Lestronic II repair attempt

[JohnnieB]

Originally Posted by coosa

1. Johnnie, I have never figured out which generation the DPI is. I think it is a 3, but it doesn't say anything about generation on it. It's probably 4 years old. I had unplugged it after it charged yesterday, and it's been cold, so no doubt it discharged a little.

2. The Lester did shut off when DC was unplugged.

3. I think that the DVM batteries are ok. It read the pack at 38.0 before I charged it yesterday.

4. I'm thinking that the Lester is putting out too much voltage. The DPI has always seemed to keep the batteries about where they should be.

1. If it looks like the attached Picture, it is a Gen-III

2. That means the control board is shutting it off when the voltage gets high enough. Originally adjusted to shut off in the 44V to 46V range, but may have drifted a bit over the years, but still within the max charging voltage for a T-105.

3. Personally, I'd check the DVM batteries since we don't know if the 38.0V on the battery pack was actually a correct value. Might have been 37.5V and the Lester's voltage was 46.0V or so.

4. Attached is a chart from the most recent Trojan battery user guide showing the recommended charge voltages. Check the finish volts for a 36V pack. It's 48.6V, so the Lester is well below that.

[coosa]

Thanks again, JohnnieB. I don't think the batteries on my meter are bad, as they are pretty fresh, but I think the meter itself tends to read a little high. That could easily explain .5 volts of it, and based on that chart, even 46.5 would be ok. I suspect it was close to cutting off anyway when I unplugged it, since the ammeter was only reading 1 amp.

Since I was testing the charger on a 42 volt cart, I was not doing my pack any good by charging 6 of them way past the 7th orphan battery. I checked them all this morning and the 6 that I charged with the Lester all read from 6.40 to 6.44. The orphan battery was 6.29, so I was gonna charge it with my 6 volt charger; it was dead. :(. I have not had good luck with battery chargers lately. This one was a cheap Harbor Freight charger that was utter junk anyway. It would cut off before putting a full charge on any battery. I cut the clips and cord off and set it on the junk pile.

So I will use the cart today and then use a 12 volt charger on the orphan battery and the weakest one attached to it and try to bring it up before I use the 42 volt charger on it. I have done this any time I used the winch, and I keep a close watch to keep the pack equalized.

Attached is a picture of my DPI:

exxonmobil near me now

I think it is indeed a generation 3? About a year ago the ammeter on it quit, but it still charges ok. When I plug it in, it hums softly and the charging light blinks for about 5 seconds, then the light stays constantly on and I can hear the transformer get louder, like it's grabbing another gear. It cuts off when the charge is complete, so it appears to me that it's working fine; it's just the ammeter that is dead.

I have thought of trying to replace it, but it really doesn't matter as long as it keeps charging. I think I am better off not messing with it.

I am declaring the Lester fixed and will take it to the farm next trip. Thanks again to all who helped out.

[kernal]

Looks like a gen III to me. Green light should come on when charge is complete and charger is in float mode.

[Sergio]

I believe in the GEN III vocabulary the word "float" has a different meaning.

It does not keep the pack a constant voltage and instead does like all other modern chargers designed to charge a string of batteries and only turns ON if the pack drops considerably or the cycle timer expires (I think it is 30 days).

Edit:

Maybe I am thinking of the Gen IV, either way floating a string of batteries is not the best idea.



Edit #2:

The reason why the practice of "floating" is a bad idea for a string of cells is what happens if you develop a single bad cell.

If your maintainer is connected to a single 6/8/12 volts battery and a single cell goes bad, it does not really matter what the maintainer does since the entire battery is bad and needs to be replaced.

However, if the maintainer is trying to "float" an entire pack, that single cell will cause the maintainer to destroy the remaining good batteries.

Batteries kept on a maintainer are also not at the same capacity as freshly charged batteries, so if the reason for a "float" is to make sure the batteries are at a full capacity after a week of not driving, a better approach is to set it up so you can initiate a charge remotely (for ad-hoc frequency of operation) or on a weekly timer for pre-defined times (every Friday at 06:00).