Cheap Optimate desulphating battery chargers on Ebay

[KevR]

If you've ever fancied an Optimate to keep your batteries happy, have a look at this on that there ebay: 160759873093.
I've never seen them so cheap - main Honda motorcycle dealer shifting surplus stock so they're Honda-branded but exactly the same as Optimate-branded versions. Ideal especially if you've got a car that's not used for extended periods.

[Birotor]

A good price have sent for one.

[KevR]

I sent for two!

[MULLEY]

Do these actually work? I've got a couple of car batteries that are effectively dead, they've been left in my garage as i never got around to throwing them out. I've never tried to get them to work again, would these make them come back to life?

[KevR]

If they're dead completely dead - zero volts - then no, nothing can rescue them as they've probably goy a dead short somewhere. If they're weak because they're sulphated then they may well be recoverable but the longer they've been left, the less chance there is that they'll come back from the dead. Best practice is to keep lead/acid batteries at or near max charge, and occasionally desulphate (which is the clever bit of the Optimate system). Lots of chargers claim to do this, but AFAIK only the Optimate and the CTEK (as sold under the Yamaha brand) actually do it. Optimate invented the process at Honda's request in the 80s – they were getting huge warranty comeback on dead batteries as they were fitted in Japan, sat discharging for months on container ships, then got blast-charged at dealers to get them going, which damaged them even more. They reduced their warranty claims to single figures almost overnight.
I'm still using a battery I bought for my Xantia in 1998 - it's now on the H van and rarely used, but it spends its downtime attached to an Optimate and starts the van every time, even though it takes a good 30s of cranking to get the fuel through to the carb when it's been stood...

I coudl bang on about this all day - maybe tomorrow I will!

[mat_fenwick]

I use one of these for battery maintenance; obviously not as sophisticated at the Optimate/CTEK chargers but will do the basics of keeping a battery charged without overcharging, which is just as bad. For an extra £10 though, I'd get an Optimate at that price.

I could do with something for the van actually; I've dropped hints for Christmas...

[MULLEY]

What about this instead, it's a fair bit cheaper:

http://www.ebay.co.uk/itm/Battery-Desul ... 20cd72a73d" onclick="window.open(this.href);return false;

If i've understood this correctly, you can leave it plumbed in permanantly?

[mat_fenwick]

I'm very sceptical. As I understand it (more information here) sulphation is caused by regularly not charging fully. So by avoiding short trips, and keeping it topped up when not in use, you shouldn't suffer.

I really can't see how a circuit can apply a pulse to the same terminals that it's drawing a current from, with this standalone device.

[MULLEY]

I thought sulfation just occured through use over time, albeit speeded up by non use? The sulfation eventually causes the battery to lose its charge retaining capability?

[mat_fenwick]

It does occur during use; it's just that the discharge period allows the sulphate crystals to grow to a damaging size. At least that's my understanding from what I've read - not something I've seen first hand. The link is very interesting (to me at least ), particularly the comments.

[Birotor]

When I was Engineer Officer of the submarines TALENT and OCELOT during the Cold War my life potentially depended on our multi million pound batteries. There IS NO SUBSTITUTE for regular cycling across the full range of battery voltage and there are specific dangers from excessive discharge and charging rates... but I am prepared to give one of these a go. As Vinny says in the TV advert for first aid "I have one I prepared earlier" a long dead battery in my daughter's Morris Minor 1000 - we shall see......

[KevR]

I asked the guys in the Optimate R+D department about the self-powered unit (plans are available on the interweb to build then for pennies) and they just laughed. If the battery's got enough power in it for the circuit to do anything useful, then it doesn't really need desulphating in the first place ad - just charging it carefully will be enough to bring itt back to 80-90% of capacity, which is all most batteries work at most of the time anyway.
Yes, sulphation happens as a consequence of normal use/discharging. As the battery discharges molecules of lead sulphate form from the sulphuric acid and the lead and fix themselves to the lead plates). This process is reversed by charging, the molecules of lead sulphate recombine into their original forms and the sulphationo disperses. But it's not a complete process, there's always a build-up over time, so even if you do avoid short trips, and try and keep the battery close to full charged, it is still building up. It's made worse by neglect and disuse though, and the Optimate and CTEK chargers use small bursts of higher than usual voltage but very small current to 'tickle' the sulphates off the plates and accelerate the recombining process before then gently charging the battery to full power. If there are significant sulphate deposits on the plates, the danger is that under ths shock of a big current draw (ie starting a cold engine) the deposits will be shaken from the plates and drop down to the bottom causing a dead short in the cell – in whic case your battery is scrap. The other thing that kills batteries is overcharging – not so much extra voltage but too much current. Standard old-fashioned battery chargers that can deliver 4 or 5 amps are terrible for killing batteries over time (especially motorbike batteries, because the pates are much thinner and crammed into a smaller space so they're more vulnerable).
The one in Mat's link is a much better bet than a normal charger – I've got a similar one from Lidl which cost 7.99 euros and it's fine for maintenance charging. I often use an Optimate on a battery to get it desulphated and fully charged and then swap to the Lidl one to keep it happy. I've tested some similar ones though which tend to switch off when the battery's charged, then by the time they're triggered to switch on again, the battery's actually only at about 11-12V, so nowehere near full charge. I've also tested some that have claimed to be 'smart' chargers (the Oxford range of bike chargers in particular) and are actually as thick as a footballer. As Mat says, worth the extra for the real deal, and that price if you extend the life of one battery by 50% (and my experience says you can extend it many, many more times than that) then it's paid for itself.

[KevR]

"I have one I prepared earlier" a long dead battery in my daughter's Morris Minor 1000 - we shall see......

As I said, if it's mechanically dead, it's dead - can't recover from an internal dead short. If it's got some voltage (I think the original Optimates could try and revive something from about 2V, and current ones about 0.5V) then it's a possibility but depends just how bad it is. What also happens is that a build up of flakes from damaged plates in the lower parts of the cells reduces the effective surface area of the plates, so although you can charge back up to a specific voltage and the Optimate (or any other switching charger) will shine a nice green light at you, but it'll only be working to a fraction of its capacity, so it'll power a couple of lights for a while, but will keel over again if you ask it to power a starter motor, for example.

I'm guessing your mega-expensive submarine batteries were designed to be deep-cycle batteries - ie to give as much current as possible before being completely recharged. Car batteries are mostly pretty crudely designed and built, and haven't evolved much since the 19th century. They're a (relatively) cheap and cheerful solution to a simple problem (provide a big cranking current for a short time before being immediately recharged by the alternator). They aren't designed for that sort of duty cycle – they hate being deep-discharged.

[KevR]

Here's another Honda dealer selling the 3+ version for £32 and with cheaper postage than the first link, so a better deal overall.
Ebay no. 281030654678

[mat_fenwick]

Are you on commission Kev?

Do you think an Optimate would work on this?


It might be in need of a top-up first though...