Smart Battery Chargers - A cautionary tale
Submitted: Wednesday, Nov 25, 2009 at 12:46
ThreadID:
73987
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5357
Replies:
4
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Wok
Battery type: Wet cell - deep cycle - Supreme 31DC-36 : 140Ah 200RC
Age: 2yrs
Quantity: 2 - connected in parallel
Charger: Hi-Tec 15A 3 stage
Location: Shed - in maintenance mode - electrolyte levels checked monthly - OK [green LED] checked daily
Scene:
Had a mains power failure [about 2 hrs]. When power was restored the charger went into charging mode [
orange light].A day later it was still charging.Hydrometer test showed SG approaching 1.30+,all cells within 0.05,electrolyte level had dropped [boiling].
The self discharge current of the batteries had reached the point that the charger was fooled :(
It appears that this charger goes into Float mode when the current reaches a set level.
Workaround:
Got two Powertech 3/6A 3 stage chargers [Jaycar]..charged the battery to correct SG...disconnect the + and reconnect when light goes green [float mode]. Each battery is fed seperately.Expect to do this after a power outage :(
Moral:
A Smart charger can be fooled if it depends only on current monitoring to determine SOC.This could be an issue with DC-DC battery chargers with working loads [fridges etc].
eng hoe
Reply By: TerraFirma - Wednesday, Nov 25, 2009 at 12:53
Wednesday, Nov 25, 2009 at 12:53
Wet Cell batteries are part of the problem, since I have changed over to AGM I have no more battery problems.
AnswerID:
392555
Follow Up By: ob - Wednesday, Nov 25, 2009 at 14:17
Wednesday, Nov 25, 2009 at 14:17
My preference is for AGM but why would wet cell cause more problems?
Cheers ob
FollowupID:
660518
Follow Up By: Wok - Thursday, Nov 26, 2009 at 01:59
Thursday, Nov 26, 2009 at 01:59
I am aware that AGM batteries have lower self-discharge then wet cells.
The object of the OP was to alert users of wet cells who were maintaining them with a smart charger that there is a potential problem as the battery ages.
eng hoe
FollowupID:
660636
Reply By: TerraFirma - Wednesday, Nov 25, 2009 at 14:27
Wednesday, Nov 25, 2009 at 14:27
My experience with wet cell batterys (Compared to AGM) are as follows:
1. Shorter Life Span
2. Require Regular Maintenance
3. Require charging more often if not being used (Maintenance Again)
I really don't want to go into this further , if you know anything about AGM batteries you'll know the advantages
AnswerID:
392567
Reply By: ob - Wednesday, Nov 25, 2009 at 16:16
Wednesday, Nov 25, 2009 at 16:16
If you don't want to discuss this further fair enough your call but it seems that the problem lies with your charger not the wet cell batteries.
As a matter of fact I have, and currently do run wet cell for cranking and AGM deep cycle for fridges, lighting etc and I agree from a maintenance point of view the AGM's come out ahead generally. From what I have been able to assertain the AGM type are more susceptable to heat under a car bonnet and the deep cycle AGM's are in a somewhat confined space so I use them for safety and no topping up.
Cheers ob
AnswerID:
392588
Follow Up By: RV Powerstream P/L - Wednesday, Nov 25, 2009 at 16:54
Wednesday, Nov 25, 2009 at 16:54
Ob
The basic part of Terra firma' s statement is maintenance and lack of it reduces long life but maintained and used properly a Flooded wet cell has a long life.
Ian
FollowupID:
660552
Follow Up By: ob - Wednesday, Nov 25, 2009 at 17:11
Wednesday, Nov 25, 2009 at 17:11
RV Yes I agree 100% with what you say, lack of maintenance destroys batteries, vehicles, people etc
What I was wondering, and not in any malicious way was Terrafirma's post stating that the problem was using wet cell and not AGM type batteries, see his/her second post.
I do not contest in any way that wet cell is more maintenance intensive than a good AGM. i.e topping up etc. Just wondering if the original poster (Wok) may have a charger problem rather than a battery problem.
Cheers ob
FollowupID:
660558
Follow Up By: RV Powerstream P/L - Wednesday, Nov 25, 2009 at 19:25
Wednesday, Nov 25, 2009 at 19:25
Ob
I think that the statement covered he maybe didnt want to maintain them and now he doesnt have to so it is more personal choice than anything.
