Optimate TM-500 DC-DC charger

[PNjunction]

Got a new charger to test out because it is pretty interesting being dc-dc.

The Optimate TM-500 (2A output only) arrived in a shiny orange case. Funny to see battery clamps on both ends.

You can drive it from a source battery (12-16v) or a dc power supply (15v 3A minimum).

Source battery should be at least 1.5x the discharged battery capacity, and of course it has low voltage cutoffs to protect your source from being deeply discharged itself, still at 10v, I consider that VERY deep. Better than total damage I suppose. Note that for every 10ma of parasitic drain, you can expect to see about 0.3a drain from the source battery in a 24 hour period, so this isn't a perpetual-motion machine!

It has the usual Optimate charge / recovery / testing routines, and plenty of blinkenlights to look at - which are really informative if you read the manual.

I'll be interested to see how smart it is since it is supposed to be smart about gel / agm etc, with a variance of 14.2 to 14.5v on absorb. You bet I'll be testing that since I don't want to drastically undercharge my agm's with typical low voltage gel absorb values.

Thought I'd mention this new addition if it might come in handy for some that have say a huge bank of solar charged 12v T105's, but no practical way of charging smaller stuff when the genny is dead, and the grid is gone.

Looking forward to checking it out when I have some quality time to devote to it.

[PNjunction]

Granted I'm biased from past experience with Optimate and their full disclosure of charge method, but I try to be honest - thumbs up!

What fascinates me is instead of using very specific absorb voltages for various chemistries - flooded, gel, agm - it uses a single absorb of 14.3v, just like the larger Optimate 6. Normally the claim has been made that this is a total compromise, BUT charge verification makes the difference it seems.

When it finally hits the absorb voltage of 14.3, instead of doing the CV thing, it TESTS the charge by dropping the output to 13.6v and testing there - if the current draw is more than 200ma, then it goes into another run up to 14.3v, and the cycle continues until it feels it is finally ok to float. My guess is that since it is not held at a constant 14.3v, but is in a reduced duty cycle instead, this won't be harmful to gel, and the cycle of testing is done often enough to get agm and flooded charged that might be expecting a higher absorb. It just takes a wee bit longer to get the charge finished with all the in-between testing.

I like chargers that are not steady-state. That is, CC/CV works fine, but this has been tested against 2 other CC/CV chargers (Cotek/Samlex at 14.4, Battery Tender at 14.7v,) and after 12 hours of rest the ocv of the test battery is within .01v of each other. So for now I feel ok that the Optimate's charge verification testing and oscillating absorb if you will, does the job properly.

Float is at 13.2v like the Battery Tender. This is not ok with Odyssey, and I must say I expect 13.5v or so instead. However, this may be done to extend the length of time that the "donor" or source battery is trying to keep your battery under charge floated the longest. I'll have to do some long-term extended float to see if it will eventually walk-up to 13.6v.

If you need a quality 2A charger / maintainer, then this thing is pretty sweet, being able to charge from a donor battery, or your own 12v power supply. The testing and reporting is great if you want to follow the bouncing led's, but since there are no settings to make, you truly can plug into it, and walk away. Dig it.