--
Thanks,
Fred.