CTEK 25000

[ucdailoi]

I have just joined this discussion and am curious at what you have written... Could you clarify the following questions for me.

1. are you running two batteries in parallel, or series one Lithium and one Gell Cell?

2. are the batteries of different ages?

3. Did you join the 2 batteries because you replaced one that had gone bad previously?

4. Are you trying to charge the 2 batteries with the one charger?

I just need to get the ground work done so I can decide what we are talking about.

I am no auto elec and have no magic answers but the answers may throw some light (no pun intended) on what I am confused about.

[nut17]

Hi Terry, my charger is a C-Tek M300 which is just a marine version of yours with the same 25 amp capacity. It along with my solar is charging the new lithium battery through the 200amp Votronic shunt. So far it has performed faultlessly putting a full 25 amps into the battery until it is full, then into float with less than an amp being delivered. I was under the impression that C-Tek is the leader in design and quality in modern multi stage step type chargers. I would not be happy however to hook it up to a battery bank that had batteries in parallel and not exactly matched in type, size, age, condition and state of charge. I have had a major disaster in the past, and always stick to that rule now.

Cheers Chris

[oldtrack123]

[ Chris[Quote"I would not be happy however to hook it up to a battery bank that had batteries in parallel and
[1] not exactly matched in type,
[2] size,
[3]age,
[4] condition and
5]state of charge. I have had a major disaster in the past, and always stick to that rule now[.Endquote]


[1] Exact type & amp hr rating is not much of a problem IF the are both wet lead acids
or both same type AGMs
Mixing AGMs & wet lead acids can be a problem if the voltages of the charger is not set for the lower battery's 100% soc voltage
The AGMs may not be fully charged or the wet lead acids may be overcharged

[2]Relatively unimportant unless ridiculously different
each battery will output to the same level of charge[SOC voltage]
Each battery will charge to the same SOC voltage

[3]Age may simply mean lower remaining capacity , no real difference between a smaller to larger battery as in[1]
but if it has any signs of high self discharge[ partial shorting between plates ]time to definitely toss it[1]

[4]condition as in[3]

[5]Same SOC? they will equalize quite quickly when being charged or discharged If in other wise good condition

Both series & parallel connecting have their good points & their bad points


What does need to be watched with parallel setups is any sudden sign of faster than normal rate of discharge = shorted cell =all batteries in the bank over discharged if not spotted.

I suspect this was T1 problem
New batteries can &do short out prematurely TOO

But in a series it can mean the good cells being overcharged & damaged particularly if not flooded wet cells
Peter

[T1 Terry]

OK, there were 3 batteries in parallel, one Gel 120Ah C10 rated, one AGM 115Ah C20 rated, one truck size flooded cell cranking battery (can’t get down in there to see just what it is). This arrangement had functioned for quite some time in the past, the batteries would have been various ages but the gel was definitely the newest.
I think the charger tried to charge the batteries and automatically switch to a disulphation cycle. Gel batteries can not handle desulphation cycling and it killed it, at least one cell went short circuit. This dragged the other 2 batteries down as the charger decided to shut down all together, even though the lights still said it was in normal mode. The give away something was wrong turns out to be that the battery condition lights weren't on, any of them. When I disconnected the gel battery out of the parallel circuit the charger still wouldn't function. Complete shut down reboot including disconnection from the batteries and it came back to life. After around 8 hrs of charging at 25 amps, approx 200Ah, it was still trying to charge at 25 amps, the battery condition lights said ¼ charged, the battery voltage climbed to 14.7v according to the Xantrax meter, the AGM was as warm as toast, I shut the charger down and disconnected the leads.
It will head to the pile of dud gear, I'm sure not trusting my lithium batteries to that thing.

T1 Terry

[norman]

Just a wee I checked my batteries for water and noticed a slight bowing out of the end cases. They were not hot , not even warm. Does this indicate anything to anybody...

[T1 Terry]

It means they have been hot at one stage, hot enough to soften the plastic and there was enough gassing pressure to push the sides of the case out, that means the plastic had to be stretched.

[oldtrack123]

[quote="T1 Terry"].
I think the charger tried to charge the batteries and automatically switch to a disulphation cycle. Gel batteries can not handle desulphation cycling and it killed it, at least one cell went short circuit. This dragged the other 2 batteries down as the charger decided to shut down all together,

Hi Terry
I believe you have the cause
Agms & desulpation cycle , not good
One case where mixing battery types can give problems if the charger regime is not correct
Always turn off equalising .desuplphating, with AGMs & similar non wet cell batteries.

Of course no experience with Lipo4
But it would sem to me a simple constant voltage charger with an acurrate closely controlled upper voltage limit would be the best
You would need the 100% duty cycle amp capacity though or some means of protected the charger from overheating.

Peter

Peter

[T1 Terry]

That's the issues I have with fully automatic chargers, you can't just switch functions off. The CTek has a power supply mode and a constant float mode, but it will switch back to the beginning of the pulse charging, then the long absorption charge at 14.7 volts that is supposed to trim back for temp, but that will only work on a single battery and only if it the neg terminal that gets hot, every time it's switched off or has a glitch in it's supply, it switches back to the beginning of the standard charging regime. Unless I can control it's output with another control method I just don't trust it any more. There have been other reports of dead batteries linked with these chargers, so it's not just me.