Smart Charge Manager quit at 7 below zero F

[ddroit]

I have an SCM-12 and temp sensor that i bought from Ample Power in Seattle, that has been working perfect for 2 years in mild temperatures. It stopped charging in cold weather (-7 F) and displayed a "Voltage Overrun" error -- 6 on 3 off code. I disconnected the temp sensor and it is charging, but of course at a voltage much too low for 7 below.

Any ideas to fix this problem? Winter power is essential when living in an RV.

David

[Coulomb]

Years ago, Concorde Battery, manufacturer of Lifeline batteries asked us to prevent charging their batteries above 15 Volts, no matter how cold it was. The reason was never fully explained to us, but the limit is there. Hopefully it's not there for all batteries types on the SCM. We made a special Lifeline Next Step Regulator for Lifeline batteries that has the 15V limit.

This may not be the cause of the problem, but try a different selection for the battery type.

[ddroit]

Thank you. I warmed up the sensor to something above 10 F, and the scm began charging at 15.67 volts.

Which other battery type / manufacturer would you recommend? Mine is Lifeline AGM.

Thanks,
David "BitterCold" RVing fool.

[ddroit]

Or perhaps better yet, what is the charge profile for each, and i'll select one.

[ddroit]

is there a firmware upgrade for the SCM-12? it should limit the voltage, but not fail.

[Coulomb]

The sensor may be bad. What voltage does it charge at with it disconnected?

[ddroit]

14.3 volts, disconnected.
i remember once i was "equalizing" my lifelines after repeated not-full-charging and an accidental deep discharge, and i accomplished this by putting a 2K pot in place of the sensor. the scm would take it up to about 15.7, and then show the Voltage Overrun indication. Oddly, the scm creates its own voltage overrun.

i'm an embedded software engineer, and could perhaps fix this problem by adding 2 lines of code, if i could get a copy of the source code for the scm. of course, it probly wouldn't be that simple, but the controller should do voltage limiting without failing the way it does. very poor design, or unrealized flaw. this problem could be easy to fix, tho.


are there any firmware upgrades?

if not, then how could i get a copy of the source code, along with instructions for reprogramming the device? is the company still in biz?

David Droit

[Coulomb]

Ample Power Company is still in business.

There are no code upgrades to that product. It's written in 6805 assembly language, and the tools to change it only run under DOS. In any case the code won't be released because it has some proprietary charge algorithms.

There is a replacement for it expected using a more modern processor and the C language, but no date set.

[ddroit]

well, that sucks

thanks anyways