Only one permanent battery charger for two bikes...

Discussion in 'Technical' started by gobs, Nov 26, 2009.

  1. gobs

    gobs Ol'Timer

    Hi friends,

    One more time a "battery story"...
    As many others here, it happens I don't use my bikes for one or two weeks, or even more. So I had sometimes to use the "oldschool" spare car battery system...
    About 6 months ago I decided to be more "modern-style", and bought a permanent battery charger from Richco in CNX. It is a CTEK 800 model (3000 Bahts and a perfect tool...) that can permanently care battery up to 32 Ah...
    As I guessed it can be used on several batteries at the same time (up to 32 Ah), I tested this on my Yam Fazer (10 Ah lead-acid-MF batt) and my BMW F650GS (12 Ah lead-acid-open batt), so both are now cared by the same tender... And it works fine, no matter the difference MF/open-lead-acid, the CTEK is done for that...



    I installed splashproof cigarette-lighter plugs on the 2 bikes for GPS, Mobile phone or whatever (I know BMW has a plug already, but it's a "standard" DIN one... not so "standard" IMHO, and I don't want to worry with an lost or forgotten or loosen adapter), did appropriate connection cables and put the CTEK 800 unit right under the roofing of the bike shelter not to have wires lying along on the floor, and go!


    So this means I built 2 "detachable and independent" cables connected in parallel on the charger through cigarette-lighter plugs and sockets going to each bike...


    ... from the unit.

    When going for a ride, I disconnect one bike and let the other one plugged... No matter, the charger goes on working...
    When coming back, I just plug the bike back, and now forget... battery problems!
    Besides, this type of permanent charger extends battery life... and, cherry on top of the cake, I get some 10 Ah capacity left-over that could be used for a third bike :wink:

    Well, I don't know if this is useful here, but I post it in case of: I remember some previous posts about this kind of subject. And sometimes nothing is better than self-experience... At least, for the 6 first test months, it's perfect.

    Cheers to all,
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  3. Deano747

    Deano747 Ol'Timer

    Man that is a sweet set up. I love the way you have the cables coming down from the roof, and not snaking across the floor like mine. Wish you had posted this a week earlier. I bought 2 of the C-tek 800 units for around 3200 Baht each for my BMW and Ducati last Monday. Wired them direct to the Battery with the supplied cable. They are a nice unit.
  4. gobs

    gobs Ol'Timer

    Thanks Deano...
    And sorry for the delay

  5. Hoghead

    Hoghead Ol'Timer

    At first glance it would seem that this method would work but it is a bit more complicated that just having the output capacity to wire in 2 batteries.

    There are several problems with this method:
    Different battery types have different charging algorithms. The C-tek has the algorithms for the various types however there is no way to differentiate the different charging regimes when connected to a common output.

    Even if the batteries are of the same type, batteries of different capacities cannot be connected in this manner or one will be over/undercharged.

    The caveat is that in order to use this method, both batteries must be of the same type and capacity. Even so if one is significantly more discharged than the other it will still get overcharged given sufficient time even at this low output.

    The solution is to use a different C-tek charger with 2 isolated outputs, and I have asked Richie to order me one.
  6. Deano747

    Deano747 Ol'Timer

    Got busy yesterday and roof mounted both my C_Tek's above their respective bikes. Took the Ducati for a ride this morning and it was really good to be able to just park it under it's power cord and plug back in after the ride. No more tripping over extension cords. Brilliant idea.
  7. davevb

    davevb Ol'Timer

    I've also got one of these, very good units but must agree that it won't work properly on two different batteries. You would need isolated outputs. Most batteries are fine up to a month or so (unless you have a leak) and I would just change over one output between the two bikes you have.

    Another nice thing is they come with a plug arrangement that you can attach to the battery permanently and usethe clamp leads on other things. I got mine off ebay for $75 US shipped. The CTEK's have very good reviews on the 'net.
  8. davevb

    davevb Ol'Timer

    Great idea with the roof mounting, I left mine draped across the shed floor and my wife-bless her- pulled the plug on it to get it out the way. The thing is she left it still connected to the battery, didn't bother to reconnect it and by the time I got home it was toast...Luckily I found one locally that suited but it was 1500B
  9. gobs

    gobs Ol'Timer

    Hi Deano,
    Well done, mate! At least, no more wires "snaking" trough your steps!

    Hi Hoghead, Dave, Captain,
    Thanks for your inputs... All these sorts of things are very interesting...

    I'm well aware about your theoretical arguments but didn't previously want to make such a extended post. Then I really want to test this system (1 unit for 2 or 3 bikes) by myself and get my own results. The theory and the real life are sometimes on different moods*. After 6 months it's OK... It's not a long, long time for batteries life for sure, but at this time all goes well. Maybe I will come back in some 2 or 3 years and tell what happened :roll:

    As far as I know, the CTEK 800 unit doesn't "recognize" the battery type it is charging/maintaining (and AFAIK too, I'm not sure if any "permanent charger" actually on the MC market is able to do this: it's more a computer thing...). It has only one "program" in memory that fits all the different previously mentionned battery types, based on the current/voltage it is "feeling". The CTEK 800 unit is not the most accurate or performing one in the brand line: it's just an average unit that well cares batteries... No wistles and bells on this unit.

