Club 80-90 Forums

I have a pair of Trojans T105, (what great batterys they are), which I use in my T25 van on a series connection (doubling the voltage).

I have a question about recharging them.

I’ve had them 3 years now, but only ever had to charge them once, as they rarely go down too low. Last time about 18 months ago, I charged them each separately on my Troinc 3 stage charger on the 6V setting. However this took about 6/7 days for each battery to charge, as the output charge on the 6V is quite low.

I am going away next weekend & haven’t got the time to charge them both separately as 6V. I’m thinking of speeding the process up by charging them on the Tronic 12v setting both indoors at the same time the 12V series connection. It’s the same set up in my T25, which they accept charge from the split relay. Though can appreciate both battery may not get pure concentrated charge, as they sharing the charge.

Just wanted to know is charging them separately 6V each more better for them, or is sharing them 12V make no difference in the standard of charge they receive

It is unwise to store any battery type in a discharged/part discharged state if you want to keep them working at their best. I certainly wouldn't leave one part discharged for 18 months.
The only problem with charging them together is if one is ailing making them mismatched but if you are happy that they are identical charge wise charge them at 12v with them connected as they are in the van.

It is an interesting question given that each battery is already 3 seperate batteries internally connected in series to achieve the quoted 6 volts ( I guess 6.3 volts fully charged?)
So....given that a 12 volt battery is actually 6 identical cells, each individually rated at around 2.1 volts internally connected to achieve about 12.6 volts nominal (depending on battery chemistry and the active meterials used).

The only difference being, your two identical Trojans would be extenally connected when charging as one '12volt' battery.

The thing to remember here is both batteries need to be the same age and be at the same level of charge ie: both 25% .....and you need to know they are both good...as in, all electroyte hydrometer readings are to all intense and purposes, equal. Then charging the two batteries as one 12 volt battery is just the same as charging one traditional 12 volt battery.

The only issue would be when one battery is suspect, faulty or much more discharged than the other (one 10% charged whilst the other is 50% charged)
However, smart charges can 'equalise' cells to some extent although this is not ideal.
Martin

The batteries are the same age as purchased together. The voltage is roughly the same. They accept charge OK from the split relay. Though to get them to max after being run down a bit .I like to place them on external charge.

Though at the moment they only down to 60%. These batteries can take a good battering.

Sorted.....charge connected together.

If you visit the Trojan website there is quite a bit of info on charging.
My understanding has always been that the ideal bulk charge rate was somewhere around 10% of the amp hour rating of the battery....but that would require a 20amp charger for a Trojan.
This means that even the most powerful of domestic chargers (say 12amps) is still only a low charge as far as this battery is concerned.
It would drive me mad using one of those puny smart charges (3amps) and having to wait 5 - 7 days to fully charge.

The ideal I would think is something like: bulk charging to about 75% (15 - 20 amps on this battery), trickle charge to full (4 - 10 amps) then switch to a standing float charge to keep the cells active. However, unless you own some very expensive professional charging equipment, this just isn't possible.

Martin

i have this in my van http://www.outdoorgb.com/p/CTEK-MXS2500 ... dle=168379" onclick="window.open(this.href);return false;
25 amps and intelligent, so will look after your batteries. I didn't get mine from the above link, but the price was the same. It's a good charger and also works as a powerpack. Overkill for most T3 set ups, but was ideal for me and looks good for you.

Nice charger.....

You get paid too much..
Martin

or just a trigger finger on ebay

nesty wrote:The batteries are the same age as purchased together. The voltage is roughly the same. They accept charge OK from the split relay. Though to get them to max after being run down a bit .I like to place them on external charge.

Though at the moment they only down to 60%. These batteries can take a good battering.

What is the furthest you have taken them down?

I went to a festival at the weekend. When I left home on Thursday afternoon they were 90% charged. I ran a fridge until Sunday night, which took the charge down to 40%. 2 Hour drive home brought them back up to 70%.

Lowest 40% I ton them down to. That only as my split relay ceased working on my long Wales trip. Normally they get runaround charge put back into.

That not bad considering you ran a fridge for a weekend!