On Tuesday, November 13, 2018 at 11:11:52 PM UTC-5, kinsell wrote:
On 11/13/18 6:08 PM, bruce... wrote:
Mark, When K2 was fairly new on the market I contacted them asking if Battery Tender Jr. is okay and safe, they replied that it is perfectly okay and nearly the same as their charger. I also contacted Battery Tender Jr. with the reverse question and they said the BTJr is fine for LiFePO4. I used the BTJr for years on my K2 with no issues. They're about $25 on internet sites.


Have you measured the amount of charge you're getting into the K2's? It
will be considerably less than the rated amount due to using a lead-acid
charger.

Also, if K2 has cell balancing capability, it won't be used because your
Battery Tender doesn't put out enough voltage to make it work.

Many simple lead-acid chargers reach up to around 14.2-14.8 volts. That voltage would suffice to charge an LFP battery to well above 90% capacity if it stays there for a while. If it quickly shifts to "float" at 13.5V or so then it won't do well in charging LFP. So simpler is better in this case. Measure what your charger does. And disconnect it after several hours, don't leave it on "float".