[Farkyard]

I fear being told this is obvious here but I am man enough to take the ridicule. I was given an Ark Powerpack for Xmas and yesterday managed to snag a 120ah deep cycle battery for it. The box has a built in smart charger that I think inputs 1.3amp. I have another 1.25amp smart charger left over that I used to hook up to a road bike. My question is would hooking them both up at the same time charge twice as fast, cancel each other out, catch stuff on fire etc? The ark pack from my calcs will take around three to four days to get the battery up to full charge.

[fordem]

I'd say go for it - they should both charge in the initial charge phase when the battery voltage is low, but they may interact with one another as the battery approaches full charge.

[royce]

AGM have a specific charge profile, if thats what your battery is piss off both chargers and get ctek thats big enough for it.

[murcod]

Yes, buy a larger charger! Don't play around with two small chargers in parallel - smart chargers usually have different charging stages depending on the battery voltage. Every model has a different number of stages and charging profiles - who knows what they will try and do in parallel?

PS: there are plenty of options out there apart from Ctek. I've got two dead ones sitting at home that friends have thrown out - I've never owned one as I can't see the value in them. Go for something at least 10 Amps RMS or larger.

[shep]

You will need at least a 10amp charger to properly charge a 120amp battery. I have a 150amp deep cycle battery in my boat that I charge with one of these http://www.4wdbits.co.nz/ProductDetails ... uctID=1236 the battery is 4 years old and still performs like new.

[Mike57]

Just curious why a 10 amp charger is needed for a 120 amp hour battery. Wouldn't a 5 amp charger do the same job but just take twice as long?

[fordem]

^^ 100% correct.

[Rhinoman]

If its a lead acid battery then they should usually be charged at less than 10% of the Ah rating. As long as the charge rate is higher than the natural rate of discharge then it will eventually charge up. I think the low charge rate on the internal charger is to keep it cheap, I have a boost starter unit that also has a low rate of charge but it can be charged faster using an external charger if required.

[royce]

Mike57 wrote:

Just curious why a 10 amp charger is needed for a 120 amp hour battery. Wouldn't a 5 amp charger do the same job but just take twice as long?

Every battery has a minimum and maximum charging current, outside of this you aren't charging as fully and it probably wont last as long.

Though my Ctek isnt strictly big enough for my AGM but its usually charged via alternator and its just used as a float charger on it

[Mike57]

Thanks Royce. I have a 5 amp CTEK that I use to top up my two low capacity AGMs in the car. (I have 2 x Optima D51 yellow tops that are 41 Ah capacity as main/secondary setup). I have not changed the charging voltage in the car so they do not get the 14.6 volts or so that they need to keep them fully charged so every few weeks I hook up the CTEK to top them up. I guess in that situation the 5 amp charger will be OK and also given that they are relatively low capacity.

[Jezza86]

i have a bluetop in my boat, the big ass 900CCA 75AH one. i run a 22A alternator on my 60hp honda. i only ever see 13.8 come out of that regulated circuit and haven't changed the regulator.
it is always 100% full and my mates float charger refuses so charge it. one of those ctek ones, it switches straight to float mode, even after a big day and multiple engine starts. i find that the engines 13.7-13.8 volts and 22 A are enough to recharge it after starting up with a minute or 2 on the throttle. i use a gel cell up front which is on a manual switch i flick to charge and flick it off before i turn the engine off. gel powers lights, instruments cdplayer and VHF so never need to draw on the AH of the AGM starting battery