Constant current battery chargers
I don't have AGM batteries but could someday due to the horrible location of the battery (soon to be two) on my mini MH. I read some AGM manufacturers' instructions and they say clearly do not use co...
Forum Discussion
AFAIK, the only converter that keeps its Vabs till the batteries are near full is the WFCO. But it is notorious for not being able to get it to start at 14.4 and it stays at 13.6. Some report theirs works ok.
The PD has the Charge Wizard, so you can make it do 14.4 and it should then hold that ok. This makes it a good choice as long as you accept the initial charging rate will be a bit less than the "size" of the converter. (An "80" will do 75, etc.) Over-all, a good compromise for various reasons.
The PowerMax is a really good converter, but it does drop to 13.6 for the absorption stage, so it would not be the fastest. The variable voltage model seems not to have been brought to market, but you must ask Randy at bestconverters about that. (Perhaps it can be special ordered)
Mr Wiz has the WFCO 68100 which should be great although it has 14.4 as Vabs instead of 14.6 like the PowerMax. But at least it stays at 14.4 instead of dropping to 13.6 "too soon".
Iota works well but also drops to 14.2 for the absorption stage.
I find the best results are with the Vector/BD portable chargers but the highest "size" is 40a. You can run several of them at once to get more amps though. They do not do Float, etc, so they cannot substitute for a converter when on shore power.
All the above has to be balanced against your charging intentions while on gen. The SOC the batteries are at when they reach Vabs depends on the charging rate you start out with.
If you start at a 30% rate, you will have the batts to 14.x at about 65% SOC. If you use a 10% rate they will take a long time, but get to 14.x at 90% SOC.
So if you are doing "50-90s" and your batts get to Vabs by 75% SOC at about 20% initial charging rate, then you will do the remaining 75-90 with amps tapering. That is still faster than starting at a lower rate and getting to a higher SOC before amps taper. People forget that little fact :)
You might choose to run 40-80s instead of 50-90s. Now you only spend the last 5% SOC with amps tapering. Much faster, and now your PowerMax drop to 13.6 doesn't matter so much because you don't go past that point on gen very far anyway.
So you have to juggle your priorities and set-up to suit yourself.
Another thing about fast charging is that going higher in starting amps charging rate has diminishing returns. You do not halve your time by doubling the amps. But you get more time reduction going from a 30amper to a 50amper than you do going from a 60amper to an 80amper.
You can spend a lot more money to get 15 minutes less gen time for a 50-90 if you aren't careful.
The gen itself is your limiting factor in many cases, where it takes a certain VA to run that many amps worth of charging. A PF corrected charger lets you do more amps with the same amount of gen VA.
The PD has the Charge Wizard, so you can make it do 14.4 and it should then hold that ok. This makes it a good choice as long as you accept the initial charging rate will be a bit less than the "size" of the converter. (An "80" will do 75, etc.) Over-all, a good compromise for various reasons.
The PowerMax is a really good converter, but it does drop to 13.6 for the absorption stage, so it would not be the fastest. The variable voltage model seems not to have been brought to market, but you must ask Randy at bestconverters about that. (Perhaps it can be special ordered)
Mr Wiz has the WFCO 68100 which should be great although it has 14.4 as Vabs instead of 14.6 like the PowerMax. But at least it stays at 14.4 instead of dropping to 13.6 "too soon".
Iota works well but also drops to 14.2 for the absorption stage.
I find the best results are with the Vector/BD portable chargers but the highest "size" is 40a. You can run several of them at once to get more amps though. They do not do Float, etc, so they cannot substitute for a converter when on shore power.
All the above has to be balanced against your charging intentions while on gen. The SOC the batteries are at when they reach Vabs depends on the charging rate you start out with.
If you start at a 30% rate, you will have the batts to 14.x at about 65% SOC. If you use a 10% rate they will take a long time, but get to 14.x at 90% SOC.
So if you are doing "50-90s" and your batts get to Vabs by 75% SOC at about 20% initial charging rate, then you will do the remaining 75-90 with amps tapering. That is still faster than starting at a lower rate and getting to a higher SOC before amps taper. People forget that little fact :)
You might choose to run 40-80s instead of 50-90s. Now you only spend the last 5% SOC with amps tapering. Much faster, and now your PowerMax drop to 13.6 doesn't matter so much because you don't go past that point on gen very far anyway.
So you have to juggle your priorities and set-up to suit yourself.
Another thing about fast charging is that going higher in starting amps charging rate has diminishing returns. You do not halve your time by doubling the amps. But you get more time reduction going from a 30amper to a 50amper than you do going from a 60amper to an 80amper.
You can spend a lot more money to get 15 minutes less gen time for a 50-90 if you aren't careful.
The gen itself is your limiting factor in many cases, where it takes a certain VA to run that many amps worth of charging. A PF corrected charger lets you do more amps with the same amount of gen VA.