    IMHO, 10 Ah and 12 Ah are not so distant capacities to create a problem charging them both on the same unit... If you say 10 Ah AND 20 Ah, in this case maybe... But until now I never saw such a "big" battery on a bike... Maybe some HD or BMW have such ones?..

    MF batteries are "closed" lead/acid batteries so no problem IMHO to "mix" MF and "open" lead/acid batteries on only one charging line... Gel batteries may be of a different type/different charging regime (but not all of them)...

    If you plug to the unit one weak battery and a strong one together, or let's say a full discharged one and another one well charged, the unit "sees" the 2 batt as a whole, and will manage to reach its criterias in memory to get the whole charged/maintained. When a batt is correctly charged, it is "asking" a very low current (internal resistance "high") from the source of tension; at the opposite a discharged one should "ask" more current (internal resistance "low") from the same source... So all in all the discharged one will "absorb" more of what the unit sends to the 2 batteries until reaching the "balance point" that cut the charge program...
    And IMHO, in this case, no problem with some over-charge of the "good" battery as the tensions delivered are not so high to cook it, and as its internal resistance "closes" import of current...
    But yes, it may be a problem mixing a "good" battery with a "dead" one, as this last one will never reach its low internal resistance and will permanently "ask" a high current. In this case, the unit will go on delivering a no ending charging program...

    To close here, I suppose CTEK engineers do know better than me what they design. And I suppose too that 2 different chargers for 2 different bikes may be better... But I'm happy with the way I choosed, so I shall go on... And I'm open to any arguments: let me know!..

    Furthermore, I don't want to say here: "Hey, guys, do what I do, it's better!". No, I just wish to share an personnal experience... So, please, don't copy if you don't feel OK!..

    Cheers to all,
    Your humble servant,

    * Makes me thinking about the "endless" debate about mineral oil, blend or synthetic... Or the same "endless" one about riding gears... Sometimes merchant companies know how to use the "right fashion words" to put you in need... Well, IMHO :wink:
  10. davevb

    davevb Ol'Timer


    Good news for you. You can indeed charge two batteries at once as stated on Cteks website FAQ (I was curious....)

    Is it possible to charge several batteries of different sizes at the same time?

    Yes, it is possible. The charger interprets it as one battery. Although, make sure that the combined Ah is not larger than our recommendation for your charger and that the cables between the different batteries are strong enough for the energy given. You can get a lot of current from the charged battery to the uncharged battery which can overload the cables; this is regardless of the charger. The best way is to charge each battery first and then connect them all together.
    When several batteries are connected in parallel the positive clamp should be connected to the positive terminal on one side and the negative clamp connected on the negative terminal on the other side of the connected batteries.

  11. gobs

    gobs Ol'Timer

    Hi Dave,

    Thanks (and great!) to be curious, mate! :wink:

  12. Hoghead

    Hoghead Ol'Timer

    IMHO there are a couple of caveats are in order to use this method:
    Fully discharged and charged batteries cannot be connected
    Batteries should be of similar capacity
    Batteries must be of similar types
    Cables must be rated for the battery output

    The saving grace is that the output of this model of C-tek is very low, and any mismatch in capacity will take a long time before damage is done when using batteries of the same type.

    As indicated earlier there are different charging algorithms for diffferent battery types. High end chargers have a type selector function, and lower end devices have a less efficent but safe generic algorithm for all types. Some chargers can sense type by the different acceptance rates. It would appear the C-tek uses a generic charge rate, but unclear if it can sense battery type.

    AGM's (absorbed glass mat) can accept 100% charging rate VS 25% for a SLA (sealed lead acid). In my case, using the same parallel output charger for my HD with a 18 AHr AGM, and Honda with a 5 AHr SLA is not recommended as it will result in too high a rate for the SLA. Once again with the C-tek the saving grace is the low output rate, but time is the factor given the different capacities.

    One great feature of modern battery chargers is a pulse function to prevent sulphation during long term storage so that it is not necessary to perform an equalization charge. I am not clear on how this will be affected by parallel connection, and have always used individual pulsators per battery.

    I still think that either 2 individual chargers or a isolated output dual charger is the way to go for an idiot proof, long term application. It will work however if both batteries are of the same type, capacity, and discharge level. Even so if one batteries develops a dead short or other wise dies when in long term parallel connection all bets are off.

    It would be interesting to get a technical response from C-tek on this to set my inquiring mind to rest. In the interim, it is dual isolated outputs for me
  13. Azoulay

    Azoulay Ol'Timer

  14. davevb

    davevb Ol'Timer

    If it was me and I was around, I would connect one for a month then the other for a month. Or connect the bike you are not using and when you use the other change them around. Just to be sure. The batteries should be fine for a month or more.
  15. DavidFL

    DavidFL Administrator Staff Member

    Bump for Jimbobs in response to

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