If flooded wet cell did not give the life expectancy indicated for the cost no one would use them at all.
AGM batteries are more voltage sensitive to overcharging than FWC and without care they can give shortened life spans also and you cannot add
water to them to compensate.
So if AGMs were the topic of this thread under the same charging conditions they may have died sooner.
ian
FollowupID:
660574
Follow Up By: Wok - Thursday, Nov 26, 2009 at 02:31
Thursday, Nov 26, 2009 at 02:31
Ob
The Hi-Tec was only used for its Float function. The batteries are charged using the regime from Crown....then the Hi-Tec.
Now I have experienced this issue I will build a linear 13V5 supply, overcharging & boiling will no longer be a problem [no computers!]. The Jaycar chargers are a quick fix.
I don't think the Hi-Tec is "dead"...it performs correctly as a charger for three other batteries [different brands & smaller capacity].
I suspect that the self-discharge in wet cells is related to their capacity as
well as age.
eng hoe
FollowupID:
660637
Follow Up By: RV Powerstream P/L - Thursday, Nov 26, 2009 at 06:49
Thursday, Nov 26, 2009 at 06:49
eng hoe
I suspect the self-discharge in all batteries is related to their capacity as
well as age.
In your first post your moral digressed from AC chargers to DC/DC chargers and in quality DC/DC chargers a voltage sense provision is a must.
Some AC smart chargers are not truly smart as they have a fixed time bulk charge regardless whereas a true smart charger analyses the SOC everytime it is activated and sets the bulk time to suit that SOC.
If a charger does not have battery type selection which varies the absorbtion time and the float voltage and is budget priced then it is hard to assume that it can perform all the functions that a high quality and more expensive battery charger can do so I suppose you get what you pay for.
Ian
FollowupID:
660639
Follow Up By: Wok - Thursday, Nov 26, 2009 at 08:20
Thursday, Nov 26, 2009 at 08:20
Ian,
I mentioned DC-DC chargers because it's the most likely scenario where batteries are been charged with active loads.Agreed that a proper algorithm is critical here.
Quote: "....you get what you pay for"
Absolutely :) Perhaps one could add...."If the better product is made available to you."
eng hoe
FollowupID:
660648
Follow Up By: TerraFirma - Thursday, Nov 26, 2009 at 09:53
Thursday, Nov 26, 2009 at 09:53
Hi Eng, Sorry if I created any confusion with my statement re AGM batteries, my guess is the charger is the issue here, perhaps not the batteries. I use Ctek chargers with AGM batteries and have never had a problem, even with the batteries in their 5th year, this is to be expected as they are
well maintained by the Ctek's IMO. My research on Hi Tech chargers shows nothing??
My statement with regards to wet cells is perhaps better phrased as follows:
"I hate the bloody things.!" LOL
FollowupID:
660654
Follow Up By: Wok - Thursday, Nov 26, 2009 at 11:18
Thursday, Nov 26, 2009 at 11:18
Terrafirma,
The Hi-Tec is a model made by the French company Tecsup & was marketed locally by Bainbridge Technologies...purchased from Springers for $539.90.
Hi-Tec Charger
The model I have is H120151C which is ancient [7yrs+?]. The link is to the current offering.Apart from the current rating the specs are similar [from memory :)]...the French>English translation needs work.
eng hoe
FollowupID:
660675
Follow Up By: Secret Mens Business - Thursday, Nov 26, 2009 at 11:29
Thursday, Nov 26, 2009 at 11:29
Hi Eng, You won't believe it but I just replaced one of these a year ago in my boat. There was nothing wrong with it however I needed more than 10 amps because I have around 400AH's x AGM's now, I gave the charger to a mate who uses it to charge his Optima Yellow Top. I use 2 x Ctek 25amp chargers now on the boat however I had no problems with the Hi-Tec.
Here's the link of my old setup, still have the inverter.
http://picasaweb.google.com/deanrwilson/NauticWork#5342952614280296770
FollowupID:
660676
Reply By: signman - Thursday, Nov 26, 2009 at 12:47
Thursday, Nov 26, 2009 at 12:47
At the mains failure..or mains restoration..there may have been a power' spike' that may have upset a regulator (I assume solid state) in the cahrger !!
AnswerID:
392696