Thursday, May 12, 2016 at 13:50
Phil H,
I did a DIY lithium conversion in my Karavan and found the lead-acid dc-dc charger I had would often not start. This was because the lithium batteries have a very flat discharge curve and hold a higher voltage than fully charged lead-acid batteries until the lithiums drop below about 20% SOC. The lead-acid charger would look at the batteries, see a voltage that is at least as high as a freshly charged lead-acid battery and would decide that no charge is needed (so as not to overcharge what it thought was a lead-acid battery).
I am good mates with the engineer who designed my charger and he modified the software to suit lithium batteries and now it works a treat. Old story, it's not what you know, it's who you know :-)
Not all chargers behave the same way. My lead-acid mains charger doesn't. When I switch it on it goes straight into a charge cycle (with voltages set to suit the lithium pack).
It may be that your BCDC is behaving the same way as my DC-DC charger did before it was modified and that is why Redarc is saying it is unsuitable. If that is the case I cannot understand why
Kimberley is saying you must use it.
On the other hand, the lithium version of Redarcs BCDC may be indeed be unsuitable for the lithium batteries that
Kimberley uses. I suspect this is because the "float" voltage is a high 14.5 volts. That is too high for the lithium batteries I use, and it appears too high for
Kimberley's as
well.
I do not know why Redarc have chosen such a high float voltage in their lithium profile. According to the engineer who supplied my lithium batteries, such a high float voltage suits only a very small number of lithium "flavours". Something like 13.6V is far more commonly accepted.
I don't know how to solve your dilemma other than to advise you to look for a dc-dc charger that has fully programmable voltages (like
mine) or which has a range of voltage selections, one of which is suitable for
Kimberley's batteries.
A number of people in our KK owners club have had success with Sterling products.
Cheers
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