Hi, I wanted to ask some specific questions as I am trying to decide what charger to buy before a sale on Victron chargers ends here in my country a little later tonight. I couldn’t find the answers, so I found this place and signed up to ask here instead.
I was looking at the Victron IP65 Blue Smart 15A charger, but wasn’t sure if it’d be suitable for my uses. I’d prefer the 15A due to the versatility of being able to use it if I upgrade cars in the future, but that is not a deal breaker.
Current car batteries I’d be charging are 550CCA/55Ah and 650CCA/64Ah lead acid batteries. I see the charger has a low current mode of 4A, so I know it would be fine on that mode, but is it also OK to charge either of those batteries at the full 15A? I assume you can use either 4A low current mode or 15A regular charging mode?
I also wanted to ask, is it possible to charge 12V 7Ah AGM lead acid batteries with the 15A charger on low current mode? I have some of these batteries that I wanted to charge that are between 7Ah and 9Ah. Here is an example of one of them https://www.centurybatteries.com.au/products/ps1270s
Other model brand chargers such as CTEK or NOCO say you can charge as low as 1.2 or 2Ah batteries, but not sure if you can with the Victron 15A, or if I would have to get a smaller Victron charger for that. I would prefer to get the 15A, but just curious what you guys say? Even if the Victron is not rated for batteries that low, can you still try on the low current mode? Would it cause any issues to the charger or battery if trying to do so?
Yes, the very small AGM batteries can be charged at the 4A level, you may also be able to reduce this using Victron connect, but not certain of that.
generally for AGM you would want to charge between c/10 and c/2 rate, but anything up to 1c for half an hour should be ok. only issue for an AGM battery charged at too high a rate is that it can ‘dry’ the electrolyte at the plates due to rapid gassing and heating.
Hi Mike, Thanks. I will try and take a look at the settings with Victron connect when I do order one, thanks
In regard to the AGM (are you just talking AGM batteries in general or just for the small ones I wanted to try charging?), when you say c/10 and c/2, do you mean current between 10A and 2A? If not, are you able to tell me what c/10 and c/2 means and 1c means(if it’s easy to explain?)?
Also, hopefully you can understand this next question I’m asking - how can you figure out the max amperage a battery should be charged at to not cause damage? For example Sealed Lead Acid, AGM and the other different variants of lead acid batteries, and Lithium too, is there a way you can work out via the Ah what the max safe current it should be charged at? Is it specific to each battery type, or does the brand/company that make whatever battery have their own guidelines on what the max amperage/voltage you can charge their batteries at are? Is there a way to work it out mathematically?
I also assume most of these smart chargers (like Victron), they charge at full amperage during the bulk phase and drop down the amperage once it gets to about 80%. If I am understanding that correctly, does it just come down to heat during the bulk charging phase and not so much what amperage you use to get through the bulk charge phase?
And how would you guys compare the Victron to other brands suck as NOCO, CTEK etc?
Victron is my first choice, but just curious how Victron compares to those other brands. I was looking at NOCO as my second choice.
I’m also going to buy the M8 eyelets to connect to my car battery as it seems I don’t do enough driving, so I think I’d ave to regularly charge the battery every 1-2 weeks. I was going to get the set with the 3 light voltage indicator (not sure how accurate this one is).
C is the capacity of the battery in Ah.(normally specified at the 20 hour rate, this varies greatly with the rate of discharge).
So if you have a 7Ah battery, C/10 is 0.7A, and c/2 is 3.5A.
The maximum charge rate of a sealed lead acid battery depends on the rate that the battery can re-combine the oxygen and hydrogen gas produced by the charging process. {full chemistry is available on line}. Faster charging leads to increased pressure within the battery. Whilst this does speed up the recombination process, there are limits, and these batteries are provided with safety vents. The maximum rate should be specified by the manufacturer, but sometimes this data is difficult or impossible to find. C/10 is regarded as universally safe, and results in a full charge. Charging at c/2 will not result in a 100% charge, but close to it.
Victrons charge profile is voltage controlled, it will charge at full current till say 13.8V, hold that until the current drops to e.g <1A, then drop back to 13.2V for float charge. (numbers are arbitrary and used for example only). So by reducing the Absorption voltage and time, it is possible to safely charge a smaller battery with a higher initial current than c/10. Hazard is as much due to internal pressure from gas formation as heat.