Looking for some input from those who know more about batteries/charging than me.

I am running with a 48V 20Ah SLA battery pack. I own 2 chargers..one (I think it is 2.5 or 3 amps), I keep in my garage and use it everytime I come home from a ride. The other is a 2 amp charger, a bit smaller physically and I carry this one with me on the bike..although it is seldom used (I check it out once in a while at home to make sure it is still good).

My question: Would putting these 2 in parallel (generating perhaps 5 amps) be a good idea if I was in a hurry for a recharge? Is there any downside to doing this? I know they both are 3-stage chargers and the voltage put out with no load is about 57.5 volts for each of them.

Thanks for any input.

From here:
http://en.wikipedia.o...

On board EV chargers (change AC power to DC power to recharge the EV's pack) can be:
Isolated: they make no physical connection between the A/C electrical mains and the batteries being charged. These typically employ some form of Inductive charging. Some isolated chargers may be used in parallel. This allows for an increased charge current and reduced charging times. The battery has a maximum current rating that cannot be exceeded
Non-isolated: the battery charger has a direct electrical connection to the A/C outlet's wiring. Non-isolated chargers cannot be using in parallel.

And here:
http://www.diyelectri...

> Dave Delman wrote:
> Are all/most commercial EV Battery Chargers isolated? If so do the
> use a big isolation transformer or is there another method?

Some are isolated (Lester, Bycan, Zivan, etc.) and some are not (K&W,
PFC, Russco, etc.) You have to read the specs to see.

If it is isolated, there is always a transformer. It may be a big heavy
60 Hz transformer, or a smaller high-frequency switchmode transformer.

That reply in the second quote is from Lee Hart who is a real leading light in the EV community. Extremely knowledgeable guy! His message is from late 2007 but I don't believe charger tech has advanced any since then.

So ya either need to get confirmation from the charger manufacturer that the chargers are isolated, or ya have to pop their lids and see if there are the necessary transformers...

You are also tapping about watt are likely slightly dissimilar chargers, and whether this might cause some sort of dancing around while charging or at end of charge I do not know...

Even two "identical" chargers will likely be *slightly* different, but using banks of "identical" 12V chargers, one for each 12V battery in a large pack - 96V or higher - is a not unheard of scheme to keep each 12V batt "in balance" rather than utilizing one large charger plus some sort of added balancing or "battery management" electronics. When folks do this - switch on one charger connected to each 12V batt in a pack - they do not disconnect the regular wiring joining the batts in series. This is not necessary.

IF the chargers ARE isolated than yes, I believe you could connect their outputs in parallel to increase Amps into the pack. Just make up a Y-connector to plug into the charging port with two plug-ins, one for each charger...

Caveat - all this only my understanding! I have never paralleled chargers myself! But I believe others do.
Lock