Re: Building my own equilizer

[Victor Tikhonov <vtikhono@lsil.com>]

Lee Hart wrote:
> 
> Ah, then they are playing with their algorithms. That's good. They are
> learning that it isn't as simple as just holding the batteries at the
> same voltages.

Yes, I believe that the $40 version I got (from old stocks 3 weeks after
official price was set to $120) has micro in it.

If someone on the list has bad/burned powercheq, they can take it 
apart and look how it's made.
 
> The first version they offered appeared to be just a DC/DC converter
> controlled by a comparator; no micro. As time passed, it got smarter at
> each show, as they learned and tinkered. There were smarter on/off
> limits, then timers, and other fault detection. I suspect the sudden
> price increase came when they decided to put a micro in each one.

No, the price increase isn't worth improvements (<3mA stand by current
now and alg tweaks, nothing 4x drastic). The rep said the companies and
large IT computer centers who use stand-by batteries are still willing 
to pay $120 a piece since it's one time investment and not disposable
item as the battery. So Power designers just took advantage of it
(who wouldn't!) and it's pure money/marketing move. He personally
admitted that technical improvements aren't worth 4x price.
But the largest customer of theirs is Ford, and Ford set
requirement to reduce stand by current before they buy it, being afraid
of future dead EVs left on the airport parking lots while the owners are
on 3 weeks vacation. Power designers presented calculations and
arguments that 20 mA isn't enough to flatten the battery, in that time, 
but perception of Ford was that the risk (read liability) is there so 
the Ford said either <3mA stand by, or no contract (apparently many 
thousands of units). Power designers promised to do it at 4x price
knowing it wasn't really necessary but didn't want to loose Ford
as a customer. Ford said OK, 4x is fine (read we'll pass it onto 
the customers anyway, he he he). Both parties strike contract.
That's how we all ended up with $120 powercheqs with <3mA standby
current.
 
> Victor, how hard would it be to put your Emeter on one of your
> Powercheqs and watch what it actually does?

Not hard if I had emeter. I don't. My inverter's software takes
care of Ah in-out tracking (unfortunately not for external chargers)
so I can't justify emeter cost for my needs.

But, I have extra powercheq and can connect it to two
small 12V 4Ah batteries and see what it does.

Problem 1 - I don't have data logging gear and these measurements are
not momentary, they are over time.
Problem 2 - I need to have "variable voltage" battery to set
any delta I want.

I'm thinking of about 1V variable supply in series with one of
the batteries to tweak the delta and simulate imbalance.

Two 12V power supplies may fool the cheq too, but not sure if to the
right degree.

Victor